A furfuryl aniline epoxy monomer, a furfuryl aniline epoxy resin and a preparation method thereof

Abstract

The application discloses a furfuryl aniline epoxy monomer, a furfuryl aniline epoxy resin and a preparation method thereof. The furfuryl aniline epoxy monomer has the following structure: a Schiff base reaction is carried out on 4-hydroxyaniline and 2-furfuraldehyde, hydrogenation reduction is carried out on the obtained Schiff base intermediate to obtain a secondary amine intermediate; the secondary amine intermediate is subjected to a substitution reaction with epichlorohydrin to obtain the furfuryl aniline epoxy monomer; the furfuryl aniline epoxy monomer, a DOPO-based epoxy monomer and a diamino diaryl sulfone are subjected to ring-opening addition to obtain a flame-retardant epoxy resin with good thermal stability and excellent flame-retardant performance, and the flame-retardant epoxy resin can be widely applied as a flame-retardant functional epoxy resin.

Description

Technical Field

[0001] This invention relates to a furfural-based aniline epoxy resin monomer, a furfural-based aniline epoxy resin, and a method for preparing the furfural-based aniline epoxy resin monomer and epoxy resin, belonging to the field of polymer materials technology. Background Technology

[0002] Epoxy resins typically possess excellent solvent resistance, good chemical stability, and mechanical strength, making them the most widely used resins in the construction and coatings industries. In addition, functional epoxy resin oligomers are also widely used in aerospace and electronics products. Epoxy resin monomers and prepolymers generally refer to organic components containing multiple epoxy units. The epoxy groups in the molecular structure further interact with curing agents to form corresponding polymer systems. The most common and widely used system is glycidyl ether epoxy resin (DGEBA) based on bisphenol A. However, a drawback is that the structure and composition of the epoxy resin vary significantly depending on the manufacturing process, resulting in substantial differences in product performance. Therefore, the product's performance is affected to some extent.

[0003] Traditional DGEBA is mainly prepared from bisphenol A and acetone, but the presence of acetone in the preparation process poses significant safety risks, especially at high temperatures, where it inevitably presents flammability and explosiveness hazards. Therefore, developing alternative raw materials can effectively avoid the safety risks associated with bisphenol A derivation. It is worth noting that epoxy resins made from DGEBA have extremely low bio-based content. Therefore, increasing the bio-based content and establishing appropriate epoxy resin construction processes can effectively enhance the socio-economic value of the products. Furfural, as a decomposition product of agricultural byproducts, has the advantages of being widely available and less affected by geographical environment. Furthermore, the bio-based chemicals derived from furfural can demonstrate better added value and higher biomass resource utilization efficiency.

[0004] Currently, methods for constructing bio-based epoxy monomers are being gradually improved. Research on basic process conditions using furfural as a raw material facilitates further exploration of the properties of its corresponding epoxy resin polymers. In-depth research on the physicochemical and functional properties of epoxy resin materials is also one of the current directions for developing material applications, especially the construction of epoxy structures with low saponified chlorine content (<100ppm), which is currently an important indicator for electronic-grade epoxy. Furthermore, establishing corresponding flame-retardant polymer preparation methods based on furfural-based epoxy monomers is also of great significance and is expected to have wide applications in many research fields such as coatings, adhesives, aerospace materials, and the electronics industry. Summary of the Invention

[0005] To address the technical problems existing in the prior art, the first objective of this invention is to provide a furfural-based aniline epoxy monomer (EP-Fulap). This monomer introduces a diepoxy group and can be further used to construct epoxy resins through ring-opening polymerization. It also has low viscosity and low saponification chlorine value, belonging to the electronic grade epoxy class, which has greater advantages compared to existing petroleum-based epoxy resins. Furthermore, the epoxy resin constructed using furfural-based aniline epoxy monomer introduces a furan structure to increase the biomass content of the material, and the introduction of aniline groups is beneficial to improving the thermal stability of the epoxy resin.

