A vacuum-infused flame-retardant resin and its preparation method

Abstract

This invention provides a vacuum-infused flame-retardant resin and its preparation method. The vacuum-infused flame-retardant resin comprises the following components or their reaction products: 100 parts by weight of isocyanate; 5-300 parts by weight of epoxy resin; 0.1-5 parts by weight of catalyst; and 1-100 parts by weight of liquid flame retardant. The liquid flame retardant contains at least one element selected from nitrogen, phosphorus, and silicon, and its viscosity at 25°C is less than 1000 mPas. The vacuum-infused flame-retardant resin provided by this invention achieves excellent flame-retardant performance through the synergistic effect of intrinsic flame retardancy and the liquid flame retardant. The resin system has low viscosity, which is beneficial for improving process operability and the impregnation effect on carbon fibers. Furthermore, it has a high glass transition temperature, which can simultaneously meet the requirements of vacuum-infused flame-retardant resin for process performance, flame-retardant performance, and operating temperature.

Description

Technical Field

[0001] This invention relates to the field of polymer chemical technology, specifically to a vacuum-infused flame-retardant resin and its preparation method. Background Technology

[0002] Lightweighting is crucial for the development of the rail transit industry. Carbon fiber composites play an increasingly important role in the rail transit industry due to their advantages such as light weight, high specific stiffness, high specific strength and specific modulus, good corrosion resistance, strong designability, and good shock absorption. The rail transit industry not only has requirements for lightweighting and various mechanical properties of composite materials, but also puts forward high requirements for the flame retardant properties of composite materials. Currently, some flame retardant resins for composite materials on the market can be mainly classified into the following categories: (1) halogen-containing flame retardant resins; (2) resin systems using inorganic flame retardant fillers such as phosphorus, aluminum hydroxide, and expanded graphite; (3) resin systems with added halogen-free flame retardants containing nitrogen and phosphorus elements; (4) inherently flame retardant systems where the resin itself contains elements such as nitrogen and phosphorus.

[0003] Halogenated flame retardants are gradually being phased out because they easily produce toxic and harmful gases during use. Additive powder flame retardants increase the viscosity of the resin system, making them unsuitable for vacuum infusion systems. Additive halogen-free liquid flame retardants containing nitrogen and phosphorus elements solve the problem of high system viscosity, but the glass transition temperature of the curing system is low, which limits the service temperature of the cured system material.

[0004] CN 111057220 A discloses a vacuum-infused flame-retardant epoxy resin and its preparation method, comprising epoxy resin, isophorone diamine, and a flame retardant. The flame retardant is selected from any one of inorganic phosphorus compounds and organic phosphorus compounds. The organic phosphorus compounds are selected from one or more of aliphatic phosphate esters, phosphate ester compounds, condensed phosphate esters, phosphonic acid compounds, hypophosphitic acid compounds, phosphine oxide compounds, orthophosphine compounds, organic nitrogen-containing phosphorus compounds, and metal salts of hypophosphitic acids. The resin composition provided by this patent achieves a good balance between raw material cost, flame retardancy, processing, and mechanical properties.

[0005] CN 113150501 A discloses a benzoxazine flame-retardant modified epoxy resin for vacuum infusion molding and its preparation method. The flame-retardant modified epoxy resin is composed of benzoxazine resin, epoxy resin, phosphate flame retardant, curing agent, and accelerator. The preparation method includes the following steps: preparing the raw materials according to the weight ratio; heating and stirring the benzoxazine resin and epoxy resin until uniformly mixed, then cooling to room temperature; sequentially adding the phosphate flame retardant, amine curing agent, and accelerator to the mixture and stirring until uniform; vacuum degassing the resulting mixture at room temperature to remove air; pouring the vacuum-degassed mixture into a mold treated with a release agent for thermosetting and demolding to obtain the benzoxazine flame-retardant modified epoxy resin. This flame-retardant modified epoxy resin is suitable for vacuum infusion composite molding processes, has low viscosity and excellent flame-retardant properties, and its bulk flame retardant level reaches UL94V-0.

