Double p flame retardant, epoxy composite material and application in type iv hydrogen storage cylinder

Abstract

The application relates to a double-P flame retardant, an epoxy composite material and application in a type IV hydrogen storage cylinder, relates to the technical field of flame retardant materials, and solves the problem that the existing epoxy resin used in the type IV hydrogen storage cylinder cannot simultaneously consider strength, toughness and flame retardant characteristics.The double-P flame retardant is synthesized by the following steps: reacting green and environment-friendly renewable bio-based raw material vanillin with a catalyst triethylamine to obtain a first-step intermediate, then reacting the first-step intermediate with a biomass amine substance to obtain a Schiff base intermediate, and finally reacting the Schiff base intermediate with DOPO.The epoxy composite material is prepared by the flame retardant and the epoxy resin.The reaction process is convenient to operate, and the preparation method is simple, which not only provides a new idea for expanding the application of the epoxy resin in the field of high-performance materials, but also provides a relatively suitable winding layer material for hydrogen energy, especially the type IV hydrogen storage cylinder, and is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of flame retardant materials technology, specifically to a double-P flame retardant, an epoxy composite material, and its application in a Type IV hydrogen storage cylinder. Background Technology

[0002] As one of the most commonly used thermosetting materials globally, epoxy resin (EP) is readily applied in a wide range of fields, including aerospace, automotive manufacturing, adhesives, and circuit encapsulation materials, due to its high mechanical strength, transparency, and excellent thermal and chemical stability. However, the high degree of cross-linking in epoxy resin leads to brittleness and poor crack propagation resistance, while its high flammability due to the large number of flammable groups limits its application scope. It is generally believed that simultaneously improving both mechanical and flame-retardant properties is difficult.

[0003] With the increasing demand for clean energy, high-pressure hydrogen storage technology has received widespread attention. Epoxy composite materials, as one of the main manufacturing materials for hydrogen cylinders, have become a research focus due to their excellent mechanical properties and chemical corrosion resistance. High-pressure hydrogen storage cylinders have undergone several generations of development over the past few decades. Among them, the Type IV high-pressure hydrogen storage cylinder, with nylon as the inner liner and carbon fiber / epoxy resin composite material as the winding layer, has become the most mature production solution. However, Type IV hydrogen storage cylinders require resins with low curing temperatures, short curing times, high rigidity, good toughness, and flame retardancy. Existing commercially available epoxy resins are difficult to apply to the wet winding process system of Type IV hydrogen storage cylinders.

[0004] The common approach to addressing these issues is to add functional flame retardants to the epoxy resin system to improve the overall performance of epoxy resin (EP). Furthermore, introducing a second phase into the epoxy resin matrix is ​​also considered an effective means of improving the toughness of cured EP. However, the raw materials for these additives are mostly petrochemical products, which are limited in resources and contain harmful chemicals, negatively impacting the environment. Phosphorus-based flame retardants are gaining increasing attention due to their low toxicity, diverse structures, and high efficiency; however, compounds containing only phosphorus have lower flame retardant efficiency. DOPO structures can be combined with compounds containing nitrogen, sulfur, boron, or silicon. In contrast, phosphorus-nitrogen synergistic flame retardants help form an insulating, multi-dimensional, sparsely expanded char layer, acting as a barrier against air, heat, and pyrolysis products during thermal decomposition, resulting in excellent flame retardant effects. However, while adding flame retardants improves the flame retardant properties of epoxy resin, it usually sacrifices its mechanical properties.

[0005] Therefore, it is crucial to improve the safety of hydrogen storage cylinders by simultaneously enhancing the strength, toughness, and flame retardant properties of epoxy resin and comprehensively studying the synergistic effect of these three properties. Summary of the Invention

[0006] To address the problem that existing epoxy resins used in Type IV hydrogen storage cylinders cannot simultaneously achieve strength, toughness, and flame retardant properties, this invention proposes a double-P flame retardant, an epoxy composite material, and its application in Type IV hydrogen storage cylinders.

[0007] The technical solution of the present invention is as follows:

[0008] A bio-based bis-P flame retardant, with the following structural formula:

[0009] ;

[0010] In the formula, R1 is selected from , , , , , One of them;

[0011] R2 is selected from , , , , One of them, where n1 is any integer from 1 to 16, and n2 is selected from 230, 400, 600, 1000 or 2000.

