A toughened modified epoxy resin and preparation method thereof

Abstract

The present invention relates to the technical field of epoxy resin materials, specifically to a toughened modified epoxy resin and a preparation method thereof. The present invention discloses a toughened modified epoxy resin and a preparation method thereof, wherein hexachlorocyclotriphosphazene with flame retardancy is used as a raw material, grafted with allylamine, and then reacted with sodium methoxide to obtain diallylamine-modified cyclotriphosphazene; diallylamine-modified cyclotriphosphazene is polymerized with 1,1,3,3-tetramethyldisiloxane, and finally 1,2-epoxy-5-hexene is added to terminate to obtain a silicon-containing cyclotriphosphazene polymer; the silicon-containing cyclotriphosphazene polymer is stirred and mixed with an epoxy resin, a diluent, nano-silica, a coupling agent, a defoamer, an antioxidant, a curing agent, and a curing agent accelerator to obtain a toughened modified epoxy resin.

Description

Technical Field

[0001] The invention relates to the technical field of epoxy resin materials, in particular to a toughened modified epoxy resin and a preparation method thereof. Background Art

[0002] Epoxy resin is a common thermosetting resin with the characteristics of simple operation and easy processing and molding. It is widely used in construction, electronic packaging, transportation, aerospace, automotive industry, chemical coatings and other fields. With the continuous development of technology, the demand for epoxy resin in related industries has also increased, and the requirements for the performance of epoxy resin have also become higher and higher.

[0003] At present, epoxy resin is mainly general-purpose bisphenol A epoxy resin. Because it contains multiple epoxy groups in its molecular structure, it can react with amines and anhydride curing agents to form a cured product with a three-dimensional network structure. However, during the curing process, the epoxy resin shrinks in volume and produces certain internal stress, resulting in poor crack resistance; the cured epoxy resin is hard and brittle, and has poor impact resistance and fatigue durability. In addition, epoxy resin itself is extremely flammable. It generally decomposes at 300°C and then burns violently, which not only generates a large amount of toxic and harmful smoke, but also is accompanied by the phenomenon of molten droplets. Therefore, while toughening and modifying the epoxy resin, it is also very important to improve its flame retardant properties. Summary of the invention

[0004] The object of the present invention is to provide a toughened modified epoxy resin and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a toughened modified epoxy resin and a preparation method thereof, comprising the following steps:

[0006] Step 1:

[0007] The hexachlorocyclotriphosphazene is purified by the following purification method: the hexachlorocyclotriphosphazene is dissolved in anhydrous petroleum ether, filtered to remove insoluble impurities, the filtrate is removed by rotary evaporation, and the solid is vacuum dried for 24 hours; the purified hexachlorocyclotriphosphazene is added to tetrahydrofuran and stirred for 15 to 30 minutes, and an acid binding agent is added under nitrogen protection and stirred for 5 minutes; a mixed solution of allylamine and tetrahydrofuran is added, and the addition time is controlled to 30 minutes, and the reaction is stirred for 5 to 6 hours in an ice-water bath; after terminating the reaction, triethylamine hydrochloride is removed by filtering, a mixed solution of sodium methoxide and tetrahydrofuran is added, the temperature is raised to 55 to 60° C., and the reaction is refluxed for 5 to 8 hours, and then the sodium chloride is removed by cooling and filtering, and the solvent and impurities are removed by reduced pressure distillation, and the mixture is washed with chloroform and distilled water for 3 times, respectively, and vacuum dried to obtain diallyl-grafted cyclotriphosphazene;

[0008] Step 2:

[0009] Diallyl grafted cyclotriphosphazene is added to tetrahydrofuran, stirred for 5-10 minutes, and then argon is introduced for protection, 1,1,3,3-tetramethyldisiloxane is added, chloroplatinic acid isopropanol solution is used as a catalyst, the temperature is raised to 60-65°C for reaction for 8-10 hours, 1,2-epoxy-5-hexene is added for end-capping, the solvent and impurities are removed by reduced pressure distillation, the polymer is washed with anhydrous methanol and deionized water, and vacuum dried to obtain a silicon-containing cyclotriphosphazene polymer;

[0010] Step 3:

[0011] The silicon-containing cyclotriphosphazene polymer is mixed with the epoxy resin and stirred for 1-2 hours to obtain an epoxy resin mixture; a diluent, nano-silica, a coupling agent, a defoaming agent, an antioxidant, a curing agent, and a curing agent accelerator are added to the epoxy resin mixture, and the mixture is stirred to obtain a toughened modified epoxy resin.

