An ionic liquid, an ionic liquid-modified epoxy resin material, and a preparation method thereof

Abstract

The application discloses an ionic liquid, an ionic liquid modified epoxy resin material and a preparation method thereof, relates to the technical field of epoxy resin modification, and realizes the improvement of the rigidity and toughness of the epoxy resin. The preparation method of the ionic liquid comprises the following steps: 4-(bromomethyl)phenylboronic acid is dissolved in a solvent under a nitrogen atmosphere, then 1-(3-aminopropyl)imidazole is added, and reflux reaction is carried out at a specific temperature; a mixed solution of ethyl acetate and ethanol is used to precipitate and purify a crude product, and a solvent is evaporated in vacuum to obtain a nitrogen and boron-containing ionic liquid. The ionic liquid modified epoxy resin material comprises 100 parts of an epoxy resin, 0.1 parts to 1 part of an IL monomer and 20 parts of a curing agent. The IL monomer and bisphenol A epoxy resin are mixed, uniformly stirred, and vacuumized until no bubbles are generated; the curing agent is added and uniformly mixed; the mixed sample is poured into a preheated mold, is cured, and the ionic liquid modified epoxy resin material is prepared.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of epoxy resin modification, and in particular to an ionic liquid, an ionic liquid modified epoxy resin material and a preparation method thereof. BACKGROUND

[0002] Ionic liquids (ILs) are pure molten salts composed of organic cations and inorganic counter anions due to their good solubility, non-flammability and excellent electrochemical stability, which have attracted extensive attention in various manufacturing fields.

[0003] Epoxy resins (EP) are widely used in aerospace, mechanical manufacturing, electronic engineering, etc. due to their low cost, chemical corrosion resistance, excellent mechanical properties, etc. One of the characteristics of epoxy resins is the adjustability of molecular structure, which can adjust the applicability and functionality of monomers. However, the inherent disadvantages of cured epoxy resin systems, such as brittleness or lack of crack propagation resistance caused by high crosslinking density and strong covalent network, limit their development in many fields. And it is very difficult to simultaneously improve the stiffness and toughness of epoxy resins.

[0004] Many methods for modifying epoxy resins have been proposed in existing research. For example, patent document CN112961468A provides a modified epoxy resin composite material and a manufacturing method thereof, which uses polyether sulfone and silicon dioxide for modification to improve the mechanical properties of epoxy resins, but the preparation process is complex and difficult to realize large-scale production and application; patent document CN115490996A uses graphene and epoxy resin to prepare a composite material, which realizes the uniform dispersion of graphene in the composite material matrix, but the improvement of the mechanical properties of the composite material is not obvious, which is difficult to meet the use requirements of high-performance epoxy composites.

[0005] In summary, how to simultaneously improve the stiffness and toughness of epoxy composites has become a technical problem to be solved in the field. SUMMARY

[0006] In order to simultaneously improve the stiffness and toughness of epoxy resins, the present application provides an ionic liquid, an ionic liquid modified epoxy resin material and a preparation method thereof.

[0007] The technical solutions of the present application are as follows:

[0008] An ionic liquid has the following structural formula:

[0009]

[0010] A preparation method of the above ionic liquid, comprising the following steps:

[0011] Dissolve 4-(bromomethyl)phenylboronic acid in a solvent under nitrogen atmosphere, then add 1-(3-aminopropyl)imidazole, and reflux the reaction at a specific temperature;

[0012] Purify the crude product by precipitating with a mixed solution of ethyl acetate and ethanol, and evaporate the solvent under vacuum to obtain the nitrogen-containing and boron-containing ionic liquid.

[0013] The reaction scheme is as follows:

[0014]

[0015] Preferably, the solvent is anhydrous ethanol.

[0016] Preferably, the specific temperature is 90℃.

[0017] Preferably, the reflux reaction time is 20h-24h.