[0006] The second objective of this invention is to provide a method for preparing furfural-based aniline epoxy monomers. This method uses bio-based furfural as a raw material, which is widely available, renewable, and the preparation method is simple, mild, and can be industrialized.

[0007] The third objective of this invention is to provide a furfural-based aniline epoxy resin, which has good thermal stability and excellent flame retardant properties, and can be widely used as a flame-retardant functional epoxy resin.

[0008] The fourth objective of this invention is to provide a method for preparing furfural-based aniline epoxy resin, which has simple synthesis steps and widely available raw materials, thus facilitating large-scale production.

[0009] To achieve the above technical objectives, the present invention provides a furfural-based aniline epoxy monomer having the structure of Formula 1:

[0010]

[0011] The EP-Fulap of this invention is a pale yellow liquid with a viscosity of η = 168 mP·s (300 r / min) at 25°C, a volatile content of <0.195%, and a saponification chlorine value of 0.00936%.

[0012] The furfural-based aniline epoxy monomer of the present invention has two epoxy groups, which can be used to construct epoxy resins with other monomers. It has an electronic grade epoxy resin, which has greater advantages compared with existing petroleum-based epoxy resins. Furthermore, the furfural-based aniline epoxy monomer contains both furan groups and aniline groups, which is beneficial to improving the thermal stability of epoxy resins.

[0013] This invention also provides a method for preparing furfural-based aniline epoxy monomers, the method comprising the following steps:

[0014] 1) 4-hydroxyaniline reacts with 2-furan carboxaldehyde via a Schiff base reaction to obtain a Schiff base intermediate with structure 2.

[0015] 2) The Schiff base intermediate is subjected to a hydrogenation reduction reaction to obtain a secondary amine intermediate with structure 3;

[0016] 3) The secondary amine intermediate reacts with epichlorohydrin via a substitution reaction to yield furfural-based aniline epoxy monomer;

[0017]

[0018] As a preferred embodiment, 4-hydroxyaniline and 2-furancarbaldehyde are reacted in a polar solvent under acidic conditions at a temperature of 10–30°C for 18–30 h. This reaction can be carried out in an air atmosphere. The acidic conditions are achieved by adding an organic acid, such as formic acid. The amount of formic acid is 2%–8% of the molar amount of 2-furancarbaldehyde, preferably 3%–5%. The reaction temperature is further preferably at room temperature of 20–30°C. The reaction time is further preferably 20–26 hours.

[0019] As a preferred embodiment, the polar solvent can be a low-carbon alcohol, such as C1-C5 alcohols, specifically methanol and / or ethanol. The amount of polar solvent used ensures that the concentration of 2-furan carbaldehyde is 0.8-1 mmol / mL, preferably 0.9-0.92 mmol / mL.

[0020] As a preferred embodiment, the molar ratio of 4-hydroxyaniline to 2-furanaldehyde is (0.9–1.1):1. Schiff base reactions are generally quite complete, and 4-hydroxyaniline and 2-furanaldehyde can preferably react in a stoichiometric ratio of 1:1.

[0021] As a preferred method, the Schiff base intermediate reacts with the hydrogenation reducing agent in a protic solvent at a temperature of -5 to 5°C for 2 to 8 hours. The most preferred reaction temperature is 0°C, and the most preferred reaction time is 4 to 5 hours.

[0022] As a preferred embodiment, the protic solvent is at least one of methanol, ethanol, and water. The amount of protic solvent used is intended to ensure that the concentration of the Schiff base intermediate is 0.05–0.15 g / mL, preferably 0.1–0.11 g / mL.

[0023] As a preferred embodiment, the hydrogenation reducing agent includes at least one selected from sodium borohydride, sodium cyanoborohydride, and sodium triacetoxyborohydride. Sodium borohydride is more preferably preferred.

[0024] As a preferred embodiment, the molar ratio of the hydrogenation reducing agent to the Schiff base intermediate is (0.5–1.5):1. The most preferred molar ratio is 0.8–1.2:1.

