Nitrogen-phosphorus epoxy resin, modified epoxy resin, preparation method and application

Abstract

The invention relates to the technical field of epoxy resin preparation, and discloses nitrogen-phosphorus epoxy resin, modified epoxy resin, a preparation method and application. The nitrogen-phosphorus epoxy resin contains a compound with a structure shown in a formula (1), R1 and R2 are independently selected from hydrogen or alkyl, m is an integer of 1-6, and n is an integer of 1-10. The modified epoxy resin provided by the invention is good in mechanical property, the highest tensile strength can reach 48 MPa, and the toughness can reach 3500 kJ / m < 3 >; the modified epoxy resin provided by the invention is excellent in flame retardant property, the highest oxygen index can reach 27, and the flame retardant property of the modified epoxy resin is obviously superior to that of a traditional phosphorus-containing and halogen-containing flame retardant material; the modified epoxy resin provided by the invention is high in combustion grade, is not easy to burn under the action of flames, has the combustion grade capable of reaching V0 grade, and has relatively good flame retardant property.

Description

Technical Field

[0001] The present invention relates to the technical field of epoxy resin preparation, and in particular to a nitrogen-phosphorus epoxy resin and a modified epoxy resin, as well as a preparation method and application thereof. Background Art

[0002] Epoxy resin has the advantages of small curing shrinkage, good processing performance, good stability and good heat resistance, and is the most widely used type of thermosetting resin. However, the cured epoxy material still has some disadvantages, such as brittleness and flammability. Traditional flame-retardant epoxy resins usually use compounds containing elements such as halogens, but they produce a large amount of toxic and harmful gases and smoke during production and use, which seriously endangers human health and the environment. In comparison, nitrogen-phosphorus flame-retardant epoxy resins have the advantages of being green, environmentally friendly and low in toxicity. They not only have good flame retardant effects, but can also reduce smoke density, toxicity and harm to the human body, playing an important protective role in the environment and human health. Nitrogen-phosphorus flame-retardant epoxy resin is a new type of flame retardant material. Its flame retardant principle is to add nitrogen-phosphorus compounds to epoxy resin to achieve the purpose of flame retardancy by slowing down or blocking the thermal decomposition reaction of the substance.

[0003] In recent years, the research on nitrogen-phosphorus flame-retardant epoxy resins has received widespread attention. With the development of materials science and the expansion of application fields, the research on nitrogen-phosphorus flame-retardant materials has become more and more in-depth, and its performance has gradually been improved. CN112851912B discloses a hyperbranched epoxy resin cured product, which contains a large amount of flame retardant elements and has a highly branched structure. At the same time, the hyperbranched epoxy resin modified composition corresponds to the cured resin material with excellent impact resistance and flame retardant properties. The impact strength of the hyperbranched epoxy resin cured product is 30-100kJ / m 2CN115819772A discloses a silicon-phosphorus heteroatom intrinsic flame-retardant epoxy resin and a preparation method thereof. Allyl glycidyl ether, hydrogen-containing silane and platinum catalyst are heated under nitrogen protection to generate silicone epoxy resin. Then, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-1-oxide is added to the prepared silicone epoxy resin and heated to obtain the silicon-phosphorus heteroatom intrinsic flame-retardant epoxy resin. The silicon-phosphorus heteroatom intrinsic flame-retardant epoxy resin can directly participate in the curing process. The cured product prepared by the additive has good rigidity and an elongation at break of about 4%. The cured product prepared by the additive exhibits good flame-retardant performance and reaches V0 level in UL-94 test. CN115894860A discloses a hyperbranched flame-retardant epoxy resin and an epoxy resin composition prepared therefrom. The unsaturated acid anhydride is introduced with a phosphorus-containing compound, and then a carboxyl-terminated phosphorus-containing monomer is constructed with a secondary amine compound. The hyperbranched flame-retardant epoxy resin is constructed by reacting the monomer with a tri-functional epoxy compound. After curing modification with bisphenol A type epoxy resin, the hyperbranched flame-retardant epoxy resin has good mechanical strength and excellent flame-retardant effect, the bending strength can reach 130 MPa, and the flame-retardant grade reaches V0. At present, nitrogen-phosphorus flame-retardant epoxy resin has made great progress in mechanical strength and flame-retardant performance, but there are still some problems in flame-retardant effect and material toughness, which need to be further researched and solved. SUMMARY

