Flame-retardant hp-rtm epoxy resin and method for producing the same

Abstract

The application relates to the technical field of high polymer materials, and particularly discloses a flame-retardant HP-RTM epoxy resin and a preparation method thereof. The flame-retardant HP-RTM epoxy resin comprises resin mixture, a curing agent and a release agent in a weight ratio of 100:(10-25):(2-4), and the resin mixture comprises the following raw materials in percentage by weight based on the total weight of the resin mixture: 45%-85% of an epoxy resin, 7%-40% of a flame-retardant mixture and 5-20% of a diluent; the flame-retardant mixture comprises the following raw materials in parts by weight based on the total weight of the flame-retardant mixture: 10-15 parts of ammonium polyphosphate, 8-12 parts of melamine cyanurate and 5-8 parts of nano-magnesium hydroxide. The application forms a carbon layer skeleton, a porous foam structure and a dense ceramic outer layer in sequence by constructing a temperature gradient, so that the flame-retardant performance of the HP-RTM epoxy resin material is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, and in particular to a flame-retardant HP-RTM epoxy resin and a preparation method thereof. BACKGROUND

[0002] With the rapid development of the new energy industry and the wide popularity of new energy vehicles, lightweight and low cost of new energy vehicles have become the focus of attention. Fiber-reinforced epoxy resin composites have high specific modulus, high specific strength, low density, low curing shrinkage, heat resistance, low temperature resistance, and performance design, and many other advantages, and have become the preferred material for lightweight new energy vehicles.

[0003] HP-RTM (High Pressure Resin Transfer Molding) is the abbreviation of high pressure resin transfer molding process. It refers to the use of high pressure to flush and mix resin and inject it into a vacuum sealed mold with pre-laid fiber reinforced materials and pre-embedded parts, and then flow, impregnate, cure and demold to obtain a composite product. Compared with RTM molding process, HP-RTM uses high pressure to flush and mix resin and inject it into a vacuum sealed mold with pre-laid fiber reinforced materials and pre-formed parts, and then flow, impregnate, cure and demold to obtain a composite product. HP-RTM often uses pre-formed parts to complete resin impregnation and rapid curing through high pressure injection, which significantly improves impregnation effect and product performance. The mixing process of HP-RTM is fast, and high reactivity resin can be used to produce complex structures in a short time, solving the bottleneck of injection and curing, and becoming one of the widely used resin molding processes in many industries.

[0004] However, when applied to the battery cover, it needs to be able to deal with battery fires and other accidents, so the HP-RTM epoxy resin material needs to have higher flame retardant properties. SUMMARY

[0005] In order to improve the flame retardant properties of HP-RTM epoxy resin material, the present application provides a flame-retardant HP-RTM epoxy resin and a preparation method thereof.

[0006] In the first aspect, the present application provides a flame-retardant HP-RTM epoxy resin, which adopts the following technical scheme:

[0007] The flame-retardant HP-RTM epoxy resin comprises a resin mixture, a curing agent and a release agent in a weight ratio of 100:(10-25):(2-4), and the resin mixture comprises the following raw materials in a weight percentage of 45%-85% of epoxy resin, 7%-40% of flame-retardant mixture and 5-20% of diluent, and the flame-retardant mixture comprises the following raw materials in a weight percentage of 10-15 parts of ammonium polyphosphate, 8-12 parts of melamine cyanurate and 5-8 parts of nano-magnesium hydroxide.

[0008] By adopting the above technical scheme, the ammonium polyphosphate is decomposed to generate polyphosphoric acid at 250-300°C, which can catalyze the dehydration crosslinking of the epoxy resin to form an expanded carbon layer. The released phosphoric acid reacts with the melamine cyanurate to generate a phosphorus-nitrogen complex, which improves the graphitization degree of the carbon layer. The melamine cyanurate is decomposed to release NH3, HCNO and other inert gases at 300-350°C, which dilutes the oxygen concentration and generates an expansion pressure to make the carbon layer foam. NH3 reacts with the PO· free radicals released by the ammonium polyphosphate to block the combustion chain reaction. The nano-magnesium hydroxide is endothermic decomposition at 340-430°C, which releases H2O to reduce the system temperature and generates a MgO covering layer to isolate oxygen. The MgO nanoparticles fill the pores of the carbon layer, reduce the thermal conductivity of the carbon layer, and react with the decomposition products of the ammonium polyphosphate to generate Mg2P2O7 ceramic phase, which improves the high-temperature stability of the carbon layer. The diluent is used to reduce the viscosity to ensure the uniform dispersion of the flame-retardant mixture. The curing agent prolongs the gel time to ensure that the resin fully infiltrates the fibers.

