A high-strength epoxy resin and a method for preparing the same

Abstract

The application discloses high-strength epoxy resin and a preparation method thereof, and belongs to the technical field of epoxy resin.The high-strength epoxy resin comprises the following raw materials in parts by weight: 80-90 parts of epoxy resin, 6-8 parts of a curing agent, 0.5-1.5 parts of a curing accelerator, 8-12 parts of a reaction-type reinforcing agent, 6-8 parts of a reaction-type flame retardant, 1-2 parts of a silane coupling agent and 1-2 parts of an antioxidant.The reaction-type reinforcing agent is generated by the reaction of tricyanopyridine and 10-amino-n-decanoic acid to form a double-substituted compound, the reaction of the double-substituted compound with 3-methoxy-4-hydroxybenzaldehyde to form a tri-substituted compound, the reaction of the tri-substituted compound with 4,4'-diamino diphenyl ether to form a Schiff base compound and the reaction of the Schiff base compound with epichlorohydrin to form the reaction-type reinforcing agent.The epoxy resin prepared by the application has excellent tensile strength, notched impact strength and flame retardant performance.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin preparation technology, specifically to a high-strength epoxy resin and its preparation method. Background Technology

[0002] Epoxy resin materials possess high adhesive strength, low curing shrinkage, excellent chemical resistance, and good electrical insulation, making them widely used in aerospace, construction, automotive, and electronics industries. However, with the rapid development of high-tech fields such as aerospace, higher demands are placed on the comprehensive performance of epoxy resin materials, namely, high strength, high toughness, excellent flame retardancy, good transparency, and thermal stability. General-purpose epoxy resins often fail to meet these requirements. Although general-purpose epoxy resin modifiers can effectively improve certain properties of cured materials, they also have other significant shortcomings. For example, while flame retardants improve flame retardancy, they often weaken the mechanical properties and density of the coating. Some flame retardants also have poor compatibility with the resin matrix, easily leading to migration or precipitation. Therefore, developing an epoxy resin with high strength and excellent flame retardancy is of significant application value.

[0003] Chinese invention patent CN116848169A discloses epoxy resin, a method for manufacturing the epoxy resin, an epoxy resin composition using the epoxy resin, and a cured product. The epoxy resin obtained by this method has good heat resistance, high thermal conductivity, and low thermal expansion, and can be effectively used in lamination, molding, casting, bonding and other fields, but its mechanical properties are still insufficient. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a high-strength epoxy resin and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A high-strength epoxy resin, comprising the following raw materials in parts by weight:

[0007] 80-90 parts epoxy resin, 6-8 parts curing agent, 0.5-1.5 parts curing accelerator, 8-12 parts reactive reinforcing agent, 6-8 parts reactive flame retardant, 1-2 parts silane coupling agent, and 1-2 parts antioxidant;

[0008] The reactive enhancer is prepared by the following method:

[0009] S1: Cyanuric chloride reacts with 10-aminodecanoic acid to form a disubstituted compound, the structural formula of which is as follows:

[0010]

[0011] S2: The disubstituted compound reacts with 3-methoxy-4-hydroxybenzaldehyde to form a trisubstituted compound, the structural formula of which is as follows:

[0012]

[0013] S3: The trisubstituted compound reacts with 4,4'-diaminodiphenyl ether to form a Schiff base compound, the structural formula of which is as follows:

[0014]

[0015] S4: Schiff base compounds react with epichlorohydrin to generate a reactive reinforcing agent, the reaction structure of which is as follows:

[0016]

[0017] In step S1, the molar ratio of cyanuric chloride and 10-aminodecanoic acid is 1:(2.05-2.1).

[0018] In step S2, the molar ratio of the disubstituted compound to 3-methoxy-4-hydroxybenzaldehyde is 1:(1.03-1.05).

[0019] In step S3, the molar ratio of the trisubstituted compound to 4,4'-diaminodiphenyl ether is (2.05-2.15):1.

[0020] In step S4, the molar ratio of the Schiff base compound to epichlorohydrin is 1:(4.1-4.3).

[0021] The reactive flame retardant is prepared by the following method:

[0022] N1: Benzophosphonyl dichloro reacts with p-hydroxybenzoic acid to generate intermediate 1, the structural formula of which is as follows:

[0023]

[0024] N2: Intermediate 1 reacts with 3-amino-1,2-propanediol to generate intermediate 2, the structural formula of which is as follows:

[0025]

[0026] N3: Intermediate 2 reacts with 4-aminophenylborate salt to form a reactive flame retardant, the reaction structure of which is as follows:

[0027]

[0028] In step N1, the molar ratio of phenylphosphonic dichloride to p-hydroxybenzoic acid is 1:2.08; in step N2, the molar ratio of intermediate 1 to 3-amino-1,2-propanediol is 1:2.05; in step N3, the molar ratio of intermediate 2 to 4-aminophenylborate salt is 1:2.1.