[0012] This invention also provides a method for preparing the above-mentioned bio-based bis-P flame retardant, comprising the following steps:

[0013] Step 1: Dissolve raw material A and triethylamine in ethyl acetate, then add diphenyl chlorophosphate dropwise under a nitrogen atmosphere at 0℃~5℃. After stirring for 30min~60min, gradually raise the system to room temperature and continue stirring for 12h~24h. Then perform post-processing to obtain the intermediate of the first step.

[0014] Step 2: Dissolve the intermediate obtained in Step 1 in a solvent, then add raw material B, and reflux at 30℃~90℃ for 2h~10h. After the reaction is completed, remove the solvent by rotary evaporation, and then vacuum dry at 50℃~80℃ for 12h~24h to obtain the Schiff base intermediate.

[0015] Step 3: Dissolve the Schiff base intermediate in a solvent, then add DOPO dropwise under a nitrogen atmosphere, and reflux at 50℃~120℃ for 8h~20h. After the reaction is completed, remove the solvent by rotary evaporation, and then vacuum dry at 50℃~100℃ for 12h~24h to obtain the reactive bio-based bis-P flame retardant.

[0016] Wherein, raw material A is selected from one or a combination of at least two of vanillin, p-hydroxybenzaldehyde, 5-hydroxymethylfurfural, salicylaldehyde, protocatechuic aldehyde, and syringaldehyde;

[0017] The raw material B is selected from one or a combination of at least two of Pramamine 1074, diethylenetriamine, triethylenetetramine, 1,5-pentanediamine, 1,6-hexanediamine, polyetheramine D-230, polyetheramine D-400, polyetheramine D-600, polyetheramine D-1000, and polyetheramine D-2000.

[0018] Preferably, the post-processing method includes: filtration, washing, drying, and rotary evaporation.

[0019] Preferably, the solvent in step two is one or a combination of at least two of the following: anhydrous ethanol, methanol, tetrahydrofuran, dichloromethane, chloroform, ethyl acetate, acetone, toluene, and 1,4-dioxane.

[0020] Preferably, the solvent in step three is one or a combination of at least two of methanol, anhydrous ethanol, acetone, toluene, 1,4-dioxane, and N,N-dimethylformamide.

[0021] The present invention also provides an epoxy composite material, wherein the raw materials, by weight, include: 1-20 parts of the bio-based bis-P flame retardant as described in claim 1, 100 parts of epoxy resin, and 25 parts of curing agent.

[0022] Preferably, the epoxy resin is bisphenol A epoxy resin, and the curing agent is 4,4'-diaminodiphenylmethane.

[0023] The preparation method of the above-mentioned epoxy composite material includes the following steps:

[0024] The bio-based double-P flame retardant and epoxy resin were stirred and mixed at 70℃~120℃ to obtain a homogeneous system. After vacuuming, when there were no bubbles in the mixture in the vacuum, the curing agent was added at 50℃~120℃ and mixed evenly. Finally, the mixture was poured into a preheated mold for curing.

[0025] Preferably, the mold preheating temperature is 80℃~120℃ and the preheating time is 30min~90min; the curing process is specifically as follows: after curing at 100℃~140℃ for 60min~120min, the temperature is adjusted to 120℃~160℃ and then cured for another 60min~150min.

[0026] The present invention also provides an application of the above-mentioned epoxy composite material, specifically for the preparation of the winding layer of a type IV fully wound hydrogen storage cylinder.

[0027] Compared with the prior art, the specific beneficial effects of the present invention are as follows:

[0028] This invention synthesizes a double-P flame retardant using green, environmentally friendly, and renewable bio-based raw materials. It exhibits high viscosity at room temperature and excellent flowability upon heating, demonstrating good thermal responsiveness and processing performance. Because the -NH groups in the flame retardant of this composite material can participate in the curing reaction of epoxy resin, cross-linking with the epoxy resin to form a unique network structure, it greatly improves the compatibility between the flame retardant and the epoxy resin. The main chain aromatic ring and phosphorus-containing aryl side chains of the flame retardant act as rigid groups, while the flexible chains can withstand and disperse stress when the composite material is subjected to external forces, increasing the free space for movement and thus increasing toughness. The combination of rigid groups and flexible chains, with their unique rigid-flexible structure, endows the epoxy resin matrix with excellent mechanical properties. In addition, the dual phosphorus structure in the flame retardant and the synergistic effect between nitrogen and phosphorus elements achieve a good flame retardant effect. The flame retardant decomposes into some phosphorus-based groups, such as phosphoric acid or polyphosphoric acid compounds, to catalyze the coking of molecular chain segments. At the same time, nitrogen-based gases are released into the gas phase to dilute combustible volatiles, leading to combustion termination and preventing the degradation and combustion of the internal matrix. This gives the epoxy composite material excellent flame retardant properties.

