Flame-retardant epoxy resin composition, flame-retardant epoxy resin material and preparation method and application thereof

Abstract

The invention relates to the technical field of high polymer materials, and discloses a flame-retardant epoxy resin composition which comprises the following components based on the total amount of the composition: 30-40 wt% of epoxy resin, 20-40 wt% of a curing agent, 0.5-2 wt% of an accelerant, 20-30 wt% of a flame retardant, 1-10 wt% of a diluent, 1-5 wt% of a coupling agent and 0-1 wt% of a defoaming agent. The flame-retardant epoxy resin composition has the effects of high flame-retardant efficiency and good mechanical property, meets the highest-grade flame-retardant requirement in UL94 and other standard requirements, and has excellent manufacturability in the processing process of a composite material, and an obtained product is attractive in appearance.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a flame retardant epoxy resin composition, a flame retardant epoxy resin material, and a preparation method and application thereof. Background Art

[0002] Epoxy resin, as the main thermosetting resin, is widely used in various fields. Especially as a resin matrix for composite materials, epoxy resin has significant advantages. However, epoxy resin is one of the more flammable thermosetting resins. The oxygen index of ordinary epoxy resin is only about 19.8%. It will continue to burn after the fire source is evacuated, increasing the risk of fire. At the same time, toxic mist and gas produced by ablation can cause casualties to people around. For the application of composite materials in transportation, construction, electronic appliances and other fields with flame retardant requirements, it is necessary to give epoxy resin flame retardant properties and perform flame retardant treatment.

[0003] The commonly used technical approach to prepare flame-retardant epoxy resins is mainly to add flame retardants to the epoxy resin system. Flame retardants are generally divided into halogen-containing flame retardants and halogen-free flame retardants. Halogen-containing flame retardants have high flame retardant efficiency, but are not friendly to products and the environment, so halogen-free flame retardants are mostly used. Compared with halogen-containing flame retardants, halogen-free flame retardants have relatively low flame retardant efficiency. In order to achieve a certain flame retardant effect, it is necessary to increase the amount of flame retardant. On the one hand, it will lead to an increase in the viscosity of the epoxy resin system and reduce the processing performance of the resin. On the other hand, excessive use of flame retardants will have an adverse effect on the mechanical and thermodynamic properties of the resin. How to balance the flame retardant properties and mechanical properties of the epoxy resin system is one of the difficulties in current research.

[0004] Therefore, it is necessary to study a high-performance flame-retardant epoxy resin that has high flame-retardant efficiency and excellent mechanical properties to meet the needs of various processing techniques. Summary of the invention

[0005] The purpose of the present invention is to overcome the problem in the prior art that excessive use of flame retardants leads to reduced mechanical properties of epoxy resins, and to provide a flame retardant epoxy resin composition, a flame retardant epoxy resin material, and a preparation method and application thereof. The resin has high flame retardant efficiency and good mechanical properties, meets the highest level of flame retardant requirements in standards such as UL94, and has excellent processability during composite material processing, and the resulting product has a beautiful appearance.

[0006] In order to achieve the above-mentioned object, the first aspect of the present invention provides a flame retardant epoxy resin composition, which comprises the following components based on the total amount of the composition: 30-40wt% of epoxy resin, 20-40wt% of curing agent, 0.5-2wt% of accelerator, 20-30wt% of flame retardant, 1-10wt% of diluent, 1-5wt% of coupling agent and 0-1wt% of defoaming agent.

[0007] A second aspect of the present invention provides a method for preparing a flame retardant epoxy resin material, comprising the following steps:

[0008] (1) mixing the epoxy resin and the diluent uniformly under a first stirring condition to obtain a mixture I;

[0009] (2) adding the flame retardant and the defoaming agent to the mixture I, and mixing them evenly under the second stirring condition to obtain a mixture II;

[0010] (3) Adding a coupling agent, a curing agent and an accelerator to the mixture II, mixing them evenly under the third stirring condition, and curing them to obtain a flame retardant epoxy resin material.

[0011] The third aspect of the present invention provides a flame retardant epoxy resin material prepared by the method described in the second aspect of the present invention, wherein the flame retardant epoxy resin material has a limiting oxygen index of 25-35%, a viscosity of less than 1000 mPa·s at 25°C, a tensile property of 40-70 MPa, a tensile modulus of 2.5-3.4 GPa, a flexural property of 90-135 MPa, and a flexural modulus of 2.5-3 GPa.

[0012] The fourth aspect of the present invention provides an application of the flame retardant epoxy resin material described in the third aspect of the present invention in a carbon fiber composite material.

