CN116675954A - A kind of phosphorous, nitrogen-containing ionic liquid/epoxy resin composite material and preparation method thereof - Google Patents

Abstract

A phosphorus and nitrogen-containing ionic liquid/epoxy resin composite material and a preparation method thereof relate to the technical field of composite materials, realize improvement of mechanical properties and flame retardance of epoxy composite materials, simplify the process and realize mass production. The phosphorus and nitrogen-containing ionic liquid/epoxy resin composite material comprises: 1-3 parts of phosphorus-nitrogen-containing ionic liquid, 100 parts of epoxy resin and 25 parts of curing agent. Dissolving phenylphosphoric acid in a solvent at room temperature, dropwise adding 1-ethylimidazole into the phenylphosphoric acid solution under magnetic stirring for reaction, and then removing the solvent by rotary evaporation and vacuum drying the solution to obtain yellowish transparent phosphorus and nitrogen-containing ionic liquid; uniformly mixing epoxy resin and a curing agent at a specific temperature, adding the phosphorus-nitrogen-containing ionic liquid, uniformly stirring again, vacuumizing, rapidly pouring the mixed sample into a preheated mold, and heating and curing to obtain the phosphorus-nitrogen-containing ionic liquid/epoxy resin composite material.

Description

A kind of phosphorous, nitrogen-containing ionic liquid/epoxy resin composite material and preparation method thereof

technical field

The invention relates to the technical field of composite materials, in particular to a phosphorous and nitrogen-containing ionic liquid/epoxy resin composite material and a preparation method thereof.

Background technique

Ionic liquid (IL) is a new type of green material, which is widely used in various manufacturing fields due to its good thermal stability, high gas solubility and non-flammability, and ionic liquid has made remarkable achievements in enhancing the performance of polymers. Achievement.

Epoxy resin (EP) is a three-dimensional network structure thermosetting polymer formed by the reaction of epoxy prepolymer and curing agent, because of its low volume shrinkage, strong adhesion, good chemical stability, high mechanical strength, and It is easy to process and shape, and can be used as adhesives, coatings or resin-based composite materials, etc., and is widely used in aerospace, automotive industry, electronics, electrical and civil construction and other fields. However, EP is usually brittle but not tough enough, and the inherent flammability of EP threatens human safety, which greatly limits the use of EP in many fields. Therefore, it is imperative to improve the flame retardancy and mechanical properties of EP.

Many methods for modifying epoxy resins have been proposed in existing studies. For example, in the patent document CN114891227A "Preparation Method of a Halogen-Free Flame-Retardant Modified Epoxy Resin" (published on August 12, 2022), the phosphorus-containing cage oligosilsesquioxane DOPO-POSS, bis Preparation of halogen-free flame retardant modified epoxy resin with phenol A epoxy vinyl ester slurry and curing agent, which improves the flame retardant efficiency of epoxy resin, but affects the mechanical properties of epoxy composites, limiting its application in many fields . Patent document CN115894860A "A Hyperbranched Flame Retardant Epoxy Resin and Its Prepared Epoxy Resin Composition" (published on August 12, 2022) discloses a hyperbranched flame retardant epoxy resin and its epoxy resin Although the preparation method of the composition improves the thermal and mechanical properties of the epoxy resin, the preparation process is complex and the addition amount is large, making it difficult to achieve large-scale production.

To sum up, how to simultaneously improve the mechanical properties and flame retardancy of epoxy composites, simplify the process, and achieve mass production has become an urgent technical problem in this field.

Contents of the invention

In order to simultaneously improve the mechanical properties and flame retardancy of the epoxy composite material, simplify the process, and realize large-scale production, the present invention proposes a phosphorous and nitrogen-containing ionic liquid/epoxy resin composite material and a preparation method thereof.

The present invention firstly provides a kind of phosphorus-containing, nitrogen-containing ionic liquid/epoxy resin composite material, comprising the components in parts by mass:

1~3 parts of ionic liquid containing phosphorus and nitrogen, 100 parts of epoxy resin, 25 parts of curing agent;

Wherein, the structural formula of the phosphorus-containing and nitrogen-containing ionic liquid is as follows:

.

Preferably, the epoxy resin is bisphenol A epoxy resin.