[0004] The present application aims to solve the problem of defects in flame-retardant effect and material toughness of the flame-retardant epoxy resin in the prior art, and provides a nitrogen-phosphorus epoxy resin, a modified epoxy resin and a preparation method and application thereof. The present application provides a new nitrogen-phosphorus epoxy resin. The mechanical properties of the modified epoxy resin obtained by blending and modifying the nitrogen-phosphorus epoxy resin with other epoxy resins are obviously improved, and the modified epoxy resin has excellent flame-retardant performance.

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides a nitrogen-phosphorus epoxy resin containing a compound having a structure represented by formula (1),

[0006]

[0007] wherein R1 and R2 are each independently selected from hydrogen or an alkyl group, m is an integer of 1-6, and n is an integer of 1-10.

[0008] Preferably, R1 and R2 are each independently selected from hydrogen or a C1-C5 alkyl group.

[0009] Preferably, R1 and R2 are each independently selected from hydrogen, methyl, ethyl or butyl.

[0010] The second aspect of the present application provides a method for preparing a nitrogen-phosphorus epoxy resin, comprising the following steps:

[0011] (1) reacting a compound of formula (2) with an alcohol amine compound of formula (3) in the presence of an organic amine and a first solvent to obtain a compound of formula (4);

[0012] (2) reacting the compound of formula (4) with a dihydric alcohol in the presence of an organic tin catalyst and a second solvent to obtain a compound of formula (5);

[0013] (3) reacting the compound of formula (5) with a compound of formula (6) in the presence of an organic salt catalyst, a third solvent and a base to obtain a compound of formula (1);

[0014]

[0015] wherein R1, R2, m, n are the same as defined in claim 1 or 2; R3 is chlorine or bromine; and R4 is chlorine or bromine.

[0016] Preferably, in step (1), the alcohol amine compound of formula (3) is selected from one or more of 3-diethylamino-1-propanol, 3-dibutylamino-1-propanol, 3-dimethylamino-1-propanol, 3-[ethyl(methyl)amino]propan-1-ol, dimethylaminobutanol, 2-(dimethylamino)butan-1-ol and 1-diethylamino-2-propanol.

[0017] Preferably, in step (1), the organic amine is triethylamine and / or diisopropylethylamine.

[0018] Preferably, in step (1), the first solvent is selected from one or more of tetrahydrofuran, ethyl acetate, dioxane and toluene.

[0019] Preferably, in step (1), the weight ratio of the amounts of the organic amine, the amine compound of formula (3) and the compound of formula (2) is 15-20:8-15:10.

[0020] Preferably, the weight ratio of the amounts of the compound of formula (2) and the first solvent is 10-30:100, preferably 15-20:100.

[0021] Preferably, in step (1), the reaction conditions include a temperature of -20 to 0°C and a time of 4-8 hours.

[0022] Preferably, in step (2), the organic tin catalyst is selected from stannous octoate and / or monobutyltin tris octoate.

[0023] Preferably, in step (2), the dihydric alcohol has a carbon number of 2-8, preferably one or more than two of ethylene glycol, butylene glycol, propylene glycol and trihydroxypropane.

[0024] Preferably, in step (2), the second solvent is selected from one or more than two of tetrahydrofuran, dioxane and toluene.

[0025] Preferably, in step (2), the weight ratio of the amount of the organotin catalyst to the amount of the dihydric alcohol is 0.1-0.2:1.

