High-heat-resistance epoxy modified bismaleimide resin, preparation method thereof and prepreg

Abstract

The invention discloses high-heat-resistance epoxy modified bismaleimide resin as well as a preparation method and prepreg thereof, and relates to the technical field of thermosetting resin. The resin comprises the following raw materials in parts by weight: 30-60 parts of bismaleimide monomer resin, 10-30 parts of polyfunctional epoxy resin and 20-40 parts of an allyl mixture, the bismaleimide monomer resin at least comprises special bismaleimide monomer resin with a structural formula and / or a structural formula; the allyl mixture at least comprises 1, 2-bis (4-(allyloxy) phenyl) disulfane. The structural heat resistance can be effectively improved by specifically selecting the component raw materials and limiting the dosage, aggregation and accumulation of polymer chains are promoted, and the crosslinking density of the bismaleimide resin is further improved. Meanwhile, the curing temperature of the bismaleimide resin is obviously reduced to 190 DEG C, so that the problems of high manufacturing cost, long curing period and the like of the bismaleimide resin are solved, the dimensional stability of a bismaleimide composite material product can be improved, and the dimensional precision is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of thermosetting resins, and in particular to a high-heat-resistant epoxy-modified bismaleimide resin, a preparation method thereof, and a prepreg. Background Art

[0002] In recent decades, high-performance thermosetting resins have been widely used in aerospace, electronics, and other industrial fields, and have attracted much attention and favor from researchers. Bismaleimide resin (BMI) is a high-performance thermosetting polymer that exhibits excellent heat resistance, electrical insulation, radiation resistance, good mechanical properties, and dimensional stability after curing. It has become a key raw material for manufacturing high-temperature resistant aerospace components. However, bismaleimide resin has disadvantages such as high melting point, poor solubility, high curing temperature, and high brittleness after curing. Therefore, the BMI monomer itself does not have the characteristics for direct use and must first be modified. Common BMI modifiers, such as allyl compounds and diamine compounds, two chain extenders, often produce resin systems with curing exothermic peaks as high as 240-260°C, and the curing temperature generally needs to reach 230-250°C. There are problems such as high requirements for molding molds and auxiliary materials and high energy consumption. For example, CN115232310B provides a method for preparing a bismaleimide resin modified with an acetylene toughening component. The glass transition temperature of the resin can reach 380°C, but the maximum curing temperature needs to be 250°C.

[0003] As new aircraft require higher temperature resistance grades for bismaleimide resins, there is an urgent need for a simple and effective solution for non-high-temperature curing of high-temperature resistant bismaleimide resins. Epoxy resins (EP) have an insurmountable position in the field of advanced matrix resins due to their outstanding performance characteristics and excellent processing capabilities, but they have a relatively low glass transition temperature. Therefore, the combination of bismaleimide and epoxy systems is expected to result in a material with the beneficial properties of both components. CN118725568A discloses a mixture of bismaleimide monomers, liquid allyl compounds, and naphthol-type or biphenyl-type epoxy resins that can be cured at 200°C and has good heat resistance.

[0004] The present invention aims to further reduce the curing temperature, ensure good heat resistance requirements, and expand the application range of bismaleimide resin.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The present invention aims to provide a high-heat-resistant epoxy-modified bismaleimide resin, a preparation method thereof, and a prepreg.

[0007] The present invention is achieved in that:

[0008] In a first aspect, the present invention provides a high heat-resistant epoxy-modified bismaleimide resin, which comprises, by weight, 30-60 parts of a bismaleimide monomer resin, 10-30 parts of a multifunctional epoxy resin, and 20-40 parts of an allyl mixture;

[0009] The bismaleimide monomer resin at least includes a special bismaleimide monomer resin, and the structural formula of the special bismaleimide monomer resin is The allyl mixture includes at least 1,2-bis(4-(allyloxy)phenyl)disulfane.