[0006] However, there is still considerable room for improvement in vacuum-infused flame-retardant resins. Summary of the Invention

[0007] In view of the problems existing in the prior art, one of the objectives of the present invention is to provide a vacuum-infused flame-retardant resin. By using a combination of isocyanate, epoxy resin and liquid flame retardant, the intrinsic flame retardancy is combined with the added liquid flame retardant, which solves the problem of increased system viscosity and poor processability caused by the addition of powdered flame retardant. At the same time, it solves the problem of low glass transition temperature of the curing system caused by the addition of liquid flame retardant. The prepared vacuum-infused flame-retardant resin can be used in the preparation of main load-bearing structures and non-load-bearing components of carbon fiber composite materials with flame retardant requirements in the rail transit field.

[0008] The second objective of this invention is to provide a method for preparing a vacuum-infused flame-retardant resin, which corresponds to the first objective.

[0009] A third objective of this invention is to provide a resin-reinforced carbon fiber product corresponding to the above-mentioned objective.

[0010] The fourth objective of this invention is to provide an application of resin-reinforced carbon fiber articles corresponding to the above-mentioned objective.

[0011] To achieve one of the above objectives, the technical solution adopted by the present invention is as follows:

[0012] A vacuum-infused flame-retardant resin comprising the following components or the reaction product of the following components:

[0013]

[0014] The liquid flame retardant contains at least one flame retardant element selected from nitrogen, phosphorus and silicon, and its viscosity at 25°C is less than 1000 mPas, preferably 100 to 600 mPas.

[0015] In some preferred embodiments of the present invention, the content of flame retardant elements in the liquid flame retardant is 5wt% to 40wt%.

[0016] In some specific embodiments of the present invention, the weight parts of each substance in the vacuum-infused flame-retardant resin are as follows:

[0017]

[0018] In some specific embodiments of the present invention, the weight parts of each substance in the vacuum-infused flame-retardant resin are as follows:

[0019]

[0020] In some specific embodiments of the present invention, the weight parts of each substance in the vacuum-infused flame-retardant resin are as follows:

[0021]

[0022] In some specific embodiments of the present invention, the weight parts of each substance in the vacuum-infused flame-retardant resin are as follows:

[0023]

[0024] In some preferred embodiments of the present invention, the liquid flame retardant contains diphenyl phosphate groups.

[0025] In some preferred embodiments of the present invention, each molecule of liquid flame retardant contains two diphenyl phosphate groups.

[0026] In some preferred embodiments of the present invention, the liquid flame retardant is selected from at least one of bisphenol A bis(diphenyl phosphate), bisphenol S bis(diphenyl phosphate), resorcinol bis(diphenyl phosphate), toluene diphenyl phosphate, diphenyl isooctyl phosphate, diphenyl isopropyl phosphate, diphenyl isodecyl phosphate, and ethylenediamine diphenyl phosphate.

[0027] In some preferred embodiments of the present invention, the viscosity of the isocyanate at 25°C is 60–400 mPas.

[0028] In some preferred embodiments of the present invention, the isocyanate is selected from at least one of difunctional isocyanates and polyfunctional isocyanates.

[0029] According to the present invention, the term "multifunctionality" refers to N-functionality, where N is an integer greater than or equal to 3.

[0030] In some preferred embodiments of the present invention, the isocyanate is selected from at least one of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), and polymethylene polyphenyl polyisocyanate (PAPI).

[0031] In some preferred embodiments of the present invention, the epoxy resin has a viscosity of 2000 to 18000 mPas at 25°C.

[0032] In some preferred embodiments of the present invention, the epoxy resin has a viscosity of 10,000 to 18,000 mPas at 25°C.

[0033] In some preferred embodiments of the present invention, the epoxy resin has a viscosity of 1000-2000 mPas at 52°C.

[0034] In some preferred embodiments of the present invention, the epoxy resin is selected from at least one of glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, alicyclic epoxide, and linear aliphatic epoxide.