[0026] Preferably, the weight ratio of the amount of the compound of formula (4) to the amount of the dihydric alcohol is 5-30:1, preferably 10-20:1.

[0027] Preferably, the weight ratio of the total amount of the compound of formula (4) to the amount of the dihydric alcohol to the amount of the second solvent is 5-35:100.

[0028] Preferably, in step (2), the reaction conditions include a temperature of 40-60°C and a time of 4-6h.

[0029] Preferably, in step (3), the organic salt catalyst is selected from one or more than two of benzyltriethylammonium chloride, tetrabutylammonium bromide and tetrabutylammonium chloride.

[0030] Preferably, in step (3), the base is selected from one or more than two of sodium hydroxide, potassium hydroxide and calcium hydroxide.

[0031] Preferably, in step (3), the third solvent is selected from one or more than two of toluene, xylene and N,N-dimethylformamide.

[0032] Preferably, in step (3), the weight ratio of the amount of the compound of formula (6) to the amount of the compound of formula (5) is 1-1.5:1, preferably 1.2-1.4.

[0033] Preferably, the weight ratio of the amount of the organic salt catalyst to the amount of the compound of formula (5) is 0.2-0.6:1.

[0034] Preferably, the weight ratio of the amount of the compound of formula (5) to the amount of the third solvent is 10-15:100.

[0035] Preferably, in step (3), the reaction conditions include a reaction at 10-40°C for 30-60 hours, followed by a reaction at 60-80°C for 2-3 hours.

[0036] The third aspect of the present application provides a nitrogen-phosphorus epoxy resin prepared by the method described above.

[0037] The fourth aspect of the present application provides an epoxy resin composition containing a nitrogen-phosphorus epoxy resin, a bisphenol-A type epoxy resin and an amine curing agent.

[0038] Preferably, the nitrogen-phosphorus epoxy resin is the nitrogen-phosphorus epoxy resin as described above.

[0039] Preferably, the amount of the bisphenol-A type epoxy resin is 80-90 parts by weight and the amount of the nitrogen-phosphorus epoxy resin is 10-20 parts by weight, based on 100 parts by weight of the total amount of the bisphenol-A type epoxy resin and the nitrogen-phosphorus epoxy resin.

[0040] Preferably, the weight ratio of the total amount of the bisphenol-A type epoxy resin and the nitrogen-phosphorus epoxy resin to the amount of the amine curing agent is 100:10-30, preferably 100:15-25.

[0041] Preferably, the bisphenol-A type epoxy resin is selected from one or more of E54, E51 and E44.

[0042] Preferably, the amine curing agent is selected from one or more of a polyamide curing agent, an aliphatic polyamine curing agent and an aromatic polyamine curing agent.

[0043] The fifth aspect of the present application provides a method for preparing a modified epoxy resin, which is prepared from the epoxy resin composition as described above.

[0044] The method comprises mixing a bisphenol-A type epoxy resin, a nitrogen-phosphorus epoxy resin and an amine curing agent, and then deaerating, curing.

[0045] Preferably, the mixing is performed at a temperature of 60-80℃ for 0.5-3h.

[0046] Preferably, the deaerating is performed at a temperature of 80-120℃ for 0.5-2h under a vacuum of 0-10kPa.

[0047] Preferably, the curing is performed in a stepwise temperature increasing manner.

[0048] Preferably, the stepwise temperature increasing manner comprises: a first stage of curing at 110-130℃ for 0.5-1.5h; a second stage of curing at 150-170℃ for 1.5-2.5h; and a third stage of curing at 170-190℃ for 1.5-2.5h.

[0049] The sixth aspect of the present application provides a modified epoxy resin prepared by the method as described above.

[0050] The seventh aspect of the present application provides application of the nitrogen-phosphorus epoxy resin and the modified epoxy resin in a flame-retardant material.

