High-toughness flame-retardant smoke-suppressing benzoxazine composition, cured product and method of making and use thereof

Abstract

This invention discloses a high-toughness, flame-retardant, and smoke-suppressing benzoxazine composition, its cured product, its preparation method, and its applications. The benzoxazine composition comprises: daidzein-based benzoxazine resin and a low-curing-temperature benzoxazine resin; wherein the curing temperature of the daidzein-based benzoxazine resin is lower than that of the low-curing-temperature benzoxazine resin. This invention employs polymerization-induced phase separation technology, using two benzoxazine resins with different curing activities and properties to obtain a benzoxazine cured product with in-situ toughening effect and flame-retardant and smoke-suppressing capabilities. The process is simple, and the product exhibits excellent overall performance, making it promising for applications in electronic packaging, aerospace, and composite materials.

Description

Technical Field

[0001] This invention belongs to the field of benzoxazine material technology, specifically relating to a high-toughness, flame-retardant, and smoke-suppressing benzoxazine composition, its cured product, its preparation method, and its application. Background Technology

[0002] In recent years, benzoxazine resins have attracted much attention as a new type of high-performance thermosetting resin. Benzoxazine resins possess characteristics such as small free volume, strong molecular chain interactions, and strong intermolecular packing, resulting in good thermodynamic and chemical properties. However, the prevalent presence of intermolecular and intramolecular hydrogen bonds hinders network formation, leading to drawbacks such as high brittleness, poor fracture toughness, and low crosslinking degree. Furthermore, commercially available cured benzoxazine resins typically exhibit low intrinsic flame retardancy and smoke suppression properties, thus limiting their application in many fields.

[0003] To address the toughness issue in materials, a common approach is to add additional toughening agents. For example, patent CN109354823A discloses a high-temperature resistant hot-melt benzoxazine resin and its preparation method, which uses second phases such as rubber elastomers, thermoplastic resins, and thermosetting resins as toughening agents. Patent CN113583276A discloses a benzoxazine toughening modification method, which modifies polybenzoxazine with a polyhexahydrotriazine structure to form a toughening crosslinking network. However, the introduced second-phase components or structures often have high flammability, resulting in poor flame retardancy of the modified material. Therefore, how to simultaneously improve toughness and flame retardancy is one of the technical problems that urgently needs to be solved in this field. Summary of the Invention

[0004] The main objective of this invention is to provide a highly tough, flame-retardant, and smoke-suppressing benzoxazine composition, its cured product, its preparation method, and its application, in order to overcome the shortcomings of the prior art.

[0005] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0006] This invention provides a high-toughness, flame-retardant, and smoke-suppressing benzoxazine composition, comprising: daidzein-based benzoxazine resin and low-curing-temperature benzoxazine resin; wherein the curing temperature of the daidzein-based benzoxazine resin is lower than the curing temperature of the low-curing-temperature benzoxazine resin.

[0007] This invention also provides a high-toughness, flame-retardant, and smoke-suppressing benzoxazine cured product. The benzoxazine cured product is formed by curing the aforementioned high-toughness, flame-retardant, and smoke-suppressing benzoxazine composition. The benzoxazine cured product has an "island" structure. Daidzein-based benzoxazine resin is cured to form a continuous phase, and low-curing-temperature benzoxazine resin is cured to form a dispersed phase. At the same time, a copolymer of daidzein-based benzoxazine resin and low-curing-temperature benzoxazine resin is formed at the interface between the continuous phase and the dispersed phase.

[0008] This invention also provides a method for preparing the aforementioned high-toughness, flame-retardant, and smoke-suppressing benzoxazine cured product, comprising:

[0009] Provided the aforementioned high-toughness, flame-retardant, and smoke-suppressing benzoxazine composition;

[0010] Furthermore, the soybean aglycone benzoxazine resin is mixed with a low-curing-temperature benzoxazine resin and subjected to a stepped-heat curing treatment to obtain a high-toughness, flame-retardant, and smoke-suppressing benzoxazine cured product.