[0035] In some preferred embodiments of the present invention, the epoxy value of the epoxy resin is 0.10 to 1.00 mol / 100g.

[0036] In some preferred embodiments of the present invention, the epoxy value of the epoxy resin is 0.10 to 0.60 mol / 100g.

[0037] In some preferred embodiments of the present invention, the epoxy value of the epoxy resin is 0.30 to 0.60 mol / 100g.

[0038] In some preferred embodiments of the present invention, the epoxy resin is selected from at least one of bisphenol A epoxy resin, phenolic epoxy resin, bisphenol F epoxy resin, N,N-diglycidyl-4-glycidyloxyaniline and 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester.

[0039] In some preferred embodiments of the present invention, the catalyst is selected from at least one of imidazole compounds, imidazole modifiers, 2,4,6-tris(dimethylaminomethyl)phenol DMP-30, triphenylphosphine, ethyltriphenylphosphine bromide, and dibutyltin dilaurate.

[0040] In some preferred embodiments of the present invention, the imidazole compound is selected from at least one of imidazole, 2-methylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 1-cyanoethyl-2-ethyl-4-methylimidazolium, and 1-cyanoethyl-2-phenylimidazolium.

[0041] In some preferred embodiments of the present invention, the imidazole modifier is selected from at least one of imidazole, 2-methylimidazolium, 2-ethylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 1-cyanoethyl-2-ethyl-4-methylimidazolium, 1-cyanoethyl-2-phenylimidazolium and isocyanate modifiers.

[0042] According to the present invention, the catalyst can be stored alone or as a component with the isocyanate. The catalyst and the isocyanate can be physically mixed or the corresponding product can exist in the isocyanate after a chemical reaction.

[0043] In some preferred embodiments of the present invention, the viscosity of the vacuum-infused flame-retardant resin at 25°C is 200–2000 mPas.

[0044] According to the present invention, other functional additives may also be added to the vacuum-infused flame-retardant resin.

[0045] To achieve the second objective mentioned above, the technical solution adopted by the present invention is as follows:

[0046] A method for preparing a vacuum-infused flame-retardant resin according to any one of the above embodiments includes: mixing the required amounts of the isocyanate, the epoxy resin, the catalyst, and the liquid flame retardant and optionally performing a degassing treatment to obtain the vacuum-infused flame-retardant resin.

[0047] In some preferred embodiments of the present invention, the mixing conditions include a temperature of 20°C to 85°C.

[0048] In some preferred embodiments of the present invention, the degassing treatment is carried out under vacuum conditions, with a vacuum degree of -0.05MPa to -0.1MPa.

[0049] To achieve the third objective mentioned above, the technical solution adopted by the present invention is as follows:

[0050] A resin-reinforced carbon fiber product is made from carbon fiber and the vacuum-infused flame-retardant resin as described in any one of the above embodiments, or the vacuum-infused flame-retardant resin prepared according to any one of the above embodiments.

[0051] In some preferred embodiments of the present invention, the resin-reinforced carbon fiber product is prepared by a vacuum infusion process.

[0052] According to the present invention, the vacuum infusion process is a conventional process in the art.

[0053] To achieve the fourth objective mentioned above, the technical solution adopted by the present invention is as follows:

[0054] Application of a resin-reinforced carbon fiber product according to any one of the above embodiments in the field of rail transportation.

[0055] In some preferred embodiments of the invention, the application includes use as a primary load-bearing structure or a non-load-bearing component.

[0056] The beneficial effects of the vacuum-infused flame-retardant resin provided by this invention are at least in the following aspects:

[0057] Firstly, the low viscosity of the resin system is beneficial for improving process operability and the impregnation effect on carbon fibers.

[0058] Secondly, there is no need to add additional powdered flame retardants, thus avoiding the problem of increased viscosity of the resin system caused by the addition of inorganic flame retardant fillers.

[0059] Third, the high glass transition temperature of the resin curing system avoids the problem of a low glass transition temperature caused by the addition of liquid flame retardants. Detailed Implementation

[0060] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the following description.