[0029] The reaction process of this invention is easy to operate and the preparation method is simple. It not only provides a new idea for expanding the application of epoxy resin in the field of high-performance materials, but also provides a more suitable winding layer material for hydrogen energy, especially for Type IV hydrogen storage cylinders, which is suitable for industrial production. Attached Figure Description

[0030] Figure 1 Infrared spectra of the products at each stage in Example 1;

[0031] Figure 2 The tensile stress-strain curves of the epoxy composite materials in Examples 1-3 and Comparative Examples 1-2 are shown.

[0032] Figure 3 The graph shows a comparison of the flexural strength and flexural modulus of the epoxy composite materials in Examples 1-3 and Comparative Examples 1-2.

[0033] Figure 4 The image shows a comparison of the impact strength of the epoxy composite materials in Examples 1-3 and Comparative Examples 1-2. Detailed Implementation

[0034] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as limiting the present invention.

[0035] The raw materials and equipment used in this invention are all known products, obtained by purchasing commercially available products.

[0036] Example 1

[0037] (1) In a three-necked round-bottom flask, vanillin and the catalyst triethylamine were dissolved in ethyl acetate. Then, under a nitrogen atmosphere at 0℃~5℃, diphenyl chlorophosphate was slowly added dropwise to the above solution. After stirring for 30 min, the system was gradually raised to room temperature and stirred for another 16 h. After the end, the mixture was filtered to remove the generated salt. The resulting filtrate was then washed successively with deionized water and salt water. The organic phase was dried with anhydrous magnesium sulfate for 12 h. Then, ethyl acetate was removed by rotary evaporation. The mixture was then dried under vacuum at 60℃ for 24 h to obtain the desired first-step intermediate VD.

[0038] (2) In a three-necked round-bottom flask, VD was dissolved in anhydrous ethanol, and then Pramine1074 was added to the solution and refluxed at 70°C for 4 h. The solvent was removed by rotary evaporation, and then the solution was dried under vacuum at 70°C for 24 h to obtain the desired Schiff base intermediate VDP.

[0039] (3) In a three-necked round-bottom flask, the VDP obtained above was dissolved in anhydrous ethanol. Then, DOPO was added dropwise to the solution under a nitrogen atmosphere, and the mixture was refluxed at 85°C for 20 h. The solvent was removed by rotary evaporation, and then the mixture was dried under vacuum at 80°C for 24 h to obtain the desired flame retardant VDPD.

[0040] The reaction route described above is as follows:

[0041] .

[0042] The infrared spectra of the products at each stage are shown below. Figure 1 In the VD spectrum, at 1700 cm⁻¹ -1 The peak at 1645 cm⁻¹ belongs to the stretching vibration of the aldehyde group C=O, and no characteristic peak of -OH was detected, indicating the successful synthesis of VD. In the VDP spectrum, the C=O peak in VP disappears, and the peak at 1645 cm⁻¹ is [missing information]. -1 The appearance of a new stretching vibration belonging to the Schiff base C=N at this point indicates the successful synthesis of VDP. In the VDPD spectrum, VDP shows a stretching vibration at 1645 cm⁻¹. -1 The C=N peak at 2435 cm⁻¹ and the DOPO peak at 2435 cm⁻¹ -1 The pH peak disappeared at 1510 cm⁻¹. −1 A new peak belonging to the -NH group appeared at 1234 cm⁻¹. Additionally, at 1234 cm⁻¹... -1 and 926cm -1 The bending vibration peaks corresponding to P=O and PO-Ph, respectively, all indicate the successful synthesis of the final product VDPD. This proves that the reaction proceeded smoothly along the above route.