Preferably, the curing agent is an amine curing agent or an acid anhydride curing agent.

The present invention also provides a kind of preparation method of above-mentioned phosphorus-containing, nitrogen-containing ionic liquid/epoxy resin composite material, comprising the following steps:

S1. Dissolve phenylphosphoric acid in a solvent at room temperature to obtain a phenylphosphoric acid solution. Add 1-ethylimidazole dropwise to the phenylphosphoric acid solution under magnetic stirring to react, then rotate the solution to remove the solvent and dry it in vacuum. , to obtain a light yellow transparent liquid, that is, phosphorus and nitrogen-containing ionic liquid;

S2. Mix the epoxy resin and curing agent evenly at a specific temperature, then add the phosphorous and nitrogen-containing ionic liquid obtained in step S1, stir again and then vacuumize. When the mixture has no bubbles in the vacuum, quickly mix the sample Pour it into a preheated mold for heating and curing to obtain a phosphorous and nitrogen-containing ionic liquid/epoxy resin composite material.

Preferably, the molar ratio of phenylphosphoric acid to 1-ethylimidazole is 1:2.

Preferably, the solvent described in step S1 is absolute ethanol.

Preferably, the temperature of the rotary evaporation is 30°C-120°C; the temperature of the vacuum drying is 20°C-60°C.

Preferably, the reaction time in step S1 is 1h~6h.

Preferably, the specific temperature in step S2 is 80°C-100°C.

Preferably, the preheating temperature is 120°C, and the preheating time is 20 minutes; the heat curing is specifically: curing at 120°C for 2 hours, then raising the temperature to 150°C for another 2 hours.

Compared with prior art, concrete beneficial effect of the present invention is:

1. The present invention provides a kind of phosphorus-containing, nitrogen-containing ionic liquid/epoxy resin composite material, wherein the imidazole structure in phosphorus-containing, nitrogen-containing ionic liquid can play the effect of promoting curing, and simultaneously, epoxy resin breakage is accompanied by on the molecular scale The destruction and regeneration of a series of ionic bonds leads to a large amount of energy dissipation and enhanced fracture toughness. Compared with ordinary E51 epoxy resins on the market, its flexural strength, flexural modulus, elongation at break, impact strength and flame retardancy have significantly improved;

2. Phosphorus and nitrogen elements in ionic liquids containing phosphorus and nitrogen will generate phosphorus oxygen radicals and nitrogen gas when the epoxy resin composite material is burned, which will quench the flame and achieve excellent flame retardancy;

3. The preparation method provided by the invention is simple and easy to operate, and is suitable for large-scale industrial production.

Description of drawings

Fig. 1 is the infrared spectrogram of the ionic liquid that embodiment 1 makes;

Fig. 2 is the proton nuclear magnetic resonance spectrogram of the ionic liquid that embodiment 1 makes;

Fig. 3 is the XPS figure of the ionic liquid that embodiment 1 makes;

Fig. 4 is the histogram of flexural strength of different phosphorus-containing and nitrogen-containing ionic liquids/epoxy resin composites;

Fig. 5 is the histogram of flexural modulus of different content containing phosphorus, nitrogen ionic liquid/epoxy resin composite material;

Fig. 6 is the stress-strain curve figure of different content containing phosphorus, nitrogen ionic liquid/epoxy resin composite material;

Fig. 7 is a histogram of the impact strength of different phosphorus-containing and nitrogen-containing ionic liquids/epoxy resin composites;

Fig. 8 is the SEM image of the impact test fracture surface of different contents of phosphorous and nitrogen ionic liquid/epoxy resin composites;

Fig. 9 is the histogram of the flexural strength of the phosphorus-containing and nitrogen-containing ionic liquid/epoxy resin carbon fiber composite material sample of different contents;

Fig. 10 is a histogram of flexural modulus of ionic liquid/epoxy resin carbon fiber composite material samples with different contents of phosphorus and nitrogen.

Detailed ways

In order to make the technical solution of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. It should be noted that the following examples are only for better understanding The technical solution of the present invention should not be construed as a limitation of the present invention.

Example 1.