[0009] Therefore, the present application can form the following temperature gradient response: at 250-300°C, the ammonium polyphosphate catalyzes the crosslinking of the epoxy resin to form a phosphate network, and the carbon layer skeleton is initially established. At 300-350°C, the decomposition gas of the melamine cyanurate makes the carbon layer expand by 5-8 times in volume to form a porous foam structure. At 340-430°C, the MgO nanoparticles generated by the nano-magnesium hydroxide accumulate on the surface of the carbon layer to form a dense ceramic outer layer, which helps to improve the flame-retardant performance of the HP-RTM epoxy resin material.

[0010] In a specific implementation, the flame-retardant mixture further comprises the following raw materials in a weight percentage of 3-5 parts of pentaerythritol.

[0011] By adopting the above technical scheme, during the curing process, the hydroxyl groups of the pentaerythritol can participate in the curing reaction of the epoxy resin to adjust the crosslinking density and improve the glass transition temperature. The ammonium polyphosphate is decomposed to generate polyphosphoric acid at high temperature, which catalyzes the dehydration crosslinking of the pentaerythritol to form a three-dimensional crosslinked dense carbon layer, improves the carbon residue rate, and forms a stable graphitized carbon layer at high temperature to effectively isolate oxygen and heat, thereby further improving the flame-retardant performance of the HP-RTM epoxy resin material.

[0012] In one embodiment, the flame retardant mixture further comprises the following ingredients: 4-6 parts by weight of phosphated starch.

[0013] By using the above technical solution, the phosphated starch is decomposed at 200-250°C to release phosphoric acid and polyphosphoric acid, which catalyzes the dehydration crosslinking of epoxy resin and pentaerythritol to form a dense phosphorus-rich carbon layer, thereby improving the carbon residue rate and the graphitization degree of the carbon layer. The phosphoric acid released by the phosphated starch reacts with the cyanuric acid decomposed from melamine cyanurate to form thermally stable cyanuric phosphate, thereby inhibiting smoldering. The carbonized phosphated starch forms nanometer carbon spheres, which fill the pores of the ammonium polyphosphate / melamine cyanurate expanded carbon layer, thereby reducing the thermal conductivity of the carbon layer and improving the high-temperature stability of the carbon layer.

[0014] In one embodiment, the flame retardant mixture further comprises the following ingredients: 1-3 parts by weight of sulfonated lignin.

[0015] By using the above technical solution, the sulfonated lignin contains a large number of aromatic structures, which are carbonized at high temperatures to form a high-graphitization carbon layer, thereby improving the carbon residue rate. The sulfonic acid groups release sulfuric acid at 200-300°C, which cooperates with the polyphosphoric acid of ammonium polyphosphate to catalyze the dehydration of epoxy resin into carbon, thereby improving the density of the carbon layer.

[0016] In one embodiment, the flame retardant mixture further comprises the following ingredients: 1-3 parts by weight of polyamide microspheres.

[0017] By using the above technical solution, the polyamide microspheres expand to form a closed-cell foam structure at the initial stage of resin combustion, thereby reducing the heat transfer efficiency. The microsphere shell releases CO2 and N2 when it decomposes, thereby diluting the concentration of oxygen and combustible gases and inhibiting the combustion chain reaction. The expanded microsphere debris fills the pores of the expanded carbon layer formed by ammonium polyphosphate / melamine cyanurate, thereby reducing the thermal conductivity of the carbon layer. The amine groups released by the microspheres react with the phosphoric acid groups of the phosphated starch to form a phosphorus-nitrogen crosslinking network, thereby improving the carbon residue rate. The fragments of the decomposed microspheres combine with the cyanuric acid of melamine cyanurate to form a nitrogen-containing carbon layer with higher thermal stability.