[0011] The embodiments of the present invention also provide the application of the aforementioned high-toughness, flame-retardant, and smoke-suppressing benzoxazine cured products as high-performance resin matrices or structural materials in the fields of electronic packaging, aerospace, or composite materials.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] (1) The preparation method provided by the present invention is simple and the process control is stable;

[0014] (2) The high-toughness, flame-retardant, and smoke-suppressing benzoxazine cured product provided by the present invention has the advantages of being halogen-free, flame-retardant, and environmentally friendly;

[0015] (3) The high-toughness flame-retardant and smoke-suppressing benzoxazine cured product provided by the present invention has both flame-retardant and smoke-suppressing properties and mechanical properties. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a bar chart showing the impact strength and limiting oxygen index of the combined cured product and the pure component cured product in Example 1;

[0018] Figure 2 The 1H NMR spectrum of the daidzein benzoxazine prepared in Example 1 is shown. 1 H-NMR spectrum. Detailed Implementation

[0019] In view of the deficiencies of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. It mainly utilizes the principle of polymerization-induced phase separation, using daidzein benzoxazine with a low curing temperature as the continuous phase and commercially available benzoxazine with a high curing temperature as the dispersed phase. By controlling the curing reaction in the blending system, nanoclusters with toughening and smoke-suppressing effects are formed. At the same time, daidzein benzoxazine itself has good flame retardancy and charring properties, giving the resulting cured product excellent toughness and flame retardancy and smoke suppression properties.

[0020] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Specifically, as one aspect of the technical solution of the present invention, a high-toughness, flame-retardant, and smoke-suppressing benzoxazine composition includes: daidzein-based benzoxazine resin and low-curing-temperature benzoxazine resin; wherein the curing temperature of the daidzein-based benzoxazine resin is lower than the curing temperature of the low-curing-temperature benzoxazine resin.

[0022] In some preferred embodiments, the curing temperature of the daidzein benzoxazine resin is 150~200℃.

[0023] In some preferred embodiments, the curing temperature of the low-curing-temperature benzoxazine resin is 200~300°C.

[0024] In some preferred embodiments, the low-curing-temperature benzoxazine resin is a commercially available benzoxazine resin.

[0025] In some preferred embodiments, the mass ratio of the daidzein benzoxazine resin to the low-curing-temperature benzoxazine resin is 40-80:1-30.

[0026] In some preferred embodiments, the method for preparing the daidzein benzoxazine resin includes: subjecting a mixed reaction system containing at least an amine compound, an aldehyde compound, daidzein, and a solvent to a Mannich reaction to obtain the daidzein benzoxazine resin.

[0027] Furthermore, the amine compound has the structural formula R1-NH2; wherein R1 is selected from alkyl, alkyl-substituted, phenyl, or phenyl-substituted compounds having 1 to 20 carbon atoms.

[0028] Furthermore, the aldehyde compound has the structural formula R2-CHO; wherein R2 is selected from alkyl, alkyl-substituted, phenyl, or phenyl-substituted compounds having 1 to 20 carbon atoms.

[0029] Furthermore, the molar ratio of the daidzein, amine compound, and aldehyde compound is 1:1:1 to 1:6:6;

[0030] Furthermore, the solvent includes any one or more combinations of toluene, xylene, 1,4-dioxane, ethanol, tetrahydrofuran, chloroform, dichloromethane, N,N-dimethylformamide, and dimethyl sulfoxide, and is not limited thereto.

[0031] Furthermore, the Mannich reaction is carried out at a temperature of 60-150°C for a duration of 6-24 hours.

[0032] Furthermore, the preparation method of the daidzein benzoxazine resin further includes: after the Mannich reaction is completed, adding deionized water to the obtained reaction solution, and then filtering, washing and drying to obtain the daidzein benzoxazine resin.

[0033] In some preferred embodiments, the low-curing-temperature benzoxazine resin includes any one or more combinations of monofunctional benzoxazine, bisphenol benzoxazine, diamine benzoxazine, and polyfunctional benzoxazine, and is not limited thereto.

[0034] For example, the structural formulas of phenol / aniline type benzoxazine, bisphenol A / aniline type benzoxazine, and phenol / 4,4'-diaminodiphenylmethane type benzoxazine are shown below:

[0035] .