[0013] Through the above technical solution, the present invention has the following beneficial effects:

[0014] (1) The flame-retardant epoxy resin composition provided by the present invention has high flame retardant efficiency, small amount of flame retardant, small effect on the viscosity of the epoxy resin system, and good resin processing performance;

[0015] (2) The flame retardant epoxy resin composition provided by the present invention can improve the toughness of the epoxy resin, while having little effect on the tensile strength and bending strength, thereby ensuring that the resin system has high toughness and high strength mechanical properties, and is suitable for processes with high requirements on mechanical properties, such as winding molding.

[0016] (3) The flame-retardant epoxy resin composition provided by the present invention has good wettability for large-tow carbon fibers. The hydroxyl groups in the resin react and combine with the surface groups of the large-tow carbon fibers, which can give full play to the high strength characteristics of the carbon fibers. The composite material of the present invention has high mechanical properties and high interlaminar shear strength. DETAILED DESCRIPTION

[0017] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0018] The first aspect of the present invention provides a flame retardant epoxy resin composition, which comprises the following components based on the total amount of the composition: 30-40wt% of epoxy resin, 20-40wt% of curing agent, 0.5-2wt% of accelerator, 20-30wt% of flame retardant, 1-10wt% of diluent, 1-5wt% of coupling agent and 0-1wt% of defoaming agent.

[0019] In the present invention, by adding a coupling agent to the flame retardant epoxy resin composition, the effect of the flame retardant on the viscosity of the epoxy resin system is reduced, the flame retardant efficiency of the flame retardant epoxy resin composition is improved, and at the same time, excellent mechanical properties are obtained, thereby meeting the process requirements for later processing of composite materials.

[0020] According to the present invention, the mass ratio of the coupling agent to the flame retardant is 1-5:20-30.

[0021] In the present invention, the coupling agent in the epoxy resin system can improve the bonding performance between the epoxy resin and the additional additives, improve the stability, help optimize the curing process of the epoxy resin, and improve the performance and durability of the final product.

[0022] Furthermore, the role of coupling agents in flame retardant epoxy resin systems is mainly manifested in the following aspects: 1. Improving the dispersibility of flame retardants in epoxy resins and improving flame retardant effects. 2. Producing good interface bonding between epoxy resins and flame retardants and enhancing the compatibility between the three. 3. Helping flame retardants to better exert their flame retardant effects and improving the flame retardant properties of epoxy resins. 4. Improving the processing properties and mechanical properties of epoxy resins. In summary, coupling agents play multiple roles in flame retardant epoxy resin systems, such as promoting compatibility, improving flame retardant properties, and improving processing properties and mechanical properties.

[0023] Furthermore, the mass ratio of the coupling agent to the flame retardant is 1-2:24-28.

[0024] In the present invention, when the mass ratio between the coupling agent and the flame retardant satisfies the above relationship, the synergistic effect between the two is optimal.

[0025] According to the present invention, based on the total amount of the composition, the composition includes the following components: 33-38wt% of epoxy resin, 28-35wt% of curing agent, 1-1.5wt% of accelerator, 25-28wt% of flame retardant, 4-6wt% of diluent, 2-3wt% of coupling agent and 0.2-0.6wt% of defoaming agent.

[0026] According to 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, phenolic epoxy resin and mixed epoxy resin.

[0027] According to one embodiment of the present invention, the epoxy equivalent of the epoxy resin is 110-200 g / eq.

[0028] In the present invention, the glycidyl ether epoxy resin is at least one selected from bisphenol A epoxy resin, bisphenol F epoxy resin, and bisphenol S epoxy resin.

[0029] According to one embodiment of the present invention, the bisphenol A epoxy resin has an epoxy equivalent of 110-230 g / eq. and a viscosity of 1500-10000 mPa·s at 25°C.

[0030] According to one embodiment of the present invention, the bisphenol F epoxy resin has an epoxy equivalent of 170-190 g / eq.,

[0031] The viscosity is 2000-5000mPa·s at 25°C.

[0032] According to one embodiment of the present invention, the bisphenol S epoxy resin has an epoxy equivalent of 180-200 g / eq.,

[0033] The viscosity is 2000-3000mPa·s at 25°C.

[0034] In the present invention, the hybrid epoxy resin is an epoxy-based multifunctional epoxy resin, selected from at least one of 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester (TDE85), high-purity triglycidyl p-aminophenol MY0510, and 4,4'-diaminodiphenylmethane tetraglycidylamine (AG80).