[0043] (4) Add 10 parts of the prepared VDPD to 100 parts of bisphenol A epoxy resin, stir evenly at 90°C and then vacuum. When there are no bubbles in the mixture in the vacuum, add 25 parts of molten 4,4-diaminodiphenylmethane (DDM) as a curing agent at 105°C and mix evenly. Quickly pour the mixed sample into a mold, preheat the mold at 110°C for 30 min, cure at 120°C for 2 h, adjust the temperature to 150°C, and then cure for 2 h to obtain the epoxy composite material 10VDPD.

[0044] Example 2

[0045] (1) In a three-necked round-bottom flask, vanillin and the catalyst triethylamine were dissolved in ethyl acetate. Then, under a nitrogen atmosphere at 0℃~5℃, diphenyl chlorophosphate was slowly added dropwise to the above solution. After stirring for 30 min, the system was gradually raised to room temperature and stirred for another 16 h. After the end, the mixture was filtered to remove the generated salt. The resulting filtrate was then washed successively with deionized water and salt water. The organic phase was dried with anhydrous magnesium sulfate for 12 h. Then, ethyl acetate was removed by rotary evaporation. The mixture was then dried under vacuum at 60℃ for 24 h to obtain the desired first-step intermediate VD.

[0046] (2) In a three-necked round-bottom flask, VD was dissolved in anhydrous ethanol, and then Pramine1074 was added to the solution and refluxed at 70°C for 4 h. The solvent was removed by rotary evaporation, and then the solution was dried under vacuum at 70°C for 24 h to obtain the desired Schiff base intermediate VDP.

[0047] (3) In a three-necked round-bottom flask, the VDP obtained above was dissolved in anhydrous ethanol. Then, DOPO was added dropwise to the solution under a nitrogen atmosphere, and the mixture was refluxed at 85°C for 20 h. The solvent was removed by rotary evaporation, and then the mixture was dried under vacuum at 80°C for 24 h to obtain the desired flame retardant VDPD.

[0048] (4) Add 15 parts of the prepared VDPD to 100 parts of bisphenol A epoxy resin, stir evenly at 90°C and then vacuum. When there are no bubbles in the mixture under vacuum, add 25 parts of molten 4,4-diaminodiphenylmethane (DDM) as a curing agent at 105°C and mix evenly. Quickly pour the mixed sample into a mold, preheat the mold at 110°C for 30 min, cure at 120°C for 2 h, adjust the temperature to 150°C, and then cure for 2 h to obtain the epoxy composite material 15VDPD.

[0049] Example 3

[0050] (1) In a three-necked round-bottom flask, vanillin and the catalyst triethylamine were dissolved in ethyl acetate. Then, under a nitrogen atmosphere, diphenyl chlorophosphate was slowly added dropwise to the above solution at 0-5°C. After stirring for 30 min, the system was gradually raised to room temperature and stirred for another 16 h. After the reaction, the mixture was filtered to remove the generated salt. The resulting filtrate was then washed successively with deionized water and brine solution, and the organic phase was dried with anhydrous magnesium sulfate for 12 h. Ethyl acetate was then removed by rotary evaporation, and the mixture was dried under vacuum at 60°C for 24 h to obtain the desired first-step intermediate VD.

[0051] (2) In a three-necked round-bottom flask, VD was dissolved in anhydrous ethanol. Then, Pramine 1074 was added to the above solution, and the mixture was refluxed at 70°C for 4 h. The solvent was removed by rotary evaporation, and then the mixture was dried under vacuum at 70°C for 24 h to obtain the desired Schiff base intermediate VDP.

[0052] (3) In a three-necked round-bottom flask, the VDP obtained above was dissolved in anhydrous ethanol. Then, DOPO was added dropwise to the solution under a nitrogen atmosphere, and the mixture was refluxed at 85°C for 20 h. The solvent was removed by rotary evaporation, and then the mixture was dried under vacuum at 80°C for 24 h to obtain the desired flame retardant VDPD.

[0053] (4) Add 20 parts of the prepared VDPD to 100 parts of bisphenol A epoxy resin, stir evenly at 90°C and then vacuum. When there are no bubbles in the mixture under vacuum, add 25 parts of molten 4,4-diaminodiphenylmethane (DDM) as a curing agent at 105°C and mix evenly. Quickly pour the mixed sample into a mold, preheat the mold at 110°C for 30 min, cure at 120°C for 2 h, adjust the temperature to 150°C, and then cure for 2 h to obtain the epoxy composite material 20VDPD.

