Reactive branched flame retardant, flame retardant prepreg, resin-reinforced carbon fiber product and preparation method and application thereof

Abstract

The application provides a reactive branched flame retardant, a flame retardant prepreg resin, a flame retardant prepreg resin matrix adhesive film, a flame retardant prepreg, a resin reinforced carbon fiber product and a preparation method and application thereof. The reactive branched flame retardant is prepared from raw materials including 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide, isocyanate trimer, epoxy polysiloxane, solvent, catalyst A and catalyst B; the prepared reactive branched flame retardant contains aromatic heterocycle and aromatic ring, has good thermal stability, and significantly improves the flame retardance of the system through the synergistic effect of nitrogen, phosphorus and silicon; and the prepared resin reinforced carbon fiber product has high flame retardance grade, high mechanical properties and high glass transition temperature.

Description

Technical Field

[0001] This invention relates to the field of resin composite material technology, and more specifically, to a reactive branched flame retardant, a flame retardant prepreg resin, a flame retardant prepreg resin matrix film, a flame retardant prepreg, resin-reinforced carbon fiber products, and their preparation methods and applications. Background Technology

[0002] Currently, the flame-retardant resins used in composite materials on the market can be mainly categorized as follows: (1) halogen-containing flame-retardant resins; (2) resin systems using inorganic flame-retardant fillers such as phosphorus, aluminum hydroxide, and expanded graphite; and (3) resin systems with added halogen-free flame retardants containing nitrogen and phosphorus elements.

[0003] Adding halogenated flame retardants to flame retardant resins is detrimental to environmental protection; adding inorganic flame retardant fillers increases the resin viscosity, and a larger amount is required to achieve a good flame retardant effect, but the mechanical properties of the resin system deteriorate after the amount added increases; nitrogen and phosphorus element organic flame retardants include powder flame retardants and liquid flame retardants. Powder nitrogen and phosphorus element organic flame retardants have the same drawbacks as inorganic flame retardant fillers, leading to the deterioration of the mechanical properties of the resin system, while liquid nitrogen and phosphorus element organic flame retardants will cause a decrease in the heat resistance of the system.

[0004] Due to the limitations of the aforementioned flame retardants, many prepreg resin composites can only reach the HL2 level. Developing flame-retardant prepregs that achieve HL3 without compromising the mechanical strength and heat resistance of the resin system is a recognized challenge in the industry. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention provides a reactive branched flame retardant, a flame retardant prepreg resin, a flame retardant prepreg resin matrix film, a flame retardant prepreg, resin-reinforced carbon fiber products, their preparation methods, and applications.

[0006] This invention utilizes isocyanate trimer, DOPO-HQ, and epoxy polysiloxane to prepare a reactive branched flame retardant. This flame retardant contains aromatic heterocyclic and aromatic rings, exhibiting good thermal stability. Furthermore, the flame retardancy of the system is significantly enhanced through the synergistic effect of nitrogen, phosphorus, and silicon. Because the prepared reactive branched flame retardant is epoxy-terminated, it can participate in the curing network of the system, avoiding the problem of decreased mechanical properties and glass transition temperature caused by external flame retardants.

[0007] One of the objectives of this invention is to provide a reactive branched flame retardant.

[0008] The reactive branched flame retardant is prepared from raw materials including 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-HQ), isocyanate trimer, epoxy polysiloxane, catalyst A and catalyst B.

[0009] In a preferred embodiment of the present invention,

[0010] The molar ratio of the isocyanate group of the isocyanate trimer to the hydroxyl group of 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:(1.7-2.5); preferably 1:(1.9-2.2).

[0011] The reaction of 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide with isocyanate trimer yields a hydroxyl-terminated product, wherein the molar ratio of the hydroxyl group to the epoxy group of the epoxy polysiloxane in the hydroxyl-terminated product is 1:(1.5-2.5); preferably 1:(1.8-2.3).

[0012] In a preferred embodiment of the present invention,

[0013] The 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide is a relatively effective flame retardant, but it can lead to a decrease in mechanical properties, so it is necessary to improve the mechanical properties of the resin.

[0014] The isocyanate trimer is at least one of toluene diisocyanate (TDI) trimer, isophorone diisocyanate (IPDI) trimer, diphenylmethane diisocyanate (MDI) trimer, dicyclohexylmethane diisocyanate (HMDI) trimer, hexamethylene diisocyanate (HDI) trimer, lysine diisocyanate (LDI) trimer, and polymethylene polyphenyl polyisocyanate (PAPI) trimer;

[0015] The epoxy polysiloxane molecule contains at least two epoxy groups; the epoxy value is 0.1 to 0.9 equivalents / 100g, preferably 0.1 to 0.6 equivalents / 100g;

[0016] Catalyst A is at least one of stannous octoate, dibutyltin dilaurate, triethylenediamine, lead octoate, zinc naphthenate, or tetraisobutyl titanate.