[0029] The curing agent is 4,4'-diaminodiphenylmethane; the curing accelerator is one of 2-methylimidazole and 2-ethyl-4-methylimidazole.

[0030] The silane coupling agent is silane coupling agent KH-560; the antioxidant is antioxidant 1010.

[0031] A method for preparing a high-strength epoxy resin includes the following steps:

[0032] (1) Weigh out the following by weight: 80-90 parts epoxy resin, 6-8 parts curing agent, 0.5-1.5 parts curing accelerator, 8-12 parts reactive reinforcing agent, 6-8 parts reactive flame retardant, 1-2 parts silane coupling agent, and 1-2 parts antioxidant.

[0033] (2) Stir the epoxy resin, reactive reinforcing agent, reactive flame retardant, silane coupling agent and antioxidant evenly, add curing agent and curing accelerator and stir, heat and cure, cool and demold to obtain high-strength epoxy resin.

[0034] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include:

[0035] The epoxy resin prepared by this invention exhibits excellent tensile strength, notched impact strength, and flame retardant properties. This is because the reactive reinforcing agent added to the components achieves effective energy dissipation through the formation of a three-dimensional cross-linked network, conformational changes in flexible segments, and non-covalent interactions, thereby simultaneously improving tensile strength and notched impact strength. Furthermore, the reactive flame retardant added to the components effectively enhances the flame retardant properties and thermal stability of the material under the dual action of the gas and condensed phases. Attached Figure Description

[0036] Figure 1 The 1H NMR spectrum of the reactive enhancer prepared in Example 1;

[0037] Figure 2 The 1H NMR spectrum of the reactive flame retardant prepared in Example 4. Detailed Implementation

[0038] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments.

[0039] Example 1: Preparation of reactive enhancers:

[0040] S1: Under ice bath conditions, 300 ml of tetrahydrofuran (THF), 0.205 mol of 10-aminodecanoic acid, and 0.4 mol of triethylamine were added to a reaction vessel and stirred until homogeneous. Under nitrogen protection, 100 ml of a THF solution containing 0.1 mol of cyanuric chloride was added dropwise over 30 min. After reacting for 2 h, the temperature was raised to 30 °C and the reaction was continued for 4 h. The mixture was then cooled to room temperature, filtered, and distilled under reduced pressure at 40 °C for 1 h. The mixture was recrystallized using 200 ml of anhydrous ethanol, filtered, and dried under vacuum at 50 °C for 10 h to obtain the disubstituted compound. Its 1H NMR spectrum data are as follows: 1 H NMR (400 MHz, DMSO-) d 6) δ 11.68 (s, 2H), 6.94 (t, J = 4.6 Hz, 2H), 3.44 (td, J =7.1, 4.6 Hz, 4H), 2.26 (t, J = 8.9 Hz, 4H), 1.69 (p, J = 7.3 Hz, 4H), 1.54(ddd, J = 16.6, 9.0, 7.6 Hz, 4H), 1.39 - 1.22 (m, 20H); HRMS(m / z): 486.2751[M+H] + ;

[0041] S2: 400 ml of N,N-dimethylformamide (DMF), 0.1 mol of the disubstituted compound, 0.103 mol of 3-methoxy-4-hydroxybenzaldehyde, and 0.12 mol of potassium carbonate were added to a reaction vessel, stirred and mixed, heated to 85 °C, and reacted for 7 h. After cooling to room temperature, 800 ml of 5 wt% HCl was added, and the mixture was stirred to precipitate. The precipitate was filtered, recrystallized using a mixed solution of 300 ml of ethyl acetate and anhydrous ethanol (ethyl acetate to anhydrous ethanol volume ratio of 1:9), filtered, and dried under vacuum at 60 °C for 10 h to obtain the trisubstituted compound. Its 1H NMR data are as follows: 1 H NMR (400 MHz, DMSO- d6) δ 11.68 (s, 2H), 9.88 (s, 1H), 7.93 (d, J = 8.7 Hz, 1H), 7.62 (dd, J = 8.7, 1.9 Hz, 1H), 7.43 (d, J = 1.8Hz, 1H), 7.13 (t, J = 4.7 Hz, 2H), 3.87 (s, 3H), 3.46 (td, J = 7.3, 4.7 Hz,4H), 2.26 (t, J = 8.9 Hz, 4H), 1.67 (p, J = 7.3 Hz, 4H), 1.54 (tt, J = 8.9,7.6 Hz, 4H), 1.40 - 1.22 (m, 20H); HRMS(m / z): 602.3458[M+H] + ;