[0018] An ionic liquid modified epoxy resin material comprises the following components by mass fraction:

[0019] Epoxy resin 100 parts, IL monomer 0.1-1 part, curing agent 20 parts;

[0020] Preferably, the IL monomer is obtained by vacuum drying the above-mentioned ionic liquid.

[0021] Preferably, the epoxy resin is a bisphenol A type epoxy resin.

[0022] Preferably, the curing agent is DDM.

[0023] A preparation method of the above-mentioned ionic liquid modified epoxy resin material, comprising the following steps:

[0024] S1. Mix the IL monomer and bisphenol A epoxy resin according to the mass fraction, stir until uniform, and then vacuumize until no bubbles are generated;

[0025] S2. Add the curing agent at 80-100℃ and mix until uniform;

[0026] S3. Pour the mixed sample into a preheated mold, and sequentially cure at 120℃ for 2h, at 140℃ for 2h, and at 160℃ for 2h to obtain the ionic liquid modified epoxy resin material.

[0027] Compared with the prior art, the present application has the following specific advantages:

[0028] 1.The present application provides a preparation method of nitrogen and boron ion liquid and epoxy resin composite material, the phenylboronic acid structure in the ion liquid can form a dynamic borate ester bond with the epoxy resin, under certain conditions, the dynamic covalent bond can be broken, reconnected or exchanged, providing self-healing, reprocessing and solid plasticity for the material; the amino group and imidazole structure in the ion liquid can also promote curing, thereby simultaneously improving the stiffness, toughness and transparency of the epoxy composite material, obtaining a material with excellent performance;

[0029] 2.The preparation method of the ion liquid and the modified epoxy resin provided by the present application is simple, easy to operate and suitable for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is the infrared spectrum of the ion liquid prepared in Example 1;

[0031] Figure 2 It is the XPS photoelectron spectrum of the C element of the ion liquid prepared in Example 1;

[0032] Figure 3 It is the XPS photoelectron spectrum of the B element of the ion liquid prepared in Example 1;

[0033] Figure 4 It is the XPS photoelectron spectrum of the N element of the ion liquid prepared in Example 1;

[0034] Figure 5 It is a comparison chart of the bending strength test results of the modified epoxy resin with different contents of ion liquid;

[0035] Figure 6 It is a comparison chart of the tensile property test results of the modified epoxy resin with different contents of ion liquid;

[0036] Figure 7 It is a comparison chart of the impact strength test results of the modified epoxy resin with different contents of ion liquid. DETAILED DESCRIPTION

[0037] In order to make the technical solutions of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings of the specification of the present application. It should be noted that the following embodiments are only used to better understand the technical solutions of the present application, and should not be understood as a limitation of the present application.

[0038] The raw materials and equipment used in the following embodiments can be obtained by purchasing commercially available products.

[0039] Example 1.

[0040] (1) Ion liquid preparation:

[0041] In a three-necked round bottom flask, 4-(bromomethyl)phenylboronic acid (0.4297 g, 2 mmol) was dissolved in anhydrous ethanol (15 ml) under nitrogen atmosphere, then 1-(3- aminopropyl)imidazole (0.281 ml, 2.5 mmol) was added to the above solution and refluxed at 90°C for 24 h; the crude product was purified by precipitation with a mixture of ethyl acetate and ethanol, and the solvent was evaporated under vacuum to obtain the IL monomer.

[0042] The IL monomer was vacuum dried at 70°C for 12 h.

[0043] (2) Preparation of IL modified epoxy resin material:

[0044] 0.1 part of the prepared IL monomer was added to 100 parts of bisphenol A epoxy resin, and after stirring evenly, vacuum was applied, when there was no bubble in the mixture under vacuum, 20 parts of molten diamino diphenyl methane (DDM) was mixed evenly at 80°C; the mold was preheated at 120°C for 20 min, the mixed sample was quickly poured into the mold, and was successively cured at 120°C for 2 h, at 140°C for 2 h, and at 160°C for 2 h to obtain the IL modified epoxy resin material.