[0061] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0062] In the following embodiments, the polymethylene polyphenyl polyisocyanate of brand name WANNATE PM-200 has a viscosity of 150-250 mPas at 25°C; the bisphenol A epoxy resin of brand name CYD128 has a viscosity of 11000-14000 mPas at 25°C and an epoxy equivalent of 184-194 g / eq; and the phenolic epoxy resin of brand name NPPN-631 has a viscosity of 1100-1700 mPas at 52°C and an epoxy equivalent of 168-178 g / eq.

[0063]

Example 1

[0064] Example 1 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0065]

[0066]

[0067] When using, polymethylene polyphenyl polyisocyanate, 2-methylimidazole, bisphenol A epoxy resin and bisphenol A bis(diphenyl phosphate) are mixed evenly at 60°C, and vacuum degassing is performed under a vacuum degree lower than -0.07MPa. The resulting resin is then ready for use.

[0068]

Example 2

[0069] Example 2 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0070]

[0071] When using, polymethylene polyphenyl polyisocyanate, 2-methylimidazole, bisphenol A epoxy resin and resorcinol bis(diphenyl phosphate) are mixed evenly at 60°C, and vacuum degassing is performed under a vacuum degree lower than -0.07MPa. The resulting resin is then ready for use.

[0072]

Example 3

[0073] Example 3 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0074]

[0075] When using, polymethylene polyphenyl polyisocyanate, 2-methylimidazole, bisphenol A epoxy resin and bisphenol A bis(diphenyl phosphate) are mixed evenly at 60°C, and vacuum degassing is performed under a vacuum degree lower than -0.07MPa. The resulting resin is then ready for use.

[0076]

Example 4

[0077] Example 4 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0078]

[0079] When using, polymethylene polyphenyl polyisocyanate, 2-methylimidazole, phenolic epoxy resin and bisphenol A bis(diphenyl phosphate) are mixed evenly at 60°C, and vacuum degassing is performed under a vacuum degree lower than -0.07MPa. The resulting resin is then ready for use.

[0080]

Example 5

[0081] Example 5 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0082]

[0083] Polymethylene polyphenyl polyisocyanate is used as component A, 2-methylimidazole is used as component B, and bisphenol A epoxy resin, phenolic epoxy resin and bisphenol A bis(diphenyl phosphate) are mixed evenly as component C. When using, the three components A, B and C are mixed evenly at 60°C and vacuum degassed under a vacuum degree of less than -0.07MPa. The resulting resin is ready for use.

[0084]

Example 6

[0085] Example 6 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0086]

[0087] When using, polymethylene polyphenyl polyisocyanate, 2-methylimidazole, bisphenol A epoxy resin and bisphenol A bis(diphenyl phosphate) are mixed evenly at 60°C, and vacuum degassing is performed under a vacuum degree lower than -0.07MPa. The resulting resin is then ready for use.

[0088]

Example 7

[0089] Example 7 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0090]

[0091] When using, mix polymethylene polyphenyl polyisocyanate, 2-methylimidazole, bisphenol A epoxy resin and bisphenol A bis(diphenyl phosphate) evenly, and then degas under vacuum before use.

[0092]

Example 8

[0093] Example 8 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0094]

[0095] When using, polymethylene polyphenyl polyisocyanate, 2-ethyl-4-methylimidazolium, bisphenol A epoxy resin and bisphenol A bis(diphenyl phosphate) are mixed evenly at 60°C, and vacuum degassing is performed under a vacuum degree below -0.07 MPa. The resulting resin is then ready for use.

[0096]

Example 9

[0097] Example 9 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0098]

[0099] When using, polymethylene polyphenyl polyisocyanate, 2,4,6-tris(dimethylaminomethyl)phenol, bisphenol A epoxy resin and bisphenol A bis(diphenyl phosphate) are mixed evenly at 60°C, and vacuum degassing is performed under a vacuum degree lower than -0.07MPa. The resulting resin is then ready for use.