[0010] In an optional embodiment, the bismaleimide monomer resin further comprises one or a combination of several components selected from 4,4'-bismaleimidodiphenylmethane, N,N'-1,3-phenylenebismaleimide and N,N'-(4-methyl-1,3-phenylene)bismaleimide.

[0011] In an optional embodiment, the mass ratio of the special bismaleimide monomer resin to the bismaleimide monomer resin is 20-40%.

[0012] In an optional embodiment, the allyl mixture further comprises 2,2'-diallyl bisphenol A;

[0013] Preferably, the mass ratio of the 2,2'-diallylbisphenol A to the 1,2-bis(4-(allyloxy)phenyl)disulfane is 2-4:1.

[0014] In an optional embodiment, the multifunctional epoxy resin is one or a combination of several components selected from N,N,N',N'-tetrakis(oxiranylmethyl)-1,3-phenylenediamine and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

[0015] In a second aspect, the present invention provides a method for preparing a high-heat-resistant epoxy-modified bismaleimide resin, comprising uniformly mixing the component raw materials of the high-heat-resistant epoxy-modified bismaleimide resin according to any one of the aforementioned embodiments;

[0016] Preferably, mixing the component raw materials evenly includes: first heating and melting the allyl mixture, adding the multifunctional epoxy resin monomer, and stirring evenly; adding part of the bismaleimide monomer resin for dissolution and prepolymerization, stirring the resin mixture until its color becomes a uniform and transparent reddish brown, and then stopping heating; adding the remaining bismaleimide monomer resin, stirring and mixing evenly, and cooling to room temperature to obtain a semi-solid high heat-resistant epoxy modified bismaleimide resin.

[0017] In an optional embodiment, the allyl mixture and the multifunctional epoxy resin monomer are stirred at 60-80° C. for 5-25 min.

[0018] In an optional embodiment, the pre-added amount of the bismaleimide monomer resin is 50-70% of the added amount of the allyl mixture, and the stirring condition is stirring at 100-130° C. for 30-60 minutes.

[0019] In an optional embodiment, the stirring condition after adding the remaining bismaleimide monomer resin is 60-80° C. and stirring for 10-30 minutes.

[0020] In a third aspect, the present invention provides a prepreg comprising carbon fiber and the high heat-resistant epoxy-modified bismaleimide resin according to any one of the aforementioned embodiments.

[0021] The present invention has the following beneficial effects:

[0022] The highly heat-resistant epoxy-modified bismaleimide resin provided by the present invention is characterized by the specific selection and limited dosage of its component raw materials. Specifically, a special bismaleimide monomer resin is selected as one of the components of the bismaleimide monomer resin. The bissulfone group has high polarity and steric hindrance, and the naphthalene ring can expand the conjugated system, both of which effectively improve the heat resistance of the structure. Furthermore, 1,2-bis(4-(allyloxy)phenyl)disulfane, a novel allyl compound containing a disulfide, is selected as one of the components of the allyl compound. The unique chemical structure of 1,2-bis(4-(allyloxy)phenyl)disulfane makes it easier for chain segments to entangle with each other after growth, promoting the aggregation and stacking of polymer chains, further increasing the crosslink density of the bismaleimide resin. The combination of the special bismaleimide monomer resin and 1,2-bis(4-(allyloxy)phenyl)disulfane significantly increases the crosslink density of the bismaleimide resin and exhibits excellent heat resistance. At the same time, its curing temperature is significantly reduced to 190°C, which helps to solve the problems of high manufacturing cost and long curing cycle of bismaleimide resin. It can also improve the dimensional stability of bismaleimide composite parts and improve the dimensional accuracy of bismaleimide composite parts. When preparing bismaleimide resin prepreg, bismaleimide resin with good processability can improve the processability of the prepreg, and through the prepolymerization process during the resin mixing process, its flow characteristics during the curing and molding process can be controlled to achieve a stable and controllable state of the prepreg. The preparation process of this high-heat-resistant epoxy-modified bismaleimide resin is simple, controllable, and easy to operate, providing an ideal material for high-temperature resistant composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 Schematic diagram of the DSC curve of Example 1 of the present invention;