[0017] The catalyst B is at least one of ammonium sulfate, potassium persulfate, tetrabutylammonium bromide, triphenylphosphine, ethyltriphenylphosphine bromide, and triethanolamine.

[0018] In a preferred embodiment of the present invention,

[0019] The mass of catalyst A is 0.5% to 5% of the mass of 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide, preferably 1% to 3%; and / or,

[0020] The mass of catalyst B is 0.005% to 1.00% of the mass of the epoxy polysiloxane, preferably 0.01% to 0.2%.

[0021] A second objective of this invention is to provide a method for preparing a reactive branched flame retardant, comprising the following steps:

[0022] (1) Under the protection of a protective gas, the catalyst A and the isocyanate trimer are added to the solution of the 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide to react and obtain the hydroxyl-terminated product.

[0023] (2) The hydroxyl-terminated product obtained in step (1), epoxy polysiloxane, and catalyst B are mixed and reacted to obtain the reactive branched flame retardant.

[0024] In a preferred embodiment of the present invention,

[0025] Step (1),

[0026] The protective gas is at least one of nitrogen and an inert gas; and / or,

[0027] The mass percentage concentration of the solution of 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide is 5-60%, preferably 10-30%.

[0028] The solvent of the solution of 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide is at least one of methanol, ethanol, dimethyl sulfoxide, chloroform, dimethylformamide, and dioxane, preferably at least one of dimethyl sulfoxide, chloroform, and dimethylformamide.

[0029] The isocyanate trimer is added dropwise.

[0030] The reaction temperature is 30–100℃, preferably 60–90℃; the reaction time is 0.5–5 h, preferably 1–3 h; and / or,

[0031] Step (2),

[0032] The reaction temperature is 100–200℃, preferably 160–180℃; the reaction time is 1–5 h, preferably 2–3 h.

[0033] The third objective of this invention is to provide a flame-retardant prepreg resin.

[0034] The flame-retardant prepreg resin includes the flame-retardant prepreg resin, epoxy resin, and curing agent;

[0035] Based on 100 parts by weight of epoxy resin,

[0036] 100 parts by weight of epoxy resin;

[0037] 5-150 parts by weight of reactive branched flame retardant; preferably 50-100 parts by weight;

[0038] 2 to 90 parts by weight of curing agent; preferably 10 to 50 parts by weight.

[0039] In a preferred embodiment of the present invention,

[0040] The epoxy resin is at least one of glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidylamine epoxy resin, alicyclic epoxide, and linear aliphatic epoxide; preferably 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; and / or,

[0041] The curing agent is at least one of amine curing agents, acid anhydride curing agents, linear phenolic curing agents, polyester resin curing agents, polyurethane curing agents, styrene-maleic anhydride copolymer resin curing agents, and polysulfide rubber curing agents; preferably at least one of 4,4'-diaminodiphenyl sulfone, diaminodiphenylmethane, and dicyandiamide.

[0042] In a preferred embodiment of the present invention,

[0043] The flame-retardant prepreg resin also includes a curing accelerator;

[0044] The curing accelerator is preferably at least one of tertiary amines and their derivatives, quaternary ammonium salts, substituted ureas, imidazole compounds and their derivatives; more preferably at least one of substituted urea UR300, substituted urea UR500, and 2-ethyl-4-methylimidazole.

[0045] The amount of curing accelerator is 1 to 20 parts by weight, preferably 3 to 8 parts by weight, based on 100 parts by weight of epoxy resin.

[0046] The fourth objective of this invention is to provide a method for preparing a flame-retardant prepreg resin, comprising:

[0047] The raw materials are mixed evenly according to the specified weight proportions to prepare a flame-retardant prepreg resin.

[0048] The mixing temperature is preferably 30–110°C, and more preferably 50–80°C.

[0049] The fifth objective of this invention is to provide a flame-retardant prepreg resin matrix film.

[0050] The sixth objective of this invention is to provide a method for preparing a flame-retardant prepreg resin matrix film, comprising:

[0051] The flame-retardant prepreg resin is coated to obtain the flame-retardant prepreg resin matrix film; preferably, the coating temperature is 50-120℃, more preferably 60-90℃.