[0025] As a preferred method, the secondary amine intermediate and epichlorohydrin are first reacted at 75–85°C for 2–8 hours in the presence of a phase transfer catalyst; then cooled to room temperature, an alkaline solution is added, and the reaction is stirred for 15–45 minutes. In this reaction, epichlorohydrin acts as both a solvent and a reactant. The stirring speed is 600–1000 rpm. The optimal reaction time is 25–35 minutes.

[0026] As a preferred embodiment, the phase transfer catalyst comprises tetrabutylammonium bromide.

[0027] As a preferred embodiment, the molar ratio of the phase transfer catalyst to the secondary amine intermediate and epichlorohydrin is (0.15-0.25):1:(15-25).

[0028] As a preferred embodiment, the alkaline solution includes at least one of potassium carbonate solution, sodium carbonate solution, sodium hydroxide solution, and potassium hydroxide solution.

[0029] As a preferred embodiment, the mass concentration of the alkaline solution is 20% to 50%.

[0030] As a preferred embodiment, the molar ratio of the alkaline component to the secondary amine intermediate in the alkaline solution is (2-6):1.

[0031] The present invention also provides a method for preparing furfural-based aniline epoxy resin, wherein the preparation method involves reacting the furfural-based aniline epoxy monomer with a DOPO-based epoxy monomer of formula 4 and a diaminodiaryl sulfone through a melt and curing reaction to obtain the resin.

[0032]

[0033] The DOPO-based epoxy monomer of this invention (hereinafter referred to as EP-DOPO) can be purchased directly (CAS: 102486-95-3), or synthesized according to existing known techniques. The infrared properties of EP-DOPO are as follows: Figure 7 As shown.

[0034] The diaminodiaryl sulfones of this invention include, but are not limited to, 4,4'-diaminodiphenyl sulfone, with the following structural formula:

[0035]

[0036] As a preferred embodiment, the molar ratio of the total number of epoxy groups in the furfural-based aniline epoxy monomer and the DOPO-based epoxy monomer to the NH bond in the diaminodiaryl sulfone is (0.8–1.5):1.

[0037] As a preferred embodiment, the molar ratio of furfural-based aniline epoxy monomer to DOPO-based epoxy monomer is (1.5–15):1. The ratio of furfural-based aniline epoxy monomer to DOPO-based epoxy monomer can adjust the phosphorus content in the epoxy resin. Increasing the proportion of DOPO-based epoxy monomer significantly improves the flame retardancy of the epoxy resin, while a low proportion of furfural-based aniline epoxy monomer will affect the stability of the reduced resin to some extent.

[0038] As a preferred embodiment, the melting temperature is 100–180°C. A more preferred melting temperature is 105–120°C.

[0039] As a preferred embodiment, the curing reaction conditions are: a temperature of 190–220°C and a time of 2–5 hours. A further preferred curing reaction temperature is 200–210°C. A further preferred curing reaction time is 2–3 hours.

[0040] The present invention also provides a furfural-based aniline epoxy resin, which is obtained by the aforementioned preparation method.

[0041] The furfural-based aniline epoxy resin provided by this invention has the following structural formula (the following structural formula is only used as a typical example for illustration):

[0042]

[0043] Furfural-based aniline epoxy resin is composed of three types of units: A, B, and C; the structural units A, B, and C are as follows:

[0044]

[0045] As can be seen from the above structural formula, structural units A and C are connected to structural unit B via CN, respectively. There is no specific requirement for the connection order of structural units A and C. Specifically, structure B is a diaminodiarylsulfone curing agent unit with two amino groups and four connection sites, which can be connected to structural units A and / or C in any manner. The molar ratio between structural units A and C can be adjusted within the range of (1.5–15):1.