[0054] Example 4

[0055] (1) In a three-necked round-bottom flask, vanillin and the catalyst triethylamine were dissolved in ethyl acetate. Then, under a nitrogen atmosphere, diphenyl chlorophosphate was slowly added dropwise to the above solution at 0-5°C. After stirring for 30 min, the system was gradually raised to room temperature and stirred for another 16 h. After the reaction, the mixture was filtered to remove the generated salt. The resulting filtrate was then washed successively with deionized water and brine solution, and the organic phase was dried with anhydrous magnesium sulfate for 12 h. Ethyl acetate was then removed by rotary evaporation, and the mixture was dried under vacuum at 60°C for 24 h to obtain the desired first-step intermediate.

[0056] (2) In a three-necked round-bottom flask, the product obtained in (1) was dissolved in anhydrous ethanol. Then, 1,6-hexanediamine was added to the above solution and refluxed at 50°C for 5 h. The solvent was removed by rotary evaporation, and then the product was dried under vacuum at 60°C for 24 h to obtain the desired Schiff base intermediate.

[0057] (3) In a three-necked round-bottom flask, the Schiff base obtained in (2) was dissolved in anhydrous ethanol. Then, DOPO was added dropwise to the above solution under a nitrogen atmosphere, and the mixture was refluxed at 85°C for 20 h. The solvent was removed by rotary evaporation, and then the product was dried under vacuum at 80°C for 24 h to obtain the desired product.

[0058] (4) Add 15 parts of the target product prepared above to 100 parts of bisphenol A epoxy resin, stir evenly at 90°C and then vacuum. When there are no bubbles in the mixture under vacuum, add 25 parts of molten 4,4-diaminodiphenylmethane (DDM) as a curing agent at 105°C and mix evenly. Quickly pour the mixed sample into a mold, preheat the mold at 110°C for 30 min, cure at 120°C for 2 h, adjust the temperature to 150°C, and then cure for 2 h to obtain the epoxy composite material.

[0059] Example 5

[0060] (1) In a three-necked round-bottom flask, p-hydroxybenzaldehyde and the catalyst triethylamine were dissolved in ethyl acetate. Then, under a nitrogen atmosphere, diphenyl chlorophosphate was slowly added dropwise to the above solution at 0-5°C. After stirring for 30 min, the system was gradually raised to room temperature and stirred for another 16 h. After the reaction, the mixture was filtered to remove the generated salt. The resulting filtrate was then washed successively with deionized water and brine solution, and the organic phase was dried with anhydrous magnesium sulfate for 12 h. Ethyl acetate was then removed by rotary evaporation, and the mixture was dried under vacuum at 60°C for 24 h to obtain the desired first-step intermediate.

[0061] (2) In a three-necked round-bottom flask, the product obtained in (1) was dissolved in anhydrous ethanol. Then, Pramine 1074 was added to the above solution and refluxed at 70°C for 4 h. The solvent was removed by rotary evaporation, and then the product was dried under vacuum at 70°C for 24 h to obtain the desired Schiff base intermediate.

[0062] (3) In a three-necked round-bottom flask, the Schiff base obtained in (2) was dissolved in anhydrous ethanol. Then, DOPO was added dropwise to the above solution under a nitrogen atmosphere, and the mixture was refluxed at 85°C for 20 h. The solvent was removed by rotary evaporation, and then the product was dried under vacuum at 80°C for 24 h to obtain the desired product.

[0063] (4) Add 15 parts of the prepared target product to 100 parts of bisphenol A epoxy resin, stir evenly at 90°C, and then vacuum. When there are no bubbles in the mixture under vacuum, add 25 parts of molten 4,4-diaminodiphenylmethane (DDM) as a curing agent at 105°C and mix evenly. Quickly pour the mixed sample into a mold, preheat the mold at 110°C for 30 min, cure at 120°C for 2 h, adjust the temperature to 150°C, and then cure for 2 h to obtain the epoxy composite material.