[0052] The seventh objective of this invention is to provide a flame-retardant prepreg.

[0053] The flame-retardant prepreg comprises a flame-retardant prepreg resin matrix film and reinforcing fibers; the reinforcing fibers are preferably at least one of carbon fiber, aramid fiber, glass fiber, and basalt fiber.

[0054] The content of reinforcing fibers and flame-retardant prepreg resin (i.e., flame-retardant prepreg resin matrix film) in the flame-retardant prepreg of this invention is not particularly limited; generally, it can be calculated based on 100 parts by weight of reinforcing fibers.

[0055] 100 parts by weight of reinforcing fiber;

[0056] The flame-retardant prepreg resin matrix film consists of 20 to 100 parts by weight; preferably 35 to 80 parts by weight.

[0057] In practice, the amount of reinforcing fiber and adhesive film can be measured by areal density.

[0058] The eighth objective of this invention is to provide a method for preparing a flame-retardant prepreg, comprising the following steps:

[0059] A layer of the flame-retardant prepreg resin matrix film is attached to each side of the reinforcing fiber, and the flame-retardant prepreg is obtained after impregnation; the impregnation temperature is preferably 70-130℃, more preferably 90-110℃.

[0060] The ninth objective of this invention is to provide a resin-reinforced carbon fiber product.

[0061] The tenth objective of this invention is to provide a method for preparing resin-reinforced carbon fiber articles, comprising:

[0062] The flame-retardant prepreg is cut, laid up, and cured to obtain the resin-reinforced carbon fiber product.

[0063] The curing can be achieved through various methods, such as, but not limited to, heat curing and light curing. Heat curing offers a wide range of curing conditions, aiming to achieve curing. For example, but not limited to, a curing temperature of 60–150°C, preferably 80–120°C, and a curing time of 2–6 hours, preferably 3–4 hours, such as 80°C / 1 hour + 120°C / 2 hours.

[0064] The eleventh objective of this invention is to provide an application of resin-reinforced carbon fiber products in the field of rail transportation, preferably in the application of carbon fiber composite main load-bearing structures and non-load-bearing components.

[0065] The beneficial effects of the flame-retardant prepreg resin provided by this invention are at least as follows:

[0066] The reactive branched flame retardant prepared by this invention contains aromatic heterocyclic rings and aromatic rings, exhibits good thermal stability, and significantly improves the flame retardancy of the system through the synergistic effect of nitrogen, phosphorus and silicon.

[0067] The reactive branched flame retardant prepared in this invention is epoxy group-terminated, so it can participate in the curing network of the system, avoiding the problem of decreased mechanical properties and glass transition temperature of the system caused by the addition of flame retardants. Detailed Implementation

[0068] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0069] The raw materials used in the examples and comparative examples are all commercially available products.

[0070] Test method:

[0071] The testing standards for resin-reinforced carbon fiber products are as follows:

[0072] JC / T 773-2010 Determination of interlaminar shear strength of fiber-reinforced plastics by short beam method;

[0073] ASTM E1640-2013 Standard Test Method for Determining Glass Transition Temperature by Dynamic Mechanical Analysis;

[0074] Fire risk level of resin-reinforced carbon fiber products (BS EN45545-2).

[0075] The parts used in the examples and comparative examples refer to parts by weight.

[0076]

Example 1

[0077] (1) Preparation of reactive branched flame retardants:

[0078] 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-HQ) was mixed with dimethyl sulfoxide (DMSO) at a mass percentage of 10% and added to a reaction vessel. The system was protected under nitrogen atmosphere and stirred. The temperature was raised to 40°C, and dibutyltin dilaurate was added at a mass ratio of 2 wt% of DOPO-HQ. Toluene diisocyanate (TDI) trimer was added dropwise to DOPO-HQ at a molar ratio of isocyanate groups in the TDI trimer to hydroxyl groups in DOPO-HQ of 1:2. After the addition was complete, the temperature was raised to 90°C and the reaction was carried out for 3 hours. The mixture was then filtered, washed three times with chloroform, and dried to obtain the hydroxyl-terminated product.

[0079] The obtained hydroxyl-terminated product was added to an epoxy polysiloxane (epoxy value 0.3), with the molar ratio of hydroxyl groups in the hydroxyl-terminated product to epoxy groups in the epoxy polysiloxane being 1:2. The system was heated to 120°C, and ethyltriphenylphosphine bromide was added at an amount of 0.05 wt% of the epoxy polysiloxane. The system was then heated to 180°C and reacted for 2 hours to obtain a reactive branched flame retardant.

