Bismaleimide monomer as well as preparation method and application thereof

Abstract

The invention relates to the technical field of high-performance thermosetting resin, and discloses a bismaleimide monomer as well as a preparation method and application thereof. The preparation method comprises the following steps: dispersing bisphenol F and a halogenated nitrobenzene compound in a polar aprotic solvent, and carrying out a heating reaction under the action of an alkaline nucleophilic reagent to obtain a dinitro intermediate; dispersing the dinitro intermediate and a first catalyst in an organic solvent, and carrying out amination reaction under the action of hydrazine hydrate to obtain a diamino structure compound; the preparation method comprises the following steps: reacting a diamino structure compound and maleic anhydride in a polar aprotic solvent to obtain bismaleimide acid; and adding the bismaleimide acid, a second catalyst and a dehydrating agent into a polar aprotic solvent, and carrying out a dehydration cyclization reaction to obtain the bismaleimide monomer. The bismaleimide monomer disclosed by the invention has low dielectric constant, low water absorption rate and excellent dielectric property; the preparation process is simple, the yield is high, and continuous production can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of high-performance thermosetting resins, and in particular to a bismaleimide monomer and a preparation method and application thereof. Background Art

[0002] Bismaleimide resin (BMI) is a high-performance thermosetting material with excellent heat resistance, electrical insulation, wave transmission and flame retardancy. Its glass transition temperature (Tg) is usually over 250°C, suitable for use in high temperature environments of 177°C to 232°C, and is widely used in aerospace, machinery, electronics and other fields.

[0003] The synthesis methods of BMI resin include acetic anhydride dehydration method, thermal dehydration closed-loop method and azeotropic distillation dehydration method. Among them, the acetic anhydride dehydration method is to react diamine with maleimide in a solvent to generate an intermediate amide acid; then acetic anhydride is used as a dehydrating agent, acetate (sodium acetate, zinc acetate, etc.) is used as a catalyst, and the amide acid is dehydrated and cyclized to generate BMI resin. It is easy to prepare and has a high reaction yield. However, a variety of toxic solvents are used in its preparation, which has certain toxicity, and the production cost is high, and the product quality is relatively poor. The thermal dehydration closed-loop method uses toluene, dichloromethane and DMF as a mixed solvent and sodium p-toluenesulfonate as a dehydrating agent. Dehydration cyclization is performed at a higher temperature to obtain BMI resin. It has a high yield and produces less hazardous waste, but its dehydration time is long and the preparation efficiency is low. The azeotropic distillation dehydration method uses toluene as the main solvent to form BMI resin after dehydration and cyclization. It has high production efficiency and low cost, but due to the uneven reaction system, the quality of the prepared BMI resin is relatively poor.

[0004] Although commercial BMI has achieved great success, the quality of ordinary BMI resin prepared by the above method is relatively poor, which is manifested in high melting point, strong water absorption, poor toughness of cured product, and high dielectric properties, which cannot meet the development needs. Based on this, it is urgent to design a new method to synthesize new bismaleimide monomers. Summary of the invention

[0005] The present application provides a bismaleimide monomer and a preparation method and application thereof, aiming to solve the problems of low safety and low yield in the existing preparation method, as well as the problem of high dielectric constant of the prepared BMI resin.

[0006] In order to achieve the above objectives, the present application adopts the following technical solutions.

[0007] In the first aspect of the present application, a bismaleimide monomer is provided, the chemical structure of which is shown in formula (1):

[0008]

[0009] Among them, R is selected from

[0010] The second aspect of the present application provides a method for preparing the above-mentioned bismaleimide monomer, comprising:

[0011] S1, dispersing bisphenol F and a halogenated nitrobenzene compound in a polar aprotic solvent, and heating the mixture under the action of an alkaline nucleophile to obtain a dinitro intermediate;

[0012] S2, dispersing the dinitro intermediate and the first catalyst in an organic solvent, and performing an amination reaction under the action of hydrazine hydrate to obtain a diamine structure compound;

[0013] S3, reacting the diamine structure compound and maleic anhydride in a polar aprotic solvent to obtain bismaleimide acid;

[0014] S4, adding bismaleimide acid, a second catalyst and a dehydrating agent into a polar aprotic solvent to carry out a dehydration cyclization reaction to obtain a bismaleimide monomer.