[0046] The furfural-based aniline epoxy resin of the present invention has an initial decomposition temperature of 340-360°C (preferably 345-355°C) and a maximum decomposition temperature of 400-420°C (preferably 405-415°C, most preferably 408-412°C).

[0047] The furfural-based aniline epoxy resin of the present invention extinguishes completely 40 seconds after being removed from the heat source, preferably 30 seconds, more preferably 20 seconds, even more preferably 10 seconds, and most preferably 5 seconds.

[0048] The phosphorus content in the furfural-based aniline epoxy resin of the present invention is controlled within the range of 0.5% to 5%.

[0049] Compared with the prior art, the beneficial technical effects of the technical solution of the present invention are as follows:

[0050] (1) The EP-Fulap preparation process provided by the present invention is simple, mild and green, and belongs to a safe epoxy monomer.

[0051] (2) The EP-Fulap provided by the present invention has a low viscosity, is easy to use, is easy to mix materials efficiently, and has a low saponification chlorine value. It belongs to the electronic grade epoxy grade, which has greater advantages compared with existing petroleum-based epoxy resins.

[0052] (3) The epoxy polymer constructed by EP-Fulap, EP-DOPO and diaminodiaryl sulfone provided by the present invention has the characteristics of good thermal stability and excellent flame retardant properties, and can be widely used as a flame retardant functional resin.

[0053] (4) The main monomer 2-furan carboxaldehyde used in the synthesis process of EP-Fulap of the present invention is a bio-based raw material, which is obtained by conversion or separation of biomass such as corn cobs. It is a renewable resource with high biological added value and good biological safety.

[0054] (5) The synthesis steps of furfural-based aniline epoxy resin in this invention are simple, the raw materials are widely available, the product has high biosafety, the prepared epoxy resin has excellent heat resistance and good flame retardant properties, and has greater advantages compared with existing petroleum-based epoxy resins. Attached Figure Description

[0055] Figure 1 The reaction pathway for the synthesis of EP-Fulap is shown.

[0056] Figure 2 This is the actual appearance of the EP-Fulap.

[0057] Figure 3 The 1H NMR spectrum of EP-Fulap.

[0058] Figure 4 This is the carbon NMR spectrum of EP-Fulap.

[0059] Figure 5 This is a high-resolution mass spectrometry representation of EP-Fulap.

[0060] Figure 6 This is the Fourier transform infrared spectrum of EP-Fulap.

[0061] Figure 7This is the Fourier transform infrared spectrum of EP-DOPO.

[0062] Figure 8 The Fourier transform infrared spectrum of the furfural-based aniline epoxy resin in Example 4 is shown.

[0063] Figure 9 The Fourier transform infrared spectrum of the furfural-based aniline epoxy resin in Example 5 is shown.

[0064] Figure 10 The Fourier transform infrared spectrum of the furfural-based aniline epoxy resin in Example 6 is shown.

[0065] Figure 11 The image shows the TGA diagram of the furfural-based aniline epoxy resin in Example 4.

[0066] Figure 12 The image shows the TGA diagram of the furfural-based aniline epoxy resin in Example 5.

[0067] Figure 13 The image shows the TGA diagram of the furfural-based aniline epoxy resin in Example 6.

[0068] Figure 14 This is a combustion test diagram of the furfural-based aniline epoxy resin in Example 4.

[0069] Figure 15 This is a combustion test diagram of the furfural-based aniline epoxy resin in Example 5.

[0070] Figure 16 This is a combustion test diagram of the furfural-based aniline epoxy resin in Example 6. Detailed Implementation

[0071] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0072] Example 1

[0073] Preparation of compound a (see Figure 1 ):

[0074] 4-hydroxyaniline (20 g, 0.1834 mol) was added to a 500 mL round-bottom flask, followed by ethanol (200 mL). 2-furanaldehyde (17.47 g, 0.1818 mol) was slowly added while stirring (1000 rpm), and formic acid (0.335 g, 0.0073 mol) was added dropwise. After the reaction was complete, the mixture was stirred at room temperature for 24 h, and the reaction progress was monitored by thin-layer chromatography. After the reaction was complete, the mixture was filtered through a Buchner funnel. The filter cake was washed with ethanol (60 mL) and a small amount of ethyl acetate (20 mL), and then dried under negative pressure in a vacuum drying oven to obtain a brownish-gray solid powder, which was compound a (33.5 g), with a yield of 98.5%.