[0080] (2) A flame-retardant prepreg resin, comprising an epoxy resin, a reactive branched flame retardant, and a curing agent. The flame-retardant prepreg resin may contain a curing accelerator, and the content of each substance is as follows:

[0081]

[0082] All components are mixed and heated to 70°C to disperse evenly, thus obtaining flame-retardant prepreg resin.

[0083] (3) Preparation of flame-retardant prepreg:

[0084] Preparation of flame-retardant prepreg resin-based film: Flame-retardant prepreg resin is poured into the resin tank of a coating machine, and the resin matrix is ​​uniformly coated onto release paper at a coating temperature of 70℃. The areal density of the resin-based film is 108 g / m³. 2 .

[0085] Pre-impregnation: Toray T700×12k carbon fiber was used to prepare fibers with a surface density of 400 g / m². 2 For the prepreg, two rolls of resin matrix film are placed on the upper and lower unwinding stations at the front of the prepreg machine. At the first, second, and third heating rollers and heating plate, the upper and lower layers of matrix resin film impregnate the unidirectionally aligned carbon fibers at an impregnation temperature of 90℃. After cooling on the cooling plate, the upper release paper is wound up, covered with a PE film, and finally the prepreg is wound up.

[0086] (4) Preparation and evaluation of resin-reinforced carbon fiber products

[0087] The prepreg was cut to appropriate sizes according to the relevant standards, laid up, and cured at 80℃ for 1 hour followed by 120℃ for 2 hours. After being placed in an autoclave, the laminate was cut to obtain the test samples. The samples were tested according to the relevant standards. The results are shown in Table 1.

[0088]

Example 2

[0089] The resin-reinforced carbon fiber products were prepared according to the method of Example 1, except that the isocyanate trimer used in the preparation of the reactive branched flame retardant was isophorone diisocyanate (IPDI) trimer.

[0090]

Example 3

[0091] The resin-reinforced carbon fiber products were prepared according to the method of Example 1, except that the isocyanate trimer used in the preparation of the reactive branched flame retardant was hexamethylene diisocyanate (HDI) trimer.

[0092]

Example 4

[0093] Resin-reinforced carbon fiber products were prepared according to the method of Example 1, except that the epoxy polysiloxane used in the preparation of the reactive branched flame retardant had an epoxy value of 0.6.

[0094]

Example 5

[0095] Resin-reinforced carbon fiber products were prepared according to the method of Example 1, except that the epoxy polysiloxane used in the preparation of the reactive branched flame retardant had an epoxy value of 0.1.

[0096]

Example 6

[0097] Resin-reinforced carbon fiber products were prepared according to the method of Example 1, except that the catalyst for the reaction of DOPO-HQ with isocyanate trimer in the preparation of reactive branched flame retardant was stannous octoate.

[0098]

Example 7

[0099] Resin-reinforced carbon fiber products were prepared according to the method of Example 1, except that the catalyst for the reaction of the hydroxyl-terminated product with the epoxy polysiloxane in the preparation of the reactive branched flame retardant was triphenylphosphine.

[0100]

Example 8

[0101] Resin-reinforced carbon fiber products were prepared according to the method of Example 1, except that the epoxy resin in the flame-retardant prepreg resin was bisphenol F epoxy DER354.

[0102]

Example 9

[0103] Resin-reinforced carbon fiber products were prepared according to the method of Example 1, except that the epoxy resin in the flame-retardant prepreg resin was phenolic epoxy resin Nanya NPPN-631.

[0104]

Example 10

[0105] Resin-reinforced carbon fiber products were prepared according to the method of Example 1, except that the amount of reactive branched flame retardant in the flame-retardant prepreg resin was different, and the composition of the flame-retardant prepreg resin was as follows:

[0106]

[0107]

Example 11

[0108] Resin-reinforced carbon fiber products were prepared according to the method of Example 1, except that the curing agent in the flame-retardant prepreg resin was different. The composition of the flame-retardant prepreg resin was as follows:

[0109] Bisphenol A epoxy resin CYD128 100 parts by weight;

[0110] 100 parts by weight of reactive branched flame retardant;

[0111] 37 parts by weight of diaminodiphenylmethane;

[0112] The curing process is 120℃ / 1h + 160℃ / 2h.