[0015] Preferably, the halogenated nitrobenzene compound is selected from any one of the following compounds:

[0016]

[0017] Preferably, the polar aprotic solvent includes any one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran or acetone;

[0018] The alkaline nucleophile is potassium carbonate;

[0019] and / or,

[0020] The organic solvent includes any one of methanol, ethanol or isopropanol;

[0021] The first catalyst is a palladium-carbon catalyst;

[0022] and / or,

[0023] The dehydrating agent includes any one of acetic anhydride, pyridine or isoquinoline;

[0024] The second catalyst comprises a catalyst and a promoter, wherein the catalyst comprises any one of sodium acetate, zinc acetate, nickel acetate, cobalt acetate, magnesium chloride or magnesium sulfate; and the promoter comprises triethylamine.

[0025] Preferably, in S1, the molar ratio of the halogenated nitrobenzene compound to bisphenol F is ≥ 2:1; the mass of the polar aprotic solvent is at least 10 times the mass of bisphenol F;

[0026] In S2, the mass of the organic solvent is at least 10 times the mass of the dinitro intermediate; and the molar number of the first catalyst is 0.1-10% of the molar number of the dinitro intermediate.

[0027] Preferably, in S3, the mass of the polar aprotic solvent is at least 10 times the total mass of the diamine structure compound and maleic anhydride;

[0028] The molar ratio of the diamine structure compound to maleic anhydride is 1:2 to 1:2.5.

[0029] Preferably, in S4, the molar ratio of the dehydrating agent to the bismaleimide acid is 3 to 8:1;

[0030] The molar ratio of the catalyst promoter to the bismaleimide acid is 0.5-5:1; each mole of the bismaleimide acid corresponds to 0.5-5g of the catalyst.

[0031] Preferably, in step S1, the reaction temperature is 80-130°C;

[0032] In step S2, the temperature of the amination reaction is 75-85°C;

[0033] In step S3, the reaction temperature is room temperature;

[0034] In step S4, the temperature of the dehydration cyclization reaction is 45-55°C.

[0035] The third aspect of the present application provides the use of the above-mentioned bismaleimide monomer or the bismaleimide monomer prepared by the above-mentioned preparation method in the preparation of polymer-based composite materials.

[0036] The fourth aspect of the present application provides the use of the bismaleimide monomer or the bismaleimide monomer prepared by the above preparation method in the preparation of dielectric polymer materials.

[0037] Compared with the prior art, the beneficial effects of this application are:

[0038] The bismaleimide monomer of the present application has a large volume structure, which can increase the free volume fraction, thereby having a low dielectric constant; in addition, the fluorine-containing group it contains can reduce the polarizability of the molecule, further reduce the dielectric constant, and reduce its water absorption. The bismaleimide monomer of the present application has an active double bond, has a high cross-linking activity, and has a symmetrical structure, and can be used as a matrix for high-performance polymer-based composite materials, which can be prepared alone or with other organic monomers. High-performance polymer materials. Based on its low dielectric constant, it can give polymer materials good dielectric properties and can be used to prepare dielectric polymer materials.

[0039] The present application prepares bismaleimide monomer by combining a diamine structure compound and maleic anhydride to obtain bismaleimide acid, and performing a dehydration cyclization step of the bismaleimide acid. The reaction system is always in a homogeneous phase and no resinous viscous material is produced, so that the product yield is stable, the yield of the bismaleimide monomer is greatly improved, the preparation process is simple, and the product is easy to separate, has a high controllability, and has little pollution, and can meet the requirements of low-cost continuous production. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 This is the H-NMR spectrum of the bismaleimide monomer prepared in Example 1;

[0042] Figure 2 This is the NMR carbon spectrum of the bismaleimide monomer prepared in Example 1. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0044] In the following description of this embodiment, the terms "include", "comprising", "having" and "containing" are all open terms, meaning including but not limited to.

[0045] In the following description of this embodiment, the term "and / or" is used to describe the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, B exists alone, and A and B exist at the same time. A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0046] In the following description of this embodiment, the term "at least one" refers to one or more, and "plurality" refers to two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c", can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.

[0047] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0048] Those skilled in the art should understand that in the following description of the embodiments of the present application, the order of serial numbers does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0049] Those skilled in the art will appreciate that the numerical ranges in the embodiments of the present application are to be construed as specifically disclosing each intermediate value between the upper and lower limits of the scope. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present application. The upper and lower limits of these smaller ranges may be independently included or excluded in the scope.