[0035] In a specific embodiment of the present invention, the epoxy resin is selected from bisphenol A type liquid epoxy resin, trifunctional liquid epoxy resin glycidyl ether and trifunctional liquid epoxy resin glycidyl amine, and the mass ratio is 10-15:10-15:10-15.

[0036] In a specific embodiment of the present invention, the epoxy resin is selected from bisphenol F type liquid epoxy resin, trifunctional liquid epoxy resin glycidyl ether and trifunctional liquid epoxy resin glycidyl amine, and the mass ratio is 10-15:10-15:10-15.

[0037] In a specific embodiment of the present invention, the epoxy resin is selected from bisphenol A type liquid epoxy resin and trifunctional liquid epoxy resin glycidyl ether, with a mass ratio of 13-17:15-20.

[0038] According to the present invention, the curing agent is selected from anhydride curing agents and / or amine curing agents.

[0039] According to the present invention, the acid anhydride curing agent is selected from at least one of monofunctional acid anhydride, difunctional acid anhydride and linear phenolic resin.

[0040] According to the present invention, the amine curing agent is at least one of diamines, aromatic amines, dicyandiamide and organic hydrazides.

[0041] In the present invention, the inventors have found through extensive research that the curing agent selected from anhydride curing agents can achieve better technical effects. According to the present invention, anhydride curing agents have better coupling effects than amine curing agents, and can better improve the dispersibility of flame retardants in epoxy resins and improve flame retardant effects. In addition, the compatibility between epoxy resins and flame retardants can be enhanced to improve flame retardant properties. It can help flame retardants to better exert their flame retardant effects and improve the processing properties and mechanical properties of epoxy resins. It has excellent properties such as high temperature resistance, aging resistance, and small shrinkage. It is also easy to use and has good process operability.

[0042] According to the present invention, the accelerator is at least one selected from tertiary amine salt complexes, imidazole and modified imidazole.

[0043] In the present invention, the accelerator may be diethyltetramethylimidazole.

[0044] According to the present invention, the diluent is selected from glycidyl ether and / or glycidyl amine.

[0045] According to the present invention, the defoaming agent is at least one selected from tributyl phosphate, 2,4,7,9-tetramethyl-5-decyne-4,7-diol and BYKA530.

[0046] According to the present invention, the coupling agent is selected from the phosphanitrogen silane coupling agent shown in structural formula (1),

[0047]

[0048] Wherein, R1 is selected from C1-C5 alkylene, and R2 and R3 are each independently selected from C1-C5 alkoxy.

[0049] In the present invention, the phosphorus nitrogen silane coupling agent has the function of adding flame retardant elements and improving the flame retardant effect on the basis of improving the dispersibility of the mixture and enhancing the stability of the mixture by the silane coupling agent.

[0050] In the present invention, the coupling agent shown in formula (1) is prepared in the laboratory by the following method: γ-aminopropyltriethoxysilane, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-ethanol 10-oxide (CAS No.: 63562-41-4) and anhydrous ethanol are mixed, and the mixture is reacted at 60-90° C. for 5-8 hours by microwave reflux method to obtain a reaction mixture. The reaction mixture is then rotary evaporated at 50° C. for half an hour, removed and then placed in a vacuum oven at 30° C. for 4 hours to obtain a phosphanitrogen silane coupling agent.

[0051] In a particularly preferred embodiment of the present invention, the coupling agent is selected from the phosphanitrosilane coupling agent shown in structural formula (2).

[0052]

[0053] In the present invention, the phosphorus nitrogen silane coupling agent is homemade in the laboratory. The phosphorus nitrogen silane coupling agent is a multifunctional auxiliary agent that can not only improve the organic-inorganic compatibility of the composite material, improve the mechanical properties of the composite material, but also significantly improve the flame retardancy of the composite material. The phosphorus and nitrogen elements contained in its molecular structure can generate phosphoric acid at high temperature to play a dehydrating role, and the nitrogen generated can dilute oxygen, thereby effectively hindering combustion, while improving the toughness and thermal stability of the epoxy resin.

[0054] According to the present invention, the flame retardant comprises component A and component B, wherein component A is selected from at least one of phosphazene flame retardants, alkyl phosphinates, phosphaphenanthrene flame retardants, phosphate flame retardants, phosphorus-containing ionic liquids and phosphate flame retardants; and component B is selected from at least one of organosilicon compounds, metal oxides, metal hydroxides and graphite substances.