[0042] S3: 800 ml DMF, 50 g 4A molecular sieve, 0.205 mol of the trisubstituted compound, and 0.1 mol of 4,4'-diaminodiphenyl ether were added to a reaction vessel. Under nitrogen protection, the mixture was stirred and mixed thoroughly. The temperature was raised to 60 °C, and the reaction was carried out for 7 h. After cooling to room temperature, the mixture was filtered. The filtrate was slowly poured into 1500 ml of stirred deionized water, and a precipitate was formed. The precipitate was filtered, washed with 50 wt% ethanol aqueous solution (2 × 100 ml), and dried under vacuum at 60 °C for 12 h to obtain the Schiff base compound. Its 1H NMR data are as follows: 1 H NMR (400 MHz, DMSO- d 6) δ 11.68 (s, 4H), 8.54 (s, 2H), 7.89 (d, J = 8.2 Hz, 2H), 7.47 - 7.37(m, 4H), 7.21 - 7.16 (m, 4H), 7.13 (t, J = 4.7 Hz, 4H), 7.02 - 6.97 (m, 4H), 3.87 (s, 6H), 3.46 (td, J = 7.2, 4.7 Hz, 8H), 2.26 (t, J = 8.9 Hz, 8H), 1.67(p, J = 7.3 Hz, 8H), 1.60 - 1.47 (m, 8H), 1.40 - 1.22 (m, 40H); HRMS(m / z): 1367.7662[M+H] + ;

[0043] S4: Add 1000 ml toluene, 0.1 mol Schiff base compound, 0.01 mol tetramethylammonium chloride, and 100 ml 1M NaOH aqueous solution to a reaction vessel, stir and mix well, then add 0.41 mol epichlorohydrin dropwise over 60 min. After the addition is complete, raise the temperature to 60℃ and react for 6 h. Cool to room temperature, adjust the pH to 7 using 5 wt% hydrochloric acid, allow to stand, and separate the liquids. Wash the organic phase three times with saturated brine (150 ml each time), dry with 40 g anhydrous sodium sulfate, filter, and distill under reduced pressure at 60℃ for 2 h to obtain the reaction enhancer; its 1H NMR spectrum is shown below. Figure 1 As shown, the data is as follows: 1 H NMR (400 MHz, DMSO- d 6) δ 8.54 (s, 2H), 7.89 (d, J = 8.2 Hz, 2H), 7.45 (d, J = 1.7 Hz, 2H), 7.41 (dd, J = 8.2, 1.7 Hz,2H), 7.21 - 7.16 (m, 4H), 7.13 (t, J = 4.7 Hz, 4H), 7.02 - 6.97 (m, 4H), 4.30- 4.16 (m, 8H), 3.87 (s, 6H), 3.77 (p, J = 3.3 Hz, 4H), 3.54-3.38 (m, 8H), 3.18 (dd, J = 5.0, 3.0 Hz, 4H), 3.07 (dd, J = 5.0, 3.0 Hz, 4H), 2.31 (t, J =8.5 Hz, 8H), 1.73 - 1.53 (m, 16H), 1.40 - 1.22 (m, 40H); HRMS (m / z): 1591.8749[M+H] + .

[0044] Example 2 Preparation of Reactive Enhancer

[0045] S1: Under ice bath conditions, 300 ml of THF, 0.208 mol of 10-aminodecanoic acid, and 0.4 mol of triethylamine were added to a reaction vessel and stirred until homogeneous. Under nitrogen protection, 100 ml of THF solution containing 0.1 mol of cyanuric chloride was added dropwise over 30 min. After reacting for 2 h, the temperature was raised to 35 °C and reacted for 3 h. The mixture was then cooled to room temperature, filtered, and distilled under reduced pressure at 40 °C for 1 h. The mixture was recrystallized using 200 ml of anhydrous ethanol, filtered, and dried under vacuum at 50 °C for 10 h to obtain the disubstituted compound.