[0025] Figure 2 Schematic diagram of the DSC curve of Comparative Example 10 of the present invention. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0027] The present invention provides a high-heat-resistant epoxy-modified bismaleimide resin. The raw materials of the resin include, by weight, 30-60 parts of a bismaleimide monomer resin, 10-30 parts of a multifunctional epoxy resin, and 20-40 parts of an allyl mixture. The bismaleimide monomer resin includes at least a special bismaleimide monomer resin, and the structural formula of the special bismaleimide monomer resin is BMI01: and / or BMI02: The allyl mixture includes at least 1,2-bis(4-(allyloxy)phenyl)disulfane.

[0028] The present invention limits the specific selection of bismaleimide monomer resins and the specific selection of allyl mixtures, wherein a special bismaleimide monomer resin is selected as one of the components of the bismaleimide monomer resins, wherein the bissulfone group has high polarity and steric hindrance effect, and the naphthalene ring can expand the conjugated system, both of which can effectively improve the heat resistance of the structure.

[0029] The present invention uses a new allyl mixture containing disulfide, 1,2-bis(4-(allyloxy)phenyl)disulfane (DBS). Compared with the tetrahedral structure of 2,2'-diallylbisphenol A (DBA), it has a more unique molecular structure. That is, due to the repulsive effect between the two pairs of unbonded p-orbital electron pairs in the two sulfur atoms of the SS bond, the two groups connected to the SS bond in the DBS molecule are located on two nearly perpendicular planes. Therefore, the molecular structure of the entire DBS is twisted rather than linear. The unique chemical structure of DBS makes it easier for the chain segments to entangle with each other after growth, promotes the aggregation and accumulation of polymer chains, and further increases the crosslinking density of the bismaleimide resin.

[0030] By combining the above-mentioned special bismaleimide monomer resin and 1,2-bis(4-(allyloxy)phenyl)disulfane, the crosslinking density of the bismaleimide resin can be significantly improved, while its curing temperature is significantly reduced and its heat resistance is excellent.

[0031] It should be understood that, on the basis of the above components, some other bismaleimide monomer resins or allyl mixture substances may also be added.

[0032] Specifically, in some embodiments, the bismaleimide monomer resin further comprises one or more of 4,4'-bismaleimidodiphenylmethane, N,N'-1,3-phenylene bismaleimide, and N,N'-(4-methyl-1,3-phenylene)bismaleimide. When selected from a combination of multiple components, the combination ratio is not limited in this application and can be any ratio.

[0033] When the BMA monomer resin is composed of multiple resins, the weight ratio of the special BMA monomer resin to the BMA monomer resin is 20-40%. If the special BMA monomer is used in too little amount, high heat resistance cannot be achieved. If the special BMA monomer is used in an amount exceeding 40%, the reaction degree at 190°C is affected by the steric effect, thereby affecting the heat resistance.

[0034] In some embodiments, the allyl mixture also includes 2,2'-diallyl bisphenol A. Since the allyl mixture contains only 1,2-bis(4-(allyloxy)phenyl)disulfane, although its unique chemical structure makes the chain segments easier to entangle with each other after growth, promotes the aggregation and accumulation of polymer chains, and is beneficial to improving the crosslinking density of the bismaleimide resin, it also leads to a decrease in the mobility of the chain segments in the resin, resulting in incomplete reaction. Therefore, the allyl mixture in the present invention also includes 2,2'-diallyl bisphenol A, and a bismaleimide resin with high heat resistance is obtained by simultaneously using DBA for regulation.

