Preparation method of bismaleimide resin monomer

Abstract

The invention relates to the technical field of high-performance thermosetting resin, in particular to the field of IPC C07D207, and more particularly relates to a preparation method of a bismaleimide resin monomer. Comprising the following steps: S1, dissolving 4, 4-diaminodiphenyl methane and a carbonyl compound in toluene, and reacting to obtain an intermediate Schiff base; and S2, dropwise adding the intermediate Schiff base into a toluene solution of maleic anhydride, adding a catalyst, carrying out a heating reaction, and carrying out post-treatment. The invention provides a new thought for preparing bismaleimide series products, which has guiding significance for preparation of bismaleimide and reduces the use of a dehydrating agent; toluene and ketone or aldehyde compounds used in the reaction process can be recycled, and the process is more economical and green.

Description

Technical Field

[0001] The invention relates to the technical field of high-performance thermosetting resins, in particular to the field of IPC C07D207, and more specifically to a method for preparing a bismaleimide resin monomer. Background Art

[0002] Bismaleimide resin (BMI) is a kind of high-performance thermosetting resin, which is widely used in aerospace, electronics and other high-tech fields. Among them, bismaleimide 1000 (BMI1000), chemical name N, N'-4, 4'-diphenylmethane bismaleimide, is a kind of multi-purpose bifunctional compound, whose double bond has high electrophilicity, making it easy to react with a variety of nucleophilic reagents; due to its unique structure such as rigid high symmetry and no active hydrogen, it has many unique properties such as high temperature resistance, wear resistance, high dielectric, high strength, high weather resistance, etc., and is widely used in aerospace, electronics, insulation materials and other fields. At present, there are many methods for preparing bismaleimide in China, such as acetic anhydride dehydration closed loop method, thermal dehydration closed loop method, azeotropic dehydration closed loop method, which generally have many by-products, low yield, high waste liquid treatment cost and other problems. Therefore, it is imperative to find a preparation method that is more economical and greener than the traditional method.

[0003] Chinese invention patent CN118754839A discloses a bismaleimide monomer and its preparation method and application. The bismaleimide acid is obtained by combining a diamine structure compound with maleic anhydride, and the bismaleimide acid is dehydrated and cyclized to greatly improve the yield of the bismaleimide monomer. However, there are disadvantages such as a large number of by-products and complex purification. Summary of the invention

[0004] The present invention provides a method for preparing a bismaleimide resin monomer, and the preparation reaction formula is shown in Formula 1:

[0005]

[0006] Formula 1; wherein R1 and R2 both include one of H, linear C1-C8 alkyl, branched C1-C8 alkyl, phenyl, halogen-substituted phenyl and alkyl-substituted phenyl.

[0007] The preparation method of the bismaleimide resin monomer comprises the following steps:

[0008] S1, dissolving 4,4-diaminodiphenylmethane and a carbonyl compound in toluene, and reacting them to obtain an intermediate Schiff base;

[0009] S2, dropping the intermediate Schiff base into a toluene solution of maleic anhydride, adding a catalyst, heating for reaction, and obtaining the product through post-treatment.

[0010] The carbonyl compound includes a ketone compound or an aldehyde compound.

[0011] Preferably, the ketone compound includes one of methyl isobutyl ketone, methyl ethyl ketone, cyclopentanone and cyclohexanone.

[0012] Preferably, the aldehyde compound includes one of benzaldehyde, 4-chlorobenzaldehyde and p-tolualdehyde.

[0013] More preferably, the carbonyl compound is benzaldehyde.

[0014] The reaction temperature in S1 is 100-180°C.

[0015] Preferably, the reaction temperature in S1 is 120-180°C.

[0016] More preferably, the reaction temperature in S1 is 140°C.

[0017] The catalyst includes an acid catalyst.

[0018] Preferably, the acid catalyst comprises at least one of acetic acid, sulfuric acid, phosphoric acid, p-toluenesulfonic acid and methanesulfonic acid.

[0019] Further preferably, the acid catalyst comprises p-toluenesulfonic acid.

[0020] The molar ratio of maleic anhydride to catalyst is 1:(0.001-0.1).