[0012] Furthermore, in step 1, the acid binding agent is triethylamine.

[0013] Furthermore, in step 1, the molar ratio of hexachlorocyclotriphosphazene, allylamine and sodium methoxide is 1:2:4.

[0014] Further, in step 2, the concentration of the chloroplatinic acid isopropanol solution is 0.02-0.03 g / L.

[0015] Furthermore, in step 2, the molar ratio of 1,1,3,3-tetramethyldisiloxane, diallyl-grafted cyclotriphosphazene, and 1,2-epoxy-5-hexene is 1:(0.6-0.8):0.5.

[0016] Furthermore, in step 3, the epoxy resin mixture comprises, by weight percentage, 13-21% of the silicon-containing cyclotriphosphazene polymer and 79-87% of the epoxy resin.

[0017] Furthermore, in step 3, the contents of the components in the toughened modified epoxy resin are, by weight, 35 to 48 parts of epoxy resin mixture, 6 to 7 parts of diluent, 3 to 5 parts of nano-silicon dioxide, 0.5 to 1 part of coupling agent, 0.3 to 0.5 part of defoaming agent, 0.2 to 0.5 part of antioxidant, 18 to 22 parts of curing agent, and 0.5 to 0.8 part of curing agent accelerator.

[0018] Furthermore, in step 3, the coupling agent is any one of KH550, KH560, and KH570; and the antioxidant is any one of antioxidant 1010, antioxidant 1076, and antioxidant 168.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention prepares a silicon-containing cyclotriphosphazene polymer, the silicon-containing cyclotriphosphazene polymer is terminated with epoxy groups, and can be cross-linked with epoxy resin under the action of a curing agent, thereby achieving modification of the epoxy resin.

[0020] Firstly, the present invention uses hexachlorocyclotriphosphazene as a raw material. The hexachlorocyclotriphosphazene is an inorganic-organic hybrid compound, in which P and N are alternately arranged to form a skeleton. Since the chlorine atom has a chemical property similar to that of acyl chloride and has a strong reaction activity, it is reacted with allylamine and sodium methoxide in a molar ratio of 1:2:4 to obtain diallyl grafted cyclotriphosphazene. The diallyl grafted cyclotriphosphazene, as a phosphazene derivative, not only contains two unsaturated carbon-carbon double bonds, but also has two elements, P and N. P and N have a synergistic effect in providing flame retardant performance, and can improve flame retardant efficiency.

[0021] Although a single diallyl-grafted cyclotriphosphazene has good flame retardant properties, its molecular weight is relatively small. When directly added as an additive to a high molecular weight epoxy resin, it will migrate to the surface of the epoxy resin material after a period of time and eventually precipitate, which will not only affect the appearance of the epoxy resin, but also cause a decrease in the flame retardant effect. Therefore, on the basis of synthesizing diallyl-grafted cyclotriphosphazene, the present invention further utilizes the addition reaction between the carbon-carbon double bond and the silicon-hydrogen bond to polymerize diallyl-grafted cyclotriphosphazene with 1,1,3,3-tetramethyldisiloxane, and then uses 1,2-epoxy-5-hexene containing an epoxy group to end-cap the polymerization product to obtain a silicon-containing cyclotriphosphazene polymer. Under the action of a curing agent, the silicon-containing cyclotriphosphazene polymer undergoes a cross-linking reaction with the epoxy resin, and the silicon-oxygen chain segment is introduced into the epoxy resin, thereby achieving an improvement in the toughness, flame retardancy, and heat resistance of the epoxy resin. Due to the flexibility of the silicon-oxygen chain segment, it can buffer the internal stress generated by the volume shrinkage of the epoxy resin during the curing process to a certain extent, thereby improving the crack resistance of the epoxy resin.

