Intrinsic flame-retardant modified vinyl ester resin and preparation method thereof

Abstract

The invention relates to an intrinsic flame-retardant modified vinyl ester resin and a preparation method thereof. Vinyl ester resin with chemical reaction activity with isocyanato and a phosphorus-containing flame retardant are used as raw materials, diisocyanate compounds are used as bridge bond compounds, and the intrinsic flame-retardant modified vinyl ester resin is prepared through a one-step reaction. The flame retardant resin is obtained by introducing a phosphorus-containing flame retardant into a resin molecular structure in a chemical bonding manner. Wherein the vinyl ester resin has secondary hydroxyl which has chemical reaction activity with isocyanato; the phosphorus-containing flame retardant has hydroxyl with chemical reaction activity with isocyanato, and is obtained by taking a phosphorus-containing organic acid compound and a hydroxyl-containing tertiary amine compound as raw materials and combining an acidic group of the phosphorus-containing organic acid compound and a tertiary amine group of the hydroxyl-containing tertiary amine compound through an ionic bond. The intrinsic flame-retardant modified vinyl ester resin disclosed by the invention still keeps relatively high curing activity, and a cured product has good flame-retardant property and heat resistance; the modification method is simple, wide in raw material source and free of complex synthesis.

Description

Technical Field

[0001] The invention relates to the technical field of vinyl ester resins, and in particular to an intrinsic flame retardant modified vinyl ester resin and a preparation method thereof. Background Art

[0002] As a type of high-performance thermosetting material, vinyl ester resin is widely used in high value-added fields such as wind turbine blades, ship corrosion protection, and electronic packaging due to its excellent corrosion resistance, mechanical strength, and processability. However, the limiting oxygen index (LOI) of traditional vinyl ester resin is usually less than 22%, which is a flammable material with inherent defects such as poor flame retardancy, rapid flame spread, and high heat release during combustion. It is difficult to meet the increasingly stringent flame retardant standards (such as UL94V-0, LOI>30%) in the fields of rail transportation, aerospace, etc. Therefore, the development of intrinsic flame retardant vinyl ester resins that have both high-efficiency flame retardancy and heat resistance without sacrificing processing performance has become an important research direction in the field of material modification.

[0003] At present, the flame retardant modification of vinyl ester resin can be roughly divided into two methods: physical method and chemical method. The physical method mainly relies on adding additives or fillers with flame retardant functions to achieve the purpose. This method has technical pain points such as poor interface compatibility, easy migration and precipitation, and low flame retardant efficiency; the chemical method is to introduce flame retardant elements (halogen, phosphorus, nitrogen, silicon, etc.) into the resin system in a chemically bonded manner. Among them, halogen flame retardants have been restricted in recent years due to environmental reasons, and nitrogen and silicon flame retardants have poor effects when used alone. Phosphorus flame retardants have high flame retardant efficiency, low toxicity, and rich modification methods, so they have attracted much attention from researchers. For example, CN 112279873A discloses a method for preparing a vinyl organosilicon caged thiophosphate, which is copolymerized with an unsaturated resin to form a cured product with good flame retardant properties. However, the preparation process of the phosphate compound is long and the reaction conditions are harsh, which is not conducive to industrial application; CN 111777640A discloses a method for preparing a liquid acrylate monomer containing phosphorus and nitrogen elements and a flame-retardant vinyl ester resin thereof, which also involves multi-step synthesis; CN 116178661A discloses a method for preparing a class of phosphorus-containing intrinsic flame-retardant resins, the core idea of ​​which is to use the bridge bond of diisocyanate to connect the phosphorus-containing group to the long chain of the resin, but the phosphorus-containing compound must contain hydroxyl, amino or carboxyl functional groups, which greatly limits the design of the modification route. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides an intrinsic flame retardant modified vinyl ester resin and a preparation method thereof. The modified resin still maintains a relatively high curing activity, and the cured product has good flame retardant properties and heat resistance. The modification method is simple, the raw material source is wide, and no complex synthesis is involved.