[0055] According to the present invention, the component A is selected from at least one of polydiphenoxyphosphazene, hexaphenoxycyclotriphosphazene, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide, phosphaphenanthrene triazine compounds, DOPO ester compounds, triphenyl phosphate, resorcinol bis(diphenyl) phosphate, toluene diphenyl phosphate, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, ammonium polyphosphate, and melamine polyphosphate.

[0056] According to the present invention, the component B is selected from at least one of antimony oxide, zinc borate, magnesium hydroxide, aluminum hydroxide, molybdenum oxide, ammonium molybdate, zirconium phosphate, polysiloxane, polysilazane, silicon dioxide, graphite, carbon nanotubes and graphene.

[0057] According to the present invention, the mass ratio of component A to component B is 80-20:99-1, preferably 60-40:10-2.

[0058] In the present invention, component A and component B in the flame retardant can work synergistically. Usually, the coupling agent has the effect of "increasing the stability of the system" and adds phosphorus and nitrogen elements (which are flame retardant elements), thereby increasing the phosphorus and nitrogen content in the entire system, which helps the flame retardancy of the entire system. However, if too much flame retardant is simply added, it will have a great impact on the performance of the entire resin system, such as mechanical properties, and the viscosity will increase, which is not good for the performance of the final product. Therefore, the amount of flame retardant added is limited, so the content of flame retardant elements in the system is also limited. Supplementing flame retardant elements by means of phosphorus nitrogen silane coupling agent to reduce the impact on the mechanical properties of the resin system is a way to introduce phosphorus and nitrogen. The obtained product can have both good flame retardant properties and mechanical properties.

[0059] A second aspect of the present invention provides a method for preparing a flame retardant epoxy resin material, comprising the following steps:

[0060] (1) mixing the epoxy resin and the diluent uniformly under a first stirring condition to obtain a mixture I;

[0061] (2) adding the flame retardant and the defoaming agent to the mixture I, and mixing them evenly under the second stirring condition to obtain a mixture II;

[0062] (3) Adding a coupling agent, a curing agent and an accelerator to the mixture II, mixing them evenly under the third stirring condition, and curing them to obtain a flame retardant epoxy resin material.

[0063] In the present invention, the step (1) further includes a preheating step of the mixing device.

[0064] In the present invention, the step (3) further comprises cooling the mixture II to 30-50°C.

[0065] The invention mixes epoxy resin, diluent, flame retardant, defoamer, coupling agent, curing agent and accelerator step by step and evenly prepares flame retardant epoxy resin material. The preparation method is simple and easy to operate. The prepared flame retardant epoxy resin material has good wettability to large-tow carbon fiber. The hydroxyl groups in the resin react and combine with the surface groups of the large-tow carbon fiber, which can give full play to the high strength characteristics of the carbon fiber.

[0066] In the present invention, when the epoxy resin, diluent, flame retardant, defoamer, coupling agent, curing agent and accelerator are added in the above proportions, the flame retardant property and mechanical property of the prepared flame retardant epoxy resin material are optimal.

[0067] According to the present invention, the first stirring condition includes: a stirring temperature of 50-80° C. and a stirring speed of 200-400 rpm.

[0068] According to the present invention, the second stirring condition includes: a stirring temperature of 80-200° C. and a stirring speed of 200-500 rpm.

[0069] According to the present invention, the third stirring condition includes: a stirring temperature of 30-50° C. and a stirring speed of 100-300 rpm.

[0070] According to the present invention, the curing conditions include: keeping the temperature at 80-100° C. for 60-120 minutes under normal pressure, then heating to 130-150° C. and reacting for 90-180 minutes.

[0071] In a specific application of the present invention, the prepared flame-retardant epoxy resin material can be wound with large-tow carbon fibers to form a composite material. The large-tow carbon fibers have good wettability, and the hydroxyl groups in the resin react and combine with the surface groups of the large-tow carbon fibers, which can give full play to the high-strength characteristics of the carbon fibers. The composite material of the present invention has high mechanical properties and high interlaminar shear strength. The large-tow carbon fibers can be 48K large-tow carbon fibers of SCF35S.

[0072] The third aspect of the present invention provides a flame retardant epoxy resin material prepared by the method described in the second aspect of the present invention, wherein the viscosity of the flame retardant epoxy resin material is less than 1000mPa·s at 25°C, the limiting oxygen index is 25-35%, the tensile properties are 40-70MPa, the tensile modulus is 2.5-3.4GPa, the bending properties are 90-135MPa, and the bending modulus is 2.5-3GPa.

[0073] The fourth aspect of the present invention provides a use of the flame-retardant epoxy resin material described in the third aspect of the present invention in an epoxy resin composite material.