[0113]

Example 12

[0114] Resin-reinforced carbon fiber products were prepared according to the method of Example 1, except that the curing agent in the flame-retardant prepreg resin was different. The composition of the flame-retardant prepreg resin was as follows:

[0115] Bisphenol A epoxy resin CYD128 100 parts by weight;

[0116] 100 parts by weight of reactive branched flame retardant;

[0117] 50 parts by weight of 4,4'-diaminodiphenyl sulfone;

[0118] The curing process is 120℃ / 1h + 180℃ / 2h.

[0119]

Example 13

[0120] (1) Preparation of reactive branched flame retardants:

[0121] 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-HQ) was mixed with dimethylformamide at a mass percentage concentration of 30% and added to a reaction vessel. The system was protected under nitrogen atmosphere and stirred. The system was heated to 40°C, and dibutyltin dilaurate was added at a mass ratio of 1 wt% of DOPO-HQ. Toluene diisocyanate (TDI) trimer was added dropwise to DOPO-HQ, with the molar ratio of isocyanate groups in the TDI trimer to hydroxyl groups in DOPO-HQ being 1:1.9. After the addition was complete, the temperature was raised to 60°C and the reaction was carried out for 3 hours. The mixture was then filtered, washed three times with chloroform, and dried to obtain the hydroxyl-terminated product.

[0122] The obtained hydroxyl-terminated product was added to an epoxy polysiloxane (epoxy value 0.3), with a molar ratio of hydroxyl groups in the hydroxyl-terminated product to epoxy groups in the epoxy polysiloxane of 1:1.8. The system was heated to 120°C, and ethyltriphenylphosphine bromide was added at an amount of 0.01 wt% of the epoxy polysiloxane. The system was then heated to 160°C and reacted for 3 hours to obtain a reactive branched flame retardant.

[0123] (2) A flame-retardant prepreg resin, comprising an epoxy resin, a reactive branched flame retardant, and a curing agent. The flame-retardant prepreg resin may contain a curing accelerator, and the content of each substance is as follows:

[0124]

[0125] Mix all components and heat to 50°C to disperse them evenly to obtain flame-retardant prepreg resin.

[0126] (3) Preparation of flame-retardant prepreg:

[0127] Preparation of flame-retardant prepreg resin-based film: The flame-retardant prepreg resin is poured into the resin tank of a coating machine, and the resin matrix is ​​uniformly coated onto release paper at a coating temperature of 90℃. The areal density of the resin-based film is 70 g / m³. 2 .

[0128] Pre-impregnation: Toray T700×12k carbon fiber was used to prepare fibers with a surface density of 400 g / m². 2 For the prepreg, two rolls of resin matrix film are placed on the upper and lower unwinding stations at the front of the prepreg machine. At the first, second, and third heating rollers and heating plate, the upper and lower layers of matrix resin film impregnate the unidirectionally aligned carbon fibers at an impregnation temperature of 110℃. After cooling on the cooling plate, the upper release paper is wound up, covered with a PE film, and finally the prepreg is wound up.

[0129] (4) Preparation and evaluation of resin-reinforced carbon fiber products

[0130] The prepreg was cut to appropriate sizes according to the relevant standards, laid up, and cured at 80℃ for 1 hour followed by 120℃ for 2 hours. After being placed in an autoclave, the laminate was cut to obtain the test samples. The samples were tested according to the relevant standards. The results are shown in Table 1.

[0131]

Example 14

[0132] (1) Preparation of reactive branched flame retardants:

[0133] 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-HQ) was mixed with chloroform at a mass percentage concentration of 10% and added to a reaction vessel. The system was protected under nitrogen atmosphere and stirred. The system was heated to 40°C, and dibutyltin dilaurate was added at a mass ratio of 3 wt% of DOPO-HQ. Toluene diisocyanate (TDI) trimer was added dropwise to DOPO-HQ at a molar ratio of isocyanate groups in the TDI trimer to hydroxyl groups in DOPO-HQ of 1:2.2. After the addition was complete, the mixture was heated to 90°C and reacted for 1 hour. The mixture was then filtered, washed three times with chloroform, and dried to obtain the hydroxyl-terminated product.

[0134] The obtained hydroxyl-terminated product was added to an epoxy polysiloxane (epoxy value 0.3), with the molar ratio of hydroxyl groups in the hydroxyl-terminated product to epoxy groups in the epoxy polysiloxane being 1:2.3. The system was heated to 120°C, and ethyltriphenylphosphine bromide was added at an amount of 0.2 wt% of the epoxy polysiloxane. The system was then heated to 180°C and reacted for 2 hours to obtain a reactive branched flame retardant.