[0018] In one embodiment, the curing agent comprises a phenolic amine with an amine value of 300-350 mgKOH / g.

[0019] By adopting the technical scheme, the amino group of the phenolic amine reacts with the phosphoric acid generated by the decomposition of the ammonium polyphosphate to form a phosphorus-nitrogen crosslinking structure, which promotes graphitization of the carbon layer. The crosslinking network captures nano magnesium hydroxide particles to form a MgO-phosphorus-nitrogen ceramic phase, thereby improving the carbon residue rate. The rigid benzene ring structure of the phenolic amine forms a dense three-dimensional network with the epoxy resin, thereby improving the glass transition temperature. Moreover, the phenolic amine with the amine value has moderate reactivity in the temperature range of 80-130°C, and the gel time is controlled in the range of 8-12 minutes, which is more suitable for the injection-mold-filling-curing time window of the HP-RTM process.

[0020] In one specific implementation, the curing agent further includes 2-ethyl-4-methyl imidazole.

[0021] By adopting the technical scheme, the 2-ethyl-4-methyl imidazole promotes the homopolymerization reaction of the epoxy resin to form a more uniform crosslinking network, thereby improving the glass transition temperature. The 2-ethyl-4-methyl imidazole reduces the activation energy of the reaction by nucleophilic attack on the epoxy group, thereby reducing the curing initiation temperature. At 80°C, the gel time is shortened, and the mold-filling time window is more suitable for high-pressure injection.

[0022] In one specific implementation, the diluent is phenyl glycidyl ether.

[0023] By adopting the technical scheme, the phenyl glycidyl ether can reduce the overall viscosity of the epoxy resin mixture, which is more suitable for the HP-RTM high-pressure injection process. The benzene ring structure of the phenyl glycidyl ether is compatible with the polar surface of the flame retardant, which can reduce the proportion of agglomerates and ensure uniform distribution of the flame retardant. Moreover, the carbonized product of the phenyl glycidyl ether cooperates with the phosphoric acid of the ammonium polyphosphate and the nitrogen of the melamine cyanurate to form an expanded carbon layer, thereby further improving the flame retardant performance.

[0024] In a second aspect, the application provides a preparation method of a flame-retardant HP-RTM epoxy resin, which adopts the following technical scheme:

[0025] A preparation method of a flame-retardant HP-RTM epoxy resin includes the following steps:

[0026] The epoxy resin is heated to 60-65°C, the diluent is added, and stirring is performed until the resin matrix is obtained;

[0027] The ammonium polyphosphate, melamine cyanurate, and nano magnesium hydroxide are uniformly mixed to obtain a flame-retardant mixture, the flame-retardant mixture is added to the resin matrix, and uniform dispersion is performed, and vacuum degassing treatment is performed until the bubble volume is less than 0.3%, thereby obtaining a standby resin;

[0028] Preheat the mold to 78-85℃, spray the release agent, lay the carbon fiber preform, close the mold, mix the standby resin and curing agent at a weight ratio of 100:(20-25) and inject into the mold, flow into the mold, impregnate, cure and demold to obtain the flame-retardant HP-RTM epoxy resin.

[0029] By adopting the technical scheme, the method adds a diluent to reduce the resin annual, so as to be injected at low viscosity, and by adopting the flame-retardant mixture and the HP-RTM process, synergistic flame retardation and rapid curing are achieved, and the epoxy resin material with flame retardation, high mechanical properties and industrial production efficiency is obtained.

[0030] In summary, the present application has the following beneficial effects:

[0031] 1. The present application forms a carbon layer skeleton, a porous foam structure and a dense ceramic outer layer in turn by constructing a temperature gradient, which helps to improve the flame retardant properties of the HP-RTM epoxy resin material.

[0032] 2. In the present application, pentaerythritol, phosphated starch and sulfonated lignin are preferably used, which can further improve the flame retardant properties of the HP-RTM epoxy resin material.