[0005] The technical solution adopted by the present invention to solve its technical problems is as follows: An intrinsically flame-retardant modified vinyl ester resin is prepared from a vinyl ester resin having chemical reactivity with isocyanate groups and a phosphorus-containing flame retardant as raw materials, and a diisocyanate compound as a bridging compound, and the phosphorus-containing flame retardant is introduced into the resin molecular structure in a chemically bonded manner; wherein, the vinyl ester resin has secondary hydroxyl groups having chemical reactivity with isocyanate groups; the phosphorus-containing flame retardant has hydroxyl groups having chemical reactivity with isocyanate groups, and it is obtained by ionic bonding of the acidic groups of phosphorus-containing organic acid compounds and the tertiary amine groups of hydroxyl-containing tertiary amine compounds.

[0006] Further, the molar ratio of the isocyanate groups of the diisocyanate compound to the hydroxyl groups of the phosphorus-containing flame retardant is 2:1; the molar ratio of the acidic groups of the phosphorus-containing organic acid compound to the tertiary amine groups of the hydroxyl-containing tertiary amine compound is 1:1; the mass of the vinyl ester resin is 2.5 - 5 times the total mass of the diisocyanate compound, the phosphorus-containing organic acid compound, and the hydroxyl-containing tertiary amine compound.

[0007] Further, the vinyl ester resin is selected from one or more of acrylic vinyl ester resin, methacrylic vinyl ester resin, phenolic vinyl ester resin, and high cross-linking density vinyl ester resin.

[0008] Further, the phosphorus-containing organic acid compounds are selected from one or more of phenylphosphonic acid, diphenylphosphinic acid, 2-carboxyethylphenylphosphinic acid, diphenyl phosphate, 10-hydroxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 10-(2,5-dicarboxypropyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0009] Further, the hydroxyl-containing tertiary amine compounds are selected from one or more of N,N-dimethylethanolamine, N,N-dibutylethanolamine, triethanolamine, N-methyldiethanolamine, 1-(2-hydroxyethyl)-4-methylpiperazine, and 1,4-bis(2-hydroxyethyl)piperazine.

[0010] Further, the diisocyanate compounds are selected from one or more of toluene diisocyanate, p-phenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate.

[0011] The preparation method of the above-mentioned intrinsically flame-retardant modified vinyl ester resin is specifically carried out according to the following steps:

[0012] S1. Mix the phosphorus-containing organic acid compound, the hydroxyl-containing tertiary amine compound, and the solvent, and react for 0.5 - 1 h;

[0013] S2. Mix the diisocyanate, catalyst, and solvent evenly. Under an inert gas atmosphere, slowly add the reaction product of step S1 thereto. After the addition is completed, continue the reaction at 30 - 50 °C with stirring for 1 - 2 h;

[0014] S3. Add vinyl ester resin to the reaction product of step S2 and continue the reaction at 50 - 60 °C with stirring for 0.5 - 1 h;

[0015] S4. Add an initiator to the reaction product of step S3, mix evenly, and then perform vacuum degassing treatment to obtain the intrinsically flame - retardant modified vinyl ester resin.

[0016] Further, the catalyst is dibutyltin dilaurate; the addition amount of the catalyst is 0.4 - 0.6% of the mass of the vinyl ester resin.

[0017] Further, the initiator is benzoyl peroxide; the addition amount of the initiator is 2 - 4% of the mass of the vinyl ester resin.

[0018] Further, the solvent contains unsaturated double bonds and is used as a cross - linking monomer for the vinyl ester resin, so it does not need to be removed after the reaction.

[0019] Further, the solvent is selected from one or more of styrene, vinyltoluene, methyl acrylate, butyl acrylate, and methyl methacrylate.

[0020] Advantages of the present invention: 1. The present invention utilizes the reaction activity of the secondary hydroxyl groups of the vinyl ester resin to attach the flame - retardant groups to the side chains, which has a low negative impact on the curing behavior of the system. The resin cured product has good flame - retardant properties due to the synergistic effect of phosphorus / nitrogen, and has good heat - resistant properties due to the phosphorus - containing rigid groups, polar urethane groups, and possibly increased cross - linking points; 2. The modification method of the present invention is simple, does not involve complex synthesis, all raw materials are commercial compounds, the sources are wide, and no special treatment is required; 3. According to the reactivity between functional groups and the characteristic that the vinyl ester resin needs to be diluted with a cross - linking monomer during use, by controlling the feeding sequence and ratio, chemical modification is directly completed in the cross - linking monomer. The reaction steps are simple and no post - treatment is required. The entire modification idea combines the speed of physical methods and the performance advantages of chemical methods. Detailed implementation manners

[0021] In order to deepen the understanding of the present invention, the following will further describe the present invention in detail with reference to the embodiments. These embodiments are only used to explain the present invention and do not limit the protection scope of the present invention.

