Ionic liquid modified epoxy resin, carbon fiber pultruded composite material and preparation method thereof

Abstract

An ionic liquid-modified epoxy resin and carbon fiber pultruded composite material and its preparation method relate to the field of composite material technology and address the issue of poor overall mechanical properties. The ionic liquid-modified epoxy resin comprises 100 parts epoxy resin, 0.1-3 parts ionic liquid, 105 parts curing agent, 2 parts accelerator, and 10 parts release agent. The ionic liquid and bisphenol A epoxy resin are mixed, stirred evenly, and then vacuumed. The curing agent is added at 80-100°C. The mixture is poured into a mold and cured at 120°C for 2 hours, 140°C for 2 hours, and 160°C for 2 hours. The carbon fiber epoxy resin composite material comprises 15-30 parts epoxy resin, 0.5 parts ionic liquid, 30-60 parts carbon fiber, and 10-20 parts aromatic amine curing agent; or alternatively, 100 parts epoxy resin, 1.0 part ionic liquid, 55-65 parts carbon fiber, 105 parts anhydride curing agent, 2.0 parts accelerator, and 10 parts release agent.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and in particular to an ionic liquid modified epoxy resin and carbon fiber pultruded composite material and a preparation method thereof. Background Art

[0002] Ionic liquids (ILs) are pure molten salts composed of positive and negative ion pairs of organic ions and inorganic counterions. They have attracted widespread attention in various manufacturing fields due to their good solubility, non-flammability, and excellent electrochemical stability.

[0003] Epoxy resin (EP) is widely used in aerospace, mechanical manufacturing, electronic engineering, and other fields due to its advantages such as low cost, chemical corrosion resistance, and excellent mechanical properties. One of the characteristics of epoxy resin is the adjustability of its molecular structure, which can adjust the applicability and functionality of the monomer. 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, have limited its development in many fields. In addition, it is very difficult to simultaneously improve the stiffness and toughness of epoxy resin.

[0004] Carbon fiber is a filamentous material with a diameter in the micron range. Its structure is composed of carbon atoms, with a carbon content of at least 92%. Compared with other synthetic fibers, carbon fiber has a more regular fiber structure and possesses both compressive and tensile physical and mechanical properties. It is a leader in structural applications. Most importantly, due to its high specific strength, the use of carbon fiber can make composite materials lighter. Carbon fiber is currently the most promising raw material for the manufacture of advanced structural composite materials. Its unique combination of properties, such as high strength and stiffness, good heat resistance, low density, and excellent thermal conductivity, has led to its widespread application in advanced composite materials, aircraft, and automotive parts.

[0005] Despite the aforementioned advantages, carbon fiber is often difficult to use alone and requires the preparation of composite materials to compensate for the deficiencies of its components. Carbon fiber composites use carbon fiber as the reinforcement, and the matrix can include resins, metals, ceramics, etc. Epoxy resin is the most widely used matrix. After curing, the resin itself also exhibits excellent mechanical properties, chemical resistance, and dimensional stability, making it one of the most important matrix materials in carbon fiber reinforced resin-based composites.

[0006] The molding process of different carbon fibers is very different, and the compatibility of the components of the composite material with the molding process is an important factor in determining the performance of the carbon fiber and whether it can be industrialized. Pultrusion technology is that the carbon fiber is drawn out from the creel under the action of traction, and then bundled through the creel, enters the open resin tank, and is fully impregnated with resin glue in the resin tank; the impregnated carbon fiber leaves the resin tank and enters the preforming mold, and then is cured by heating the mold. In the heated mold, the liquid carbon fiber / resin system begins to undergo a cross-linking reaction, and the resin gradually solidifies from the periphery to the center of the composite material. Under the action of the traction machine, the hot solid composite material comes out of the mold, is post-cured and air-cooled, and finally wound into a finished product on the winder. This realizes the continuous molding of carbon fiber bundles and their fabrics. The characteristics of this technology are simple process, mature process, fast molding speed and high production efficiency.