[0075] 1 H NMR(400MHz, DMSO-d6)δ9.52(s,1H),8.42(s,1H),7.90(d,J=1.7Hz,1H),7.24–7.10 (m,2H),7.05(dd,J=3.5,0.7Hz,1H),6.84–6.72(m,2H),6.68(dd,J=3.5,1.8Hz,1H).

[0076] Example 2

[0077] Preparation of compound b (see Figure 1 ):

[0078] Compound a (26.6 g, 0.1422 mol) prepared in Example 1 was added to a 500 mL round-bottom flask and 250 mL of methanol was added to dissolve it completely. If necessary, sonication was used to assist dissolution. Sodium borohydride (5.38 g, 0.1422 mol) was added at 0 °C in four portions over 1 h. The mixture was then stirred for 4 h, and the reaction was monitored by thin-layer chromatography. After the reaction was complete, 50 mL of distilled water was added to quench the reaction. The reaction solution was extracted three times with ethyl acetate (120 mL), dried with anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The obtained solid was dried in a vacuum drying oven to give compound b (26.47 g, 0.14 mol), a pink to brownish-red solid, with a yield of 99%.

[0079] 1 H NMR (400MHz, DMSO-d6) δ8.44(s,1H),7.54(d,J=1.8Hz,1H),6.51(q,J=9.0Hz,4H),6.3 6(t,J=2.5Hz,1H), 6.24(d,J=3.1Hz,1H), 5.38(t,J=6.3Hz,1H), 4.13(d,J=6.1Hz,2H).

[0080] Example 3

[0081] Preparation of EP-Fulap (see Figure 1 ):

[0082] At room temperature, epichlorohydrin (245 g, 2.64 mol) and tetrabutylammonium bromide (8.5 g, 0.0264 mol) were added to a 500 mL round-bottom flask. While stirring, compound b (25 g, 0.1322 mol) was slowly added and the mixture was stirred rapidly. Then the temperature of the reaction system was raised to 80 °C and the reaction was stirred for 6 h. After the reaction was complete, the reaction system was cooled to room temperature. A sodium hydroxide aqueous solution (30%, 21.2 g NaOH + 50 g H2O) was slowly added dropwise using a constant-pressure low-pressure funnel. After stirring for 30 min, the reaction solution was diluted with an appropriate amount of distilled water, extracted with ethyl acetate, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. Purification was achieved by eluting with a petroleum ether-ethyl acetate system to obtain furfural-based aniline epoxy resin monomer EP-Fulap (25.57 g), with a yield of 64.24%. It was a pale yellow liquid with a viscosity of η = 300 r / min 168 mP·s, volatile matter < 0.195%, and saponification chlorine value of 0.00936%. The actual appearance is as follows. Figure 2 As shown, the nuclear magnetic mass spectrometry is as follows Figures 3-4 As shown, high-resolution mass spectrometry is as follows Figure 5 As shown, infrared is Figure 6 As shown.

[0083] 1 H NMR(400MHz, CDCl3)δ7.32(d,J=1.7Hz,1H),6.88–6.75(m,4H),6.27(dd,J=3.3,1.9Hz,1 H),6.13(d,J=3.2Hz,1H),4.44(s,2H),4.12(dd,J=11.1,3.2Hz,1H),3.87(dd,J=11.1,5 .6Hz,1H),3.56(dd,J=15.5,3.4Hz,1H),3.40–3.25(m,2H),3.18–3.05(m,1H),2.84(t,J =4.6Hz,1H),2.80–2.72(m,1H),2.70(dd,J=5.0,2.7Hz,1H),2.53(dd,J=5.0,2.7Hz,1H).