[0022] In addition, the researchers considered that only when the two ends of the polymer of 1,1,3,3-tetramethyldisiloxane and diallyl-grafted cyclotriphosphazene are silicon-hydrogen bonds, the resulting polymer can undergo an addition reaction with the double bond on 1,2-epoxy-5-hexene to obtain an epoxy-terminated silicon-containing cyclotriphosphazene polymer. Therefore, the amount of 1,1,3,3-tetramethyldisiloxane is higher than that of diallyl-grafted cyclotriphosphazene. Considering the poor compatibility between organosilicon and epoxy resin, the excessive length of the molecular chain of the silicon-containing cyclotriphosphazene polymer or its excessive use will cause the organosilicon molecular chain to migrate to the surface of the epoxy resin and cause phase separation, which will eventually lead to a decrease in the performance of the epoxy resin. After repeated experiments by R&D personnel, it was found that when the molar ratio of 1,1,3,3-tetramethyldisiloxane, diallyl-grafted cyclotriphosphazene, and 1,2-epoxy-5-hexene is 1:(0.6~0.8):0.5 for reaction, the prepared silicon-containing cyclotriphosphazene polymer has a suitable molecular weight; in terms of weight percentage, mixing 13~21% silicon-containing cyclotriphosphazene polymer and 79~87% epoxy resin has the best toughening and flame retardant modification effects. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Materials and sources used in the present invention: the diluent is n-butyl glycidyl ether, the coupling agent is KH560, the antioxidant is antioxidant 1010, the curing agent is methyltetrahydrophthalic anhydride, and the curing agent accelerator is 2,4,6-tris(dimethylaminomethyl)phenol, all of which are from Shanghai Yuanye Biotechnology Co., Ltd.; the defoaming agent is from Henan Henglande Environmental Protection Technology Co., Ltd., model JK-8601; nano silicon dioxide is from; the epoxy resin is from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd., model XFI03; the epoxy resin is epoxy resin E51, which is from Hebei Linyuan Fine Chemical Co., Ltd.

[0025] Embodiment 1: A toughened modified epoxy resin and a preparation method thereof, comprising the following steps:

[0026] Step 1:

[0027] Hexachlorocyclotriphosphazene is purified by the following purification method: dissolving hexachlorocyclotriphosphazene in anhydrous petroleum ether, removing insoluble impurities by suction filtration, removing the filtrate by rotary evaporation, and then vacuum drying the solid for 24 hours; adding the purified hexachlorocyclotriphosphazene to tetrahydrofuran and stirring for 15 minutes, adding acid-binding agent triethylamine and stirring for 5 minutes under nitrogen protection; adding a mixed solution of allylamine and tetrahydrofuran, controlling the adding time to 30 minutes, and stirring the mixture in an ice-water bath for 5 hours; after terminating the reaction, removing triethylamine hydrochloride by suction filtration, adding a mixed solution of sodium methoxide and tetrahydrofuran, heating to 55°C, reflux reaction for 5 hours, cooling, removing sodium chloride by suction filtration, removing the solvent and impurities by reduced pressure distillation, washing with chloroform and distilled water for 3 times respectively, and vacuum drying to obtain diallyl-grafted cyclotriphosphazene; wherein the molar ratio of hexachlorocyclotriphosphazene, allylamine, and sodium methoxide is 1:2:4;

[0028] Step 2:

[0029] Diallyl grafted cyclotriphosphazene is added to tetrahydrofuran, stirred for 5 minutes, and then argon is introduced for protection, 1,1,3,3-tetramethyldisiloxane is added, and a 0.02g / L chloroplatinic acid isopropanol solution is used as a catalyst, the temperature is raised to 60°C for reaction for 8 hours, and then 1,2-epoxy-5-hexene is added for end-capping, the solvent and impurities are removed by reduced pressure distillation, and the mixture is washed with anhydrous methanol and deionized water, and vacuum dried to obtain a silicon-containing cyclotriphosphazene polymer; wherein the molar ratio of 1,1,3,3-tetramethyldisiloxane, diallyl grafted cyclotriphosphazene, and 1,2-epoxy-5-hexene is 1:0.8:0.5;

[0030] Step 3:

[0031] The silicon-containing cyclotriphosphazene polymer and the epoxy resin are mixed and stirred for 1 to 2 hours to obtain an epoxy resin mixture, wherein the epoxy resin mixture contains 13% of the silicon-containing cyclotriphosphazene polymer and 87% of the epoxy resin by weight percentage; 6.8kg of diluent, 4.7kg of nano-silicon dioxide, 0.8kg of coupling agent, 0.4kg of defoaming agent, 0.3kg of antioxidant, 21kg of curing agent, and 0.5kg of curing agent accelerator are added to 46kg of the epoxy resin mixture, and the mixture is stirred and mixed to obtain a toughened modified epoxy resin.