[0021] Preferably, the molar ratio of maleic anhydride to catalyst is 1:(0.001-0.01).

[0022] Further preferably, the molar ratio of maleic anhydride to catalyst is 1:0.005.

[0023] The molar ratio of the 4,4-diaminodiphenylmethane to maleic anhydride is 1:(2-3).

[0024] Preferably, the molar ratio of 4,4-diaminodiphenylmethane to maleic anhydride is 1:(2-2.5).

[0025] Further preferably, the molar ratio of 4,4-diaminodiphenylmethane to maleic anhydride is 1:2.2.

[0026] The applicant has found that the introduction of the intermediate Schiff base can recycle the reaction solvent toluene and the ketone or aldehyde compounds involved in the reaction, while reducing the use of dehydrating agents and the use of reaction solvents, thereby reducing manufacturing costs. Aldehyde or ketone compounds (containing carbonyl groups) and amine compounds (primary amines) undergo nucleophilic addition reactions. In this reaction, the amine compound acts as a nucleophilic reagent, and the nitrogen atom with a lone electron pair in its structure attacks the carbon atom with a positive charge on the carbonyl group to complete the nucleophilic addition reaction, and the Schiff base can be decomposed back to the original aldehyde or ketone and amine.

[0027] The dropping time is 0.3-1.5h.

[0028] Preferably, the dropping time is 0.5-1h.

[0029] More preferably, the dropping time is 0.8 h.

[0030] The reaction temperature in S2 is 100-180°C and the reaction time is 2-5h.

[0031] Preferably, the reaction temperature in S2 is 120-180° C. and the reaction time is 3-4 h.

[0032] Further preferably, the reaction temperature in S2 is 140° C. and the reaction time is 3.5 h.

[0033] The post-treatment comprises: adding methanol after reduced pressure distillation, beating and filtering in sequence to obtain a filter cake, washing the filter cake with methanol, sodium bicarbonate aqueous solution and aqueous solution respectively, and drying the obtained solid.

[0034] Preferably, the post-treatment includes: distillation under reduced pressure, collecting toluene and benzaldehyde separately, adding 180g of methanol after evaporation, beating for 10 minutes, filtering, washing the filter cake with methanol, sodium bicarbonate aqueous solution and aqueous solution respectively, and drying the obtained solid. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the infrared spectrum of diphenylmethane bismaleimide prepared in Example.

[0036] Figure 2 This is the H-NMR spectrum of diphenylmethane bismaleimide prepared in Example.

[0037] Figure 3 This is the carbon NMR spectrum of diphenylmethane bismaleimide prepared in Example.

[0038] Figure 4 This is the thermal analysis diagram of diphenylmethane bismaleimide prepared in Example.

[0039] Figure 5The HPLC spectrum of diphenylmethane bismaleimide prepared in Example 1 is shown.

[0040] Beneficial Effects

[0041] 1. The present application introduces the intermediate Schiff base, which can recycle the reaction solvent toluene and the ketone or aldehyde compounds involved in the reaction, while reducing the use of dehydrating agents and the use of reaction solvents, thereby reducing manufacturing costs.

[0042] 2. The acid catalyst includes p-toluenesulfonic acid, and the molar ratio of maleic anhydride to the catalyst is 1:(0.001-0.1), which can increase the product yield and improve the post-processing efficiency.

[0043] 3. By limiting the reaction temperature in S1 to 100-180°C, the reaction efficiency can be improved while reducing the degree of side reactions, and the yield is greater than 85%.

[0044] 4. By limiting the molar ratio of 4,4-diaminodiphenylmethane to maleic anhydride to 1:(2-3), the purity of the product can be increased to 97%.

[0045] 5. The preparation method of the present application is simple and can be applied to industrial continuous production. DETAILED DESCRIPTION

[0046] Example 1

[0047] A method for preparing a bismaleimide resin monomer, wherein the reaction formula for the preparation is shown in Formula 2:

[0048]

[0049] Formula 2; wherein R1 is H and R2 is phenyl.