[0007] During the pultrusion process, epoxy resin carbon fiber composite materials are prone to problems such as high viscosity at room temperature, difficult to control gel time, strong adhesion to the mold, and small curing shrinkage, which can easily lead to product shedding and even blockage. At the same time, the modification process can easily deteriorate the resin / fiber interface bonding, thereby reducing the comprehensive mechanical properties of the composite material. Summary of the Invention

[0008] In order to solve the problem of poor comprehensive mechanical properties of existing materials, the present invention proposes an ionic liquid modified epoxy resin and carbon fiber pultruded composite material and a preparation method thereof.

[0009] An ionic liquid modified epoxy resin comprises the following components in parts by weight:

[0010] 100 parts of epoxy resin, 0.1 to 3 parts of ionic liquid, 105 parts of curing agent, 2 parts of accelerator, and 10 parts of release agent;

[0011] The structural formula of the ionic liquid is as follows:

[0012]

[0013] The ionic liquid can be prepared by the following method:

[0014] Under nitrogen atmosphere, 4-(bromomethyl)phenylboronic acid was dissolved in anhydrous ethanol, followed by addition of 1-(3-aminopropyl)imidazole, and the mixture was refluxed at 90°C for 20-24 hours;

[0015] The crude product is purified by precipitation using a mixed solution of ethyl acetate and ethanol, and the solvent is evaporated in vacuo to obtain a nitrogen- and boron-containing ionic liquid.

[0016] The reaction route is as follows:

[0017]

[0018] Preferably, the epoxy resin is bisphenol A epoxy resin.

[0019] Preferably, the curing agent is an acid anhydride curing agent.

[0020] Preferably, the anhydride curing agent is selected from one or a mixture of at least two of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, maleic anhydride, phthalic anhydride, and citric anhydride.

[0021] A method for preparing the above-mentioned ionic liquid modified epoxy resin comprises the following steps:

[0022] S1, mixing the IL monomer and bisphenol A epoxy resin according to parts by mass, stirring evenly and then vacuuming until there are no bubbles;

[0023] S2. Add curing agent at 80℃~100℃ and mix well;

[0024] S3. Pour the mixed sample into a preheated mold, and cure it at 120°C for 2 h, 140°C for 2 h, and 160°C for 2 h to obtain an ionic liquid modified epoxy resin material.

[0025] A carbon fiber pultruded composite material comprising the following components in parts by mass:

[0026] 15 to 30 parts of epoxy resin, 0.5 parts of ionic liquid, 30 to 60 parts of carbon fiber, and 10 to 20 parts of aromatic amine curing agent;

[0027] Or 100 parts of epoxy resin, 1.0 part of ionic liquid, 55-65 parts of carbon fiber, 105 parts of acid anhydride curing agent, 2.0 parts of accelerator, and 10 parts of release agent;

[0028] The structural formula of the ionic liquid is as follows:

[0029]

[0030] Preferably, the epoxy resin is bisphenol A epoxy resin.

[0031] Preferably, the aromatic amine curing agent is DDM.

[0032] Preferably, the anhydride curing agent is selected from one or a mixture of at least two of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, maleic anhydride, phthalic anhydride, and citric anhydride.

[0033] A method for preparing the carbon fiber pultruded composite material as described above, the method being implemented using a pultrusion molding device, the method comprising:

[0034] S1. Mix epoxy resin, ionic liquid, curing agent, accelerator and release agent in a uniform ratio and remove bubbles under vacuum;

[0035] S2. The pultrusion rate is set to 200 mm / min to 500 mm / min, the winding length is 0 m to 354 m, the traction force is 15 KN to 35 KN, the glue tank temperature is set to 40 ° C to 55 ° C, the sol temperature of the automatic glue dispensing machine is set to 36 ° C to 43 ° C, the temperature of the mold zone 1 of the pultrusion equipment is set to 140 ° C to 180 ° C, the temperature of the mold zone 2 is set to 160 ° C to 190 ° C, the temperature of the mold zone 3 is set to 160 ° C to 190 ° C, the temperature of the post-curing furnace zone 1 is set to 160 ° C to 190 ° C, the temperature of the post-curing furnace zone 2 is set to 140 ° C to 180 ° C, and the temperature of the post-curing furnace zone 3 is set to 140 ° C to 180 ° C, and the mixture is placed in the pultrusion machine for pultrusion to obtain a pultruded composite material.