[0074] The flame retardant epoxy resin material provided by the present invention has high flame retardant efficiency, high-toughness and high-strength mechanical properties, and is suitable for processes with high requirements for mechanical properties.

[0075] The present invention will be described in detail below by way of examples. In the following examples and comparative examples,

[0076] The mechanical properties of the resin casting body are tested using a fully automatic material testing machine:

[0077] The tensile performance test of resin casting body is in accordance with the national standard GB / T 2567;

[0078] The bending performance test of resin casting body is in accordance with the national standard GB / T 2570;

[0079] Viscosity The viscosity of the flame retardant epoxy resin composition at 25°C was tested using a rotational viscometer (BROCKFIELD DV-IIRo);

[0080] The resin combustion performance is tested using an oxygen index tester and a horizontal and vertical combustion tester:

[0081] Oxygen index measurement is in accordance with national standard GB / T 2406;

[0082] Vertical combustion measurement is in accordance with the national standard GB / T 2408 (UL94);

[0083] The mechanical properties of composite material Noel rings are tested using a universal material testing machine:

[0084] The tensile properties of composite materials are measured according to the national standard GB / T 3354;

[0085] The measurement of composite material layer shear performance is in accordance with the national standard GB / T 3357.

[0086] Coupling agent A: R1 is a C3 alkylene group, R2 is a C2 alkoxy group, and R3 is a C2 alkoxy group;

[0087] Coupling agent B: R1 is a C5 alkylene group, R2 is a C5 alkoxy group, and R3 is a C5 alkoxy group.

[0088] Unless otherwise specified, the epoxy equivalent of the bisphenol A epoxy resin involved in the examples and comparative examples is 200 g / eq. and the viscosity is 5000 mPa·s at 25° C. The epoxy equivalent of the bisphenol F epoxy resin is 180 g / eq. and the viscosity is 3000 mPa·s at 25° C.

[0089] Diluent: Glycidylamine, purchased from Hubei Zhenzhengfeng New Materials Co., Ltd., brand MF-2133, epoxy equivalent 105-118 g / eq., viscosity 50-150 mPa·s at 25°C.

[0090] Glycidyl ether, polypropylene glycol diglycidyl ether, CAS number: 26142-30-3.

[0091] Commercially available KH550 was purchased from Klein (Shandong) Biotechnology Co., Ltd.

[0092] Example 1

[0093] The composition of the flame retardant epoxy resin composition disclosed in this embodiment is as follows (by weight):

[0094] Epoxy resin 33%, curing agent 31%, accelerator 1%, flame retardant 25%, diluent 7%, coupling agent 2.8%, defoaming agent 0.2%. (The mass ratio of coupling agent to flame retardant is 3.8:25)

[0095] The first step is to weigh 15 g of bisphenol A liquid epoxy resin, 18 g of trifunctional liquid epoxy resin glycidyl ether, and 7 g of MF-2133 diluent, heat to 80° C., and mechanically stir to obtain an epoxy resin matrix;

[0096] The second step is to weigh 20g of the composite phosphorus-containing flame retardant hexaphenoxy cyclotriphosphazene, 2g of 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide, a total of 22%, 1.5g of other flame retardants ammonium molybdate, 1.5g of polysilazane, a total of 3g, and 0.2g of defoamer 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and add them to the above epoxy resin matrix, heat to 180°C to melt, and quickly stir mechanically to evenly mix;

[0097] The third step is to cool the mixture obtained in the second step to below 50° C., add 2.8 g of coupling agent A, 31 g of curing agent methyl nadic anhydride, and 1 g of accelerator diethyltetramethylimidazole, and quickly mix them to obtain a flame retardant epoxy resin composition;

[0098] In the fourth step, the flame retardant epoxy resin composition is vacuum degassed at 50°C and divided into two parts: one part is placed in a mold for heating and curing to prepare a resin casting. The curing process of the epoxy resin is to keep it warm at 90°C for about 120 minutes until the resin gels, then heat it to 140°C and continue to react for 120 minutes; the other part is wound with SCF35S 48K large tow carbon fiber through a winding machine. The composite material curing process is: 90°C / 90min+135°C / 180min.