[0051] Compared with the prior art, the present application has at least the following advantages:

[0052] The present application provides a new nitrogen-phosphorus epoxy resin, and the modified epoxy resin obtained by blending the nitrogen-phosphorus epoxy resin with a bisphenol A type epoxy resin has excellent flame-retardant performance, and also has good toughness and tensile strength.

[0053] Specifically, the modified epoxy resin provided by the present application has good mechanical properties, and the tensile strength can reach up to 48 MPa, and the toughness can reach up to 3500 kJ / m 3 The modified epoxy resin provided by the present application has excellent flame-retardant performance, and the oxygen index can reach up to 27, and the flame-retardant performance is obviously better than that of traditional phosphorus-containing and halogen-containing flame-retardant materials; the modified epoxy resin provided by the present application has a high combustion grade, and is not easy to burn under the action of flame, and the combustion grade can reach up to V0 level, and has good flame-retardant performance. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 The infrared spectrum of the nitrogen-phosphorus epoxy resin of Example 1 is shown in the figure.

[0055] Figure 2 The tensile curve of Example 1, Example 2 and Example 3 is shown in the figure. DETAILED DESCRIPTION

[0056] The specific embodiments of the present application are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0057] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and the values are approximate values and should be understood to include values approximately near these ranges and values within these ranges. For ranges of values, the endpoints of the ranges are combined with the individual points to form new ranges within the scope of the present application.

[0058] The first aspect of the present application provides a nitrogen-phosphorus epoxy resin containing a compound having a structure shown in formula (1),

[0059]

[0060] wherein R1 and R2 are each independently selected from hydrogen or alkyl, m is an integer of 1-6, and n is an integer of 1-10.

[0061] In the present application, R1 and R2 can be the same or different. In a specific embodiment, R1 and R2 are each independently selected from hydrogen or C1-C5 alkyl. In a further preferred embodiment, R1 and R2 are each independently selected from hydrogen, methyl, ethyl or butyl.

[0062] In a preferred embodiment, m is any integer between 1 and 3.

[0063] In a preferred embodiment, n is any integer between 2 and 6.

[0064] The second aspect of the present application provides a method for preparing a nitrogen-phosphorus epoxy resin, comprising the following steps:

[0065] (1) reacting a compound represented by formula (2) with an alcohol amine compound represented by formula (3) in the presence of an organic amine and a first solvent to obtain a compound represented by formula (4);

[0066] (2) reacting the compound represented by formula (4) with a dihydric alcohol in the presence of an organic tin catalyst and a second solvent to obtain a compound represented by formula (5);

[0067] (3) reacting the compound represented by formula (5) with a compound represented by formula (6) in the presence of an organic salt catalyst, a third solvent and a base to obtain a compound represented by formula (1);

[0068]

[0069] wherein R1, R2, m, n and R3 are as defined above; R4 is chlorine or bromine.

[0070] The nitrogen-phosphorus epoxy resin described in the present application is obtained by ring-opening reaction of phosphonate modified by nitrogen element and terminal group epoxidation reaction. The reactions of steps (1), (2) and (3) are all carried out in an inert atmosphere.

[0071] In a preferred embodiment, m is any integer between 1 and 3.

[0072] In a preferred embodiment, n is any integer between 2 and 6.

[0073] In a specific embodiment, the halogen in R3 and R4 is each independently selected from fluorine, chlorine, bromine or iodine. In a preferred embodiment, when R3 is chlorine, the efficiency of the reaction in step (1) is further improved. In a preferred embodiment, when R4 is chlorine, the efficiency of the reaction in step (3) is further improved.