[0035] Preferably, the mass ratio of 2,2'-diallyl bisphenol A to 1,2-bis(4-(allyloxy)phenyl)disulfane is 2-4:1. In some typical but non-limiting examples, the mass ratio of 2,2'-diallyl bisphenol A to 1,2-bis(4-(allyloxy)phenyl)disulfane can be, for example, any one of 4:1, 3.5:1, 3:1, 2.5:1, 2:1, or a range between any two of them.

[0036] In some embodiments, the multifunctional epoxy resin is a combination of one or more components of N,N,N',N'-tetrakis (oxiranylmethyl)-1,3-phenylenediamine and 1,3-bis (N,N-diglycidylaminomethyl) cyclohexane. When selected from a combination of multiple components, the combination ratio is not limited in this application and can be any ratio. In the present invention, the multifunctional epoxy resins selected are all highly active epoxy resins. Compared with ordinary tetrafunctional epoxy resins with low activity (such as N,N,N,N,-tetracyclyl-4,4-diaminodiphenylmethane), it is crucial that the multifunctional epoxy resin of the present application can reduce the curing temperature of the bismaleimide resin, and it is necessary to ensure heat resistance greater than 300°C and good processability of the prepreg.

[0037] Furthermore, the present invention provides a method for preparing a high-heat-resistant epoxy-modified bismaleimide resin, which comprises uniformly mixing component raw materials of the high-heat-resistant epoxy-modified bismaleimide resin.

[0038] Specifically, the following steps are included:

[0039] S1. First, heat and melt the allyl mixture, add the multifunctional epoxy resin monomer, and stir evenly.

[0040] The stirring condition of the allyl mixture and the multifunctional epoxy resin monomer is 60-80° C. for 5-25 minutes.

[0041] S2. Add part of the BMI monomer resin to dissolve and prepolymerize, and stir the resin mixture until its color changes to a uniform, transparent reddish brown, then stop heating.

[0042] The amount of the bismaleimide monomer resin added in advance is 50-70% of the amount of the allyl mixture added, and the stirring condition is stirring at 100-130° C. for 30-60 minutes.

[0043] If too little BMI monomer is added, prepolymerization will not proceed effectively. If too much BMI monomer is added, exceeding 70% of the amount of the allyl mixture added, the viscosity of the prepreg decreases, the hardness increases, and it cannot be used normally. In the present invention, the reaction can be accelerated by increasing the temperature during the prepolymerization process.

[0044] S3. Add the remaining bismaleimide monomer resin, stir and mix evenly, and cool to room temperature to obtain a semi-solid high heat-resistant epoxy modified bismaleimide resin.

[0045] After adding the remaining BMA monomer resin, the stirring condition is 60-80°C for 10-30 minutes. After adding the remaining BMA monomer resin, stirring is carried out at a temperature of 60-80°C. The temperature at this time is lower than the temperature during the prepolymerization process to ensure that the BMA monomer no longer undergoes any reaction and physical dissolution.

[0046] In addition, the present invention provides a prepreg comprising carbon fiber and the above-mentioned high heat-resistant epoxy-modified bismaleimide resin.

[0047] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0048] Example 1

[0049] Weigh 32g of 2,2'-diallylbisphenol A, 8g of 1,2-bis(4-(allyloxy)phenyl)disulfane and 20g of N,N,N',N'-tetra(oxiranylmethyl)-1,3-phenylenediamine and heat to melt at 80°C, stir for 15 minutes, add 28g of 4,4'-bismaleimidodiphenylmethane and dissolve the prepolymer at 110°C, stir for 40 minutes, until the solution becomes a uniform transparent reddish-brown liquid, then add the remaining 17g of 4,4'-bismaleimidodiphenylmethane and 15g of BMI01 and disperse at 80°C, stir for 15 minutes, and cool to room temperature to obtain a semi-solid high heat-resistant epoxy modified bismaleimide resin.