[0099] Example 2

[0100] The composition of the flame retardant epoxy resin composition disclosed in this embodiment is as follows (by weight):

[0101] Epoxy resin 35%, curing agent 31%, accelerator 1.5%, flame retardant 20.5%, diluent 8%, coupling agent 3.8%, defoaming agent 0.2%. (The mass ratio of coupling agent to flame retardant is 3.8:20.5)

[0102] The first step is to weigh 17 g of bisphenol A liquid epoxy resin, 18 g of trifunctional liquid epoxy resin glycidyl ether, and 8 g of MF-2133 diluent, heat to 80° C., and mechanically stir to obtain an epoxy resin matrix;

[0103] The second step is to weigh 18g of a composite phosphorus-containing flame retardant polydiphenoxyphosphazene, 1g of 1-butyl-3-methylimidazole dibutyl phosphate salt, a total of 19g, 0.7g of other flame retardants zinc borate, 0.8g of carbon nanotubes, a total of 1.5g, and 0.2g of tributyl phosphate, mix them with the above epoxy resin matrix, heat to 130°C to melt, and quickly stir mechanically to make them uniform;

[0104] Step 3: After the mixture obtained in the second step is cooled to below 50° C., 3.8 g of coupling agent A, 31 g of curing agent methyl nadic anhydride, and 1.5 g of accelerator diethyltetramethylimidazole are added, and the mixture is quickly mixed to obtain a flame retardant epoxy resin composition;

[0105] In the fourth step, the flame retardant epoxy resin composition is vacuum degassed at 50°C and divided into two parts: one part is placed in a mold for heating and curing to prepare a resin casting. The curing process of the epoxy resin is to keep it at 100°C for about 120 minutes until the resin gels, then heat it to 140°C and continue to react for 180 minutes; the other part is wound with SCF35S 48 large tow carbon fiber, and the composite material curing process is: 100°C / 90min+135°C / 240min.

[0106] Example 3

[0107] The composition of the flame retardant epoxy resin composition disclosed in this embodiment is as follows (by weight):

[0108] Epoxy resin 38%, curing agent 32%, accelerator 1%, flame retardant 21.5%, diluent 3.6%, coupling agent 1.8%, defoaming agent 0.1%. (The mass ratio of coupling agent to flame retardant is 1.8:21.5)

[0109] The first step is to weigh 12g of bisphenol A liquid epoxy resin, 13g of trifunctional liquid epoxy resin glycidyl ether, 13g of trifunctional liquid epoxy resin glycidyl amine, and 3.6g of MF-2133 diluent, heat to 80°C, and mechanically stir to obtain an epoxy resin matrix;

[0110] The second step is to weigh 18 g of a composite phosphorus flame retardant polydiphenoxyphosphazene, 2 g of DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide), a total of 20 g, 1.5 g of other flame retardants zirconium phosphate, and 0.1 g of a defoaming agent tributyl phosphate, add them to the epoxy resin matrix, heat to 130° C. to melt, and quickly stir mechanically to evenly mix;

[0111] Step 3: After the mixture obtained in the second step is cooled to below 50° C., 1.8 g of coupling agent A, 32 g of curing agent methyl nadic anhydride, and 1 g of accelerator diethyltetramethylimidazole are weighed, added into the mixture, and mixed quickly to obtain a flame retardant epoxy resin composition;

[0112] In the fourth step, the flame retardant epoxy resin composition was vacuum degassed at 50°C and divided into two parts: one part was placed in a mold for heating and curing to prepare a resin casting for characterization testing. The curing process of the epoxy resin was to keep the temperature at 90°C for about 120 minutes until the resin gelled, then raise the temperature to 135°C and continue the reaction for 120 minutes; the other part was wound with SCF35S 48 large tow carbon fiber through a winding machine. The composite material curing process was: 90°C / 90min+130°C / 180min.

[0113] Example 4

[0114] The composition of the flame retardant epoxy resin composition disclosed in this embodiment is as follows (by weight):

[0115] Epoxy resin 35%, curing agent 31%, accelerator 1%, flame retardant 23%, diluent 7.8%, coupling agent 2%, defoaming agent 0.2%. (The mass ratio of coupling agent to flame retardant is 2:23)

[0116] The first step is to weigh 10 g of bisphenol F liquid epoxy resin, 13 g of trifunctional liquid epoxy resin glycidyl ether, 12 g of trifunctional liquid epoxy resin glycidyl amine, and 7.8 g of diluent polypropylene glycol diglycidyl ether, heat to 80° C., and mechanically stir to obtain an epoxy resin matrix;

[0117] The second step is to weigh 20g of a compound phosphorus-containing flame retardant phosphaphenanthrene triazine compound (TAD), 1.5g of 1-butyl-3-methylimidazole dibutyl phosphate salt, a total of 21.5g, 1.5g of other flame retardants zinc borate, and 0.2g of defoaming agent tributyl phosphate, add them to the above epoxy resin matrix, heat to 180°C to melt, and quickly stir mechanically to evenly mix;