[0046] S2: Add 400 ml DMF, 0.1 mol of the disubstituted compound, 0.104 mol of 3-methoxy-4-hydroxybenzaldehyde, and 0.12 mol of potassium carbonate to a reaction vessel, stir and mix well, heat to 90 °C, react for 6 h, cool to room temperature, add 800 ml of 5 wt% HCl, stir to precipitate, filter, recrystallize using a mixed solution of 300 ml ethyl acetate and anhydrous ethanol (volume ratio of ethyl acetate to anhydrous ethanol is 1:9), filter, and vacuum dry at 60 °C for 10 h to obtain the trisubstituted compound;

[0047] S3: Add 800 ml DMF, 50 g 4A molecular sieve, 0.21 mol trisubstituted compound, and 0.1 mol 4,4'-diaminodiphenyl ether to a reaction vessel. Under nitrogen protection, stir and mix well, heat to 65 °C, react for 7 h, cool to room temperature, filter, and slowly pour the filtrate into 1500 ml of stirred deionized water to precipitate. Filter, wash with 50 wt% ethanol aqueous solution (2 × 100 ml), and dry under vacuum at 60 °C for 12 h to obtain Schiff base compound;

[0048] S4: Add 1000 ml toluene, 0.1 mol Schiff base compound, 0.01 mol tetramethylammonium chloride, and 100 ml 1M NaOH aqueous solution to a reaction vessel, stir and mix well, add 0.42 mol epichlorohydrin dropwise over 60 min, raise the temperature to 65℃, react for 6 h, cool to room temperature, adjust the pH to 7 with 5 wt% hydrochloric acid, allow to stand and separate, wash the organic phase three times with saturated brine (150 ml each time), dry with 40 g anhydrous sodium sulfate, filter, and distill under reduced pressure at 60℃ for 2 h to obtain the reaction enhancer.

[0049] Example 3 Preparation of Reactive Enhancer

[0050] S1: Under ice bath conditions, 300 ml of THF, 0.21 mol of 10-aminodecanoic acid, and 0.4 mol of triethylamine were added to a reaction vessel and stirred until homogeneous. Under nitrogen protection, 100 ml of THF solution containing 0.1 mol of cyanuric chloride was added dropwise over 30 min. After reacting for 2 h, the temperature was raised to 40 °C and reacted for 3 h. The mixture was then cooled to room temperature, filtered, and distilled under reduced pressure at 40 °C for 1 h. The mixture was recrystallized using 200 ml of anhydrous ethanol, filtered, and dried under vacuum at 50 °C for 10 h to obtain the disubstituted compound.

[0051] S2: Add 400 ml DMF, 0.1 mol of the disubstituted compound, 0.105 mol of 3-methoxy-4-hydroxybenzaldehyde, and 0.12 mol of potassium carbonate to a reaction vessel, stir and mix well, heat to 95 °C, react for 5 h, cool to room temperature, add 800 ml of 5 wt% HCl, stir to precipitate, filter, recrystallize using a mixed solution of 300 ml ethyl acetate and anhydrous ethanol (volume ratio of ethyl acetate to anhydrous ethanol is 1:9), filter, and dry under vacuum at 60 °C for 10 h to obtain the trisubstituted compound;

[0052] S3: Add 800 ml DMF, 50 g 4A molecular sieve, 0.215 mol trisubstituted compound, and 0.1 mol 4,4'-diaminodiphenyl ether to a reaction vessel. Under nitrogen protection, stir and mix well, heat to 70 °C, react for 5 h, cool to room temperature, filter, and slowly pour the filtrate into 1500 ml of stirred deionized water to precipitate. Filter, wash with 50 wt% ethanol aqueous solution (2 × 100 ml), and dry under vacuum at 60 °C for 12 h to obtain Schiff base compound;

[0053] S4: Add 1000 ml toluene, 0.1 mol Schiff base compound, 0.01 mol tetramethylammonium chloride, and 100 ml 1M NaOH aqueous solution to a reaction vessel, stir and mix well, add 0.43 mol epichlorohydrin dropwise over 60 min, raise the temperature to 70℃, react for 5 h, cool to room temperature, adjust the pH to 7 with 5 wt% hydrochloric acid, allow to stand and separate, wash the organic phase three times with saturated brine (150 ml each time), dry with 40 g anhydrous sodium sulfate, filter, and distill under reduced pressure at 60℃ for 2 h to obtain the reaction enhancer.

[0054] Example 4: Preparation of reactive flame retardants:

[0055] N1: Under nitrogen protection, 300 ml of THF, 0.208 mol of p-hydroxybenzoic acid, and 0.45 mol of triethylamine were added to a reaction vessel and stirred until well mixed. 100 ml of a THF solution containing 0.1 mol of phenylphosphonic dichloroamide was added dropwise over 1 hour. The reaction was carried out at room temperature for 8 hours, filtered, washed with deionized water (2 × 100 ml), dried over 30 g of anhydrous magnesium sulfate, filtered again, and distilled under reduced pressure at 45 °C for 1 hour to obtain intermediate 1. Its 1H NMR data are as follows: 1 H NMR (400 MHz, DMSO- d6) δ 12.30 (s, 2H), 7.96 - 7.88(m, 4H), 7.84 - 7.76 (m, 2H), 7.60 - 7.51 (m, 1H), 7.49 - 7.40 (m, 2H), 7.19- 7.11 (m, 4H), HRMS(m / z): 399.0574[M+H] + ;