[0032] Embodiment 2: A toughened modified epoxy resin and a preparation method thereof, comprising the following steps:

[0033] Step 1:

[0034] Hexachlorocyclotriphosphazene is purified by the following purification method: dissolving hexachlorocyclotriphosphazene in anhydrous petroleum ether, removing insoluble impurities by suction filtration, removing the filtrate by rotary evaporation, and then vacuum drying the solid for 24 hours; adding the purified hexachlorocyclotriphosphazene to tetrahydrofuran and stirring for 25 minutes, adding acid-binding agent triethylamine under nitrogen protection and stirring for 5 minutes; adding a mixed solution of allylamine and tetrahydrofuran, controlling the adding time to 30 minutes, and stirring the mixture in an ice-water bath for 5.5 hours; after terminating the reaction, removing triethylamine hydrochloride by suction filtration, adding a mixed solution of sodium methoxide and tetrahydrofuran, heating to 58°C, reflux reaction for 7 hours, cooling, removing sodium chloride by suction filtration, removing the solvent and impurities by reduced pressure distillation, washing with chloroform and distilled water for 3 times respectively, and vacuum drying to obtain diallyl-grafted cyclotriphosphazene; wherein the molar ratio of hexachlorocyclotriphosphazene, allylamine, and sodium methoxide is 1:2:4;

[0035] Step 2:

[0036] Diallyl grafted cyclotriphosphazene is added to tetrahydrofuran, stirred for 8 minutes, and then argon is introduced for protection, 1,1,3,3-tetramethyldisiloxane is added, and a 0.02 g / L chloroplatinic acid isopropanol solution is used as a catalyst, the temperature is raised to 62°C for reaction for 9 hours, and then 1,2-epoxy-5-hexene is added for end-capping, the solvent and impurities are removed by reduced pressure distillation, and the mixture is washed with anhydrous methanol and deionized water, and vacuum dried to obtain a silicon-containing cyclotriphosphazene polymer; wherein the molar ratio of 1,1,3,3-tetramethyldisiloxane, diallyl grafted cyclotriphosphazene, and 1,2-epoxy-5-hexene is 1:0.8:0.5;

[0037] Step 3:

[0038] The silicon-containing cyclotriphosphazene polymer and the epoxy resin are mixed and stirred for 1.5 hours to obtain an epoxy resin mixture, in which, by weight percentage, 17% of the silicon-containing cyclotriphosphazene polymer and 83% of the epoxy resin are added; 6.8kg of diluent, 4.7kg of nano-silicon dioxide, 0.8kg of coupling agent, 0.4kg of defoaming agent, 0.3kg of antioxidant, 21kg of curing agent, and 0.5kg of curing agent accelerator are added to 46kg of the epoxy resin mixture, and the mixture is stirred and mixed to obtain a toughened modified epoxy resin.

[0039] Embodiment 3: A toughened modified epoxy resin and a preparation method thereof, comprising the following steps:

[0040] Step 1:

[0041] Hexachlorocyclotriphosphazene is purified by the following purification method: dissolving hexachlorocyclotriphosphazene in anhydrous petroleum ether, removing insoluble impurities by suction filtration, removing the filtrate by rotary evaporation, and then vacuum drying the solid for 24 hours; adding the purified hexachlorocyclotriphosphazene to tetrahydrofuran and stirring for 30 minutes, adding acid-binding agent triethylamine and stirring for 5 minutes under nitrogen protection; adding a mixed solution of allylamine and tetrahydrofuran, controlling the adding time to 30 minutes, and stirring the mixture in an ice-water bath for 6 hours; after terminating the reaction, removing triethylamine hydrochloride by suction filtration, adding a mixed solution of sodium methoxide and tetrahydrofuran, heating to 60°C, reflux reaction for 8 hours, cooling, removing sodium chloride by suction filtration, removing the solvent and impurities by reduced pressure distillation, washing with chloroform and distilled water for 3 times respectively, and vacuum drying to obtain diallyl-grafted cyclotriphosphazene; wherein the molar ratio of hexachlorocyclotriphosphazene, allylamine, and sodium methoxide is 1:2:4;

[0042] Step 2:

[0043] Diallyl grafted cyclotriphosphazene is added to tetrahydrofuran, stirred for 10 minutes, and then argon is introduced for protection, 1,1,3,3-tetramethyldisiloxane is added, and a 0.02 g / L chloroplatinic acid isopropanol solution is used as a catalyst, the temperature is raised to 65°C for reaction for 10 hours, and then 1,2-epoxy-5-hexene is added for end-capping, the solvent and impurities are removed by reduced pressure distillation, and the mixture is washed with anhydrous methanol and deionized water, and vacuum dried to obtain a silicon-containing cyclotriphosphazene polymer; wherein the molar ratio of 1,1,3,3-tetramethyldisiloxane, diallyl grafted cyclotriphosphazene, and 1,2-epoxy-5-hexene is 1:0.8:0.5;

[0044] Step 3:

[0045] The silicon-containing cyclotriphosphazene polymer and the epoxy resin are mixed and stirred for 2 hours to obtain an epoxy resin mixture, in which, by weight percentage, 21% of the silicon-containing cyclotriphosphazene polymer and 79% of the epoxy resin are added; 6.8kg of diluent, 4.7kg of nano-silicon dioxide, 0.8kg of coupling agent, 0.4kg of defoaming agent, 0.3kg of antioxidant, 21kg of curing agent, and 0.5kg of curing agent accelerator are added to 46kg of the epoxy resin mixture, and the mixture is stirred and mixed to obtain a toughened modified epoxy resin.

[0046] Comparative Example 1: No silicon-containing cyclotriphosphazene polymer was added, and other parameters were the same as those in Example 1.

[0047] 6.8 kg of diluent, 4.7 kg of nano-silicon dioxide, 0.8 kg of coupling agent, 0.4 kg of defoaming agent, 0.3 kg of antioxidant, 21 kg of curing agent, and 0.5 kg of curing agent accelerator were added to 46 kg of epoxy resin, and the mixture was stirred and mixed to obtain a toughened modified epoxy resin.

[0048] Comparative Example 2: The amount of diallyl-grafted cyclotriphosphazene in step 2 was increased, and the other parameters were the same as those in Example 2.

[0049] Step 1:

[0050] Hexachlorocyclotriphosphazene is purified by the following purification method: dissolving hexachlorocyclotriphosphazene in anhydrous petroleum ether, removing insoluble impurities by suction filtration, removing the filtrate by rotary evaporation, and then vacuum drying the solid for 24 hours; adding the purified hexachlorocyclotriphosphazene to tetrahydrofuran and stirring for 25 minutes, adding acid-binding agent triethylamine under nitrogen protection and stirring for 5 minutes; adding a mixed solution of allylamine and tetrahydrofuran, controlling the adding time to 30 minutes, and stirring the mixture in an ice-water bath for 5.5 hours; after terminating the reaction, removing triethylamine hydrochloride by suction filtration, adding a mixed solution of sodium methoxide and tetrahydrofuran, heating to 58°C, reflux reaction for 7 hours, cooling, removing sodium chloride by suction filtration, removing the solvent and impurities by reduced pressure distillation, washing with chloroform and distilled water for 3 times respectively, and vacuum drying to obtain diallyl-grafted cyclotriphosphazene; wherein the molar ratio of hexachlorocyclotriphosphazene, allylamine, and sodium methoxide is 1:2:4;

[0051] Step 2:

[0052] Diallyl grafted cyclotriphosphazene is added to tetrahydrofuran, stirred for 8 minutes, and then argon is introduced for protection, 1,1,3,3-tetramethyldisiloxane is added, and a 0.02 g / L chloroplatinic acid isopropanol solution is used as a catalyst, the temperature is raised to 62°C for reaction for 9 hours, and then 1,2-epoxy-5-hexene is added for end-capping, the solvent and impurities are removed by reduced pressure distillation, and the mixture is washed with anhydrous methanol and deionized water, and vacuum dried to obtain a silicon-containing cyclotriphosphazene polymer; wherein the molar ratio of 1,1,3,3-tetramethyldisiloxane, diallyl grafted cyclotriphosphazene, and 1,2-epoxy-5-hexene is 1:1.2:0.5;

[0053] Step 3:

[0054] The silicon-containing cyclotriphosphazene polymer and the epoxy resin are mixed and stirred for 1.5 hours to obtain an epoxy resin mixture, in which, by weight percentage, 17% of the silicon-containing cyclotriphosphazene polymer and 83% of the epoxy resin are added; 6.8kg of diluent, 4.7kg of nano-silicon dioxide, 0.8kg of coupling agent, 0.4kg of defoaming agent, 0.3kg of antioxidant, 21kg of curing agent, and 0.5kg of curing agent accelerator are added to 46kg of the epoxy resin mixture, and the mixture is stirred and mixed to obtain a toughened modified epoxy resin.