[0118] The third step is to cool the mixture obtained in the second step to below 50° C., weigh 2 g of coupling agent A, 31 g of curing agent methyl nadic anhydride, and 1 g of accelerator diethyltetramethylimidazole, add them to the mixture, and quickly mix them to obtain a flame retardant epoxy resin composition;

[0119] In the fourth step, the flame retardant epoxy resin composition is vacuum degassed at 50°C and divided into two parts: one part is placed in a mold for heating and curing to prepare a resin casting. The curing process of the epoxy resin is to keep it warm at 90°C for about 120 minutes until the resin gels, then heat it to 140°C and continue to react for 120 minutes; the other part is wound with SCF35S 48K large tow carbon fiber through a winding machine. The composite material curing process is: 90°C / 90min+135°C / 180min.

[0120] Example 5

[0121] The method of Example 1 is followed, except that 12 g of bisphenol A liquid epoxy resin and 20 g of diluent glycidylamine are used, so that the content of epoxy resin in the composition is 30% and the content of diluent is 10%.

[0122] Example 6

[0123] The method of Example 1 is followed, except that the amount of coupling agent A used is 5 g, hexaphenoxy cyclotriphosphazene is 20 g, 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide is 2 g, a total of 22%, and other flame retardant ammonium molybdate is 0.8 g.

[0124] Example 7

[0125] The method of Example 1 was followed, except that an externally purchased phosphorus-containing flame retardant (Disflamoll DPK flame retardant purchased by Shanghai Guangbin Trading) was selected.

[0126] Example 8

[0127] The method of Example 1 is followed, except that the coupling agent is purchased KH550.

[0128] Example 9

[0129] The method of Example 1 is followed, except that the flame retardant is a single hexaphenoxy cyclotriphosphazene, and the amount used is 25 g.

[0130] Comparative Example 1

[0131] The method of Example 1 was followed, except that no coupling agent was added.

[0132] Comparative Example 2

[0133] The method of Example 1 is followed, except that 20 g of bisphenol A liquid epoxy resin, 30 g of trifunctional liquid epoxy resin glycidyl ether, 2 g of diluent glycidyl amine, 15 g of flame retardant hexaphenoxy cyclotriphosphazene, 0.2 g of defoaming agent 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 8 g of coupling agent A, 23 g of curing agent methyl nadic anhydride, and 1.8 g of accelerator diethyltetramethylimidazole are used.

[0134] The resin casting bodies prepared in the examples and comparative examples were subjected to mechanical property tests, and the carbon fiber composite materials were subjected to tensile and layer shear tests. The results are shown in Table 1.

[0135] Table 1

[0136]

[0137]

[0138] Table 1 (continued)

[0139]

[0140] Note: D1 and D2 represent comparative example 1 and comparative example 2 respectively.

[0141] It can be seen from the results in Table 1 that the flame retardant epoxy resin compositions prepared by Examples 1-4 of the technical solution of the present invention have good bonding properties with Shanghai Petrochemical SCF35S 48k large tow while ensuring flame retardancy, and the prepared composite materials have high performance.

[0142] Combining Example 1 and Example 9, it can be seen that the flame retardant system using the scheme of the present invention has high flame retardant performance compared with the commercially available flame retardant system, and has little effect on the mechanical and thermodynamic properties of the resin system. It has good bonding properties with Shanghai Petrochemical SCF35S 48k large tow, and the prepared composite material has high performance.

[0143] Comparing Example 1 with Comparative Example 1, it can be seen that the addition of the coupling agent helps to further improve the flame retardant properties of the system and has a positive effect on the mechanical properties, toughness and bonding properties of the resin with carbon fibers.

[0144] Compared with the prior art, the flame retardant resin preparation method of the present invention has a simple process, a stable system, a winding molding method, good processability, simple curing conditions, excellent product mechanical properties, good bonding with Shanghai Petrochemical SCF35S large tow, and the prepared composite material has high mechanical properties.

[0145] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A flame retardant epoxy resin composition, characterized in that: Based on the total amount of the composition, the composition includes the following components: Epoxy resin 30-40wt%, curing agent 20-40wt%, accelerator 0.5-2wt%, flame retardant 20-30wt%, diluent 1-10wt%, coupling agent 1-5wt% and defoaming agent 0-1wt%.