[0036] Compared with the prior art, the present invention has the following specific beneficial effects:

[0037] 1. The modified epoxy resin and carbon fiber epoxy resin composite materials provided by the present invention both include nitrogen- and boron-containing ionic liquid components. The phenylboronic acid structure on the ionic liquid can form dynamic borate ester bonds with the epoxy resin. The dynamic covalent bonds can be broken, reconnected, or exchanged under certain conditions, providing the material with self-healing, reprocessing, and solid-state plasticity. In addition, the amino groups and imidazole structures in the ionic liquid can also promote curing, thereby simultaneously improving the overall mechanical properties of the material, resulting in a material with excellent performance.

[0038] 2. The present invention improves the wettability and adhesion of epoxy resin and carbon fiber by adding ionic liquid, and increases the curing speed, thereby improving the mechanical properties of carbon fiber composite materials; the pultrusion molding process provided by the present invention is easy to operate and the preparation method is simple, which is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is the infrared spectrum of the ionic liquid used in Example 1;

[0040] Figure 2 This is the XPS photoelectron spectrum of the ionic liquid C element used in Example 1;

[0041] Figure 3 This is the XPS photoelectron spectrum of the ionic liquid element B used in Example 1;

[0042] Figure 4 This is the XPS photoelectron spectrum of the ionic liquid N element used in Example 1. DETAILED DESCRIPTION

[0043] In order to make the technical solution of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the specification of the present invention. It should be noted that the following embodiments are only used to better understand the technical solution of the present invention and should not be understood as limiting the present invention.

[0044] The raw materials and equipment used in the present invention are all known products and are obtained by purchasing commercially available products.

[0045] Example 1.

[0046] (1) Preparation of ionic liquid modified epoxy resin:

[0047] 0.1 parts of ionic liquid monomer were added to 100 parts of bisphenol A epoxy resin, stirred evenly and then vacuumed. When there were no bubbles in the mixture in the vacuum, 105 parts of anhydride curing agent were added at 80°C and mixed evenly. The mold was preheated at 120°C for 20 minutes, and then the mixed sample was quickly poured into the preheated mold and cured at 120°C for 2 hours, 140°C for 2 hours, and 160°C for 2 hours to obtain an ionic liquid modified epoxy resin material.

[0048] The ionic liquid monomer was prepared by the following steps: 4-(bromomethyl)phenylboronic acid (0.4297 g, 2 mmol) was dissolved in anhydrous ethanol (15 ml) in a three-necked round-bottom flask under a nitrogen atmosphere, and 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 precipitated and purified with a mixed solution of ethyl acetate and ethanol, and the solvent was evaporated in vacuo to obtain a nitrogen- and boron-containing ionic liquid; the ionic liquid was vacuum-dried at 70°C for 12 h to obtain an IL monomer.

[0049] (2) Preparation of carbon fiber pultruded composite materials:

[0050] 100 parts of epoxy resin, 105 parts of anhydride curing agent, 2 parts of accelerator, 10 parts of release agent and 1.0 part of the above-mentioned ionic liquid monomer are fully stirred and mixed, and then placed in a vacuum oven to remove bubbles in the resin; 58 parts of carbon fiber are added and mixed evenly, the pultrusion rate is set to 350 mm / min, the winding length is 100 m, the traction machine pulling force is 25 KN, the glue tank temperature is set to 50 ° C, the automatic glue dispensing machine sol temperature is set to 40 ° C, the mold zone 1 temperature of the pultrusion molding equipment is set to 160 ° C, the mold zone 2 temperature is set to 180 ° C, the mold zone 3 temperature is set to 180 ° C, the post-curing furnace zone 1 temperature is set to 180 ° C, the post-curing furnace zone 2 temperature is set to 160 ° C, the post-curing furnace zone 3 temperature is set to 160 ° C, the mixture is placed in a pultrusion molding machine for pultrusion molding to obtain a pultruded carbon fiber epoxy resin composite material.