[0036] Another aspect of the present invention provides a high-toughness, flame-retardant, and smoke-suppressing benzoxazine cured product, wherein the benzoxazine cured product is formed by curing the aforementioned high-toughness, flame-retardant, and smoke-suppressing benzoxazine composition, the benzoxazine cured product has an "island" structure, wherein daidzein-based benzoxazine resin is cured to form a continuous phase, and low-curing-temperature benzoxazine resin is cured to form a dispersed phase, and a copolymer of daidzein-based benzoxazine resin and low-curing-temperature benzoxazine resin is formed at the interface between the continuous phase and the dispersed phase.

[0037] Furthermore, the benzoxazine cured product has the structures shown in formulas (I), (II), and (III):

[0038] ;

[0039] Wherein, R3 is selected from alkyl, alkyl-substituted, phenyl or phenyl-substituted compounds with 1 to 20 carbon atoms, and R4 and R5 are independently selected from hydrogen atoms, alkyl, alkyl-substituted compounds with 1 to 20 carbon atoms, phenyl or phenyl-substituted compounds; m, n, l are independently 1 to 100; X is derived from the main part of the low curing temperature benzoxazine resin, and the structure of formula (III) is a copolymer formed by soybean aglycone benzoxazine resin and low curing temperature benzoxazine resin.

[0040] In some preferred embodiments, the low-curing-temperature benzoxazine resin includes any one or more combinations of monofunctional benzoxazine, bisphenol benzoxazine, diamine benzoxazine, and polyfunctional benzoxazine, and is not limited thereto.

[0041] For example, the structural formulas of phenol / aniline type benzoxazine, bisphenol A / aniline type benzoxazine, and phenol / 4,4'-diaminodiphenylmethane type benzoxazine are shown below:

[0042] .

[0043] In some preferred embodiments, the benzoxazine cured product has an "island" structure, wherein the daidzein-based benzoxazine resin is cured to form a continuous phase, and the benzoxazine resin is cured at a low curing temperature to form a dispersed phase.

[0044] Another aspect of the present invention provides a method for preparing the aforementioned high-toughness, flame-retardant, and smoke-suppressing benzoxazine cured product, comprising:

[0045] Provided the aforementioned high-toughness, flame-retardant, and smoke-suppressing benzoxazine composition;

[0046] Furthermore, the soybean aglycone benzoxazine resin is mixed with a low-curing-temperature benzoxazine resin and subjected to a stepped-heat curing treatment to obtain a high-toughness, flame-retardant, and smoke-suppressing benzoxazine cured product.

[0047] In some preferred embodiments, the step-temperature curing process includes: sequentially holding at 100~160℃ for 1~5h, 160~170℃ for 1~5h, 170~180℃ for 1~5h, 180~200℃ for 1~5h, and 200~220℃ for 1~5h.

[0048] This invention employs polymerization-induced phase separation technology to obtain benzoxazine cured products with in-situ toughening effect and flame retardant and smoke suppression ability by using two benzoxazine resins with different curing activities and properties. The operation is simple and the overall performance is excellent, and it is expected to be applied in fields such as electronic packaging, aerospace, and composite materials.

[0049] This invention is based on polymerization-induced phase separation technology, using a low-curing-temperature soybean aglycone benzoxazine resin as the continuous phase and a high-curing-temperature low-curing-temperature benzoxazine resin as the dispersed phase. The resulting cured product has high toughness, flame retardancy and smoke suppression properties, and can be used as a high-performance resin matrix or structural material in fields such as electronic packaging, aerospace, and composite materials.

[0050] Another aspect of the present invention provides the application of the aforementioned high-toughness, flame-retardant, and smoke-suppressing benzoxazine cured products as high-performance resin matrices or structural materials in the fields of electronic packaging, aerospace, or composite materials.

[0051] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0052] The daidzein benzoxazine used in the embodiments and comparative examples of this invention was prepared in-house, while other raw materials were purchased from the market.

[0053] In the examples and comparative examples, the toughness of the specimens was tested using a V-notch impact test with a Zwick / Roell Z030 instrument according to the GB / T 2567-2021 standard for mechanical property testing. Six sets of tests were performed on each specimen, and the average value was taken.

[0054] In the examples and comparative examples, the glass transition temperature of the samples was tested according to the ISO 6721-11 standard and using a dynamic thermomechanical analyzer (TA DMAQ800).