[0084] 13 C NMR (101MHz, CDCl3) δ152.33,151.27,143.67,141.91,115.75,115.35,110.27,107.67,69.55,53.13,50.77,50.33,49.12,45.46,44.72.

[0085] HRMS(ESI-TOF)m / z Calcd for[M+H] + :302.1387,found:302.1395.[M+Na] + :324.1206,found:324.1214.[M+K] + :340.0946,found:340.0951.

[0086] Example 4

[0087] Furfural-based aniline epoxy resin EP-Fulap (0.64 g, 0.00212 mol) was weighed into a reaction flask. Under air atmosphere and at 25°C, curing agent 4,4'-diaminodiphenyl sulfone (0.398 g, 0.0016 mol) and epoxy resin EP-DOPO (0.47 g, 0.00108 mol) were added in metered amounts. The mixture was heated to 110°C and stirred rapidly for 30 min to ensure that the materials were fully melted and mixed evenly. The mixture was then poured evenly onto a metal template and transferred to a curing chamber under nitrogen atmosphere. The temperature was slowly raised to 200°C and cured for 2 h. The mixture was then allowed to cool naturally under nitrogen atmosphere to obtain furfural-based aniline epoxy resin polymer.

[0088] Analysis of its thermogravimetric data under nitrogen, such as Figure 11 As shown, the initial decomposition temperature is 351℃ and the maximum decomposition temperature is 408℃, and the obtained material has good heat resistance.

[0089] In combustion experiments, such as Figure 14 The polymer was ignited with an open flame for 5 seconds, and the combustion was observed. During the combustion test, the flame extinguished immediately after the flame source was removed, and the polymer could not burn without an open flame, indicating that the polymer has very good flame retardant properties.

[0090] By judging its infrared data, such as Figure 8 As shown, the characteristic epoxy group ethylene oxide in the substrate participating in the reaction exhibits an infrared peak (914 cm⁻¹). -1 The disappearance of the epoxy groups indicates that the epoxy groups and amine groups of the epoxy resin have been completely polymerized.

[0091] Polymer infrared data assignment: 1038cm -1 This represents the carbon-oxygen bond vibration in CO; 1230 cm⁻¹ -1 Stretching vibrations of the COC bond in the furan ring; 1595, 1509, 1449 cm⁻¹ -1 Benzene ring peak; 1104.5 cm⁻¹ -1 The characteristic carbon-oxygen peak of 2° ROH generated by ring opening of epoxy; 3417 cm⁻¹ -1 The strong and broad absorption peak at that point is formed by the appearance of the -OH group after the ring opening of ethylene oxide.

[0092] Example 5

[0093] Furfural-based aniline epoxy resin EP-Fulap (0.85 g, 0.00282 mol) was weighed into a reaction flask. Under air atmosphere and at 25°C, curing agent 4,4'-diaminodiphenyl sulfone (0.4167 g, 0.00168 mol) and epoxy resin EP-DOPO (0.234 g, 0.000537 mol) were added in metered amounts. The mixture was heated to 110°C and stirred rapidly for 30 min to ensure that the materials were fully melted and mixed evenly. The mixture was then poured evenly onto a metal template and transferred to a curing chamber under nitrogen atmosphere. The temperature was slowly raised to 200°C and cured for 2 h. The mixture was then allowed to cool naturally under nitrogen atmosphere to obtain furfural-based aniline epoxy resin polymer.

[0094] Analysis of its thermogravimetric data under nitrogen, such as Figure 12 As shown, the initial decomposition temperature is 345℃, the maximum decomposition temperature is 412℃, and the obtained material has good heat resistance.

[0095] In combustion experiments, such as Figure 15 The polymer was ignited with an open flame for 5 seconds, and the combustion was observed. During the combustion test, the flame extinguished immediately after the flame source was removed, and the polymer could not burn without an open flame, indicating that the polymer has very good flame retardant properties.