[0022] In the following examples, nitrogen is used as the protective gas, and other inert gases can also be used. The present invention does not make specific limitations. Unless otherwise specified, the experimental operations during the reaction (such as dropping, stirring, etc.) can be achieved by conventional technical means, and those skilled in the art can adjust according to actual needs.

[0023] Example 1

[0024] This example provides an intrinsically flame-retardant modified vinyl ester resin, and its raw materials include: 10.9 g (0.05 mol) of diphenylphosphinic acid, 4.5 g (0.05 mol) of N,N-dimethylethanolamine, 8.7 g (0.05 mol) of toluene diisocyanate, 60 g of acrylic vinyl ester resin, 40 g of styrene, 0.3 g of dibutyltin dilaurate, and 1.8 g of benzoyl peroxide.

[0025] This example also provides a preparation method of the above-mentioned intrinsically flame-retardant modified vinyl ester resin:

[0026] S1. Prepare diphenylphosphinic acid and N,N-dimethylethanolamine according to the above weights, and stir and react the two in 20 g of styrene for 0.5 h to obtain a homogeneous transparent liquid for standby;

[0027] S2. Weigh toluene diisocyanate and dibutyltin dilaurate according to the above weights, and add them together with 20 g of styrene to the reaction kettle. After mixing evenly, slowly drop the mixture obtained in step S1 under an inert gas atmosphere. After the dropping is completed, continue to stir and react at 30 °C for 1 h;

[0028] S3. Weigh the acrylic vinyl ester resin according to the above weight, add it to the reaction kettle described in step S2, and stir and react at 50 °C for 0.5 h;

[0029] S4. Weigh benzoyl peroxide according to the above weight, add it to the mixture obtained in step S3, stir evenly and then perform vacuum degassing treatment to obtain an intrinsically flame-retardant modified vinyl ester resin system (numbered FRVER-A).

[0030] Example 2

[0031] This example provides an intrinsically flame-retardant modified vinyl ester resin, and its raw materials include: 7.9 g (0.05 mol) of phenylphosphonic acid, 7.2 g (0.05 mol) of 1-(2-hydroxyethyl)-4-methylpiperazine, 12.5 g (0.05 mol) of diphenylmethane diisocyanate, 80 g of acrylic vinyl ester resin, 50 g of butyl acrylate, 0.4 g of dibutyltin dilaurate, and 2.4 g of benzoyl peroxide.

[0032] This embodiment also provides a preparation method of the above-mentioned intrinsically flame-retardant modified vinyl ester resin:

[0033] S1. Prepare phenylphosphonic acid and 1-(2-hydroxyethyl)-4-methylpiperazine according to the above weights, and stir and react the two in 20 g of butyl acrylate for 0.5 h to obtain a homogeneous transparent liquid for standby;

[0034] S2. Weigh diphenylmethane diisocyanate and dibutyltin dilaurate according to the above weights, add them together with 30 g of butyl acrylate to a reaction kettle, mix evenly, and slowly dropwise add the mixture obtained in step S1 under an inert gas atmosphere. After the addition is complete, continue to stir and react at 40 °C for 1 h;

[0035] S3. Weigh acrylic vinyl ester resin according to the above weight, add it to the reaction kettle described in step S2, and stir and react at 50 °C for 0.5 h;

[0036] S4. Weigh benzoyl peroxide according to the above weight, add it to the mixture obtained in step S3, stir evenly, and then perform vacuum degassing treatment to obtain an intrinsically flame-retardant modified vinyl ester resin system (number FRVER-B).

[0037] Example 3

[0038] This embodiment provides an intrinsically flame-retardant modified vinyl ester resin, and its raw materials include: 11.6 g (0.05 mol) of 10-hydroxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-OH), 6.0 g (0.05 mol) of N-methyldiethanolamine, 22.2 g (0.1 mol) of isophorone diisocyanate, 100 g of methacrylic acid vinyl ester resin, 50 g of methyl acrylate, 0.5 g of dibutyltin dilaurate, and 3 g of benzoyl peroxide.