[0056] N2: 300 ml of anhydrous chloroform and 0.1 mol of intermediate 1 were added to a reaction vessel and stirred until homogeneous. 0.25 mol of thionyl chloride was added dropwise over 30 min. The mixture was stirred at room temperature for 2 h, then heated to reflux for 3 h. After cooling to room temperature, it was distilled under reduced pressure at 50 °C for 3 h to obtain the acyl chloride compound. 400 ml of toluene, the acyl chloride compound, 0.205 mol of 3-amino-1,2-propanediol, and 0.25 mol of triethylamine were added to a reaction vessel and stirred until homogeneous. The mixture was heated to 40 °C and reacted for 5 h. After filtration, the mixture was washed with deionized water (2 × 100 ml), dried with 30 g of anhydrous magnesium sulfate, filtered, and distilled under reduced pressure at 60 °C for 2 h to obtain intermediate 2. Its 1H NMR data are as follows: 1 H NMR (400 MHz, DMSO-) d 6) δ 8.36 (t, J = 6.9 Hz, 2H), 7.90 - 7.85 (m, 4H), 7.82 -7.77 (m, 2H), 7.58 - 7.53 (m, 1H), 7.47 - 7.41 (m, 2H), 7.28 - 7.23 (m, 4H), 4.67 (d, J = 5.7 Hz, 2H), 4.45 (d, J = 11.2 Hz, 2H), 3.79 (dp, J = 5.8, 4.8Hz, 2H), 3.53 - 3.30 (m, 8H), HRMS(m / z): 545.1607[M+H] + ;

[0057] N3: Add 500 ml of anhydrous DMF, 0.1 mol of intermediate 2, 0.23 mol of potassium carbonate, and 20 g of anhydrous magnesium sulfate to a reaction vessel and stir until well mixed. Add 0.21 mol of 4-aminophenylborate acid salt in 5 batches (each batch 15 min apart) and stir at room temperature for 10 h. Filter the mixture and slowly pour the reaction solution into 800 ml of anhydrous diethyl ether. Stir to precipitate the precipitate, filter, and wash with a mixed solution of anhydrous diethyl ether and anhydrous ethanol (volume ratio of anhydrous diethyl ether to anhydrous ethanol is 1:9) (2 × 100 ml). Dry under vacuum at 50 °C for 12 h to obtain the reactive flame retardant; its 1H NMR spectrum is shown below. Figure 2As shown, the data is as follows: 1 H NMR (400 MHz, DMSO- d 6) δ 8.22 (t, J = 5.9 Hz, 2H), 7.91 - 7.85 (m, 4H), 7.82 - 7.77 (m,2H), 7.59 - 7.53 (m, 1H), 7.52 - 7.41 (m, 6H), 7.29 - 7.22 (m, 4H), 6.68 -6.61 (m, 4H), 4.95 (d, J = 5.9 Hz, 2H), 4.79 (d, J = 5.7 Hz, 2H), 4.52 (p, J= 3.6 Hz, 2H), 4.27 (s, 2H), 4.22 (d, J = 3.5 Hz, 2H), 3.53 (dd, J = 5.9, 3.6Hz, 4H), HRMS(m / z): 747.2465[M+H] + .

[0058] Example 5: Preparation of high-strength epoxy resin

[0059] (1) Weigh out: 80g of epoxy resin, 6g of curing agent (4,4'-diaminodiphenylmethane), 0.5g of curing accelerator (2-methylimidazole), 8g of reactive reinforcing agent (prepared in Example 1), 6g of reactive flame retardant (prepared in Example 4), 1g of silane coupling agent (silane coupling agent KH-560), and 1g of antioxidant (antioxidant 1010);

[0060] (2) Stir epoxy resin, reactive reinforcing agent, reactive flame retardant, silane coupling agent and antioxidant at 90°C and 500 rpm for 30 min. Add curing agent and curing accelerator and continue stirring for 20 min. Pour into an 80 mm × 15 mm × 4 mm mold, cure at 100°C for 2 h, cure at 150°C for 2 h, cool naturally to room temperature, demold, and obtain high-strength epoxy resin.