[0033] 3. The method of the present application injects at low viscosity, uses a flame-retardant mixture and a HP-RTM process to achieve synergistic flame retardation and rapid curing, and obtains an epoxy resin material with flame retardation, high mechanical properties and industrial production efficiency. DETAILED DESCRIPTION

[0034] The raw materials used in the present application are commercially available, except for special instructions. Among them, the release agent is Shinku KM-9782. The phosphated starch is prepared by mixing corn starch with ammonium dihydrogen phosphate at a ratio of 1:0.6 and reacting at 120℃ for 2 hours. The polyamide microspheres are model TR-1.

[0035] The present application is further described in detail in conjunction with the examples and comparative examples.

[0036] Examples

[0037] Example 1

[0038] This example prepares a flame-retardant mixture, which includes the following raw materials: ammonium polyphosphate 13 kg, melamine cyanurate 10 kg and nano-magnesium hydroxide 7 kg. Mix the ammonium polyphosphate, melamine cyanurate and nano-magnesium hydroxide uniformly to obtain the flame-retardant mixture.

[0039] The embodiment provides a fire-retardant HP-RTM epoxy resin, which comprises resin mixture 100 kg, curing agent 18 kg and release agent 3 kg. The resin mixture comprises the following raw materials: bisphenol A type epoxy resin 65 kg, fire-retardant mixture 23 kg and phenyl glycidyl ether 12 kg. The curing agent is phenolic amine with an amine value of 300-350 mgKOH / g.

[0040] The application further provides a preparation method of the fire-retardant HP-RTM epoxy resin.

[0041] The epoxy resin is heated to 63 DEG C, the phenyl glycidyl ether is added, and stirring is conducted until the mixture is uniform, so that a resin matrix is obtained.

[0042] The fire-retardant mixture is added into the resin matrix, and stirring is conducted until the mixture is uniformly dispersed, and vacuum defoaming treatment is conducted until the bubble volume is less than 0.3%, so that a standby resin is obtained.

[0043] The mold is preheated to 80 DEG C, the release agent is sprayed, the carbon fiber preform is laid, the mold is closed, the standby resin and the curing agent are mixed at a weight ratio of 100:22 and injected into the mold, and flowing, impregnation, curing and demolding are conducted, so that the fire-retardant HP-RTM epoxy resin is obtained.

[0044] Example 2

[0045] The embodiment differs from the embodiment 1 only in that the fire-retardant mixture comprises the following raw materials: ammonium polyphosphate 10 kg, melamine cyanurate 12 kg and nano-magnesium hydroxide 5 kg.

[0046] Example 3

[0047] The embodiment differs from the embodiment 1 only in that the fire-retardant mixture comprises the following raw materials: ammonium polyphosphate 15 kg, melamine cyanurate 10 kg and nano-magnesium hydroxide 12 kg.

[0048] Example 4

[0049] The embodiment differs from the embodiment 1 only in that the fire-retardant mixture comprises the following raw materials: ammonium polyphosphate 13 kg, melamine cyanurate 10 kg, nano-magnesium hydroxide 7 kg and pentaerythritol 3 kg. The ammonium polyphosphate, the melamine cyanurate, the nano-magnesium hydroxide and the pentaerythritol are uniformly mixed, so that the fire-retardant mixture is obtained.

[0050] Example 5

[0051] The difference between this embodiment and embodiment 1 is only that the flame-retardant mixture comprises the following raw materials: 13 kg of ammonium polyphosphate, 10 kg of melamine cyanurate, 7 kg of nano-magnesium hydroxide, 5 kg of pentaerythritol. The ammonium polyphosphate, melamine cyanurate, nano-magnesium hydroxide, and pentaerythritol are mixed uniformly to obtain the flame-retardant mixture.

[0052] Embodiment 6

[0053] The difference between this embodiment and embodiment 1 is only that the flame-retardant mixture comprises the following raw materials: 13 kg of ammonium polyphosphate, 10 kg of melamine cyanurate, 7 kg of nano-magnesium hydroxide, 5 kg of pentaerythritol, and 4 kg of phosphated starch. The ammonium polyphosphate, melamine cyanurate, nano-magnesium hydroxide, pentaerythritol, and phosphated starch are mixed uniformly to obtain the flame-retardant mixture.