2. The composition according to claim 1, characterized in that The mass ratio of the coupling agent to the flame retardant is 1-5:20-30, preferably 2-4:24-28; Preferably, based on the total amount of the composition, the composition comprises the following components: 33-38wt% epoxy resin, 28-35wt% curing agent, 1-1.5wt% accelerator, 25-28wt% flame retardant, 4-6wt% diluent, 2-3wt% coupling agent and 0.2-0.6wt% defoaming agent.

3. The composition according to claim 1 or 2, characterized in that The epoxy resin is selected from at least one of glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, phenolic epoxy resin and mixed epoxy resin; Preferably, the glycidyl ether epoxy resin is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin and bisphenol S epoxy resin.

4. The composition according to any one of claims 1 to 3, characterized in that The curing agent is selected from anhydride curing agents and / or amine curing agents; Preferably, the acid anhydride curing agent is selected from at least one of monofunctional acid anhydride, difunctional acid anhydride and linear phenolic resin; Preferably, the amine curing agent is at least one of diamines, aromatic amines, dicyandiamide and organic hydrazides.

5. The composition according to any one of claims 1 to 4, characterized in that The accelerator is selected from at least one of tertiary amine salt complexes, imidazole and modified imidazole; and / or, the diluent is selected from glycidyl ether and / or glycidyl amine; And / or, the defoaming agent is at least one selected from tributyl phosphate, 2,4,7,9-tetramethyl-5-decyne-4,7-diol and BYKA530.

6. The composition according to any one of claims 1 to 5, characterized in that The coupling agent is selected from the phosphanitrosilane coupling agent shown in structural formula (1), Wherein, R1 is selected from C1-C5 alkylene, and R2 and R3 are each independently selected from C1-C5 alkoxy; Preferably, R1 is selected from C2-C4 alkylene, and R2 and R3 are each independently selected from C2-C3 alkoxy.

7. The composition according to any one of claims 1 to 6, characterized in that The flame retardant comprises component A and component B; Wherein, the component A is selected from at least one of phosphazene flame retardants, alkyl phosphinates, phosphaphenanthrene flame retardants, phosphate flame retardants, phosphorus-containing ionic liquids and phosphate flame retardants; The component B is selected from at least one of an organic silicon compound, a metal oxide, a metal hydroxide and a graphite-based substance; Preferably, the mass ratio of component A to component B is 80-20:99-1.

8. The composition according to claim 7, characterized in that The component A is selected from at least one of polydiphenoxyphosphazene, hexaphenoxycyclotriphosphazene, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide, phosphaphenanthrene triazine compounds, DOPO ester compounds, triphenyl phosphate, resorcinol bis(diphenyl) phosphate, toluene diphenyl phosphate, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, ammonium polyphosphate, and melamine polyphosphate; And / or, the component B is selected from at least one of antimony oxide, zinc borate, magnesium hydroxide, aluminum hydroxide, molybdenum oxide, ammonium molybdate, zirconium phosphate, polysiloxane, polysilazane, silicon dioxide, graphite, carbon nanotubes and graphene.

9. A method for preparing a flame retardant epoxy resin material, characterized in that: The following steps are involved: (1) mixing the epoxy resin and the diluent uniformly under a first stirring condition to obtain a mixture I; (2) adding the flame retardant and the defoaming agent to the mixture I, and mixing them evenly under the second stirring condition to obtain a mixture II; (3) Adding a coupling agent, a curing agent and an accelerator to the mixture II, mixing them evenly under the third stirring condition, and curing them to obtain a flame retardant epoxy resin material.

10. The method according to claim 9, characterized in that The first stirring condition includes: a stirring temperature of 50-80°C and a stirring speed of 200-400 rpm; And / or, the second stirring condition includes: a stirring temperature of 80-200° C. and a stirring speed of 200-500 rpm; And / or, the third stirring condition includes: a stirring temperature of 30-50° C. and a stirring speed of 100-300 rpm.

11. The method according to claim 9 or 10, characterized in that: The curing conditions include: keeping the temperature at 80-100° C. for 60-120 minutes under normal pressure, then heating to 130-150° C. and reacting for 90-180 minutes.

12. A flame retardant epoxy resin material obtained by the method according to any one of claims 9 to 11, preferably, the flame retardant epoxy resin material has a viscosity of less than 1000 mPa·s at 25°C, a limiting oxygen index of 25-35%, tensile properties of 40-70 MPa, tensile modulus of 2.5-3.4 GPa, flexural properties of 90-135 MPa, and flexural modulus of 2.5-3 GPa.

13. Use of the flame retardant epoxy resin material according to claim 12 in carbon fiber composite materials.

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