S1. Dissolve 0.01mol phenylphosphoric acid (PPA) in the solvent at room temperature to obtain a phenylphosphoric acid solution, add 0.02mol 1-ethylimidazole (MZ) dropwise to the phenylphosphoric acid solution under magnetic stirring to react, and then The solution was evaporated at 60°C to remove the solvent, and dried in vacuum at 60°C for 1 hour to obtain a light yellow and transparent phosphorus- and nitrogen-containing ionic liquid (PIL);

Fig. 1 is the infrared spectrogram of PPA, MZ and PIL described in the present embodiment, can see, PPA appears characteristic peak at 1439cm ^-1 , 1144cm- ¹ , 938cm ^-1 place, belongs to P-Ph respectively, P= The stretching vibration of O and P-OH; the characteristic peaks of MZ at 1647cm ^-1 and 1512cm ^-1 are attributed to the stretching vibration of the imidazole ring; in the infrared spectrum of the synthesized PIL, the original P-OH disappears and the new 1545 NH ⁺ at , which proves the successful synthesis of PIL. Fig. 2 is the proton nuclear magnetic resonance spectrogram of the PIL that the present embodiment makes, and the signal peak at about 8.07ppm place among the figure is the signal peak of NH ⁺ , except that, the chemical shift and integral area of all other signal peaks and PIL The proton correspondence of the chemical structure. According to the above results and analysis, it can be shown that the target compound was successfully synthesized. Fig. 3 is the X-ray photoelectron energy spectrogram of the PIL that the present embodiment makes, and spectrum reveals that there are C, N, O, P element in PIL; For XPS C1s spectrum, PIL shows two peaks at 285.1, 283.8eV, correspond to the bonds of CN/C=N and CC, respectively; for the XPS N1s spectrum, PIL shows a peak at 400.5 eV corresponding to the bond of CN/C=N; for the XPSP1s spectrum, PIL shows two peaks at 531.6 and 530.3 eV. peaks, corresponding to PO and P=O bonds, respectively. This also indicated the successful synthesis of PIL. The above can prove that the present embodiment has successfully synthesized a novel ionic liquid with the following structural formula:

.

The synthesis route of ionic liquid is as follows:

.

S2. Mix 100 parts of bisphenol A epoxy resin with 25 parts of molten diaminodiphenylmethane (DDM) at 100°C, then add 1 part of the phosphorus- and nitrogen-containing ionic liquid obtained in step S1, and stir again After vacuuming, the mold was preheated at 120°C for 20 minutes. When the mixture had no air bubbles in the vacuum, the mixed sample was quickly poured into the mold, cured at 120°C for 2 hours, and then heated to 150°C for another 2 hours to obtain Phosphorous and nitrogenous ionic liquid/epoxy resin composites.

Example 2.

S1. Dissolve 0.01mol phenylphosphoric acid (PPA) in the solvent at room temperature to obtain a phenylphosphoric acid solution, add 0.02mol 1-ethylimidazole (MZ) dropwise to the phenylphosphoric acid solution under magnetic stirring to react, and then The solvent was removed by rotary evaporation at 40°C, and vacuum-dried at 50°C for 2 hours to obtain a light yellow and transparent phosphorus- and nitrogen-containing ionic liquid (PIL);

S2. Mix 100 parts of bisphenol A epoxy resin with 25 parts of molten diaminodiphenylmethane (DDM) at 90°C, then add 2 parts of the phosphorus- and nitrogen-containing ionic liquid obtained in step S1, and stir again After vacuuming, the mold was preheated at 120°C for 20 minutes. When the mixture had no air bubbles in the vacuum, the mixed sample was quickly poured into the mold, cured at 120°C for 2 hours, and then heated to 150°C for another 2 hours to obtain Phosphorous and nitrogenous ionic liquid/epoxy resin composites.

Example 3.