[0064] Example 6

[0065] (1) In a three-necked round-bottom flask, vanillin and the catalyst triethylamine were dissolved in ethyl acetate. Then, under a nitrogen atmosphere, diphenyl chlorophosphate was slowly added dropwise to the above solution at 0-5°C. After stirring for 30 min, the system was gradually raised to room temperature and stirred for another 16 h. After the reaction, the mixture was filtered to remove the generated salt. The resulting filtrate was then washed successively with deionized water and brine solution, and the organic phase was dried with anhydrous magnesium sulfate for 12 h. Ethyl acetate was then removed by rotary evaporation, and the mixture was dried under vacuum at 60°C for 24 h to obtain the desired first-step intermediate.

[0066] (2) In a three-necked round-bottom flask, the product obtained in (1) was dissolved in anhydrous ethanol. Then, polyetheramine was added to the above solution and refluxed at 60°C for 5 h. The solvent was removed by rotary evaporation, and then the product was dried under vacuum at 60°C for 24 h to obtain the desired Schiff base intermediate.

[0067] (3) In a three-necked round-bottom flask, the Schiff base obtained in (2) was dissolved in anhydrous ethanol. Then, DOPO was added dropwise to the above solution under a nitrogen atmosphere, and the mixture was refluxed at 85°C for 20 h. The solvent was removed by rotary evaporation, and then the product was dried under vacuum at 80°C for 24 h to obtain the desired product.

[0068] (4) Add 15 parts of the prepared target product to 100 parts of bisphenol A epoxy resin, stir evenly at 90°C, and then vacuum. When there are no bubbles in the mixture under vacuum, add 25 parts of molten 4,4-diaminodiphenylmethane (DDM) as a curing agent at 105°C and mix evenly. Quickly pour the mixed sample into a mold, preheat the mold at 110°C for 30 min, cure at 120°C for 2 h, adjust the temperature to 150°C, and then cure for 2 h to obtain the epoxy composite material.

[0069] Comparative Example 1

[0070] At 105℃, 25 parts of molten 4,4-diaminodiphenylmethane (DDM) were added as a curing agent to 100 parts of bisphenol A epoxy resin. After stirring evenly, the mixed sample was quickly poured into a mold. The mold was preheated at 110℃ for 30 min, cured at 120℃ for 2 h, and then the temperature was adjusted to 150℃ and cured for another 2 h to obtain EP epoxy resin material.

[0071] Comparative Example 2

[0072] (1) In a three-necked round-bottom flask, vanillin and the catalyst triethylamine were dissolved in ethyl acetate. Then, under a nitrogen atmosphere, diphenyl chlorophosphate was slowly added dropwise to the above solution at 0-5°C. After stirring for 30 min, the system was gradually raised to room temperature and stirred for another 16 h. After the reaction, the mixture was filtered to remove the generated salt. The resulting filtrate was then washed successively with deionized water and brine solution, and the organic phase was dried with anhydrous magnesium sulfate for 12 h. Ethyl acetate was then removed by rotary evaporation, and the mixture was dried under vacuum at 60°C for 24 h to obtain the desired first-step intermediate VD.

[0073] (2) In a three-necked round-bottom flask, VD was dissolved in anhydrous ethanol. Then, Pramine 1074 was added to the above solution, and the mixture was refluxed at 70°C for 4 h. The solvent was removed by rotary evaporation, and then the mixture was dried under vacuum at 70°C for 24 h to obtain the desired Schiff base intermediate VDP.

[0074] (3) Add 15 parts of the prepared VDP to 100 parts of bisphenol A epoxy resin, stir evenly at 90°C and then vacuum. When there are no bubbles in the mixture under vacuum, add 25 parts of molten 4,4-diaminodiphenylmethane (DDM) as a curing agent at 105°C and mix evenly. Quickly pour the mixed sample into a mold, preheat the mold at 110°C for 30 min, cure at 120°C for 2 h, adjust the temperature to 150°C, and then cure for 2 h to obtain epoxy composite material 15VDP.