[0050] Example 2

[0051] Weigh 32g of 2,2'-diallylbisphenol A, 8g of 1,2-bis(4-(allyloxy)phenyl)disulfane and 30g of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane and heat to melt at 60°C, stir for 25min, add 25g of N,N'-1,3-phenylene bismaleimide and dissolve it at 105°C for prepolymerization, stir for 30min, until the solution becomes a uniform transparent reddish-brown liquid, then add 9g of N,N'-1,3-phenylene bismaleimide and 15g of BMI01 and disperse them at 60°C, stir for 25min, and cool to room temperature to obtain a semi-solid high heat-resistant epoxy modified bismaleimide resin.

[0052] Example 3

[0053] Weigh 26g of 2,2'-diallylbisphenol A, 13g of 1,2-bis(4-(allyloxy)phenyl)disulfane and 25g of N,N,N',N'-tetra(oxiranylmethyl)-1,3-phenylenediamine and heat to melt at 70°C, stir for 20 minutes, add 25g of 4,4'-bismaleimidodiphenylmethane and dissolve the prepolymer at 115°C, stir for 50 minutes, until the solution becomes a uniform transparent reddish-brown liquid, then add the remaining 16g of 4,4'-bismaleimidodiphenylmethane and 15g of BMI02 and disperse at 70°C, stir for 20 minutes, and cool to room temperature to obtain a semi-solid high heat-resistant epoxy modified bismaleimide resin.

[0054] Example 4

[0055] Weigh 25g of 2,2'-diallylbisphenol A, 12g of 1,2-bis(4-(allyloxy)phenyl)disulfane, and 12g of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, heat and melt at 65°C, stir for 20min, add 25g of N,N'-(4-methyl-1,3-phenylene)bismaleimide and dissolve it at 120°C for prepolymerization, stir for 60min, until the solution becomes a uniform transparent reddish-brown liquid, then add 15g of N,N'-(4-methyl-1,3-phenylene)bismaleimide and 20g of BMI02 and disperse them at 65°C, stir for 20min, and cool to room temperature to obtain a semi-solid high heat-resistant epoxy modified bismaleimide resin.

[0056] Comparative Example 1

[0057] Weigh 32g of 2,2'-diallylbisphenol A, 8g of 1,2-bis(4-(allyloxy)phenyl)disulfane and 25g of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, heat and melt at 80°C, stir for 15min, add 20g of 4,4'-bismaleimidodiphenylmethane and dissolve the prepolymer at 110°C, stir for 40min, until the solution becomes a uniform transparent reddish-brown liquid, then add 9g of BMI01 and disperse at 80°C, stir for 15min, and cool to room temperature to obtain a semi-solid epoxy-modified bismaleimide resin.

[0058] Comparative Example 2

[0059] Weigh 26g of 2,2'-diallylbisphenol A, 13g of 1,2-bis(4-(allyloxy)phenyl)disulfane and 20g of N,N,N',N'-tetra(oxiranylmethyl)-1,3-phenylenediamine, heat and melt at 80°C, stir for 15min, add 25g of 4,4'-bismaleimidodiphenylmethane and dissolve the prepolymer at 110°C, stir for 40min, until the solution becomes a uniform, transparent bright yellow liquid, then add the remaining 25g of 4,4'-bismaleimidodiphenylmethane and 15g of BMI02 and disperse at 80°C, stir for 15min, and cool to room temperature to obtain a semi-solid epoxy-modified bismaleimide resin.

[0060] Comparative Example 3

[0061] Weigh 32g of 2,2'-diallylbisphenol A, 8g of 1,2-bis(4-(allyloxy)phenyl)disulfane and 20g of N,N,N',N'-tetra(oxiranylmethyl)-1,3-phenylenediamine, heat and melt at 80°C, stir for 15 minutes, add 28g of 4,4'-bismaleimidodiphenylmethane to dissolve the prepolymer at 110°C, stir for 40 minutes until the solution becomes a uniform transparent reddish-brown liquid, then add the remaining 27g of 4,4'-bismaleimidodiphenylmethane and disperse at 80°C, stir for 15 minutes, and cool to room temperature to obtain a semi-solid epoxy-modified bismaleimide resin.