[0055] Comparative Example 3: The amount of the silicon-containing cyclotriphosphazene polymer in the epoxy resin mixture was increased, and the other parameters were the same as those in Example 3.

[0056] Step 1:

[0057] Hexachlorocyclotriphosphazene is purified by the following purification method: dissolving hexachlorocyclotriphosphazene in anhydrous petroleum ether, removing insoluble impurities by suction filtration, removing the filtrate by rotary evaporation, and then vacuum drying the solid for 24 hours; adding the purified hexachlorocyclotriphosphazene to tetrahydrofuran and stirring for 30 minutes, adding acid-binding agent triethylamine and stirring for 5 minutes under nitrogen protection; adding a mixed solution of allylamine and tetrahydrofuran, controlling the adding time to 30 minutes, and stirring the mixture in an ice-water bath for 6 hours; after terminating the reaction, removing triethylamine hydrochloride by suction filtration, adding a mixed solution of sodium methoxide and tetrahydrofuran, heating to 60°C, reflux reaction for 8 hours, cooling, removing sodium chloride by suction filtration, removing the solvent and impurities by reduced pressure distillation, washing with chloroform and distilled water for 3 times respectively, and vacuum drying to obtain diallyl-grafted cyclotriphosphazene; wherein the molar ratio of hexachlorocyclotriphosphazene, allylamine, and sodium methoxide is 1:2:4;

[0058] Step 2:

[0059] Diallyl grafted cyclotriphosphazene is added to tetrahydrofuran, stirred for 10 minutes, and then argon is introduced for protection, 1,1,3,3-tetramethyldisiloxane is added, and a 0.02 g / L chloroplatinic acid isopropanol solution is used as a catalyst, the temperature is raised to 65°C for reaction for 10 hours, and then 1,2-epoxy-5-hexene is added for end-capping, the solvent and impurities are removed by reduced pressure distillation, and the mixture is washed with anhydrous methanol and deionized water, and vacuum dried to obtain a silicon-containing cyclotriphosphazene polymer; wherein the molar ratio of 1,1,3,3-tetramethyldisiloxane, diallyl grafted cyclotriphosphazene, and 1,2-epoxy-5-hexene is 1:0.8:0.5;

[0060] Step 3:

[0061] The silicon-containing cyclotriphosphazene polymer and the epoxy resin are mixed and stirred for 2 hours to obtain an epoxy resin mixture, in which, by weight percentage, 35% of the silicon-containing cyclotriphosphazene polymer and 65% of the epoxy resin are added; 6.8kg of diluent, 4.7kg of nano-silicon dioxide, 0.8kg of coupling agent, 0.4kg of defoaming agent, 0.3kg of antioxidant, 21kg of curing agent, and 0.5kg of curing agent accelerator are added to 46kg of the epoxy resin mixture, and the mixture is stirred and mixed to obtain a toughened modified epoxy resin.

[0062] Experiment: The epoxy resins prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were heated and cured. The curing conditions were: curing at 100°C for 2 hours, heating to 150°C and continuing curing for 2 hours. The cured samples were subjected to flame retardancy test, impact test and tensile test. Three valid data were obtained for each group of samples and the average value was calculated. The experimental results are shown in the following table.

[0063] Flame retardant performance test: The limiting oxygen index is used to characterize the flame retardant performance of the material.

[0064] Impact test: According to ASTM D256 standard, the unnotched impact strength was measured on an impact testing machine, and the sample size was 80mm×40mm×3mm;

[0065] Tensile test: According to ASTM D3039 standard, the tensile test was carried out on a universal testing machine with a sample size of 100 mm × 40 mm × 3 mm.