[0135] (2) A flame-retardant prepreg resin, comprising an epoxy resin, a reactive branched flame retardant, and a curing agent. The flame-retardant prepreg resin may contain a curing accelerator, and the content of each substance is as follows:

[0136]

[0137] All components are mixed and heated to 80°C to disperse evenly, thus obtaining flame-retardant prepreg resin.

[0138] (3) Preparation of flame-retardant prepreg:

[0139] Preparation of flame-retardant prepreg resin-based film: Flame-retardant prepreg resin is poured into the resin tank of a coating machine, and the resin matrix is ​​uniformly coated onto release paper at a coating temperature of 110℃. The areal density of the resin-based film is 160 g / m³. 2 .

[0140] Pre-impregnation: Toray T700×12k carbon fiber was used to prepare fibers with a surface density of 400 g / m². 2 For the prepreg, two rolls of resin matrix film are placed on the upper and lower unwinding stations at the front of the prepreg machine. At the first, second, and third heating rollers and heating plate, the upper and lower layers of matrix resin film impregnate the unidirectionally aligned carbon fibers at an impregnation temperature of 110℃. After cooling on the cooling plate, the upper release paper is wound up, covered with a PE film, and finally the prepreg is wound up.

[0141] (4) Preparation and evaluation of resin-reinforced carbon fiber products

[0142] The prepreg was cut to appropriate sizes according to the relevant standards, laid up, and cured at 80℃ for 1 hour followed by 120℃ for 2 hours. After being placed in an autoclave, the laminate was cut to obtain the test samples. The samples were tested according to the relevant standards. The results are shown in Table 1.

[0143]

Comparative Example 1

[0144] Resin-reinforced carbon fiber products were prepared according to the method of Example 1, except that the composition of the flame-retardant prepreg resin was as follows:

[0145]

[0146]

[0147] [Comparative Example 2]

[0148] Resin-reinforced carbon fiber products were prepared according to the method of Example 1, except that the composition of the flame-retardant prepreg resin was as follows:

[0149]

[0150] [Comparative Example 3]

[0151] Resin-reinforced carbon fiber products were prepared according to the method of Example 1, except that the composition of the flame-retardant prepreg resin was as follows:

[0152]

[0153] [Comparative Example 4]

[0154] Resin-reinforced carbon fiber products were prepared according to the method of Example 1, except that the branched flame retardant was not prepared first through a chemical reaction, but the raw materials in Example 1 were simply physically mixed.

[0155] The mixed components are:

[0156]

[0157]

[0158] The interlaminar shear strength, flame retardancy rating and glass transition temperature of the resin-reinforced carbon fiber products prepared in Examples 1-14 and Comparative Examples 1-4 were tested, and the results are shown in Table 1.

[0159] Table 1

[0160]

[0161] Compared with Example 1, Comparative Example 1 replaced the reactive branched flame retardant with an equal amount of bisphenol A epoxy resin DER671; the flame retardancy rating of Comparative Example 1 was lower than HL1.

[0162] Comparative Example 2 replaced the reactive branched flame retardant with 50 parts of bisphenol A epoxy resin DER671 and added 20 parts of ammonium polyphosphate flame retardant.

[0163] Comparative Example 3 replaced the reactive branched flame retardant with an equal amount of bisphenol A epoxy resin DER671 and added 20 parts of dimethyl methylphosphonate.

[0164] The flame retardant ratings of Comparative Examples 2 and 3 were HL1, while the flame retardant rating of Example 1 reached HL3. The interlaminar shear strengths of Comparative Examples 2 and 3 were 41 MPa and 57 MPa, respectively, which were much lower than the 82 MPa of Example 1. The glass transition temperature of Comparative Example 3 was 78°C, which was much lower than the 113°C of Example 1. This proves that the addition of flame retardant leads to a significant decrease in the mechanical properties of the system and also causes a decrease in the glass transition temperature.

[0165] Comparative Example 4 simply physically mixes the raw materials from Example 1 without first reacting to form a branched flame retardant. Comparative Example 4 achieves a flame retardant rating of HL2 and an interlaminar shear strength of 82 MPa. Compared with Example 1, both the interlaminar shear strength and the flame retardant rating are lower, demonstrating that although physical mixing alone can also have a certain flame retardant effect, it is not as good as reacting to obtain a branched flame retardant first and then physically mixing. At the same time, the mechanical properties are significantly reduced.

[0166] The interlaminar shear strength of Examples 1 to 14 is 65 to 89 MPa. Except for Example 10, the flame retardancy rating of BS EN45545-2 is HL3, while that of Example 10 is HL2. The glass transition temperature is 99 to 154°C. The prepared resin-reinforced carbon fiber products have high flame retardancy rating, high mechanical properties and high glass transition temperature.