[0062] Comparative Example 4

[0063] Weigh 32g of 2,2'-diallylbisphenol A, 8g of 1,2-bis(4-(allyloxy)phenyl)disulfane and 30g of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, heat and melt at 80°C, stir for 15min, add 25g of N,N'-1,3-phenylene bismaleimide and dissolve prepolymer at 110°C, stir for 40min, until the solution becomes a uniform transparent reddish-brown liquid, then add the remaining 9g of N,N'-1,3-phenylene bismaleimide and 25g of BMI01 and disperse at 80°C, stir for 15min, and cool to room temperature to obtain a semi-solid epoxy-modified bismaleimide resin.

[0064] Comparative Example 5

[0065] Weigh 32g of 2,2'-diallylbisphenol A, 8g of 1,2-bis(4-(allyloxy)phenyl)disulfane and 20g of N,N,N',N'-tetra(oxiranylmethyl)-1,3-phenylenediamine and heat to melt at 80°C, stir for 15min, add 35g of 4,4'-bismaleimidodiphenylmethane and dissolve the prepolymer at 110°C, stir for 40min, until the solution becomes a uniform transparent reddish-brown liquid, then add the remaining 10g of 4,4'-bismaleimidodiphenylmethane and 15g of BMI01 and disperse at 80°C, stir for 15min, and cool to room temperature to obtain a semi-solid epoxy-modified bismaleimide resin.

[0066] Comparative Example 6

[0067] Weigh 39g of 2,2'-diallyl bisphenol A and 25g of N,N,N',N'-tetrakis(oxiranylmethyl)-1,3-phenylenediamine, heat and melt at 80°C, stir for 15min, add 25g of 4,4'-bismaleimidodiphenylmethane and dissolve the prepolymer at 110°C, stir for 40min, until the solution becomes a uniform transparent reddish-brown liquid, then add the remaining 16g of 4,4'-bismaleimidodiphenylmethane and 15g of BMI02 and disperse at 80°C, stir for 15min, and cool to room temperature to obtain a semi-solid epoxy-modified bismaleimide resin.

[0068] Comparative Example 7

[0069] Weigh 25g of 2,2'-diallylbisphenol A, 5g of 1,2-bis(4-(allyloxy)phenyl)disulfane and 12g of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, heat and melt at 80°C, stir for 15min, add 20g of N,N'-(4-methyl-1,3-phenylene)bismaleimide and dissolve it at 110°C for prepolymerization, stir for 40min, until the solution becomes a uniform transparent reddish-brown liquid, then add the remaining 25g of N,N'-(4-methyl-1,3-phenylene)bismaleimide and 20g of BMI02 and disperse them at 80°C, stir for 15min, and cool to room temperature to obtain a semi-solid epoxy-modified bismaleimide resin.

[0070] Comparative Example 8

[0071] Weigh 8g of 2,2'-diallylbisphenol A, 32g of 1,2-bis(4-(allyloxy)phenyl)disulfane and 20g of N,N,N',N'-tetra(oxiranylmethyl)-1,3-phenylenediamine, heat and melt at 80°C, stir for 15 minutes, add 28g of 4,4'-bismaleimidodiphenylmethane and dissolve the prepolymer at 110°C, stir for 40 minutes, until the solution becomes a uniform transparent reddish-brown liquid, then add the remaining 17g of 4,4'-bismaleimidodiphenylmethane and 15g of BMI01 and disperse at 80°C, stir for 15 minutes, and cool to room temperature to obtain a semi-solid high heat-resistant epoxy modified bismaleimide resin.