[0050] The specific preparation steps are as follows:

[0051] Benzaldehyde (10.61 g, 0.1 mol), 4,4-diaminodiphenylmethane (19.8 g, 0.1 mol) and 99 g toluene were placed in a 250 mL four-necked flask equipped with a stirring device, a thermometer, a water separator and a condenser, the temperature was raised to 140°C, water was separated, and after reacting for 2 h, the temperature was lowered to room temperature (25°C) to obtain a Schiff base intermediate solution; maleic anhydride (21.1 g, 0.22 mol) was dissolved in 105.5 g toluene, and the Schiff base intermediate solution was added dropwise to the maleic anhydride solution using a constant pressure dropping funnel for 0.8 h, 0.2 g of p-toluenesulfonic acid was added, the reaction mixture was reacted at 140°C for 3.5 h, and then cooled to room temperature. The mixture was distilled under reduced pressure to collect toluene and benzaldehyde respectively, evaporated to dryness, 180 g of methanol was added, the mixture was slurried for 10 minutes, and filtered, the filter cake was washed with methanol, sodium bicarbonate aqueous solution and water respectively, and the obtained solid was dried to obtain the product diphenylmethane bismaleimide, with a product yield of 85.46%.

[0052] Performance testing methods and data

[0053] The diphenylmethane bismaleimide prepared in Example 1 was subjected to infrared, H-NMR and C-NMR detection.

[0054] like Figure 1 As shown, the infrared spectrum can confirm the amide group in diphenylmethane bismaleimide, such as Figure 2 As shown, 1 H NMR (600MHz, CDCl3) δ7.33–7.24(m,8H),6.84(s,4H),4.04(s,2H); 13 C NMR (151MHz,CDCl3)δ169.59,140.40,134.22,129.75,129.42,126.21,41.09, combined Figure 3 Carbon spectrum can confirm the synthesis of diphenylmethane bismaleimide. Figure 4 ) obtained a melting point of 161.8°C. The diphenylmethane bismaleimide prepared in Example 1 was tested for content (HPLC). Figure 5 As shown, the purity calculated by area normalization method reached 97.64%.

Claims

1. A method for preparing a bismaleimide resin monomer, characterized in that: The reaction formula of the preparation is shown in Formula 1: Formula 1; wherein R1 and R2 both include one of H, linear C1-C8 alkyl, branched C1-C8 alkyl, phenyl, halogen-substituted phenyl and alkyl-substituted phenyl.

2. The method for preparing a bismaleimide resin monomer according to claim 1, characterized in that: The following steps are involved: S1, dissolving 4,4-diaminodiphenylmethane and a carbonyl compound in toluene, and reacting them to obtain an intermediate Schiff base; S2, dropping the intermediate Schiff base into a toluene solution of maleic anhydride, adding a catalyst, heating for reaction, and obtaining the product through post-treatment.

3. The method for preparing the bismaleimide resin monomer according to claim 2, characterized in that: The carbonyl compound includes a ketone compound or an aldehyde compound.

4. The method for preparing the bismaleimide resin monomer according to claim 3, characterized in that: The ketone compound includes one of methyl isobutyl ketone, methyl ethyl ketone, cyclopentanone and cyclohexanone.

5. The method for preparing the bismaleimide resin monomer according to claim 2 or 3, characterized in that: The aldehyde compound includes one of benzaldehyde, 4-chlorobenzaldehyde and p-methylbenzaldehyde.

6. The method for preparing the bismaleimide resin monomer according to claim 5, characterized in that: The reaction temperature in S1 is 100-180°C.

7. The method for preparing the bismaleimide resin monomer according to claim 6, characterized in that: The catalyst includes an acid catalyst including at least one of acetic acid, sulfuric acid, phosphoric acid, p-toluenesulfonic acid and methanesulfonic acid.

8. The method for preparing the bismaleimide resin monomer according to claim 7, characterized in that: The molar ratio of maleic anhydride to catalyst is 1:(0.001-0.1).

9. The method for preparing the bismaleimide resin monomer according to claim 8, characterized in that: The molar ratio of the 4,4-diaminodiphenylmethane to maleic anhydride is 1:(2-3).

10. The method for preparing the bismaleimide resin monomer according to claim 9, characterized in that: The dropping time is 0.3-1.5h.

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