[0100]

Example 10

[0101] Example 10 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0102]

[0103] When using, polymethylene polyphenyl polyisocyanate, 2-methylimidazole, bisphenol A epoxy resin and bisphenol A bis(diphenyl phosphate) are mixed evenly at 60°C, and vacuum degassing is performed under a vacuum degree lower than -0.07MPa. The resulting resin is then ready for use.

[0104]

Example 11

[0105] Example 11 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0106]

[0107]

[0108] When using, isophorone diisocyanate, 2-methylimidazole, bisphenol A epoxy resin and bisphenol A bis(diphenyl phosphate) are mixed evenly at 60°C, and vacuum degassing is performed under a vacuum degree lower than -0.07 MPa. The resulting resin is then ready for use.

[0109]

Example 12

[0110] Example 12 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0111]

[0112] Modified imidazole preparation method: 2-ethyl-4-methylimidazolium and 1,6-hexamethylene diisocyanate are mixed in a mass ratio of 1:1 and heated to 75°C until no isocyanate groups are present.

[0113] Polymethylene polyphenyl polyisocyanate, modified imidazole, bisphenol A epoxy resin and bisphenol A bis(diphenyl phosphate) were stored separately. When using, the different components were mixed evenly at 60°C and vacuum degassed under a vacuum degree below -0.07 MPa. The resulting resin was then ready for use.

[0114]

Example 13

[0115] Example 13 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0116]

[0117] Preparation method of modified imidazole: 2-ethyl-4-methylimidazolium and 1,6-hexamethylene diisocyanate are mixed in a mass ratio of 1:1 and heated to 75℃.

[0118] Polymethylene polyphenyl polyisocyanate and modified imidazole are mixed evenly as component A, and bisphenol A epoxy resin and bisphenol A bis(diphenyl phosphate) are mixed evenly as component B. When using, the two components are mixed evenly at 60°C and vacuum degassed under a vacuum degree below -0.07MPa. The resulting resin is ready for use.

[0119]

Example 14

[0120] Example 14 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0121]

[0122]

[0123] When using, toluene diisocyanate, 2-methylimidazole, bisphenol A epoxy resin and bisphenol A bis(diphenyl phosphate) are mixed evenly at 60°C, and vacuum degassing is performed under a vacuum degree lower than -0.07 MPa. The resulting resin is then ready for use.

[0124]

Example 15

[0125] Example 15 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0126]

[0127] When using, toluene diisocyanate, 1-cyanoethyl-2-ethyl-4-methylimidazolium, bisphenol A epoxy resin and bisphenol A bis(diphenyl phosphate) are mixed evenly at 60°C, and vacuum degassing is performed under a vacuum degree lower than -0.07 MPa. The resulting resin is then ready for use.

[0128]

Example 16

[0129] Example 16 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0130]

[0131] When using, isophorone diisocyanate, 2-methylimidazole, 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester and bisphenol A bis(diphenyl phosphate) are mixed evenly at 60°C, and vacuum degassing is performed under a vacuum degree below -0.07 MPa. The resulting resin is then ready for use.

[0132]

Example 17

[0133] Example 17 provides a vacuum-infused flame-retardant resin, comprising the following components by weight:

[0134]

[0135] When using, isophorone diisocyanate, 2-methylimidazole, bisphenol A epoxy resin and resorcinol bis(diphenyl phosphate) are mixed evenly at 60°C, and vacuum degassing is performed under a vacuum degree lower than -0.07 MPa. The resulting resin is then ready for use.

[0136]

Comparative Example 1

[0137] Comparative Example 1 provides a vacuum-infused flame-retardant resin, comprising the following components in parts by weight:

[0138]

[0139] When using, polymethylene polyphenyl polyisocyanate, 2-methylimidazole, bisphenol A epoxy resin and ammonium polyphosphate flame retardant are mixed evenly at 60°C, and vacuum degassing is performed under a vacuum degree below -0.07MPa. The resulting resin is then ready for use.