[0072] Comparative Example 9

[0073] Weigh 32g of 2,2'-diallylbisphenol A, 8g of 1,2-bis(4-(allyloxy)phenyl)disulfane and 20g of N,N,N,N,-tetraepoxypropyl-4,4-diaminodiphenylmethane and heat to melt at 80°C, stir for 15min, add 28g of 4,4'-bismaleimidodiphenylmethane and dissolve the prepolymer at 110°C, stir for 40min, until the solution becomes a uniform transparent reddish-brown liquid, then add the remaining 17g of 4,4'-bismaleimidodiphenylmethane and 15g of BMI01 and disperse at 80°C, stir for 15min, and cool to room temperature to obtain a semi-solid high heat-resistant epoxy modified bismaleimide resin.

[0074] Performance Testing

[0075] The prepared resin was subjected to DSC testing at a scanning rate of 10°C / min to obtain the resin initial reaction temperature; the above resin was cured using a curing system of 130°C / 1h+190°C / 5h, and its glass transition temperature (Tg) was tested using the ASTM D4065-12 test method, with the Tg represented by the tanδ value in the DMA curve as the standard; the curing degree of the cured resin was tested using the DSC method.

[0076] The above resin was combined with Jiangsu Hengshen HF40A-12K carbon fiber (T800 grade) to form a 133gsm unidirectional prepreg with a resin content of 33% by hot melt method. Its viscosity was tested according to the test method HB7736.8-2004.

[0077]

[0078]

[0079] Compared with Example 2, in Comparative Example 1, the amount of BMI monomer used was too small, the Tg of the resin was greatly reduced, and the prepreg could not be separated without loss.

[0080] Compared with Example 3, in Comparative Example 2, the amount of bismaleimide monomer used is too much, and the epoxy resin is insufficient to stimulate the polymerization reaction of bismaleimide, resulting in a delayed initial reaction temperature, a low degree of curing at 190°C, resulting in low heat resistance, and insufficient viscosity of the prepreg process.

[0081] Compared with Example 1, Comparative Example 3 cannot show high heat resistance when the special bismaleimide monomer is omitted.

[0082] Compared with Example 2, in Comparative Example 4, when the amount of the special bismaleimide monomer exceeds 40%, the steric effect affects the reaction degree at 190° C., thereby affecting the heat resistance.

[0083] In Comparative Example 5, compared with Example 1, when the amount of bismaleimide monomer dissolved exceeds 70% of the amount of the allyl mixture added, the viscosity of the prepreg decreases, the hand feel hardness increases significantly, and the prepreg cannot be used normally.

[0084] Compared with Examples 3 and 4, in Comparative Examples 6, 7, and 8, the overall heat resistance is reduced when the amount of 1,2-bis(4-(allyloxy)phenyl)disulfane added is insufficient or excessive.

[0085] Comparative Example 9 Compared with Example 1, the initial reaction temperature of the low-activity ordinary tetrafunctional epoxy resin was significantly delayed. Figure 1 and Figure 2 , resulting in the inability to meet the 190℃ curing requirements and reduced heat resistance.

[0086] In summary, the highly heat-resistant epoxy-modified bismaleimide resin provided by the present invention is characterized by the specific selection and limited dosage of its component raw materials. Specifically, a special bismaleimide monomer resin is selected as one of the components of the bismaleimide monomer resin. The bissulfone group has high polarity and steric hindrance, and the naphthalene ring can expand the conjugated system, both of which effectively improve the heat resistance of the structure. Furthermore, 1,2-bis(4-(allyloxy)phenyl)disulfane, a novel allyl compound containing a disulfide, is selected as one of the components of the allyl compound. The unique chemical structure of 1,2-bis(4-(allyloxy)phenyl)disulfane makes it easier for chain segments to entangle with each other after growth, promoting the aggregation and stacking of polymer chains, further increasing the crosslink density of the bismaleimide resin. The combination of this special bismaleimide monomer resin and 1,2-bis(4-(allyloxy)phenyl)disulfane significantly increases the crosslink density of the bismaleimide resin and exhibits excellent heat resistance. At the same time, its curing temperature is significantly reduced to 190°C, which helps to solve the problems of high manufacturing cost and long curing cycle of bismaleimide resin. It can also improve the dimensional stability of bismaleimide composite parts and improve the dimensional accuracy of bismaleimide composite parts. When preparing bismaleimide resin prepreg, bismaleimide resin with good processability can improve the processability of the prepreg, and through the prepolymerization process during the resin mixing process, its flow characteristics during the curing and molding process can be controlled to achieve a stable and controllable state of the prepreg. The preparation process of this high-heat-resistant epoxy-modified bismaleimide resin is simple, controllable, and easy to operate, providing an ideal material for high-temperature resistant composite materials.