[0051] Example 2.

[0052] (1) Preparation of ionic liquid modified epoxy resin:

[0053] 0.5 parts of ionic liquid monomer were added to 100 parts of bisphenol A epoxy resin, stirred evenly and then vacuumed. When there were no bubbles in the mixture in the vacuum, 105 parts of anhydride curing agent were added at 80°C and mixed evenly. The mold was preheated at 120°C for 20 minutes, and then the mixed sample was quickly poured into the preheated mold and cured at 120°C for 2 hours, 140°C for 2 hours, and 160°C for 2 hours to obtain an ionic liquid modified epoxy resin material.

[0054] (2) Preparation of carbon fiber pultruded composite materials:

[0055] 100 parts of epoxy resin, 105 parts of anhydride curing agent, 2 parts of accelerator, 10 parts of release agent and 1.0 part of the above-mentioned ionic liquid monomer are fully stirred and mixed, and then placed in a vacuum oven to remove bubbles in the resin; 59 parts of carbon fiber are added and mixed evenly, the pultrusion rate is set to 350 mm / min, the winding length is 100 m, the traction machine pulling force is 25 KN, the glue tank temperature is set to 50°C, the automatic glue dispensing machine sol temperature is set to 40°C, the mold zone 1 temperature of the pultrusion equipment is set to 160°C, the mold zone 2 temperature is set to 180°C, the mold zone 3 temperature is set to 180°C, the post-curing furnace zone 1 temperature is set to 180°C, the post-curing furnace zone 2 temperature is set to 160°C, and the post-curing furnace zone 3 temperature is set to 160°C, and the mixture is placed in a pultrusion machine for pultrusion to obtain a pultruded carbon fiber epoxy resin composite material.

[0056] Example 3.

[0057] (1) Preparation of ionic liquid modified epoxy resin:

[0058] 1.0 part of ionic liquid monomer was added to 100 parts of bisphenol A epoxy resin, stirred evenly and then vacuumed. When there were no bubbles in the mixture in the vacuum, 105 parts of anhydride curing agent were added at 80°C and mixed evenly. The mold was preheated at 120°C for 20 minutes, and then the mixed sample was quickly poured into the preheated mold and cured at 120°C for 2 hours, 140°C for 2 hours, and 160°C for 2 hours to obtain an ionic liquid modified epoxy resin material.

[0059] (2) Preparation of carbon fiber pultruded composite materials:

[0060] 100 parts of epoxy resin, 105 parts of anhydride curing agent, 2 parts of accelerator, 10 parts of release agent and 1.0 part of the above-mentioned ionic liquid monomer are fully stirred and mixed, and then placed in a vacuum oven to remove bubbles in the resin; 60 parts of carbon fiber are added and mixed evenly, the pultrusion rate is set to 350 mm / min, the winding length is 100 m, the traction machine pulling force is 25 KN, the glue tank temperature is set to 50°C, the automatic glue dispensing machine sol temperature is set to 40°C, the mold zone 1 temperature of the pultrusion molding equipment is set to 160°C, the mold zone 2 temperature is set to 180°C, the mold zone 3 temperature is set to 180°C, the post-curing furnace zone 1 temperature is set to 180°C, the post-curing furnace zone 2 temperature is set to 160°C, and the post-curing furnace zone 3 temperature is set to 160°C, and the mixture is placed in a pultrusion molding machine for pultrusion molding to obtain a pultruded carbon fiber epoxy resin composite material.

[0061] Example 4.

[0062] (1) Preparation of ionic liquid modified epoxy resin:

[0063] 2.0 parts of ionic liquid monomer were added to 100 parts of bisphenol A epoxy resin, stirred evenly and then vacuumed. When there were no bubbles in the mixture in the vacuum, 105 parts of anhydride curing agent were added at 80°C and mixed evenly. The mold was preheated at 120°C for 20 minutes, and then the mixed sample was quickly poured into the preheated mold and cured at 120°C for 2 hours, 140°C for 2 hours, and 160°C for 2 hours to obtain an ionic liquid modified epoxy resin material.