[0045] Example 2.

[0046] (1) Preparation of IL: same as Example 1.

[0047] (2) Preparation of IL modified epoxy resin material:

[0048] The amount of IL monomer was 0.5 parts, and the rest was the same as Example 1.

[0049] Example 3.

[0050] (1) Preparation of IL: same as Example 1.

[0051] (2) Preparation of IL modified epoxy resin material:

[0052] The amount of IL monomer was 1.0 parts, and the rest was the same as Example 1.

[0053] Example 4.

[0054] (1) Preparation of IL: same as Example 1.

[0055] (2) Preparation of IL modified epoxy resin material:

[0056] The amount of IL monomer was 2.0 parts, and the rest was the same as Example 1.

[0057] Example 5.

[0058] (1) Preparation of IL: same as Example 1.

[0059] (2) Preparation of the IL-modified epoxy resin material:

[0060] The amount of IL monomer was 3.0 parts, and the rest was the same as in Example 1.

[0061] Example 1.

[0062] The structure and element of 4-(bromomethyl)phenylboronic acid (PBA), 1-(3- aminopropyl)imidazole (NH2-MZ) and the IL prepared in Example 1 were characterized, and the infrared spectrum thereof is shown in Figure 1 From the figure, it can be seen that PBA has main characteristic peaks at 1350 cm -1 (B-O), 1407 cm -1 (C-B) and 1613 cm -1 , which are the vibration peaks of the aromatic ring skeleton. For NH2-MZ, 960 cm -1 (=C-H), 1510 cm -1 (C-N) and 1581 cm -1 (C=N) are the stretching vibrations of the imidazole ring, respectively. All the above characteristic peaks can be observed in PBA-IL, and there is a certain shift. It can be proved that Example 1 proceeds according to the expected reaction route, and the nitrogen and boron-containing IL is successfully synthesized.

[0063] The XPS photoelectron spectrum of the C element of the IL is shown in Figure 2 , the XPS photoelectron spectrum of the B element is shown in Figure 3 , and the XPS photoelectron spectrum of the N element is shown in Figure 4 .

[0064] Example 2.

[0065] The bending strength of the E51 epoxy resin and the IL-modified epoxy resin materials with different contents prepared in Examples 1-5 was tested, and the comparison results are shown in Figure 5 .

[0066] The tensile properties of the E51 epoxy resin and the IL-modified epoxy resin materials with different contents prepared in Examples 1-5 were tested, and the comparison results are shown in Figure 6 .

[0067] The impact strength of the E51 epoxy resin and the IL-modified epoxy resin materials with different contents prepared in Examples 1-5 was tested, and the comparison results are shown in Figure 7 .

[0068] Through the above test, it can be seen that the modified epoxy composite prepared under the condition of low addition of ionic liquid has significantly improved bending strength, elongation at break and impact strength compared with ordinary E51 epoxy resin on the market.

Claims

1. An ionic liquid-modified epoxy resin material, characterized by, The composition comprises the following components by mass fraction: 100 parts of epoxy resin, 0.1-1 parts of IL monomer, and 20 parts of curing agent; the IL monomer is obtained by vacuum drying of an ionic liquid; The structural formula of the ionic liquid is as follows: ； The epoxy resin is a bisphenol A type epoxy resin; The curing agent is a diamino diphenyl methane.

2. A method of producing the ionic liquid-modified epoxy resin material according to claim 1, characterized by, The method comprises the following steps: S1. mixing the IL monomer and the bisphenol A epoxy resin according to the mass fraction, stirring until uniform, and then vacuumizing until no bubbles are generated; S2. adding the curing agent at 80-100 DEG C and mixing until uniform; S3. pouring the mixed sample into a preheated mold, and sequentially curing at 120 DEG C for 2 h, at 140 DEG C for 2 h, and at 160 DEG C for 2 h to obtain an ionic liquid modified epoxy resin material.

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