[0096] By judging its infrared data, such as Figure 9 As shown, the characteristic infrared peak of ethylene oxide (914 cm⁻¹), a characteristic epoxy group involved in the reaction in the substrate, is observed. -1 The disappearance of the epoxy groups (etc.) indicates that the epoxy groups and amine groups of the epoxy resin have been completely polymerized.

[0097] Polymer infrared data assignment: 1042cm -1 This represents the carbon-oxygen bond vibration in CO; 1221 cm⁻¹ -1 Stretching vibrations of the COC bond in the furan ring; 1594, 1509, 1455 cm⁻¹ -1 Benzene ring peak; 1104.4 cm⁻¹ -1 The characteristic carbon-oxygen peak of 2° ROH generated by epoxy ring opening; 3405 cm⁻¹ -1 The strong and broad absorption peak at that point is formed by the appearance of the -OH group after the ring opening of ethylene oxide.

[0098] Example 6

[0099] Furfural-based aniline epoxy resin EP-Fulap (0.956 g, 0.00317 mol) was weighed into a reaction flask. Under air atmosphere and at 25°C, curing agent 4,4'-diaminodiphenyl sulfone (0.427 g, 0.00172 mol) and epoxy resin EP-DOPO (0.1168 g, 0.00027 mol) were added in metered amounts. The mixture was heated to 110°C and stirred rapidly for 30 min to ensure that the materials were fully melted and mixed evenly. The mixture was then poured evenly onto a metal template and transferred to a curing chamber under nitrogen atmosphere. The temperature was slowly raised to 200°C and cured for 2 h. The mixture was then allowed to cool naturally under nitrogen atmosphere to obtain furfural-based aniline epoxy resin polymer.

[0100] Analysis of its thermogravimetric data under nitrogen, such as Figure 13 As shown, the initial decomposition temperature is 355℃ and the maximum decomposition temperature is 411℃, and the obtained material has good heat resistance.

[0101] In combustion experiments, such as Figure 16 The polymer was observed to burn after being ignited by an open flame for 5 seconds. During the combustion test, the flame of the polymer decreased significantly after 2 seconds of burning after the flame source was removed, and was completely extinguished after 3 seconds, indicating that the polymer has excellent flame retardant properties.

[0102] By judging its infrared data, such as Figure 10 As shown, the characteristic infrared peak of ethylene oxide (914 cm⁻¹), a characteristic epoxy group involved in the reaction in the substrate, is observed. -1 The disappearance of the epoxy groups (etc.) indicates that the epoxy groups and amine groups of the epoxy resin have been completely polymerized.

[0103] Polymer infrared data assignment: 1230cm -1 Stretching vibrations of the COC bond in the furan ring; 1594, 1508.8 cm⁻¹ -1 Benzene ring peak; 1104.4 cm⁻¹ -1 The characteristic carbon-oxygen peak of 2° ROH generated by ring opening of epoxy; 3419 cm⁻¹ -1 The strong and broad absorption peak at that point is formed by the appearance of the -OH group after the ring opening of ethylene oxide.

[0104] contrast Figures 14-16 It can be seen that when the phosphorus content in the epoxy resin decreases to 2.2 wt%, 1.1 wt%, and 0.55 wt%, respectively, it significantly reduces the phosphorus content. Figures 14-15 It's basically impossible to light it. Figure 16 The flame extinguishes after about 2 seconds, indicating that epoxy resin with a phosphorus content of 0.55wt% or higher has a good flame retardant effect. The thermogravimetric analysis data shows that as the EP-Fulap ratio increases, the 5% and 10% thermal weight loss rates of epoxy resin decrease slightly.

[0105] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. All components not explicitly stated in this embodiment can be implemented using existing technology.