[0074] In the method described in the present application, step (1) is an acyl halide esterification reaction, and the reaction route is as follows:

[0075]

[0076] In a specific embodiment, when R3 is chlorine, i.e. the compound of formula (2) is 2-chloro-2-oxo-1,3,2-dioxaphospholane, the reaction route of step (1) is:

[0077]

[0078] In the present application, the alcohol amine compound of formula (3) can be a routine selection in the art. In a specific embodiment, n in the alcohol amine compound of formula (3) is preferably any integer between 2 and 6. In a preferred embodiment, the alcohol amine compound of formula (3) in step (1) is selected from one or more than two of 3-diethylamino-1-propanol, 3-dibutylamino-1-propanol, 3-dimethylamino-1-propanol, 3-[ethyl(methyl)amino]propan-1-ol, dimethylaminobutanol, 2-(dimethylamino)butan-1-ol and 1-diethylamino-2-propanol.

[0079] In the method of the present application, the organic amine is used to treat the acidic materials, such as HCl and HBr, generated in step (1). In a specific embodiment, the organic amine can be a routine selection in the art. In a preferred embodiment, the organic amine in step (1) is triethylamine and / or diisopropylethylamine.

[0080] In a specific embodiment, the first solvent can be any anhydrous solvent commonly used in the art, as long as it can dissolve the reactants. In a preferred embodiment, the first solvent in step (1) is selected from one or more than two of tetrahydrofuran, ethyl acetate, dioxane and toluene, more preferably tetrahydrofuran.

[0081] In the method of the present application, the ratio of the amounts of the organic amine, the amine compound of formula (3) and the compound of formula (2) is controlled to facilitate the forward movement of the acyl halide esterification reaction and to inhibit side reactions, thereby obtaining more of the target product. In a preferred embodiment, the weight ratio of the amounts of the organic amine, the amine compound of formula (3) and the compound of formula (2) in step (1) is 15-20:8-15:10;

[0082] In a specific embodiment, the weight ratio of the amounts of the compound of formula (2) and the first solvent can be 10-30:100, preferably 15-20:100.

[0083] In order to reduce the by-products of the reaction in step (1) and ensure the subsequent reaction can proceed normally, in a preferred embodiment, the temperature of the reaction in step (1) is -20-0°C, for example, it can be -20°C, -15°C, -10°C, -5°C or 0°C; the time of the reaction in step (1) is 4-8h, for example, it can be 4h, 4.5h, 5h, 5.5h, 6h, 6.6h, 7h, 7.5h or 8h.

[0084] In a more specific embodiment, step (1) specifically comprises: mixing the organic amine, the amine compound of the structure shown in formula (3) and the first solvent, then placing it in a cold bath at -20-0°C, adding the compound of the structure shown in formula (2) drop by drop under the protection of inert atmosphere, reacting for 4-8h, filtering out the insoluble substances after the reaction is completed, and removing the solvent to obtain the compound of the structure shown in formula (4) (nitrogen-phosphorus small molecule).

[0085] In the method of the present application, step (2) is a phosphoric acid lactone ring-opening reaction, and the reaction route is as follows:

[0086]

[0087] In a specific embodiment, the dihydric alcohol in step (2) can be a dihydric alcohol commonly used in the art. In a preferred embodiment, the number of carbon atoms of the dihydric alcohol can be 2-8. In a more preferred embodiment, the dihydric alcohol is one or more than two of ethylene glycol, butanediol and propylene glycol.

[0088] In a specific embodiment, when the dihydric alcohol is ethylene glycol, the reaction route is as follows:

[0089]

[0090] In the present application, in order to promote the smooth progress of the reaction in step (2), in a preferred embodiment, an organotin compound is used as a catalyst. In a specific embodiment, the organotin catalyst in step (2) is stannous octoate and / or monobutyltin tris isooctoate;

[0091] In the present application, in order to control the reactivity, it is necessary to limit the ratio of the use amount of the organotin catalyst to the dihydric alcohol to an appropriate range. In a preferred embodiment, the weight ratio of the use amount of the organotin catalyst to the dihydric alcohol in step (2) is 0.1-0.2:1;

[0092] In the present application, in order to control the reaction degree and the composition of the target product, in step (2), it is necessary to control the ratio of the use amount of the compound of the structure shown in formula (4) to the dihydric alcohol to an appropriate range. In a preferred embodiment, the weight ratio of the use amount of the compound of the structure shown in formula (4) to the dihydric alcohol is 5-30:1, more preferably 10-20:1;

[0093] In a specific embodiment, the second solvent can be an anhydrous solvent commonly used in the art. In step (2), the second solvent not only serves as a reaction medium, but also makes the reaction more uniform. In a preferred embodiment, the second solvent in step (2) is selected from one or more than two of tetrahydrofuran, dioxane and toluene.