S1. Dissolve 0.01mol phenylphosphoric acid (PPA) in the solvent at room temperature to obtain a phenylphosphoric acid solution, add 0.02mol 1-ethylimidazole (MZ) dropwise to the phenylphosphoric acid solution under magnetic stirring to react, and then The solution was evaporated at 100°C to remove the solvent, and dried in vacuum at 30°C for 5 hours to obtain a light yellow and transparent phosphorus- and nitrogen-containing ionic liquid (PIL);

S2. Mix 100 parts of bisphenol A epoxy resin with 25 parts of molten diaminodiphenylmethane (DDM) at 80°C, then add 3 parts of the phosphorus- and nitrogen-containing ionic liquid obtained in step S1, and stir again After vacuuming, the mold was preheated at 120°C for 20 minutes. When the mixture had no air bubbles in the vacuum, the mixed sample was quickly poured into the mold, cured at 120°C for 2 hours, and then heated to 150°C for another 2 hours to obtain Phosphorous and nitrogenous ionic liquid/epoxy resin composites.

Comparative example 1.

S1. Dissolve 0.01mol phenylphosphoric acid (PPA) in the solvent at room temperature to obtain a phenylphosphoric acid solution, add 0.02mol 1-ethylimidazole (MZ) dropwise to the phenylphosphoric acid solution under magnetic stirring to react, and then The solution was evaporated at 60°C to remove the solvent, and dried in vacuum at 60°C for 1 hour to obtain a light yellow and transparent phosphorus- and nitrogen-containing ionic liquid (PIL);

S2. Mix 100 parts of bisphenol A epoxy resin with 25 parts of molten diaminodiphenylmethane (DDM) at 100°C and then vacuumize. The mold is preheated at 120°C for 20 minutes. When the mixture is in vacuum When there were no air bubbles, the mixed sample was quickly poured into the mold, cured at 120 °C for 2 h, and then heated to 150 °C for another 2 h to obtain an epoxy resin composite material without ionic liquid.

Test respectively the flexural strength of the phosphorus-containing and nitrogen-containing ionic liquid/epoxy resin composites of different contents prepared in Examples 1 to 3 and the epoxy resin not containing ionic liquid in Comparative Example 1, and the bending strength histogram is shown in Figure 4, the histogram of flexural modulus is shown in Figure 5; the elongation at break was tested, and the stress-strain curve was obtained as shown in Figure 6; the impact test was carried out, and the impact strength histogram was obtained as shown in Figure 7, and the epoxy composite materials with different contents The SEM image of the impact test fracture surface is shown in Figure 8.

The fire performance of the phosphorus-containing and nitrogen-containing ionic liquid/epoxy resin composites with different contents prepared in Examples 1-3 and Comparative Example were respectively tested, and the limiting oxygen index and UL-94 results obtained from the test are shown in Table 1.

Table 1

sample LOI(%) UL-94 EP (epoxy resin) 24.5 - 1.0PIL 31.6 V-0 2.0PIL 31.8 V-0 3.0PIL 32.6 V-0

It can be seen from the above test results that the phosphorus-containing and nitrogen-containing ionic liquid/epoxy composite material prepared by the present invention has significantly improved bending strength, elongation at break and flame retardancy compared with the common E51 epoxy resin on the market. When the amount of ionic liquid added is 2-3 parts, the impact strength is also significantly improved. However, due to plastic deformation, the material is more prone to deformation, so the flexural modulus decreases slightly, but the downward trend is very small. Epoxy has less of an effect. From the SEM images of the impact test fracture surface of epoxy composite materials with different ionic liquid content, it can be seen that the fracture surface of pure epoxy resin is smooth, showing obvious brittle fracture characteristics, and with the addition of ionic liquid, the fracture surface of the material appears large and small. Different dimples, which can prove that the toughness of the material has been improved, and the impact resistance has been significantly improved.

Example 4.

S1. Dissolve 0.01mol phenylphosphoric acid (PPA) in the solvent at room temperature to obtain a phenylphosphoric acid solution, add 0.02mol 1-ethylimidazole (MZ) dropwise to the phenylphosphoric acid solution under magnetic stirring to react, and then The solution was evaporated at 60°C to remove the solvent, and dried in vacuum at 60°C for 1 hour to obtain a light yellow and transparent phosphorus- and nitrogen-containing ionic liquid (PIL);

S2. Mix 100 parts of bisphenol A epoxy resin with 25 parts of molten diaminodiphenylmethane (DDM) at 100°C, then add 1 part of the phosphorus- and nitrogen-containing ionic liquid obtained in step S1, and stir again Then vacuumize to remove air bubbles;

S3. Use 3k carbon fiber cloth with a strength level of T300 to make carbon fiber boards. The size of each layer of carbon fiber cloth is 150×120mm. Each board is covered with 6 layers of carbon fiber cloth and laid flat in a vacuum bag;

S4. With the help of a vacuum pump, introduce the resin in step S2 into the carbon fiber, seal the seal and keep it in a vacuum state, then put it in an oven, adjust the temperature to 120°C for 2 hours, and then raise the temperature to 150°C for 2 hours to complete the curing. Vacuum bag, obtain phosphorous, nitrogen-containing ionic liquid/epoxy resin carbon fiber composite material.