[0064] (2) Preparation of carbon fiber pultruded composite materials:

[0065] 100 parts of epoxy resin, 105 parts of anhydride curing agent, 2 parts of accelerator, 10 parts of release agent and 1.0 part of the above-mentioned ionic liquid monomer are fully stirred and mixed, and then placed in a vacuum oven to remove bubbles in the resin; 61 parts of carbon fiber are added and mixed evenly, the pultrusion rate is set to 350 mm / min, the winding length is 100 m, the traction machine pulling force is 25 KN, the glue tank temperature is set to 50°C, the automatic glue dispensing machine sol temperature is set to 40°C, the mold zone 1 temperature of the pultrusion equipment is set to 160°C, the mold zone 2 temperature is set to 180°C, the mold zone 3 temperature is set to 180°C, the post-curing furnace zone 1 temperature is set to 180°C, the post-curing furnace zone 2 temperature is set to 160°C, and the post-curing furnace zone 3 temperature is set to 160°C. The mixture is placed in a pultrusion machine for pultrusion to obtain a pultruded carbon fiber epoxy resin composite material.

[0066] Example 5.

[0067] (1) Preparation of ionic liquid modified epoxy resin:

[0068] 3.0 parts of ionic liquid monomer were added to 100 parts of bisphenol A epoxy resin, stirred evenly and then vacuumed. When there were no bubbles in the mixture in the vacuum, 105 parts of anhydride curing agent were added at 80°C and mixed evenly. The mold was preheated at 120°C for 20 minutes, and then the mixed sample was quickly poured into the preheated mold and cured at 120°C for 2 hours, 140°C for 2 hours, and 160°C for 2 hours to obtain an ionic liquid modified epoxy resin material.

[0069] (2) Preparation of carbon fiber pultruded composite materials:

[0070] 100 parts of epoxy resin, 105 parts of anhydride curing agent, 2 parts of accelerator, 10 parts of release agent and 1.0 part of the above-mentioned ionic liquid monomer are fully stirred and mixed, and then placed in a vacuum oven to remove bubbles in the resin; 62 parts of carbon fiber are added and mixed evenly, the pultrusion rate is set to 350 mm / min, the winding length is 100 m, the traction machine pulling force is 25 KN, the glue tank temperature is set to 50 ° C, the automatic glue dispensing machine sol temperature is set to 40 ° C, the mold zone 1 temperature of the pultrusion molding equipment is set to 160 ° C, the mold zone 2 temperature is set to 180 ° C, the mold zone 3 temperature is set to 180 ° C, the post-curing furnace zone 1 temperature is set to 180 ° C, the post-curing furnace zone 2 temperature is set to 160 ° C, the post-curing furnace zone 3 temperature is set to 160 ° C, the mixture is placed in a pultrusion molding machine for pultrusion molding to obtain a pultruded carbon fiber epoxy resin composite material.

[0071] Example 6.

[0072] Preparation of carbon fiber pultrusion composite materials:

[0073] 30 parts of epoxy resin, 20 parts of DDM curing agent and 0.5 parts of the above-mentioned ionic liquid monomer are fully stirred and mixed, and then placed in a vacuum oven to remove bubbles in the resin; 60 parts of carbon fiber are added and mixed evenly, the pultrusion rate is set to 350 mm / min, the winding length is 100 m, the traction machine pulling force is 25 KN, the glue tank temperature is set to 50°C, the automatic glue dispensing machine sol temperature is set to 40°C, the mold zone 1 temperature of the pultrusion equipment is set to 160°C, the mold zone 2 temperature is set to 180°C, the mold zone 3 temperature is set to 180°C, the post-curing furnace zone 1 temperature is set to 180°C, the post-curing furnace zone 2 temperature is set to 160°C, the post-curing furnace zone 3 temperature is set to 160°C, the post-curing furnace zone 3 temperature is set to 160°C, the mixture is placed in a pultrusion machine for pultrusion molding to obtain a pultruded carbon fiber epoxy resin composite material.