[0054] Embodiment 7

[0055] The difference between this embodiment and embodiment 1 is only that the flame-retardant mixture comprises the following raw materials: 13 kg of ammonium polyphosphate, 10 kg of melamine cyanurate, 7 kg of nano-magnesium hydroxide, 5 kg of pentaerythritol, and 6 kg of phosphated starch. The ammonium polyphosphate, melamine cyanurate, nano-magnesium hydroxide, pentaerythritol, and phosphated starch are mixed uniformly to obtain the flame-retardant mixture.

[0056] Embodiment 8

[0057] The difference between this embodiment and embodiment 1 is only that the flame-retardant mixture comprises the following raw materials: 13 kg of ammonium polyphosphate, 10 kg of melamine cyanurate, 7 kg of nano-magnesium hydroxide, 5 kg of pentaerythritol, 6 kg of phosphated starch, and 1 kg of sulfonated lignin. The ammonium polyphosphate, melamine cyanurate, nano-magnesium hydroxide, pentaerythritol, phosphated starch, and sulfonated lignin are mixed uniformly to obtain the flame-retardant mixture.

[0058] Embodiment 9

[0059] The difference between this embodiment and embodiment 1 is only that the flame-retardant mixture comprises the following raw materials: 13 kg of ammonium polyphosphate, 10 kg of melamine cyanurate, 7 kg of nano-magnesium hydroxide, 5 kg of pentaerythritol, 6 kg of phosphated starch, and 3 kg of sulfonated lignin. The ammonium polyphosphate, melamine cyanurate, nano-magnesium hydroxide, pentaerythritol, phosphated starch, and sulfonated lignin are mixed uniformly to obtain the flame-retardant mixture.

[0060] Embodiment 10

[0061] The difference between this embodiment and embodiment 1 is only that the flame-retardant mixture comprises the following raw materials: ammonium polyphosphate 13 kg, melamine cyanurate 10 kg, nano-magnesium hydroxide 7 kg, pentaerythritol 5 kg, phosphated starch 6 kg, sulfonated lignin 3 kg, and polyamide microspheres 1 kg. The ammonium polyphosphate, melamine cyanurate, nano-magnesium hydroxide, pentaerythritol, phosphated starch, sulfonated lignin, and polyamide microspheres are mixed uniformly to obtain the flame-retardant mixture.

[0062] Embodiment 11

[0063] The difference between this embodiment and embodiment 1 is only that the flame-retardant mixture comprises the following raw materials: ammonium polyphosphate 13 kg, melamine cyanurate 10 kg, nano-magnesium hydroxide 7 kg, pentaerythritol 5 kg, phosphated starch 6 kg, sulfonated lignin 3 kg, and polyamide microspheres 3 kg. The ammonium polyphosphate, melamine cyanurate, nano-magnesium hydroxide, pentaerythritol, phosphated starch, sulfonated lignin, and polyamide microspheres are mixed uniformly to obtain the flame-retardant mixture.

[0064] Embodiment 12

[0065] The difference between this embodiment and embodiment 1 is only that the curing agent is a phenolic amine with an amine value of 100-250 mgKOH / g.

[0066] Embodiment 13

[0067] The difference between this embodiment and embodiment 1 is only that the curing agent is a phenolic amine with an amine value of 400-550 mgKOH / g.

[0068] Embodiment 14

[0069] The difference between this embodiment and embodiment 1 is only that the curing agent comprises a phenolic amine with an amine value of 300-350 mgKOH / g and 2-ethyl-4-methylimidazole in a weight ratio of 1:1. The phenolic amine and 2-ethyl-4-methylimidazole are mixed uniformly to obtain the curing agent.

[0070] Embodiment 15

[0071] The difference between this embodiment and embodiment 1 is only that an equal amount of dibutyl phthalate and phenyl glycidyl ether is used.