Example 5.

S1. Dissolve 0.01mol phenylphosphoric acid (PPA) in the solvent at room temperature to obtain a phenylphosphoric acid solution, add 0.02mol 1-ethylimidazole (MZ) dropwise to the phenylphosphoric acid solution under magnetic stirring to react, and then The solution was evaporated at 60°C to remove the solvent, and dried in vacuum at 60°C for 1 hour to obtain a light yellow and transparent phosphorus- and nitrogen-containing ionic liquid (PIL);

S2. Mix 100 parts of bisphenol A epoxy resin with 25 parts of molten diaminodiphenylmethane (DDM) at 100°C, then add 2 parts of the phosphorus- and nitrogen-containing ionic liquid obtained in step S1, and stir again Vacuum to remove air bubbles;

S3. Use 3k carbon fiber cloth with a strength level of T300 to make carbon fiber boards. The size of each layer of carbon fiber cloth is 150×120mm. Each board is covered with 6 layers of carbon fiber cloth and laid flat in a vacuum bag;

S4. With the help of a vacuum pump, introduce the resin in step S2 into the carbon fiber, seal the seal and keep it in a vacuum state, then put it in an oven, adjust the temperature to 120°C for 2 hours, and then raise the temperature to 150°C for 2 hours to complete the curing. Vacuum bag, obtain phosphorous, nitrogen-containing ionic liquid/epoxy resin carbon fiber composite material.

Example 6.

S1. Dissolve 0.01mol phenylphosphoric acid (PPA) in a solvent at room temperature to obtain a phenylphosphoric acid solution, add 0.02mol 1-ethylimidazole (MZ) dropwise to the phenylphosphoric acid solution under magnetic stirring to react, and then The solution was evaporated at 60°C to remove the solvent, and dried in vacuum at 60°C for 1 hour to obtain a light yellow and transparent phosphorus- and nitrogen-containing ionic liquid (PIL);

S2. Mix 100 parts of bisphenol A epoxy resin with 25 parts of molten diaminodiphenylmethane (DDM) at 100°C, then add 3 parts of the phosphorus- and nitrogen-containing ionic liquid obtained in step S1, and stir again Then vacuumize to remove air bubbles;

S3. Use 3k carbon fiber cloth with a strength level of T300 to make carbon fiber boards. The size of each layer of carbon fiber cloth is 150×120mm. Each board is covered with 6 layers of carbon fiber cloth and laid flat in a vacuum bag;

S4. With the help of a vacuum pump, introduce the resin in step S2 into the carbon fiber, seal the seal and keep it in a vacuum state, then put it in an oven, adjust the temperature to 120°C for 2 hours, and then raise the temperature to 150°C for 2 hours to complete the curing. Vacuum bag, obtain phosphorous, nitrogen-containing ionic liquid/epoxy resin carbon fiber composite material.

Comparative example 2.

S1. Dissolve 0.01mol phenylphosphoric acid (PPA) in the solvent at room temperature to obtain a phenylphosphoric acid solution, add 0.02mol 1-ethylimidazole (MZ) dropwise to the phenylphosphoric acid solution under magnetic stirring to react, and then The solution was evaporated at 60°C to remove the solvent, and dried in vacuum at 60°C for 1 hour to obtain a light yellow and transparent phosphorus- and nitrogen-containing ionic liquid (PIL);

S2. Mix 100 parts of bisphenol A epoxy resin with 25 parts of molten diaminodiphenylmethane (DDM) at 100°C, and then vacuumize to remove air bubbles;

S3. Use 3k carbon fiber cloth with a strength level of T300 to make carbon fiber boards. The size of each layer of carbon fiber cloth is 150×120mm. Each board is covered with 6 layers of carbon fiber cloth and laid flat in a vacuum bag;

S4. With the help of a vacuum pump, introduce the resin in step S2 into the carbon fiber, seal the seal and keep it in a vacuum state, then put it in an oven, adjust the temperature to 120°C for 2 hours, and then raise the temperature to 150°C for 2 hours to complete the curing. Vacuum bag, obtain the epoxy resin carbon fiber composite material that does not contain ionic liquid.