[0140] [Comparative Example 2]

[0141] Comparative Example 2 provides a vacuum-infused flame-retardant resin, comprising the following components in parts by weight:

[0142] WANNATE PM-200 (Polymethylene polyphenyl polyisocyanate, Wanhua) 100 parts

[0143] 2-Methylimidazole (National Pharmaceutical Reagent) 1 part

[0144] Bisphenol A epoxy resin (CYD128, Baling Petrochemical) 20 parts

[0145] When using, polymethylene polyphenyl polyisocyanate, 2-methylimidazole and bisphenol A epoxy resin are mixed evenly at 60°C, and vacuum degassing is performed under a vacuum degree below -0.07MPa. The resulting resin is then ready for use.

[0146] [Comparative Example 3]

[0147] Comparative Example 3 provides a vacuum-infused flame-retardant resin, comprising the following components in parts by weight:

[0148] Bisphenol A epoxy resin (CYD128, Baling Petrochemical) 100 parts

[0149] Methylhexahydrophthalic anhydride (Hubei Jusheng Technology Co., Ltd.) 90 parts

[0150] Triphenylphosphine (National Pharmaceutical Reagent) 2 portions

[0151] Bisphenol A epoxy resin is used as component A. Triphenylphosphine and methylhexahydrophthalic anhydride are mixed evenly and heated to 75°C until a homogeneous liquid is formed, which is used as component B. Vacuum degassing is performed under a vacuum degree lower than -0.07MPa, and the resulting resin is ready for use.

[0152] [Comparative Example 4]

[0153] Comparative Example 4 provides a vacuum-infused flame-retardant resin, comprising the following components in parts by weight:

[0154]

[0155]

[0156] Bisphenol A epoxy resin and ammonium polyphosphate flame retardant are mixed evenly as component A. Triphenylphosphine and methylhexahydrophthalic anhydride are mixed evenly and heated to 75°C until a homogeneous liquid is formed as component B. Components A and B are degassed under vacuum conditions below -0.07 MPa, and the resulting resin is ready for use.

[0157] [Comparative Example 5]

[0158] Comparative Example 5 provides a vacuum-infused flame-retardant resin, comprising the following components in parts by weight:

[0159]

[0160] Bisphenol A epoxy resin and bisphenol A bis(diphenyl phosphate) flame retardant are mixed evenly as component A. Triphenylphosphine and methylhexahydrophthalic anhydride are mixed evenly and heated to 75°C until a homogeneous liquid is formed as component B. Components A and B are degassed under vacuum conditions below -0.07 MPa, and the resulting resin is ready for use.

[0161]

Test Example 1

[0162] 1. Viscosity test

[0163] The viscosity of the resin system was tested using a cone-plate viscometer, and the results are shown in Table 1.

[0164] 2. Flame retardant effect test

[0165] The maximum average heat release rate (MARHE) of the vacuum-filled samples was tested according to standard BS EN45545-2, and the results are shown in Table 1.

[0166] 3. Temperature resistance test

[0167] The glass transition temperature of the resin was tested, and the results are shown in Table 1.

[0168] Table 1

[0169]

[0170]

[0171] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A vacuum-infused flame-retardant resin, comprising the following components or the reaction product of the following components: 100 parts by weight of isocyanate; 5-40 parts by weight of epoxy resin; Catalyst: 0.1-5 parts by weight; Liquid flame retardant, 1-100 parts by weight in, The liquid flame retardant contains at least one flame retardant element selected from nitrogen, phosphorus and silicon, and its viscosity at 25°C is less than 1000 mPas. The catalyst is selected from at least one of imidazole compounds, imidazole modified compounds, 2,4,6-tris(dimethylaminomethyl)phenol DMP-30, triphenylphosphine, ethyltriphenylphosphine bromide, and dibutyltin dilaurate.

2. The vacuum-infused flame-retardant resin according to claim 1, characterized in that, The liquid flame retardant contains diphenyl phosphate groups; And / or, the viscosity of the liquid flame retardant at 25°C is 100~600 mPas; And / or, the content of flame retardant elements in the liquid flame retardant is 5wt%~40wt%.