[0072] Embodiment 16

[0073] The difference between this embodiment and embodiment 1 is only that an equal amount of epoxy soybean oil and phenyl glycidyl ether is used.

[0074] Embodiment 17

[0075] The difference between this embodiment and embodiment 1 is only that the flame-retardant mixture comprises the following raw materials: ammonium polyphosphate 13 kg, melamine cyanurate 10 kg, nano-magnesium hydroxide 7 kg, pentaerythritol 5 kg, phosphated starch 6 kg, sulfonated lignin 3 kg, and polyamide microspheres 1 kg. The ammonium polyphosphate, melamine cyanurate, nano-magnesium hydroxide, pentaerythritol, phosphated starch, sulfonated lignin, and polyamide microspheres are mixed uniformly to obtain the flame-retardant mixture. The curing agent comprises phenolic amine with an amine value of 300-350 mgKOH / g and 2-ethyl-4-methylimidazole in a weight ratio of 1:1. The phenolic amine and 2-ethyl-4-methylimidazole are mixed uniformly to obtain the curing agent.

[0076] Example 18

[0077] The difference between this embodiment and embodiment 1 is only that the preparation method of the flame-retardant HP-RTM epoxy resin comprises the following steps:

[0078] The epoxy resin is warmed to 60°C, the phenyl glycidyl ether is added, and stirring is performed until uniformity is achieved to obtain the resin matrix.

[0079] The flame-retardant mixture is added to the resin matrix, stirring is performed until uniformity is achieved, and vacuum degassing treatment is performed until the bubble volume is <0.3% to obtain the standby resin.

[0080] The mold is preheated to 78°C, a release agent is sprayed, the carbon fiber preform is laid, the mold is closed, the standby resin and the curing agent are mixed in a weight ratio of 100:20 and injected into the mold, and flow filling, impregnation, curing, and demolding are performed to obtain the flame-retardant HP-RTM epoxy resin.

[0081] Example 19

[0082] The difference between this embodiment and embodiment 1 is only that the preparation method of the flame-retardant HP-RTM epoxy resin comprises the following steps:

[0083] The epoxy resin is warmed to 65°C, the phenyl glycidyl ether is added, and stirring is performed until uniformity is achieved to obtain the resin matrix.

[0084] The flame-retardant mixture is added to the resin matrix, stirring is performed until uniformity is achieved, and vacuum degassing treatment is performed until the bubble volume is <0.3% to obtain the standby resin.

[0085] The mold is preheated to 85°C, a release agent is sprayed, the carbon fiber preform is laid, the mold is closed, the standby resin and the curing agent are mixed in a weight ratio of 100:25 and injected into the mold, and flow filling, impregnation, curing, and demolding are performed to obtain the flame-retardant HP-RTM epoxy resin.

[0086] Comparative Example

[0087] Comparative Example 1

[0088] This comparative example differs from Example 1 only in that in the raw materials and preparation method of the flame-retardant HP-RTM epoxy resin, the flame-retardant mixture is replaced with an equal amount of ammonium polyphosphate.

[0089] Comparative Example 2

[0090] This comparative example differs from Example 1 only in that in the raw materials and preparation method of the flame-retardant HP-RTM epoxy resin, the flame-retardant mixture is replaced with an equal amount of melamine cyanurate.

[0091] Comparative Example 3

[0092] This comparative example differs from Example 1 only in that in the raw materials and preparation method of the flame-retardant HP-RTM epoxy resin, the flame-retardant mixture is replaced with an equal amount of nano-magnesium hydroxide.

[0093] Comparative Example 4

[0094] This comparative example differs from Example 1 only in that in the raw materials and preparation method of the flame-retardant HP-RTM epoxy resin, the phenyl glycidyl ether is replaced with an equal amount of bisphenol A type epoxy resin.

[0095] Performance detection test

[0096] For Examples 1-19 and Comparative Examples 1-4, the following performance detection was carried out:

[0097] The tensile strength of the flame-retardant HP-RTM epoxy resin of each example and comparative example was detected according to ISO527.