[0061] Example 6 Preparation of high-strength epoxy resin

[0062] (1) Weigh out: 85g of epoxy resin, 7g of curing agent (4,4'-diaminodiphenylmethane), 1g of curing accelerator (2-ethyl-4-methylimidazolium), 10g of reactive reinforcing agent (prepared in Example 2), 7g of reactive flame retardant (prepared in Example 4), 1.5g of silane coupling agent (silane coupling agent KH-560), and 1.8g of antioxidant (antioxidant 1010);

[0063] (2) Stir epoxy resin, reactive reinforcing agent, reactive flame retardant, silane coupling agent and antioxidant at 90°C and 500 rpm for 30 min. Add curing agent and curing accelerator and continue stirring for 20 min. Pour into an 80 mm × 15 mm × 4 mm mold, cure at 100°C for 2 h, cure at 150°C for 2 h, cool naturally to room temperature, demold, and obtain high-strength epoxy resin.

[0064] Example 7 Preparation of high-strength epoxy resin

[0065] (1) Weigh out: 90g of epoxy resin, 8g of curing agent (4,4'-diaminodiphenylmethane), 1.5g of curing accelerator (2-ethyl-4-methylimidazolium), 12g of reactive reinforcing agent (prepared in Example 3), 8g of reactive flame retardant (prepared in Example 4), 2g of silane coupling agent (silane coupling agent KH-560), and 2g of antioxidant (antioxidant 1010);

[0066] (2) Stir epoxy resin, reactive reinforcing agent, reactive flame retardant, silane coupling agent and antioxidant at 90°C and 500 rpm for 30 min. Add curing agent and curing accelerator and continue stirring for 20 min. Pour into an 80 mm × 15 mm × 4 mm mold, cure at 100°C for 2 h, cure at 150°C for 2 h, cool naturally to room temperature, demold, and obtain high-strength epoxy resin.

[0067] Comparative Example 1

[0068] The raw material composition and preparation method of the high-strength epoxy resin are basically the same as those in Example 6, except that the reactive reinforcing agent is replaced with an equal weight of a reactive reinforcing agent prepared by the following method:

[0069] The preparation method of the reaction enhancer is basically the same as that in Example 2, except that 10-aminodecanoic acid in step S1 is replaced with an equimolar amount of glycine.

[0070] Comparative Example 2

[0071] The raw material composition and preparation method of the high-strength epoxy resin are basically the same as those in Example 6, except that the reactive reinforcing agent is replaced with an equal weight of a reactive reinforcing agent prepared by the following method:

[0072] The preparation method of the reactive enhancer is basically the same as that in Example 2, except that the 4,4'-diaminodiphenyl ether in step S3 is replaced with an equimolar amount of 4,4'-diaminodiphenylmethane.

[0073] Comparative Example 3

[0074] The raw material composition and preparation method of the high-strength epoxy resin are basically the same as those in Example 6, except that the reactive reinforcing agent is replaced with an equal weight of a reactive reinforcing agent prepared by the following method:

[0075] The preparation method of the reactive enhancer is basically the same as that in Example 2, except that 4,4'-diaminodiphenyl ether in step S3 is replaced with an equimolar amount of p-phenylenediamine.

[0076] Comparative Example 4

[0077] The raw material composition and preparation method of the high-strength epoxy resin are basically the same as those in Example 6, except that the reactive reinforcing agent is replaced with an equal weight of a reactive reinforcing agent prepared by the following method:

[0078] S1: Under ice bath conditions, 200 ml THF, 0.208 mol 10-aminodecanoic acid, and 0.4 mol triethylamine were added to a reaction vessel and stirred until homogeneous. Under nitrogen protection, 100 ml of THF solution containing 0.1 mol cyanuric chloride was added dropwise over 30 min. The temperature was raised to 35 °C and the reaction was carried out for 3 h. The mixture was then cooled to room temperature, filtered, and distilled under reduced pressure at 40 °C for 1 h. The mixture was recrystallized using 200 ml of anhydrous ethanol, filtered, and dried under vacuum at 50 °C for 10 h to obtain the disubstituted compound.

[0079] S2: Add 400 ml DMF, 0.21 mol of the disubstituted compound, 0.1 mol of 4,4'-diaminodiphenyl ether, and 0.15 mol of potassium carbonate to a reaction vessel, stir and mix well, heat to 70 °C, react for 6 h, cool to room temperature, add 800 ml of 5 wt% HCl, stir to precipitate, filter, recrystallize using a mixed solution of 300 ml ethyl acetate and anhydrous ethanol (volume ratio of ethyl acetate to anhydrous ethanol is 1:9), filter, and vacuum dry at 60 °C for 10 h to obtain the trisubstituted compound;

[0080] S3: Add 1000 ml toluene, 0.1 mol of the trisubstituted compound, 0.01 mol of TEBAC, and 100 ml of 1 M NaOH aqueous solution to a reaction vessel, stir and mix well, then add 0.42 mol of epichlorohydrin dropwise over 30 min. After the addition is complete, heat to 65 °C and react for 6 h. Then cool to room temperature, adjust the pH to 7 using 5 wt% hydrochloric acid, allow to stand and separate the liquids. Wash the organic phase three times with saturated brine (150 ml each time), dry with 40 g of anhydrous sodium sulfate, filter, and distill under reduced pressure at 60 °C for 2 h to obtain the reaction enhancer.