[0050] Unless otherwise specified, the technical / scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which this application belongs. Although this application only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of this application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0051] In a first aspect, the present application provides a bismaleimide monomer, the chemical structure of which is shown in formula (1):

[0052]

[0053] Among them, R is selected from

[0054] The bismaleimide monomer of the present application has a bulky structure, which can increase the free volume fraction, from having a low dielectric constant. In addition, the fluorinated groups contained in the bismaleimide monomer are highly negatively charged and are not easily polarized in an electric field, further reducing its dielectric constant or dielectric loss. In addition, the fluorinated groups give it hydrophobic characteristics, reducing its water absorption rate.

[0055] The second aspect of the present application provides a method for preparing the above-mentioned bismaleimide monomer, comprising:

[0056] S1, dispersing bisphenol F and a halogenated nitrobenzene compound in a polar aprotic solvent, reacting at 80-130° C. under the action of an alkaline nucleophile to obtain a dinitro intermediate;

[0057] Wherein, the halogenated nitrobenzene compound is selected from any one of the following compounds:

[0058]

[0059] The polar aprotic solvent includes any one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran or acetone.

[0060] In the present application, bismaleimide monomer is prepared by using bisphenol F. Compared with bisphenol A, the resin prepared by bismaleimide monomer containing bisphenol F structure has advantages such as good strength and wear resistance.

[0061] In the present application, the alkaline nucleophile is potassium carbonate.

[0062] In the present application, the molar ratio of the halogenated nitrobenzene compound to bisphenol F is preferably ≥ 2:1, and the molar ratio of the halogenated nitrobenzene compound to bisphenol F is more preferably 2:1 to 2.5:1; the mass of the polar aprotic solvent is preferably at least 10 times the mass of bisphenol F. Within this ratio range, the halogenated nitrobenzene compound and bisphenol F are conducive to complete reaction, improving the yield and reducing the generation of by-products.

[0063] In the present application, the chemical structure of the dinitro intermediate obtained by the reaction is as follows:

[0064]

[0065] Among them, R is selected from

[0066] S2, dispersing the dinitro intermediate and the first catalyst in an organic solvent, and performing an amination reaction at 75-85° C. under the action of hydrazine hydrate to obtain a diamine structure compound;

[0067] Wherein, the first catalyst is preferably a palladium-carbon catalyst; the organic solvent includes any one of methanol, ethanol or isopropanol.

[0068] In the present application, the mass of the organic solvent is preferably at least 10 times the mass of the dinitro intermediate; the molar number of the first catalyst is preferably 0.1-10% of the molar number of the dinitro intermediate;

[0069] The chemical structure of the diamine structure compound obtained by amination reaction is shown below:

[0070]

[0071] Among them, R is selected from

[0072] S3, reacting the diamine structure compound and maleic anhydride in a polar aprotic solvent at room temperature for 8-10 hours to obtain bismaleimide acid;

[0073] In the present application, the mass of the polar aprotic solvent is preferably at least 10 times the total mass of the diamine structure compound and maleic anhydride; the molar ratio of the diamine structure compound to maleic anhydride is preferably 1:2 to 1:2.5.

[0074] Among them, controlling the molar ratio of the diamine structure compound to maleic anhydride in the range of 1:2 to 1:2.5 can ensure that the reaction is carried out thoroughly, which is conducive to better connection of maleic anhydride to the diamine structure compound.

[0075] The chemical structure of the bismaleimide acid obtained in this step is shown below:

[0076]

[0077] Among them, R is selected from

[0078] S4, adding bismaleimide acid, a second catalyst and a dehydrating agent into a polar aprotic solvent to carry out a dehydration cyclization reaction at 45-55° C. to obtain a bismaleimide monomer.

[0079] In the present application, the second catalyst includes a catalyst and a promoter, wherein the catalyst includes any one of sodium acetate, zinc acetate, nickel acetate, cobalt acetate, magnesium chloride or magnesium sulfate, and the promoter includes triethylamine; the dehydrating agent can be any one of acetic anhydride, pyridine or isoquinoline.

[0080] In the present application, the molar ratio of the dehydrating agent to the bismaleimide acid is preferably 3 to 8:1; the molar ratio of the co-catalyst to the bismaleimide acid is preferably 0.5 to 5:1; and the corresponding relationship between the catalyst and the bismaleimide acid is preferably 0.5 to 5 g of the catalyst per mole of the bismaleimide acid.