[0074] The tensile properties, compressive properties, bending properties, interlaminar shear properties, etc. of the composite materials with different carbon fiber contents prepared in Examples 1-6 were tested respectively. The test results of various properties were obtained by calculation and are shown in Table 1. It can be seen that the comprehensive mechanical properties of the composite materials of the present invention are significantly improved, thereby improving the durability of the carbon fiber pultruded sheet in harsh environments.

[0075] Table 1

[0076]

[0077]

Claims

1. An ionic liquid modified epoxy resin, characterized in that Contains the following components in parts by mass: 100 parts of epoxy resin, 0.1 to 3 parts of ionic liquid, 105 parts of curing agent; The structural formula of the ionic liquid is as follows: The epoxy resin is bisphenol A epoxy resin.

2. The ionic liquid modified epoxy resin according to claim 1, characterized in that The curing agent is an acid anhydride curing agent.

3. The ionic liquid modified epoxy resin according to claim 2, characterized in that The acid anhydride curing agent is selected from one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, maleic anhydride, phthalic anhydride, and citric anhydride, or a mixture of at least two of them.

4. A method for preparing an ionic liquid modified epoxy resin according to any one of claims 1 to 3, characterized in that: The steps include: S1. Mix the ionic liquid and bisphenol A epoxy resin according to their mass fractions, stir evenly, and then evacuate until there are no bubbles. S2. Add curing agent at 80℃~100℃ and mix well; S3. Pour the mixed sample into a preheated mold, and cure it at 120°C for 2 h, 140°C for 2 h, and 160°C for 2 h to obtain an ionic liquid modified epoxy resin material.

5. A carbon fiber pultruded composite material, characterized in that: Contains the following components in parts by mass: 15-30 parts of epoxy resin, 0.5 parts of ionic liquid, 30-60 parts of carbon fiber, 10-20 parts of aromatic amine curing agent, 0 parts of accelerator, and 0 parts of release agent; Or 100 parts of epoxy resin, 1.0 part of ionic liquid, 55-65 parts of carbon fiber, 105 parts of acid anhydride curing agent, 2.0 parts of accelerator, and 10 parts of release agent; The structural formula of the ionic liquid is as follows:

6. The carbon fiber pultruded composite material according to claim 5, characterized in that: The epoxy resin is bisphenol A epoxy resin.

7. The carbon fiber pultruded composite material according to claim 5, characterized in that: The aromatic amine curing agent is DDM.

8. The carbon fiber pultruded composite material according to claim 5, characterized in that: The acid anhydride curing agent is selected from one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, maleic anhydride, phthalic anhydride, and citric anhydride, or a mixture of at least two of them.

9. A method for preparing a carbon fiber pultruded composite material according to any one of claims 5 to 8, characterized in that: The method is implemented using pultrusion equipment, and the method comprises: S1. Mix epoxy resin, ionic liquid, curing agent, accelerator and release agent in a uniform ratio and remove bubbles under vacuum; S2. Add carbon fibers in proportion and mix them evenly, set the pultrusion rate to 200 mm / min to 500 mm / min, the winding length to 0 m to 354 m, the traction force to 15 KN to 35 KN, the glue tank temperature to 40°C to 55°C, the sol temperature of the automatic glue dispensing machine to 36°C to 43°C, the temperature of the mold zone 1 of the pultrusion equipment to 140°C to 180°C, the temperature of the mold zone 2 to 160°C to 190°C, the temperature of the mold zone 3 to 160°C to 190°C, the temperature of the post-curing furnace zone 1 to 160°C to 190°C, the temperature of the post-curing furnace zone 2 to 140°C to 180°C, the temperature of the post-curing furnace zone 3 to 140°C to 180°C, and place the mixture in a pultrusion machine for pultrusion to obtain a pultruded composite material.

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