[0039] This embodiment also provides a preparation method of the above-mentioned intrinsically flame-retardant modified vinyl ester resin:

[0040] S1. Prepare DOPO-OH and N-methyldiethanolamine according to the above weights, and stir and react the two in 20 g of methyl acrylate for 0.5 h to obtain a homogeneous liquid for standby;

[0041] S2. Weigh isophorone diisocyanate and dibutyltin dilaurate according to the above weights, add them together with 30 g of methyl acrylate to a reaction kettle, mix evenly, and slowly dropwise add the mixture obtained in step S1 under an inert gas atmosphere. After the addition is complete, continue to stir and react at 50 °C for 1 h;

[0042] S3. Weigh methacrylic acid vinyl ester resin according to the above weight, add it to the reaction kettle described in step S2, and stir and react at 60 °C for 0.5 h;

[0043] S4. Weigh benzoyl peroxide according to the above weight, add it to the mixture obtained in step S3, stir evenly, and then perform vacuum degassing treatment to obtain an intrinsically flame-retardant modified vinyl ester resin system (designated as FRVER-C).

[0044] Example 4

[0045] This example provides an intrinsically flame-retardant modified vinyl ester resin, the raw materials of which include: 10.0 g (0.04 mol) of diphenyl phosphate, 6.9 g (0.04 mol) of N,N-dibutylethanolamine, 6.4 g (0.04 mol) of p-phenylene diisocyanate, 100 g of phenolic vinyl ester resin, 50 g of vinyl toluene, 0.5 g of dibutyltin dilaurate, and 3 g of benzoyl peroxide.

[0046] This example also provides a preparation method of the above-mentioned intrinsically flame-retardant modified vinyl ester resin:

[0047] S1. Prepare diphenyl phosphate and N,N-dibutylethanolamine according to the above weight, and stir and react them in 20 g of vinyl toluene for 0.5 h to obtain a homogeneous liquid for standby.

[0048] S2. Weigh p-phenylene diisocyanate and dibutyltin dilaurate according to the above weight, add them together with 30 g of vinyl toluene to a reaction kettle, mix evenly, and then slowly dropwise add the mixture obtained in step S1 under an inert gas atmosphere. After the dropping is completed, continue to stir and react at 50 °C for 1 h.

[0049] S3. Weigh phenolic vinyl ester resin according to the above weight, add it to the reaction kettle described in step S2, and stir and react at 60 °C for 0.5 h.

[0050] S4. Weigh benzoyl peroxide according to the above weight, add it to the mixture obtained in step S3, stir evenly, and then perform vacuum degassing treatment to obtain an intrinsically flame-retardant modified vinyl ester resin system (designated as FRVER-D).

[0051] Example 5

[0052] This example provides an intrinsically flame-retardant modified vinyl ester resin, the raw materials of which include:

[0053] 10.7 g (0.05 mol) of 2-carboxyethylphenylphosphinic acid, 8.7 g (0.05 mol) of 1,4-bis(2-hydroxyethyl)piperazine, 16.8 g (0.1 mol) of hexamethylene diisocyanate, 120 g of high cross-linking density vinyl ester resin, 60 g of methyl methacrylate, 0.6 g of dibutyltin dilaurate, and 3.6 g of benzoyl peroxide.

[0054] This embodiment also provides a preparation method of the above-mentioned intrinsically flame-retardant modified vinyl ester resin:

[0055] S1. Prepare 2-carboxyethylphenylphosphinic acid and 1,4-bis(2-hydroxyethyl)piperazine according to the above weights, and stir and react the two in 30 g of methyl methacrylate for 0.5 h to obtain a homogeneous liquid for standby;

[0056] S2. Weigh hexamethylene diisocyanate and dibutyltin dilaurate according to the above weights, add them together with 30 g of methyl methacrylate to a reaction kettle, mix evenly, and slowly dropwise add the mixture obtained in step S1 under an inert gas atmosphere. After the dropping is completed, continue to stir and react at 50 °C for 1 h;

[0057] S3. Weigh a high cross-linking density vinyl ester resin according to the above weight, add it to the reaction kettle described in step S2, and stir and react at 60 °C for 0.5 h;

[0058] S4. Weigh benzoyl peroxide according to the above weight, add it to the mixture obtained in step S3, stir evenly, and then perform vacuum degassing treatment to obtain an intrinsically flame-retardant modified vinyl ester resin system (numbered FRVER-E).