3. The vacuum-infused flame-retardant resin according to claim 2, characterized in that, Each molecule of liquid flame retardant contains two diphenyl phosphate groups.

4. The vacuum-infused flame-retardant resin according to claim 2, characterized in that, The liquid flame retardant is selected from at least one of bisphenol A bis(diphenyl phosphate), bisphenol S bis(diphenyl phosphate), resorcinol bis(diphenyl phosphate), toluene diphenyl phosphate, diphenyl isooctyl phosphate, diphenyl isopropyl phosphate, diphenyl isodecyl phosphate, and ethylenediamine diphenyl phosphate.

5. The vacuum-infused flame-retardant resin according to any one of claims 1-4, characterized in that, The isocyanate has a viscosity of 60~400 mPas at 25°C.

6. The vacuum-infused flame-retardant resin according to claim 5, characterized in that, The isocyanate is selected from at least one of difunctional isocyanates and polyfunctional isocyanates, where polyfunctionality refers to N-functionality, where N is an integer greater than or equal to 3.

7. The vacuum-infused flame-retardant resin according to claim 6, characterized in that, The isocyanate is selected from at least one of toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), and polymethylene polyphenyl polyisocyanate (PAPI).

8. The vacuum-infused flame-retardant resin according to any one of claims 1-4, characterized in that, The epoxy resin has a viscosity of 2000~18000 mPas at 25°C; And / or, the epoxy value of the epoxy resin is 0.10~1.00 mol / 100g.

9. The vacuum-infused flame-retardant resin according to claim 8, characterized in that, The epoxy resin is selected from at least one of glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidylamine epoxy resin, alicyclic epoxide, and linear aliphatic epoxide.

10. The vacuum-infused flame-retardant resin according to claim 8, characterized in that, The epoxy resin is selected from at least one of bisphenol A epoxy resin, phenolic epoxy resin, bisphenol F epoxy resin, N,N-diglycidyl-4-glycidyloxyaniline and 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester.

11. The vacuum-infused flame-retardant resin according to any one of claims 1-4, characterized in that, The imidazole compound is selected from at least one of imidazole, 2-methylimidazolium, 2-ethylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 1-cyanoethyl-2-ethyl-4-methylimidazolium, and 1-cyanoethyl-2-phenylimidazolium; And / or, the imidazole modifier is selected from at least one of imidazole, 2-methylimidazolium, 2-ethylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 1-cyanoethyl-2-ethyl-4-methylimidazolium, 1-cyanoethyl-2-phenylimidazolium and isocyanate modifiers.

12. The vacuum-infused flame-retardant resin according to any one of claims 1-4, characterized in that, The viscosity of the vacuum-infused flame-retardant resin at 25°C is 200~2000 mPas.

13. A method for preparing a vacuum-infused flame-retardant resin according to any one of claims 1-12, comprising: The required amounts of the isocyanate, the epoxy resin, the catalyst, and the liquid flame retardant are mixed and optionally degassed to obtain a vacuum-infused flame retardant resin.

14. The preparation method according to claim 13, characterized in that, The mixing conditions include: a temperature of 20℃ to 85℃; and / or the degassing treatment is carried out under vacuum conditions, with a vacuum degree of -0.05 MPa to -0.1 MPa.

15. A resin-reinforced carbon fiber article, which is made from carbon fiber and the vacuum-infused flame-retardant resin according to any one of claims 1-12 or the vacuum-infused flame-retardant resin prepared by the preparation method according to claim 13 or 14.

16. The resin-reinforced carbon fiber article according to claim 15, characterized in that, The resin-reinforced carbon fiber product was prepared by vacuum infusion process.

17. The application of a resin-reinforced carbon fiber article as described in claim 15 or 16 in the field of rail transportation.

18. The application according to claim 17, characterized in that, The application is as a main load-bearing structure or a non-load-bearing component.

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