Claims

1. A furfural-based aniline epoxy monomer, characterized in that: It has the structure of Formula 1: Formula 1.

2. The method for preparing a furfural-based aniline epoxy monomer according to claim 1, characterized in that: Includes the following steps: 1) 4-hydroxyaniline reacts with 2-furan carboxaldehyde via a Schiff base reaction to obtain a Schiff base intermediate with structure 2; 2) The Schiff base intermediate is subjected to a hydrogenation reduction reaction to obtain a secondary amine intermediate with structure 3; 3) The secondary amine intermediate reacts with epichlorohydrin via a substitution reaction to yield furfural-based aniline epoxy monomer; Formula 2 Formula 3.

3. The method for preparing furfural-based aniline epoxy monomer according to claim 2, characterized in that: 4-Hydroxyaniline and 2-furan carboxaldehyde react in a polar solvent under acidic conditions at 10-30°C for 18-30 h.

4. The method for preparing a furfural-based aniline epoxy monomer according to claim 3, characterized in that: The polar solvent is methanol and / or ethanol.

5. The method for preparing a furfural-based aniline epoxy monomer according to claim 3, characterized in that: The molar ratio of 4-hydroxyaniline to 2-furan carboxaldehyde is (0.9~1.1):

1.

6. A method for preparing a furfural-based aniline epoxy monomer according to any one of claims 2 to 5, characterized in that: Schiff base intermediates react with hydrogenation reducing agents in a protic solvent at -5 to 5°C for 2 to 8 hours.

7. The method for preparing a furfural-based aniline epoxy monomer according to claim 6, characterized in that: The protic solvent is at least one of methanol, ethanol, and water.

8. The method for preparing a furfural-based aniline epoxy monomer according to claim 6, characterized in that: The hydrogenation reducing agent is at least one of sodium borohydride, sodium cyanoborohydride, and sodium triacetoxyborohydride.

9. The method for preparing a furfural-based aniline epoxy monomer according to claim 6, characterized in that: The molar ratio of the hydrogenation reducing agent to the Schiff base intermediate is (0.5~1.5):

1.

10. A method for preparing a furfural-based aniline epoxy monomer according to any one of claims 2-5 and 7-9, characterized in that: The secondary amine intermediate and epichlorohydrin are first reacted at 75-85°C for 2-8 h in the presence of a phase transfer catalyst; then cooled to room temperature, an alkaline solution is added, and the reaction is stirred for 15-45 min.

11. The method for preparing a furfural-based aniline epoxy monomer according to claim 10, characterized in that: The phase transfer catalyst is tetrabutylammonium bromide; The molar ratio of the phase transfer catalyst to the secondary amine intermediate and epichlorohydrin is (0.15~0.25):1:(15~25).

12. The method for preparing a furfural-based aniline epoxy monomer according to claim 10, characterized in that: The alkaline solution is at least one of potassium carbonate solution, sodium carbonate solution, sodium hydroxide solution, and potassium hydroxide solution. The mass concentration of the alkaline solution is 20%~50%; The molar ratio of the alkaline component to the secondary amine intermediate in the alkaline solution is (2~6):

1.

13. A method for preparing furfural-based aniline epoxy resin, characterized in that: The furfural-based aniline epoxy monomer of claim 1, the DOPO-based epoxy monomer of formula 4, and diaminodiaryl sulfone are reacted by melting and curing to obtain the product. Formula 4 The total number of epoxy groups in the furfural-based aniline epoxy monomer and the DOPO-based epoxy monomer has a molar ratio of (0.8~1.5):1 to the NH bond in the diaminodiaryl sulfone. The molar ratio of furfural-based aniline epoxy monomer to DOPO-based epoxy monomer is (1.5~15):

1.

14. The method for preparing a furfural-based aniline epoxy resin according to claim 13, characterized in that: The melting temperature is 100~180℃; The curing reaction conditions are: temperature 190~220℃, time 2~5 h.

15. A furfural-based aniline epoxy resin, characterized in that: Obtained by the preparation method described in claim 13 or 14.

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