[0081] The chemical structure of the bismaleimide monomer obtained in this step is as follows:

[0082]

[0083] Among them, R is selected from

[0084] The present application prepares bismaleimide monomer by combining a diamine structure compound and maleic anhydride to obtain bismaleimide acid, and performing a dehydration cyclization step of the bismaleimide acid. The reaction system is always in a homogeneous phase and no resinous viscous material is produced, so that the product yield is stable, the yield of the bismaleimide monomer is greatly improved, the preparation process is simple, and the product is easy to separate, has a high controllability, and has little pollution, and can meet the requirements of low-cost continuous production.

[0085] The bismaleimide monomer provided in the present application has an active double bond, has high cross-linking activity, and has a symmetrical structure, and can be used as a matrix for high-performance polymer-based composite materials. It can be used alone or with other organic monomers to prepare high-performance polymer materials. Based on its low dielectric constant, it can give polymer materials good dielectric properties and can be used to prepare dielectric polymer materials.

[0086] The present application is further described below by way of examples.

[0087] Example 1

[0088] This embodiment provides a method for preparing bismaleimide, comprising:

[0089] S1, add 0.01 mol of bisphenol F into a two-necked flask, then add 50 mL of N,N-dimethylformamide, then drop 0.021 mol of 2-chloro-5-nitrotrifluorotoluene, then add 0.03 mol of potassium carbonate, heat to 100 ° C and react for 8 hours to obtain a dinitro intermediate with a yield of 92%.

[0090] S2, add 0.01 mol of dinitro intermediate into a three-necked flask, then add 100 mL of ethanol and 0.55 g of palladium carbon catalyst (Pd / C, Pd loading is 5% of C mass), heat to 80°C under nitrogen atmosphere, drop 20 mL of hydrazine hydrate and react for 24 hours, filter while hot to obtain a diamino structure compound with a yield of 80%.

[0091] S3, add 0.02 mol of a diamine structure compound into a two-necked flask, then add 0.041 mol of maleic anhydride and 150 mL of acetone, react at room temperature for 8 h, and concentrate the reaction solution under reduced pressure to obtain bismaleimide acid with a yield of 85%.

[0092] S4, add 0.02 mol of bismaleimide acid, 0.02 mol of triethylamine and 200 mL of acetone into a two-necked flask, raise the temperature to 50°C and maintain it, add dropwise 0.08 mol of acetic anhydride and 0.06 g of sodium acetate, stir until the solution is transparent, react at a constant temperature for 6 hours, then cool to room temperature, pour into water and stir, filter to obtain a yellow precipitate, wash with water and NaHCO3 solution in turn, and dry the filter cake in vacuo to obtain a bright yellow bismaleimide monomer powder with a yield of 90% and a purity of 90%.

[0093] The H NMR spectrum of the bismaleimide monomer prepared in Example 1 is as follows: Figure 1 As shown, the NMR carbon spectrum is Figure 2 As shown. Figure 1 and Figure 2 It can be seen that bismaleimide is successfully prepared in Example 1. In addition, the yield of bismaleimide monomer in Example 1 reaches 90%, and the purity is 90%, which can be continuously produced at low cost.

[0094] The synthesis process of Example 1 is as follows:

[0095]

[0096] Example 2

[0097] The difference between Example 2 and Example 1 is that 2-chloro-5-nitrotrifluorotoluene is replaced by

[0098] The rest are the same as in Example 1.

[0099] The synthesis process of Example 2 is as follows:

[0100]

[0101] Example 3

[0102] The difference between Example 3 and Example 1 is that 2-chloro-5-nitrotrifluorotoluene is replaced by The rest are the same as in Example 1.

[0103] The synthesis process of Example 3 is as follows:

[0104]

[0105] Comparative Example 1

[0106] Commercially available bismaleimide monomer (Cas: 13676-54-5, brand: Macklin, purity / concentration: 98%).

[0107] The bismaleimide monomer prepared in Example 1 is mixed with bisphenol A type cyanate and diallyl bisphenol A in a molar ratio of 1:1:0.87, and hot-pressed and cured to obtain a dielectric polymer material, which is referred to as dielectric polymer material A.

[0108] The commercially available bismaleimide monomer of Comparative Example 1 was mixed with bisphenol A type cyanate and diallyl bisphenol A in a molar ratio of 1:1:0.87, and hot-pressed and cured to obtain a dielectric polymer material, which was recorded as dielectric polymer material B.