Claims

1. A reactive branched flame retardant, prepared from raw materials including 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide, isocyanate trimer, epoxy polysiloxane, catalyst A, and catalyst B; said reactive branched flame retardant is prepared by a method comprising the following steps: (1) Under the protection of a protective gas, the catalyst A and the isocyanate trimer are added to the solution of the 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide to react and obtain the hydroxyl-terminated product; (2) The hydroxyl-terminated product obtained in step (1), epoxy polysiloxane, and catalyst B are mixed and reacted to obtain the reactive branched flame retardant.

2. The reactive branched flame retardant as described in claim 1, characterized in that: The molar ratio of the isocyanate group of the isocyanate trimer to the hydroxyl group of 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:(1.7~2.5); and / or, The reaction of 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide with isocyanate trimer yields a hydroxyl-terminated product, wherein the molar ratio of the hydroxyl group to the epoxy group of the epoxy polysiloxane in the hydroxyl-terminated product is 1:(1.5~2.5).

3. The reactive branched flame retardant as described in claim 2, characterized in that: The molar ratio of the isocyanate group of the isocyanate trimer to the hydroxyl group of 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:(1.9~2.2); and / or, The reaction of 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide with isocyanate trimer yields a hydroxyl-terminated product, wherein the molar ratio of the hydroxyl group to the epoxy group of the epoxy polysiloxane in the hydroxyl-terminated product is 1:(1.8~2.3).

4. The reactive branched flame retardant as described in claim 1, characterized in that: The isocyanate trimer is at least one selected from toluene diisocyanate trimer, isophorone diisocyanate trimer, diphenylmethane diisocyanate trimer, dicyclohexylmethane diisocyanate trimer, hexamethylene diisocyanate trimer, lysine diisocyanate trimer, and polymethylene polyphenyl polyisocyanate trimer; and / or, The epoxy polysiloxane molecule contains at least two epoxy groups; the epoxy value is 0.1~0.9 equivalents / 100g; and / or, The catalyst A is at least one selected from stannous octoate, dibutyltin dilaurate, triethylenediamine, lead octoate, zinc naphthenate, or tetraisobutyl titanate; and / or, The catalyst B is at least one of ammonium sulfate, potassium persulfate, tetrabutylammonium bromide, triphenylphosphine, ethyltriphenylphosphine bromide, and triethanolamine.

5. The reactive branched flame retardant as described in claim 4, characterized in that: The epoxy value of the epoxy polysiloxane is 0.1~0.6 equivalents / 100g.

6. The reactive branched flame retardant as described in claim 1, characterized in that: The mass of catalyst A is 0.5% to 5% of the mass of 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide; and / or, The mass of catalyst B is 0.005% to 1% of the mass of the epoxy polysiloxane.

7. The reactive branched flame retardant as described in claim 6, characterized in that: The mass of catalyst A is 1% to 3% of the mass of 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide; and / or, The mass of catalyst B is 0.01% to 0.2% of the mass of the epoxy polysiloxane.

8. A method for preparing a reactive branched flame retardant as described in any one of claims 1 to 7, the method comprising the following steps: (1) Under the protection of a protective gas, the catalyst A and the isocyanate trimer are added to the solution of the 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide to react and obtain the hydroxyl-terminated product; (2) The hydroxyl-terminated product obtained in step (1), epoxy polysiloxane, and catalyst B are mixed and reacted to obtain the reactive branched flame retardant.

9. The method for preparing the reactive branched flame retardant as described in claim 8, characterized in that: Step (1), The protective gas is at least one of nitrogen and an inert gas; and / or, The mass percentage concentration of the solution of 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide is 5-60%; and / or, The solvent for the solution of 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide is at least one selected from methanol, ethanol, dimethyl sulfoxide, chloroform, dimethylformamide, and dioxane; and / or, The isocyanate trimer is added dropwise; and / or, The reaction temperature is 30~100℃; and / or, The reaction time is 0.5~5h; and / or, Step (2), The reaction temperature is 100~200℃; and / or, The reaction time is 1 to 5 hours.

10. The method for preparing the reactive branched flame retardant as described in claim 9, characterized in that: Step (1), The mass percentage concentration of the solution of 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide is 10-30%; and / or, The reaction temperature is 60~90℃; and / or, The reaction time is 1-3 hours; and / or, Step (2), The reaction temperature is 160~180℃; and / or, The reaction time is 2-3 hours.