[0055] Example 1:

[0056] (1) Synthesis of daidzein benzoxazine: Furfurylamine (20 mmol, 1.942 g), paraformaldehyde (40 mmol, 1.2 g), and daidzein (10 mmol, 2.542 g) were mixed in 50 mL of 1,4-dioxane and heated under reflux at 90 °C for 24 hours (with magnetic stirring). After the reaction was complete, the mixture was cooled to room temperature and poured into a beaker containing 200 mL of deionized water, yielding a pale yellow precipitate. After filtration, the product was washed three times with deionized water and dried at 60 °C to obtain daidzein benzoxazine. (1H NMR spectrum) 1 H-NMR spectrum as shown Figure 2 As shown.

[0057]

[0058] (2) Preparation of benzoxazine cured product: 70 parts of daidzein benzoxazine and 30 parts of phenol / 4,4'-diaminodiphenylmethane benzoxazine were weighed. Daidzein benzoxazine was first dissolved in tetrahydrofuran, and most of the solvent was evaporated at room temperature. Then, phenol / 4,4'-diaminodiphenylmethane benzoxazine was added to the liquid daidzein benzoxazine. The mixture was stirred evenly using mechanical stirring and ultrasonic dispersion to obtain a stable mixed system of daidzein benzoxazine and phenol / 4,4'-diaminodiphenylmethane benzoxazine. The mixture was injected into a mold for curing. The curing procedure was as follows: 155℃ for 2 hours, 165℃ for 2 hours, 175℃ for 1 hour, 185℃ for 1 hour, and 205℃ for 1 hour.

[0059] The glass transition temperature of the benzoxazine cured product obtained in this embodiment is 331℃, and the impact strength is 71.66 kJ / m. 2 The limiting oxygen index is 37.8%, the UL-94 rating is V-0, and the total smoke emission is 2.1 MJ / m³. 2 The test data is summarized in Table 1.

[0060] Figure 1 This is a bar chart showing the impact strength and limiting oxygen index of the combined cured product and the pure component cured product in Example 1.

[0061] Example 2:

[0062] (1) Synthesis of daidzein benzoxazine: Same as in Example 1.

[0063] (2) Preparation of benzoxazine cured product: 80 parts of daidzein benzoxazine and 20 parts of phenol / 4,4'-diaminodiphenylmethane benzoxazine were weighed. Daidzein benzoxazine was first dissolved in tetrahydrofuran, and most of the solvent was evaporated at room temperature. Then, phenol / 4,4'-diaminodiphenylmethane benzoxazine was added to the liquid daidzein benzoxazine. The mixture was stirred evenly using mechanical stirring and ultrasonic dispersion to obtain a stable mixed system of daidzein benzoxazine and phenol / 4,4'-diaminodiphenylmethane benzoxazine. The mixture was injected into a stainless steel mold for curing. The curing procedure was as follows: 155℃ for 2 hours, 165℃ for 2 hours, 175℃ for 1 hour, 185℃ for 1 hour, and 205℃ for 1 hour.

[0064] The benzoxazine cured product obtained in this embodiment has a glass transition temperature of 333℃ and an impact strength of 69.21 kJ / m. 2 The limiting oxygen index is 37.6%, the UL-94 rating is V-0, and the total smoke emission is 4.3 MJ / m³. 2 The test data is summarized in Table 1.

[0065] Example 3:

[0066] (1) Synthesis of daidzein benzoxazine: Same as in Example 1.

[0067] (2) Preparation of benzoxazine cured product: Weigh 40 parts of daidzein benzoxazine and 30 parts of phenol / 4,4'-diaminodiphenylmethane benzoxazine. First, dissolve daidzein benzoxazine in tetrahydrofuran and evaporate most of the solvent at room temperature. Then, add phenol / 4,4'-diaminodiphenylmethane benzoxazine to the liquid daidzein benzoxazine and stir evenly using mechanical stirring and ultrasonic dispersion to obtain a stable mixed system of daidzein benzoxazine and phenol / 4,4'-diaminodiphenylmethane benzoxazine. Pour the mixture into a stainless steel mold for curing. The curing procedure is as follows: keep at 155℃ for 2 hours, keep at 165℃ for 2 hours, keep at 175℃ for 1 hour, keep at 185℃ for 1 hour, and keep at 205℃ for 1 hour.