[0059] Application Example

[0060] Take a small amount of the intrinsically flame-retardant modified vinyl ester resin systems (FRVER-A to FRVER-E) prepared in Examples 1 to 5 respectively for non-isothermal testing with a differential scanning calorimeter (DSC) at a heating rate of 10 °C / min. The results are shown in Table 1; the rest are respectively poured into preheated Teflon molds, and the oven is controlled at 80 °C / 2 h + 100 °C / 4 h + 140 °C / 2 h. After curing is completed, cool to room temperature and take out for testing; the glass transition temperature (T g ) of the vinyl ester resin cured product is measured by dynamic thermomechanical analysis (DMA) (take the peak value of the loss tangent as T g , and the heating rate is 5 °C / min); the limiting oxygen index (LOI) of the vinyl ester resin cured product is measured with reference to the ASTM D2863 standard; the vertical burning test of the vinyl ester resin cured product is carried out with reference to the UL-94 test standard. The results are shown in Table 2.

[0061] Comparative Example

[0062] Corresponding to Examples 1 to 5, the vinyl ester resins and crosslinking monomers used were weighed in the same weight, and benzoyl peroxide (3% of the mass of the vinyl ester resin) with the corresponding mass was added and then mixed evenly, and they were named VER-A, VER-B, VER-C, VER-D, and VER-E in turn. A small amount was taken for non-isothermal testing with a differential scanning calorimeter (DSC) at a heating rate of 10 °C / min, and the results are shown in Table 1; the rest were poured into preheated Teflon molds respectively, and the oven was temperature-controlled at 80 °C / 2 h + 100 °C / 4 h + 140 °C / 2 h. After curing was completed, it was cooled to room temperature and taken out for testing; the glass transition temperature (T g ) of the vinyl ester resin cured product was measured by dynamic thermomechanical analysis (DMA) (taking the peak value of the loss tangent as T g , and the heating rate was 5 °C / min); the limiting oxygen index (LOI) of the vinyl ester resin cured product was measured with reference to the ASTM D2863 standard; the vertical burning test of the vinyl ester resin cured product was carried out with reference to the UL-94 test standard, and the results are shown in Table 2.

[0063] Table 1 Curing performance parameters of vinyl ester resins before and after intrinsic flame retardant modification

[0064] Sample Name Peak Temperature of Curing Exotherm (°C) Heat of Curing Exotherm (J / g) Shape of Curing Exotherm Peak VER-A 102 105 Single Peak FRVER-A 108 90 Single Peak VER-B 106 99 Single Peak FRVER-B 122 85 Single Peak VER-C 81 68 Single Peak FRVER-C 97 62 Single Peak VER-D 125 110 Single Peak FRVER-D 134 93 Single Peak VER-E 95 115 Single Peak FRVER-E 110 107 Single Peak

[0065] Table 2 Flame retardant and heat resistance performance parameters of vinyl ester resins before and after intrinsic flame retardant modification

[0066] Curing Agent LOI (%) UL-94 Flame Retardant Rating <![CDATA[T g (℃)]]> VER-A 20.8 No Rating 128.0 FRVER-A 30.1 V-0 138.9 VER-B 21.1 No Rating 132.0 FRVER-B 28.9 V-0 139.5 VER-C 19.8 No Rating 122.6 FRVER-C 26.7 V-0 130.2 VER-D 35.5 V-0 148.0 FRVER-D 40.0 V-0 152.0 VER-E 21.6 No Rating 135.5 FRVER-E 26.5 V-0 140.3

[0067] As can be seen from Table 1, for the intrinsically flame retardant modified vinyl ester resin systems (FRVER-A to FRVER-E) prepared in the present invention, compared with the comparative example systems (VER-A to VER-E), there was a small shift of the curing exothermic peak to the rear and a decrease in the curing exothermic amount. However, before and after modification, the curing exothermic peak shape of the system was a single peak, indicating that the strategy of introducing phosphorus-containing ionic compounds into the side chain would not directly affect the curing behavior of the system, and the decrease in curing exotherm might also reduce the internal stress in the cured product and improve its mechanical properties.

[0068] As can be seen from Table 2, except that VER-D has certain flame retardancy due to its own structure, the cured products of the other comparative examples all showed flammable characteristics (LOI < 22%, UL94 unrated), while after the intrinsic flame retardant modification of the present invention, the cured products all showed good flame retardant properties (LOI > 30%, UL94 V-0), and the heat resistance also showed varying degrees of improvement.

[0069] The above embodiments should not limit the present invention in any way. All technical solutions obtained by means of equivalent substitution or equivalent conversion fall within the protection scope of the present invention.