[0109] The dielectric parameters of dielectric polymer material A and dielectric polymer material B were measured, and the results are shown in Table 1.

[0110] Table 1 Test results of dielectric polymer material A and dielectric polymer material B

[0111]

[0112] As can be seen from Table 1, the dielectric constant of the polymer material prepared from the bismaleimide monomer of the present application is 3.2977 (1MHz) and the dielectric loss is 0.00892; the dielectric polymer material prepared from the commercially available bismaleimide monomer has a minimum dielectric constant of 4.3358 (1MHz) and a minimum dielectric loss of 0.01709. Compared with the dielectric polymer material prepared from the commercially available bismaleimide monomer, the bismaleimide monomer of the present application has a lower dielectric constant and dielectric loss, and has excellent dielectric properties.

[0113] Although the present application has been described in detail in general terms and in specific embodiments in this specification, it is obvious to those skilled in the art that some modifications or improvements may be made to the present application. Therefore, these modifications or improvements made without departing from the spirit of the present application are within the scope of protection claimed in the present application.

Claims

1. A bismaleimide monomer, characterized in that: Its chemical structure is shown in formula (1): Among them, R is selected from 2. The method for preparing the bismaleimide monomer according to claim 1, characterized in that: include: S1, dispersing bisphenol F and a halogenated nitrobenzene compound in a polar aprotic solvent, and heating the mixture under the action of an alkaline nucleophile to obtain a dinitro intermediate; S2, dispersing the dinitro intermediate and the first catalyst in an organic solvent, and performing an amination reaction under the action of hydrazine hydrate to obtain a diamine structure compound; S3, reacting the diamine structure compound and maleic anhydride in a polar aprotic solvent to obtain bismaleimide acid; S4, adding bismaleimide acid, a second catalyst and a dehydrating agent into a polar aprotic solvent to carry out a dehydration cyclization reaction to obtain a bismaleimide monomer.

3. The preparation method according to claim 2, characterized in that: The halogenated nitrobenzene compound is selected from any one of the following compounds:

4. The preparation method according to claim 2, characterized in that: The polar aprotic solvent includes any one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran or acetone; The alkaline nucleophile is potassium carbonate; and / or, The organic solvent includes any one of methanol, ethanol or isopropanol; The first catalyst is a palladium-carbon catalyst; and / or, The dehydrating agent includes any one of acetic anhydride, pyridine or isoquinoline; The second catalyst comprises a catalyst and a promoter, wherein the catalyst comprises any one of sodium acetate, zinc acetate, nickel acetate, cobalt acetate, magnesium chloride or magnesium sulfate; and the promoter comprises triethylamine.

5. The preparation method according to claim 2, characterized in that: In S1, the molar ratio of the halogenated nitrobenzene compound to bisphenol F is ≥ 2:1; the mass of the polar aprotic solvent is at least 10 times the mass of bisphenol F; In S2, the mass of the organic solvent is at least 10 times the mass of the dinitro intermediate; and the molar number of the first catalyst is 0.1-10% of the molar number of the dinitro intermediate.

6. The preparation method according to claim 2, characterized in that: In S3, The mass of the polar aprotic solvent is at least 10 times the total mass of the diamine structure compound and maleic anhydride; The molar ratio of the diamine structure compound to maleic anhydride is 1:2 to 1:2.

5.

7. The preparation method according to claim 2, characterized in that: In S4, The molar ratio of the dehydrating agent to the bismaleimidic acid is 3 to 8:1; The molar ratio of the catalyst promoter to the bismaleimide acid is 0.5-5:1; each mole of the bismaleimide acid corresponds to 0.5-5g of the catalyst.

8. The preparation method according to claim 2, characterized in that: In step S1, the reaction temperature is 80-130°C; In step S2, the temperature of the amination reaction is 75-85°C; In step S3, the reaction temperature is room temperature; In step S4, the temperature of the dehydration cyclization reaction is 45-55°C.

9. Use of the bismaleimide monomer according to claim 1 or the bismaleimide monomer prepared by the preparation method according to any one of claims 2 to 8 in the preparation of polymer-based composite materials.

10. Use of the bismaleimide monomer according to claim 1 or the bismaleimide monomer prepared by the preparation method according to any one of claims 2 to 8 in the preparation of dielectric polymer materials.

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