[0087] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A high heat-resistant epoxy-modified bismaleimide resin, characterized in that: The raw materials include, by weight: 30-60 parts of bismaleimide monomer resin, 10-30 parts of multifunctional epoxy resin and 20-40 parts of allyl mixture; The bismaleimide monomer resin at least includes a special bismaleimide monomer resin, and the structural formula of the special bismaleimide monomer resin is and / or The allyl mixture includes at least 1,2-bis(4-(allyloxy)phenyl)disulfane.

2. The high heat-resistant epoxy-modified bismaleimide resin according to claim 1, characterized in that The bismaleimide monomer resin further comprises one or a combination of several components selected from 4,4'-bismaleimidodiphenylmethane, N,N'-1,3-phenylene bismaleimide and N,N'-(4-methyl-1,3-phenylene)bismaleimide.

3. The high heat-resistant epoxy-modified bismaleimide resin according to claim 1 or 2, characterized in that: The mass ratio of the special bismaleimide monomer resin to the bismaleimide monomer resin is 20-40%.

4. The high heat-resistant epoxy-modified bismaleimide resin according to claim 1, characterized in that: The allyl mixture also includes 2,2'-diallyl bisphenol A; Preferably, the mass ratio of the 2,2'-diallylbisphenol A to the 1,2-bis(4-(allyloxy)phenyl)disulfane is 2-4:

1.

5. The high heat-resistant epoxy-modified bismaleimide resin according to claim 1, characterized in that: The multifunctional epoxy resin is one or a combination of several components selected from N,N,N',N'-tetra(oxiranylmethyl)-1,3-phenylenediamine and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

6. A method for preparing a high heat-resistant epoxy-modified bismaleimide resin, characterized in that: The method comprises uniformly mixing component raw materials of the high heat-resistant epoxy-modified bismaleimide resin according to any one of claims 1 to 5; Preferably, mixing the component raw materials evenly includes: first heating and melting the allyl mixture, adding the multifunctional epoxy resin monomer, and stirring evenly; adding part of the bismaleimide monomer resin for dissolution and prepolymerization, stirring the resin mixture until its color becomes a uniform and transparent reddish brown, and then stopping heating; adding the remaining bismaleimide monomer resin, stirring and mixing evenly, and cooling to room temperature to obtain a semi-solid high heat-resistant epoxy modified bismaleimide resin.

7. The method for preparing the high heat-resistant epoxy-modified bismaleimide resin according to claim 6, wherein: The stirring condition of the allyl mixture and the multifunctional epoxy resin monomer is 60-80° C. for 5-25 minutes.

8. The method for preparing the high heat-resistant epoxy-modified bismaleimide resin according to claim 6, wherein: The amount of the bismaleimide monomer resin added in advance is 50-70% of the amount of the allyl mixture added, and the stirring condition is stirring at 100-130° C. for 30-60 minutes.

9. The method for preparing the high heat-resistant epoxy-modified bismaleimide resin according to claim 6, wherein: The stirring condition after adding the remaining bismaleimide monomer resin is 60-80° C. and stirring for 10-30 minutes.

10. A prepreg, characterized in that The invention comprises carbon fiber and the high heat-resistant epoxy-modified bismaleimide resin according to any one of claims 1 to 5.

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