[0068] The glass transition temperature of the benzoxazine cured product obtained in this embodiment is 313℃, and the impact strength is 67.43 kJ / m. 2 The limiting oxygen index is 35.6%, the UL-94 rating is V-0, and the total smoke emission is 8.2 MJ / m³. 2 The test data is summarized in Table 1.

[0069] Example 4:

[0070] (1) Synthesis of daidzein benzoxazine: Same as in Example 1.

[0071] (2) Preparation of benzoxazine cured product: 70 parts of daidzein benzoxazine and 30 parts of phenol / 4,4'-diaminodiphenylmethane benzoxazine were weighed. Daidzein benzoxazine was first dissolved in tetrahydrofuran, and most of the solvent was evaporated at room temperature. Then, phenol / 4,4'-diaminodiphenylmethane benzoxazine was added to the liquid daidzein benzoxazine. The mixture was stirred evenly using mechanical stirring and ultrasonic dispersion to obtain a stable mixed system of daidzein benzoxazine and phenol / 4,4'-diaminodiphenylmethane benzoxazine. The mixture was injected into a stainless steel mold for curing. The curing procedure was: 150℃ for 2 hours, 160℃ for 2 hours, 170℃ for 2 hours, 180℃ for 2 hours, and 200℃ for 2 hours.

[0072] The glass transition temperature of the benzoxazine cured product obtained in this embodiment is 334℃, and the impact strength is 65.43 kJ / m. 2 The limiting oxygen index was 37.4%, the UL-94 rating was V-0, and the total smoke release was 4.6 MJ / m³. 2 The test data is summarized in Table 1.

[0073] Example 5:

[0074] (1) Synthesis of daidzein benzoxazine: Same as in Example 1.

[0075] (2) Preparation of benzoxazine cured product: 70 parts of daidzein benzoxazine and 30 parts of bisphenol A / aniline benzoxazine were weighed. Daidzein benzoxazine was first dissolved in tetrahydrofuran, and most of the solvent was evaporated at room temperature. Then, bisphenol A / aniline benzoxazine was added to the liquid daidzein benzoxazine and stirred evenly using mechanical stirring and ultrasonic dispersion to obtain a stable mixed system of daidzein benzoxazine and bisphenol A / aniline benzoxazine. The mixture was injected into a stainless steel mold for curing. The curing program was: 155℃ / 2 hours, 165℃ / 2 hours, 175℃ / 1 hour, 185℃ / hour, 205℃ / 1 hour.

[0076] The glass transition temperature of the benzoxazine cured product obtained in this embodiment is 302℃, and the impact strength is 66.72 kJ / m. 2 The limiting oxygen index was 36.6%, the UL-94 rating was V-0, and the total smoke emission was 6.9 MJ / m³. 2 The test data is summarized in Table 1.

[0077] Example 6:

[0078] (1) Synthesis of daidzein benzo[a]azine: Aniline (20 mmol, 1.862 g), paraformaldehyde (20 mmol, 1.2 g), and daidzein (10 mmol, 2.542 g) were mixed in 50 mL of 1,4-dioxane and heated under reflux at 90 °C for 24 hours (with magnetic stirring). After the reaction was complete, the mixture was cooled at room temperature and poured into a beaker containing 200 mL of deionized water, yielding a pale yellow precipitate. The product was filtered, washed three times with deionized water, and dried at 60 °C to obtain daidzein benzo[a]azine.

[0079]

[0080] (2) Preparation of benzoxazine cured product: Same as in Example 1.

[0081] The glass transition temperature of the benzoxazine cured product obtained in this embodiment is 352℃, and the impact strength is 68.86 kJ / m. 2 The limiting oxygen index was 37.2%, the UL-94 rating was V-0, and the total smoke emission was 4.9 MJ / m³. 2 The test data is summarized in Table 1.

[0082] Example 7:

[0083] Synthesis of daidzein benzo[a]azine: Butylamine (20 mmol, 1.462 g), paraformaldehyde (20 mmol, 1.2 g), and daidzein (10 mmol, 2.542 g) were mixed in 50 mL of 1,4-dioxane and heated under reflux at 90 °C for 24 hours (with magnetic stirring). After the reaction was complete, the mixture was cooled to room temperature and poured into a beaker containing 200 mL of deionized water, yielding a pale yellow precipitate. The product was filtered, washed three times with deionized water, and dried at 60 °C to obtain daidzein benzo[a]azine.