[0081] Comparative Example 5

[0082] The raw material composition and preparation method of the high-strength epoxy resin are basically the same as those in Example 6, except that the reactive flame retardant is replaced with an equal weight of a reactive flame retardant prepared by the following method:

[0083] The preparation method of the reactive flame retardant is basically the same as that in Example 4, except that the p-hydroxybenzoic acid in step N1 is replaced with an equimolar amount of 3-hydroxypropionic acid.

[0084] Comparative Example 6

[0085] The raw material composition and preparation method of the high-strength epoxy resin are basically the same as in Example 6, except that an equal weight of reactive flame retardant prepared by the following method will be used instead:

[0086] The preparation method of the reactive flame retardant is basically the same as that in Example 4, except that the 4-aminophenylboronic acid salt in step N3 is replaced with an equimolar amount of phenylboronic acid.

[0087] Comparative Example 7

[0088] The raw material composition and preparation method of the high-strength epoxy resin are basically the same as those in Example 6. The difference is that no reactive flame retardant is added to the components, and the curing agent is replaced with 11.5g.

[0089] The epoxy resin used in the embodiments and comparative examples of this application is model E-44, which is produced by Shandong Tianmao New Material Technology Co., Ltd.

[0090] The high-strength epoxy resins prepared in Examples 5-7 and Comparative Examples 1-6 were tested for tensile strength, notched impact strength, and flame retardant properties. The test results are shown in Table 1.

[0091] Tensile strength: The high-strength epoxy resin was cut into 5A dumbbell-shaped specimens and tested according to GB / T 1040.2-2022 standard at a tensile speed of 50 mm / min.

[0092] Notched impact strength: High-strength epoxy resin was cut into A-notch specimens and tested according to GB / T 1843-2008 standard.

[0093] Flame retardant properties: High-strength epoxy resin was cut into 80mm×10mm×4mm samples and tested according to Method A-top surface ignition method in GB / T 2406.2-2009 standard.

[0094] Table 1 Performance Data Sheet

[0095]

[0096] As can be seen from the data in Examples 5-6, the epoxy resin prepared by the present invention has excellent tensile strength, notched impact strength and flame retardant properties.

[0097] The reactive reinforcing agent added to the high-strength epoxy resin prepared in this invention contains epoxy groups, Schiff bases, long alkyl chains, triazine rings, flexible ether bonds, and para-substituted diphenyl ring structures. The epoxy groups react with active hydrogen in the resin to form a dense three-dimensional cross-linked network, effectively eliminating interfacial defects and improving the stress transfer efficiency of the cross-linked network, thereby enhancing tensile strength. The introduction of flexible long alkyl chains into the rigid cross-linked network allows for conformational changes and energy absorption under tensile and impact loads, reducing local cross-linking density and internal stress concentration, thus improving the material's fracture toughness and notched impact strength. The Schiff base, through non-covalent interactions such as hydrogen bonding and π-π stacking with the matrix, helps disperse stress and delay crack propagation under external forces, thereby improving notched impact strength. The flexible ether bonds impart conformational tunability to the para-substituted diphenyl ring structure, which helps alleviate curing shrinkage stress and improve the mobility of molecular chain segments. The benzene ring and triazine ring together constitute a rigid framework, enabling the reactive reinforcing agent to effectively bear external forces within the epoxy curing network, improving mechanical properties. The synergistic effect of multiple functional groups enables reactive reinforcing agents to effectively withstand external forces within the epoxy curing network while simultaneously inhibiting crack propagation through energy dissipation, thereby achieving a simultaneous increase in tensile strength and notched impact strength. In contrast, the reactive reinforcing agent used in Comparative Example 2 is connected to the two benzene rings by methylene groups, making it difficult to form effective hydrogen bonds with the epoxy groups. This results in relatively weak interfacial bonding, making it more prone to interfacial debonding and crack initiation under impact loads, thus reducing the notched impact strength.