The obtained material was cut into 120mm * 12.5mm * 3mm sample strips, and the flexural strength of the phosphorus-containing and nitrogen-containing ionic liquids/epoxy resin carbon fiber composite material templates of different contents obtained in Examples 4 to 6 were tested respectively, and measured The histogram of bending strength is shown in Figure 9, and the histogram of bending modulus is shown in Figure 10. It can be seen that under low addition, the phosphorous and nitrogen-containing ionic liquid/epoxy resin carbon fiber composite material prepared by the present invention has significantly improved bending strength compared with ordinary epoxy resin carbon fiber composite materials on the market.

Apparently, the above-mentioned embodiments are only examples for clear description, and other changes or changes can be made on the basis of the above-mentioned description. Therefore, the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims (10)

1. A kind of phosphorous, nitrogen ionic liquid/epoxy resin composite material, is characterized in that, comprises the component of mass fraction: 1~3 parts of ionic liquid containing phosphorus and nitrogen, 100 parts of epoxy resin, 25 parts of curing agent; Wherein, the structural formula of the phosphorus-containing and nitrogen-containing ionic liquid is as follows: . 2. The phosphorus-containing and nitrogen-containing ionic liquid/epoxy resin composite material according to claim 1, wherein the epoxy resin is bisphenol A epoxy resin. 3. The phosphorus-containing and nitrogen-containing ionic liquid/epoxy resin composite material according to claim 1, wherein the curing agent is an amine curing agent or an acid anhydride curing agent. 4. a preparation method containing phosphorus as described in any one of claim 1-3, nitrogen ionic liquid/epoxy resin composite material, is characterized in that, comprises the following steps: S1. Dissolve phenylphosphoric acid in a solvent at room temperature to obtain a phenylphosphoric acid solution. Add 1-ethylimidazole dropwise to the phenylphosphoric acid solution under magnetic stirring to react, then rotate the solution to remove the solvent and dry it in vacuum. , to obtain a light yellow and transparent phosphorus- and nitrogen-containing ionic liquid; S2. Mix the epoxy resin and curing agent evenly at a specific temperature, then add the phosphorus- and nitrogen-containing ionic liquid obtained in step S1, stir again and then vacuumize. When the mixture has no bubbles in the vacuum, pour the mixed sample Put it into a preheated mold for heating and curing to obtain phosphorus-containing and nitrogen-containing ionic liquid/epoxy resin composite material. 5. The preparation method of phosphorous and nitrogen-containing ionic liquid/epoxy resin composite material according to claim 4, characterized in that the molar ratio of phenylphosphoric acid and 1-ethylimidazole is 1:2. 6. The preparation method of phosphorous and nitrogen-containing ionic liquid/epoxy resin composite material according to claim 4, characterized in that the solvent in step S1 is absolute ethanol. 7. the preparation method of phosphorus-containing, nitrogen-containing ionic liquid/epoxy resin composite material according to claim 4, is characterized in that, the temperature of described rotary evaporation is 30 ℃～120 ℃; The temperature of described vacuum drying is 20 ℃~60℃. 8. The preparation method of phosphorous and nitrogen-containing ionic liquid/epoxy resin composite material according to claim 4, characterized in that the reaction time in step S1 is 1h~6h. 9. The preparation method of phosphorous and nitrogen-containing ionic liquid/epoxy resin composite material according to claim 4, characterized in that the specified temperature in step S2 is 80°C-100°C. 10. the preparation method of phosphorus-containing, nitrogen ionic liquid/epoxy resin composite material according to claim 4, is characterized in that, the temperature of described preheating is 120 ℃, and the time of described preheating is 20 min; The specific heating and curing process is: curing at 120° C. for 2 hours, then raising the temperature to 150° C. and curing for another 2 hours.