[0084]

[0085] (2) Preparation of benzoxazine cured product: Same as in Example 1.

[0086] The benzoxazine cured product obtained in this embodiment has a glass transition temperature of 317℃ and an impact strength of 64.43 kJ / m. 2 The limiting oxygen index is 35.4%, the UL-94 rating is V-1, and the total smoke emission is 9.9 MJ / m³. 2 The test data is summarized in Table 1.

[0087] Comparative Example 1:

[0088] The difference between this comparative example and Example 1 is that no commercially available benzoxazine with a high curing temperature is added, while other operations remain unchanged.

[0089] The glass transition temperature of the benzoxazine cured product obtained in this comparative example was 391℃, and the impact strength was 45.71 kJ / m. 2 The limiting oxygen index is 30.2%, the UL-94 rating is V-1, and the total smoke emission is 12.7 MJ / m³. 2 The test data is summarized in Table 1.

[0090] Comparative Example 2:

[0091] The difference between this comparative example and Example 1 is that the 30 parts of phenol / 4,4'-diaminodiphenylmethane benzoxazine in Example 1 were replaced with an equivalent amount of polyetherimide, while other operations remained unchanged.

[0092] The glass transition temperature of the benzoxazine cured product obtained in this comparative example was 273℃, and the impact strength was 53.93 kJ / m. 2 The limiting oxygen index is 30.4%, the UL-94 rating is V-1, and the total smoke emission is 15.9 MJ / m³. 2 The test data is summarized in Table 1.

[0093] Comparative Example 3:

[0094] The difference between this comparative example and Example 1 is that the 30 parts of phenol / 4,4'-diaminodiphenylmethane benzoxazine in Example 1 were replaced with an equivalent amount of carbon nanotubes, while other operations remained unchanged.

[0095] The glass transition temperature of the benzoxazine cured product obtained in this comparative example was 383℃, and the impact strength was 52.16 kJ / m. 2 The limiting oxygen index is 30.6%, the UL-94 rating is V-1, and the total smoke emission is 12.1 MJ / m³. 2 The test data is summarized in Table 1.

[0096] Comparative Example 4:

[0097] The difference between this comparative example and Example 1 is that no daidzein benzoxazine is added, while other operations remain unchanged.

[0098] The glass transition temperature of the benzoxazine cured product obtained in this comparative example was 225℃, and the impact strength was 58.02 kJ / m. 2 The limiting oxygen index is 28.2%, the UL-94 rating is V-2, and the total smoke emission is 18.6 MJ / m³. 2 The test data is summarized in Table 1.

[0099] Comparative Example 5:

[0100] The difference between this comparative example and Example 1 is that: 30 parts of daidzein benzoxazine and 30 parts of phenol / 4,4'-diaminodiphenylmethane benzoxazine were used, while other operations remained unchanged.

[0101] The glass transition temperature of the benzoxazine cured product obtained in this comparative example was 315℃, and the impact strength was 61.76 kJ / m. 2 The limiting oxygen index is 32.6%, the UL-94 rating is V-2, and the total smoke emission is 17.5 MJ / m³. 2 The test data is summarized in Table 1.

[0102] Comparative Example 6:

[0103] The difference between this comparative example and Example 1 is that: 90 parts of daidzein benzoxazine and 30 parts of phenol / 4,4'-diaminodiphenylmethane benzoxazine were used, while other operations remained unchanged.

[0104] The glass transition temperature of the benzoxazine cured product obtained in this comparative example was 368℃, and the impact strength was 62.84 kJ / m. 2 The limiting oxygen index was 33.8%, the UL-94 rating was V-1, and the total smoke emission was 16.9 MJ / m³. 2 The test data is summarized in Table 1.

[0105] Table 1. Properties of the benzoxazine cured products obtained in Examples 1-7 and Comparative Examples 1-6

[0106]

[0107] Note: t1 and t2 are the follow-up burning time after the first ignition and the follow-up burning time after the second ignition, respectively.

[0108] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0109] It should be understood that the technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made to the technical solutions of the present invention without departing from the spirit and scope of the claims are within the scope of protection of the present invention.