[0098] The reactive flame retardant added to the high-strength epoxy resin prepared in this invention uses phosphate ester as the core and symmetrically introduces borate ester, benzene ring, and terminal amino groups. The amino groups in the reactive flame retardant can act as curing groups to form a three-dimensional cross-linked network with the epoxy resin, improving the dispersion uniformity of the flame retardant groups (phosphate ester, borate ester), reducing the separation of flame retardant molecules from the coating matrix, improving interfacial bonding and structural integrity, and releasing inert gases such as NH3 during thermal decomposition to dilute oxygen and improve flame retardant performance. The phosphate ester structure easily decomposes during heating or combustion to generate phosphorus-containing free radicals (such as PO·, HPO·), which can effectively capture highly reactive free radicals such as ·H and ·OH in the combustion chain reaction, thereby interrupting the gas-phase combustion reaction. Simultaneously, the phosphate ester promotes epoxy resin oxidation in the condensed phase. The resin undergoes dehydration and carbonization to form a dense and continuous char layer, improving its thermal stability and heat and oxygen insulation capabilities, thus effectively enhancing flame retardant efficiency. The borate ester structure can be converted into glassy substances such as B2O3 under high-temperature conditions, covering the material surface and working synergistically with the phosphorus-based char layer to form a stable "phosphorus-boron composite protective layer." This effectively blocks heat transfer and the escape of combustible gases, further enhancing the material's flame retardant performance and heat resistance. The rigid benzene ring structure is less prone to generating combustible volatiles during thermal decomposition, reducing the oxygen demand during combustion and promoting the formation of a dense char layer, thereby improving its ability to block heat and oxygen.

[0099] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A high-strength epoxy resin, characterized in that, The ingredients include the following parts by weight: 80-90 parts epoxy resin, 6-8 parts curing agent, 0.5-1.5 parts curing accelerator, 8-12 parts reactive reinforcing agent, 6-8 parts reactive flame retardant, 1-2 parts silane coupling agent, and 1-2 parts antioxidant; The structural formula of the reactive enhancer is as follows: ； The structural formula of the reactive flame retardant is as follows: 。 2. The high-strength epoxy resin according to claim 1, characterized in that, The reactive enhancer is prepared by the following method: S1: Cyanuric chloride reacts with 10-aminodecanoic acid to form a disubstituted compound. S2: The disubstituted compound reacts with 3-methoxy-4-hydroxybenzaldehyde to form a trisubstituted compound. S3: Trisubstituted compounds react with 4,4'-diaminodiphenyl ether to form Schiff base compounds. S4: Schiff base compounds react with epichlorohydrin to generate reactive reinforcing agents; In step S3, the molar ratio of the trisubstituted compound to 4,4'-diaminodiphenyl ether is (2.05-2.15):1; in step S4, the molar ratio of the Schiff base compound to epichlorohydrin is 1:(4.1-4.3).

3. The high-strength epoxy resin according to claim 2, characterized in that, In step S1, the molar ratio of cyanuric chloride and 10-aminodecanoic acid is 1:(2.05-2.1).

4. The high-strength epoxy resin according to claim 2, characterized in that, In step S2, the molar ratio of the disubstituted compound to 3-methoxy-4-hydroxybenzaldehyde is 1:(1.03-1.05).

5. The high-strength epoxy resin according to claim 1, characterized in that, The reactive flame retardant is prepared by the following method: N1: Benzyl dichloride reacts with p-hydroxybenzoic acid to form intermediate 1. N2: Intermediate 1 reacts with 3-amino-1,2-propanediol to generate intermediate 2. N3: Intermediate 2 reacts with 4-aminophenylborate salt to form a reactive flame retardant; In step N1, the molar ratio of phenylphosphonic dichloride to p-hydroxybenzoic acid is 1:2.08; in step N2, the molar ratio of intermediate 1 to 3-amino-1,2-propanediol is 1:2.05; in step N3, the molar ratio of intermediate 2 to 4-aminophenylborate salt is 1:2.

1.

6. The high-strength epoxy resin according to claim 1, characterized in that, The curing agent is 4,4'-diaminodiphenylmethane.

7. The high-strength epoxy resin according to claim 1, characterized in that, The curing accelerator is one of 2-methylimidazole and 2-ethyl-4-methylimidazole.

8. The high-strength epoxy resin according to claim 1, characterized in that, The silane coupling agent is silane coupling agent KH-560.

9. The high-strength epoxy resin according to claim 1, characterized in that, The antioxidant is antioxidant 1010.

10. A method for preparing the high-strength epoxy resin according to any one of claims 1-9, characterized in that, Includes the following steps: (1) Weigh out the following by weight: 80-90 parts epoxy resin, 6-8 parts curing agent, 0.5-1.5 parts curing accelerator, 8-12 parts reactive reinforcing agent, 6-8 parts reactive flame retardant, 1-2 parts silane coupling agent, and 1-2 parts antioxidant. (2) Stir the epoxy resin, reactive reinforcing agent, reactive flame retardant, silane coupling agent and antioxidant evenly, add curing agent and curing accelerator and stir, heat and cure, cool and demold to obtain high-strength epoxy resin.

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