11. A flame-retardant prepreg resin, comprising the reactive branched flame retardant according to any one of claims 1 to 7 or the reactive branched flame retardant prepared by the method according to any one of claims 8 to 10, further comprising an epoxy resin and a curing agent; Based on 100 parts by weight of epoxy resin, 100 parts by weight of epoxy resin; 5-150 parts by weight of reactive branched flame retardant; 2-90 parts by weight of curing agent.

12. The flame-retardant prepreg resin as described in claim 11, characterized in that: Based on 100 parts by weight of epoxy resin, 100 parts by weight of epoxy resin; 50-100 parts by weight of reactive branched flame retardant; 10-50 parts by weight of curing agent.

13. The flame-retardant prepreg resin as described in claim 11 or 12, characterized in that: The epoxy resin is at least one selected from glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, alicyclic epoxide, and linear aliphatic epoxide; and / or, The curing agent is at least one of the following: amine curing agent, acid anhydride curing agent, linear phenolic curing agent, polyester resin curing agent, polyurethane curing agent, styrene-maleic anhydride copolymer resin curing agent, and polysulfide rubber curing agent.

14. The flame-retardant prepreg resin as described in claim 13, characterized in that: The epoxy resin is at least one of bisphenol A epoxy resin, phenolic epoxy resin, bisphenol F epoxy resin, N,N-diglycidyl-4-glycidyloxyaniline, or 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester; and / or The curing agent is at least one of 4,4'-diaminodiphenyl sulfone, diaminodiphenylmethane, and dicyandiamide.

15. The flame-retardant prepreg resin as described in claim 11 or 12, characterized in that: The flame-retardant prepreg resin also includes a curing accelerator.

16. The flame-retardant prepreg resin as described in claim 15, characterized in that: The curing accelerator is at least one of tertiary amines and their derivatives, substituted ureas, imidazole compounds and their derivatives; and / or, The amount of curing accelerator is 1 to 20 parts by weight per 100 parts by weight of epoxy resin.

17. The flame-retardant prepreg resin as described in claim 16, characterized in that: The curing accelerator is at least one selected from quaternary ammonium salts, substituted urea UR300, substituted urea UR500, and 2-ethyl-4-methylimidazole; and / or, The amount of curing accelerator is 3 to 8 parts by weight per 100 parts by weight of epoxy resin.

18. A method for preparing a flame-retardant prepreg resin as described in any one of claims 11 to 17, the method comprising: The raw materials are mixed evenly according to the specified weight proportions to prepare a flame-retardant prepreg resin.

19. The method for preparing the flame-retardant prepreg resin as described in claim 18, characterized in that: The mixing temperature is 30~110℃.

20. The method for preparing the flame-retardant prepreg resin as described in claim 19, characterized in that: The mixing temperature is 50~80℃.

21. A flame-retardant prepreg resin matrix film made from the flame-retardant prepreg resin according to any one of claims 11 to 17.

22. A method for preparing a flame-retardant prepreg resin matrix film as described in claim 21, comprising: The flame-retardant prepreg resin is coated to obtain the flame-retardant prepreg resin matrix film.

23. The method for preparing the flame-retardant prepreg resin matrix film as described in claim 22, characterized in that: The coating temperature is 50~120℃.

24. The method for preparing the flame-retardant prepreg resin matrix film as described in claim 23, characterized in that: The coating temperature is 60~90℃.

25. A flame-retardant prepreg comprising the flame-retardant prepreg resin matrix film of claim 21, wherein the flame-retardant prepreg further comprises reinforcing fibers.

26. The flame-retardant prepreg as described in claim 25, characterized in that: The reinforcing fiber is at least one of carbon fiber, aramid fiber, glass fiber, and basalt fiber.

27. A method for preparing a flame-retardant prepreg as described in claim 25 or 26, the method comprising the following steps: A layer of the flame-retardant prepreg resin matrix film is attached to each side of the reinforcing fiber, and the flame-retardant prepreg is obtained after impregnation.

28. The method for preparing the flame-retardant prepreg as described in claim 27, characterized in that: The impregnation temperature is 70~130℃.

29. The method for preparing the flame-retardant prepreg as described in claim 28, characterized in that: The impregnation temperature is 90~110℃.

30. A resin-reinforced carbon fiber article made from the flame-retardant prepreg as described in claim 25 or 26.

31. An application of the resin-reinforced carbon fiber product as described in claim 30 in the field of rail transportation.

32. The application as described in claim 31, characterized in that: Applications of carbon fiber composite materials in main load-bearing structures and non-load-bearing components.

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