Claims

1. A highly tough, flame-retardant, and smoke-suppressing benzoxazine composition, characterized in that, include: The invention comprises a daidzein-based benzoxazine resin and a low-curing-temperature benzoxazine resin; wherein the curing temperature of the daidzein-based benzoxazine resin is lower than that of the low-curing-temperature benzoxazine resin; and the mass ratio of the daidzein-based benzoxazine resin to the low-curing-temperature benzoxazine resin is 40~80:1~30. The method for preparing the daidzein-based benzoxazine resin includes: subjecting a mixed reaction system containing at least an amine compound, an aldehyde compound, daidzein, and a solvent to a Mannich reaction to obtain the daidzein-based benzoxazine resin; wherein the amine compound has the structural formula R1-NH2; wherein R1 is selected from alkyl, alkyl-substituted, phenyl, or phenyl-substituted compounds having 1 to 20 carbon atoms; wherein the aldehyde compound has the structural formula R2-CHO; wherein R2 is selected from alkyl, alkyl-substituted, phenyl, or phenyl-substituted compounds having 1 to 20 carbon atoms; and the molar ratio of daidzein, amine compound, and aldehyde compound is 1:1:1 to 1:6:6; The low-curing-temperature benzoxazine resin includes any one or more combinations of monofunctional benzoxazine, bisphenol benzoxazine, diamine benzoxazine, and polyfunctional benzoxazine.

2. The high-toughness, flame-retardant, and smoke-suppressing benzoxazine composition according to claim 1, characterized in that: The curing temperature of the daidzein benzoxazine resin is 150~200℃.

3. The high-toughness, flame-retardant, and smoke-suppressing benzoxazine composition according to claim 1, characterized in that: The curing temperature of the low-curing-temperature benzoxazine resin is 200~300℃.

4. The high-toughness, flame-retardant, and smoke-suppressing benzoxazine composition according to claim 1, characterized in that: The solvent includes any one or more combinations of toluene, xylene, 1,4-dioxane, ethanol, tetrahydrofuran, chloroform, dichloromethane, N,N-dimethylformamide, and dimethyl sulfoxide.

5. The high-toughness, flame-retardant, and smoke-suppressing benzoxazine composition according to claim 1, characterized in that: The Mannich reaction was carried out at a temperature of 60-150°C for 6-24 hours.

6. The high-toughness, flame-retardant, and smoke-suppressing benzoxazine composition according to claim 1, characterized in that, The preparation method of the daidzein benzoxazine resin further includes: after the Mannich reaction is completed, adding deionized water to the obtained reaction solution, and then filtering, washing and drying to obtain daidzein benzoxazine resin.

7. A highly tough, flame-retardant, and smoke-suppressing benzoxazine cured product, characterized in that, The benzoxazine cured product is formed by curing the high-toughness, flame-retardant, and smoke-suppressing benzoxazine composition according to any one of claims 1-6. The benzoxazine cured product has an "island" structure, with daidzein-based benzoxazine resin cured to form a continuous phase and low-curing-temperature benzoxazine resin cured to form a dispersed phase. At the same time, a copolymer of daidzein-based benzoxazine resin and low-curing-temperature benzoxazine resin is formed at the interface between the continuous phase and the dispersed phase.

8. The method for preparing the high-toughness, flame-retardant, and smoke-suppressing benzoxazine cured product according to claim 7, characterized in that, include: Provides a benzoxazine composition with high toughness, flame retardancy, and smoke suppression as described in any one of claims 1-6; Furthermore, the soybean aglycone benzoxazine resin is mixed with a low-curing-temperature benzoxazine resin and subjected to a stepped-heat curing treatment to obtain a high-toughness, flame-retardant, and smoke-suppressing benzoxazine cured product.

9. The preparation method according to claim 8, characterized in that, The stepped temperature curing process includes: sequentially holding at 100~160℃ for 1~5h, 160~170℃ for 1~5h, 170~180℃ for 1~5h, 180~200℃ for 1~5h, and 200~220℃ for 1~5h.

10. The application of the high-toughness, flame-retardant, and smoke-suppressing benzoxazine cured product as described in claim 7 as a high-performance resin matrix or structural material in the fields of electronic packaging, aerospace, or composite materials.

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