[0098] The flexural strength of the flame-retardant HP-RTM epoxy resin of each example and comparative example was detected according to ISO178.

[0099] The flame-retardant grade of the flame-retardant HP-RTM epoxy resin of each example and comparative example was detected according to the UL94 standard.

[0100] The glass transition temperature of the flame-retardant HP-RTM epoxy resin of each example and comparative example was detected according to GB / T 19466.2-2004 Plastics - Differential scanning calorimetry (DSC) - Part 2: Determination of glass transition temperature.

[0101] The detection results are shown in Table 1.

[0102] Table 1

[0103]

[0104]

[0105] It can be seen from the combination of the embodiments 1 and the comparative examples 1-4 and the table 1 that the flame retardant grades of the comparative examples 1-4 are all lower than that of the embodiment 1, and the glass transition temperatures are also lower, and the tensile strength and the bending strength change little. This shows that the raw material ratio and the preparation method of the embodiment 1 can improve the flame retardant performance of the flame-retardant HP-RTM epoxy resin.

[0106] It can be seen from the combination of the embodiments 1-11, 18-19 and the table 1 that the flame retardant grades of the embodiments 1-11, 18-19 are all higher than or equal to V0, and the glass transition temperatures are all greater than 105℃, and the tensile strength and the bending strength are all higher. This shows that the raw material ratio in the embodiments 1-11, 18-19 can all be used to prepare the HP-RTM epoxy resin with good flame retardant performance.

[0107] It can be seen from the combination of the embodiments 1, 12-17 and the table 1 that compared with the embodiment 1, the flame retardant grades of the embodiments 12, 15 and 16 are all V1, and the glass transition temperatures are all less than 105℃, the phenolic amine amine value of the embodiment 13 is greater than that of the embodiment 1, but the glass transition temperature is smaller, the curing agent of the embodiment 14 further includes 2-ethyl-4-methyl imidazole, the flame retardant grade of the embodiment 14 is V0, and the glass transition temperature is significantly larger. The flame retardant grade of the embodiment 17 is 5VB, and the glass transition temperature is significantly larger. This shows that the phenolic amine with the amine value of 300-350mgKOH / g and the raw material ratio of the embodiment 17 can help to further improve the flame retardant performance of the HP-RTM epoxy resin.

[0108] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, and the modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A flame-retardant HP-RTM epoxy resin, characterized in that, The resin mixture includes resin mixture, curing agent and release agent in a weight ratio of 100:(10-25):(2-4), the resin mixture includes raw materials in the following weight percentages: epoxy resin 45%-85%, flame-retardant mixture 7%-40%, diluent 5-20%; the flame-retardant mixture includes raw materials in the following weights based on the total weight of the flame-retardant mixture: ammonium polyphosphate 10-15 parts, melamine cyanurate 8-12 parts, nano-magnesium hydroxide 5-8 parts, pentaerythritol 3-5 parts, phosphated starch 4-6 parts, sulfonated lignin 1-3 parts, polyamide microspheres 1-3 parts; the curing agent includes 2-ethyl-4-methylimidazole and phenylamine with an amine value of 300-350 mgKOH / g; the diluent is phenyl glycidyl ether.

2. A process for the preparation of a flame retarded HP-RTM epoxy resin according to claim 1, characterized in that, The method comprises the following steps: The epoxy resin is heated to 60-65℃, the diluent is added, and stirred uniformly to obtain a resin matrix; The ammonium polyphosphate, melamine cyanurate, nano-magnesium hydroxide, pentaerythritol, phosphated starch, sulfonated lignin and polyamide microspheres are mixed uniformly to obtain a flame-retardant mixture, the flame-retardant mixture is added to the resin matrix and dispersed uniformly, and vacuum defoaming treatment is performed until the bubble volume is less than 0.3% to obtain a standby resin; The mold is preheated to 78-85℃, the release agent is sprayed, the carbon fiber preform is laid, the mold is closed, the standby resin and the curing agent are mixed at a weight ratio of 100:(20-25) and injected into the mold, and flow filling, impregnation, curing and demolding are performed to obtain a flame-retardant HP-RTM epoxy resin.

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