Claims

1. An intrinsic flame retardant modified vinyl ester resin, characterized in that: The phosphorus-containing flame retardant is obtained by using vinyl ester resin and phosphorus-containing flame retardant having chemical reaction activity with isocyanate as raw materials, using diisocyanate compounds as bridging compounds, and introducing the phosphorus-containing flame retardant into the resin molecular structure in a chemical bonding manner; wherein the vinyl ester resin has a secondary hydroxyl group having chemical reaction activity with isocyanate; the phosphorus-containing flame retardant has a hydroxyl group having chemical reaction activity with isocyanate, and is obtained by using phosphorus-containing organic acid compounds and hydroxyl-containing tertiary amine compounds as raw materials, and utilizing the acidic groups of the phosphorus-containing organic acid compounds and the tertiary amine groups of the hydroxyl-containing tertiary amine compounds to combine through ionic bonds.

2. The intrinsic flame retardant modified vinyl ester resin according to claim 1, characterized in that: The molar ratio of the isocyanate group of the diisocyanate compound to the hydroxyl group of the phosphorus-containing flame retardant is 2:1; the molar ratio of the acidic group of the phosphorus-containing organic acid compound to the tertiary amine group of the hydroxyl-containing tertiary amine compound is 1:1; the mass of the vinyl ester resin is 2.5-5 times the total mass of the diisocyanate compound, the phosphorus-containing organic acid compound and the hydroxyl-containing tertiary amine compound.

3. The intrinsic flame retardant modified vinyl ester resin according to claim 1, characterized in that: The vinyl ester resin is selected from one or more of acrylic vinyl ester resin, methacrylic vinyl ester resin, phenolic vinyl ester resin and high cross-link density vinyl ester resin.

4. The intrinsic flame retardant modified vinyl ester resin according to claim 1, characterized in that: The phosphorus-containing organic acid compound is selected from one or more of phenylphosphonic acid, diphenylphosphorous acid, 2-carboxyethylphenylphosphorous acid, diphenyl phosphate, 10-hydroxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 10-(2,5-dicarboxypropyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

5. The intrinsic flame retardant modified vinyl ester resin according to claim 1, characterized in that: The hydroxyl-containing tertiary amine compound is selected from one or more of N,N-dimethylethanolamine, N,N-dibutylethanolamine, triethanolamine, N-methyldiethanolamine, 1-(2-hydroxyethyl)-4-methylpiperazine, and 1,4-bis(2-hydroxyethyl)piperazine.

6. The intrinsic flame retardant modified vinyl ester resin according to claim 1, characterized in that: The diisocyanate compound is selected from one or more of toluene diisocyanate, p-phenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and dicyclohexylmethane diisocyanate.

7. The method for preparing the intrinsic flame retardant modified vinyl ester resin according to any one of claims 1 to 6, characterized in that: Follow these steps: S1, mixing a phosphorus-containing organic acid compound, a hydroxyl-containing tertiary amine compound, and a solvent, and reacting for 0.5-1h; S2, mixing the diisocyanate, the catalyst and the solvent uniformly, and slowly adding the reaction product of step S1 thereto under an inert gas atmosphere. After the addition is completed, continuing the reaction at 30-50° C. with stirring for 1-2 hours; S3, adding vinyl ester resin to the reaction product of step S2, and continuing the reaction at 50-60° C. with stirring for 0.5-1 h; S4, adding an initiator to the reaction product of step S3, mixing evenly, and performing vacuum degassing to obtain an intrinsic flame retardant modified vinyl ester resin.

8. The method for preparing an intrinsic flame retardant modified vinyl ester resin according to claim 7, characterized in that: The catalyst is dibutyltin dilaurate; the added amount of the catalyst is 0.4-0.6% of the mass of the vinyl ester resin.

9. The method for preparing an intrinsic flame retardant modified vinyl ester resin according to claim 7, characterized in that: The initiator is dibenzoyl peroxide; the added amount of the initiator is 2-4% of the mass of the vinyl ester resin.

10. A method for preparing an intrinsic flame retardant modified vinyl ester resin according to any one of claims 7 to 9, characterized in that: The solvent contains unsaturated double bonds and is used as a crosslinking monomer for the vinyl ester resin, and thus does not need to be removed after the reaction is completed; the solvent is selected from one or more of styrene, vinyl toluene, methyl acrylate, butyl acrylate, and methyl methacrylate.