[0075] The flexural strength, elongation at break, impact strength, and flame retardant properties of the epoxy composite materials prepared in the above six examples and two comparative examples were tested, and the data results are shown in Table 1. The tensile stress-strain curves of the epoxy composite materials in Examples 1-3 and Comparative Examples 1-2 are shown in Table 1. Figure 2 The comparison chart of bending strength and bending modulus is shown below. Figure 3 The impact strength comparison chart is shown below. Figure 4It can be demonstrated that the -NH groups in the flame retardant successfully participate in the curing reaction of the epoxy resin, cross-linking with the epoxy resin to form a special network structure, which greatly improves the compatibility between the flame retardant and the epoxy resin. The rigid groups and flexible chains in the flame retardant work together to endow the epoxy resin matrix with excellent mechanical properties. Therefore, the epoxy composite material prepared by this invention shows significant improvements in flexural strength, elongation at break, impact strength, and flame retardancy compared to ordinary E51 epoxy resin material, and also shows improvements compared to the Schiff base epoxy composite material in Comparative Example 2.

[0076] Table 1

[0077]

Claims

1. An epoxy composite material, characterized in that, The raw materials, by weight, include: 1-20 parts of bio-based double-P flame retardant, 100 parts of epoxy resin, and 25 parts of curing agent; the structural formula of the bio-based double-P flame retardant is as follows: ； In the formula, R1 is selected from , One of them; R2 is from Priamine 1074 Group.

2. The epoxy composite material according to claim 1, characterized in that, The epoxy resin is bisphenol A epoxy resin, and the curing agent is 4,4'-diaminodiphenylmethane.

3. A method for preparing a bio-based bis-P flame retardant, characterized in that, The structural formula of the bio-based bis-P flame retardant is as follows: ； In the formula, R1 is selected from , One of them; R2 is from Priamine 1074 Group; The preparation method includes the following steps: Step 1: Dissolve raw material A and triethylamine in ethyl acetate, then add diphenyl chlorophosphate dropwise under a nitrogen atmosphere at 0℃~5℃. After stirring for 30min~60min, gradually raise the system to room temperature and continue stirring for 12h~24h. Then perform post-processing to obtain the intermediate of the first step. Step 2: Dissolve the intermediate obtained in Step 1 in a solvent, then add raw material B, and reflux at 30℃~90℃ for 2h~10h. After the reaction is completed, remove the solvent by rotary evaporation, and then vacuum dry at 50℃~80℃ for 12h~24h to obtain the Schiff base intermediate. Step 3: Dissolve the prepared Schiff base intermediate in a solvent, then add DOPO dropwise under a nitrogen atmosphere, and reflux at 50℃~120℃ for 8h~20h. After the reaction is completed, remove the solvent by rotary evaporation, and then vacuum dry at 50℃~100℃ for 12h~24h to obtain the bio-based bis-P flame retardant. Wherein, raw material A is selected from vanillin and p-hydroxybenzaldehyde; The raw material B is Priamine 1074, with the structural formula [structure not provided]. .

4. The method for preparing the bio-based bis-P flame retardant according to claim 3, characterized in that, The post-processing methods include: filtration, washing, drying, and rotary evaporation.

5. The method for preparing the bio-based bis-P flame retardant according to claim 3, characterized in that, The solvent mentioned in step two is one or a combination of at least two of the following: anhydrous ethanol, methanol, tetrahydrofuran, dichloromethane, chloroform, ethyl acetate, acetone, toluene, and 1,4-dioxane.

6. The method for preparing the bio-based bis-P flame retardant according to claim 3, characterized in that, The solvent mentioned in step three is one or a combination of at least two of methanol, anhydrous ethanol, acetone, toluene, 1,4-dioxane, and N,N-dimethylformamide.

7. A method for preparing an epoxy composite material as described in claim 1 or 2, characterized in that, Includes the following steps: The bio-based double-P flame retardant and epoxy resin were stirred and mixed at 70℃~120℃ to obtain a homogeneous system. After vacuuming, when there were no bubbles in the mixture in the vacuum, the curing agent was added at 50℃~120℃ and mixed evenly. Finally, the mixture was poured into a preheated mold for curing.

8. The method for preparing the epoxy composite material according to claim 7, characterized in that, The mold preheating temperature is 80℃~120℃, and the preheating time is 30min~90min; the curing process is as follows: after curing at 100℃~140℃ for 60min~120min, the temperature is adjusted to 120℃~160℃, and then cured for another 60min~150min.

9. An application of the epoxy composite material as described in claim 1 or 2, characterized in that, Used for the preparation of the winding layer for Type IV fully wound hydrogen storage cylinders.

Images