[0066]

[0067] Conclusion: The data of Examples 1 to 3 show that the epoxy resin prepared by the present invention has excellent performance. The data of Example 1 and Comparative Example 1 show that the flame retardancy, impact resistance and mechanical properties of the epoxy resin can be improved by adding or not adding the silicon-containing cyclotriphosphazene polymer. The data of Example 2 and Comparative Example 2 show that increasing the amount of diallyl-grafted cyclotriphosphazene when synthesizing the silicon-containing cyclotriphosphazene polymer will lead to a worse modification effect on the epoxy resin. The data of Example 3 and Comparative Example 3 show that excessive use of the silicon-containing cyclotriphosphazene polymer will lead to a decrease in the performance of the modified epoxy resin.

[0068] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a toughened modified epoxy resin, characterized in that: The following steps are involved: Step 1: Diallyl grafted cyclotriphosphazene is added to tetrahydrofuran, stirred for 5-10 minutes, and then argon is introduced for protection, 1,1,3,3-tetramethyldisiloxane is added, chloroplatinic acid isopropanol solution is used as a catalyst, the temperature is raised to 60-65°C for reaction for 8-10 hours, 1,2-epoxy-5-hexene is added for end-capping, the solvent and impurities are removed by reduced pressure distillation, the polymer is washed with anhydrous methanol and deionized water, and vacuum dried to obtain a silicon-containing cyclotriphosphazene polymer; Among them, the molar ratio of 1,1,3,3-tetramethyldisiloxane, diallyl-grafted cyclotriphosphazene, and 1,2-epoxy-5-hexene is 1:(0.6-0.8):0.5; The preparation method of the diallyl-grafted cyclotriphosphazene comprises: purifying hexachlorocyclotriphosphazene, wherein the purification method comprises dissolving the hexachlorocyclotriphosphazene in anhydrous petroleum ether, removing insoluble impurities by suction filtration, removing the filtrate by rotary evaporation, and then vacuum drying the solid for 24 hours; adding the purified hexachlorocyclotriphosphazene to tetrahydrofuran and stirring for 15 to 30 minutes, adding an acid binding agent under nitrogen protection and stirring for 5 minutes; adding a mixed solution of allylamine and tetrahydrofuran, controlling the adding time to 30 minutes, and stirring the mixture in an ice-water bath for reaction for 5 to 6 hours; after terminating the reaction, suction filtering and removing impurities, adding a mixed solution of sodium methoxide and tetrahydrofuran, heating to 55 to 60° C., reflux reaction for 5 to 8 hours, cooling, suction filtering and removing sodium chloride, removing the solvent and impurities by reduced pressure distillation, washing with chloroform and distilled water for 3 times, and vacuum drying; Step 2: The silicon-containing cyclotriphosphazene polymer and the epoxy resin are mixed and stirred for 1-2 hours to obtain an epoxy resin mixture; a diluent, nano-silicon dioxide, a coupling agent, a defoaming agent, an antioxidant, a curing agent, and a curing agent accelerator are added to the epoxy resin mixture, and the mixture is stirred and mixed to obtain a toughened modified epoxy resin; in the epoxy resin mixture, the silicon-containing cyclotriphosphazene polymer contains 13-21% and the epoxy resin contains 79-87% by weight.

2. The method for preparing a toughened modified epoxy resin according to claim 1, characterized in that: The molar ratio of hexachlorocyclotriphosphazene, allylamine and sodium methoxide is 1:2:

4.

3. The method for preparing a toughened modified epoxy resin according to claim 1, characterized in that: The acid binding agent is triethylamine.

4. The method for preparing a toughened modified epoxy resin according to claim 1, characterized in that: In step 1, the concentration of the chloroplatinic acid isopropanol solution is 0.02-0.03 g / L.

5. The method for preparing a toughened modified epoxy resin according to claim 1, characterized in that: In step 2, the contents of the components in the toughened modified epoxy resin are, by weight, 35 to 48 parts of epoxy resin mixture, 6 to 7 parts of diluent, 3 to 5 parts of nano-silicon dioxide, 0.5 to 1 part of coupling agent, 0.3 to 0.5 part of defoaming agent, 0.2 to 0.5 part of antioxidant, 18 to 22 parts of curing agent, and 0.5 to 0.8 part of curing agent accelerator.

6. The method for preparing a toughened modified epoxy resin according to claim 5, characterized in that: The coupling agent is any one of KH550, KH560 and KH570; the antioxidant is any one of antioxidant 1010, antioxidant 1076 and antioxidant 168.

7. The toughened modified epoxy resin prepared by the preparation method according to any one of claims 1 to 6.

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