[0094] In the method of the present application, the amount of the second solvent can be selected according to the art. In a specific embodiment, the weight ratio of the total amount of the compound of formula (4) and the dihydric alcohol to the amount of the second solvent can be 5-35:100.

[0095] In order to improve the conversion rate of the reaction in step (2), in a preferred embodiment, the temperature of the reaction in step (2) is 40-60°C, for example, it can be 40°C, 45°C, 50°C, 55°C or 60°C; the reaction time is 4-6h, for example, it can be 4h, 4.5h, 5h, 5.5h or 6h.

[0096] In a more specific embodiment, step (2) specifically comprises: dissolving the dihydric alcohol and the organotin catalyst in the second solvent, then adding the compound of formula (4), stirring and reacting at 40-60°C under an inert atmosphere for 4-6h, after the reaction is completed, removing the solvent, and washing and drying the reaction product to obtain the compound of formula (5) (nitrogen-phosphorus oligomer).

[0097] In the method of the present application, step (3) is an end-group epoxidation reaction, and the reaction scheme is as follows:

[0098]

[0099] In a specific embodiment, when R4 is chlorine, i.e. the compound of formula (6) is epichlorohydrin, the reaction scheme is as follows:

[0100]

[0101] In the method of the present application, the organic salt catalyst can be selected according to the art. In a specific embodiment, in step (3), the organic salt catalyst can be selected from one or more than two of benzyltriethylammonium chloride, tetrabutylammonium bromide and tetrabutylammonium chloride.

[0102] In step (3) of the present application, the base can be selected according to the art, as long as it can provide an alkaline environment to remove halogen elements. In a specific embodiment, in step (3), the base can be selected from one or more than two of sodium hydroxide, potassium hydroxide and calcium hydroxide. Further, the base can be added in the form of a solution or in the form of a solid.

[0103] In a specific embodiment, the third solvent in step (3) can be selected from one or more than two of toluene, xylene and N,N-dimethylformamide, preferably toluene.

[0104] To obtain the target product, specifically, in step (3), the weight ratio of the amount of use of the compound of the structure of formula (6) to the compound of the structure of formula (5) can be 1-1.5:1. In order to improve the reaction conversion rate, in a preferred embodiment, in step (3), the weight ratio of the amount of use of the compound of the structure of formula (6) to the compound of the structure of formula (5) is 1.2-1.4.

[0105] In a specific embodiment, in step (3), the weight ratio of the amount of use of the organic salt catalyst to the compound of the structure of formula (5) can be 0.2-0.6:1.

[0106] In the present application, the amount of use of the third solvent can be a conventional selection in the art. In a specific embodiment, the weight ratio of the amount of use of the compound of the structure of formula (5) to the third solvent can be 10-15:100.

[0107] In a specific embodiment, the reaction of step (3) is divided into two stages: the first stage is to dehydrate at room temperature (10-40°C) for 30-60 hours, and the second stage is to fully react at 60-80°C for 2-3 hours. Controlling the reaction temperature at 60-80°C in the second stage can greatly improve the conversion rate.

[0108] In a more specific embodiment, step (3) specifically comprises: dissolving the compound of the structure of formula (5) in the third solvent, then adding a base solution and an organic salt catalyst, and then slowly adding the compound of the structure of formula (6) under an inert atmosphere, first reacting at room temperature for 30-60 hours, and then reacting at 60-80°C for 2-3 hours. After the reaction is completed, the obtained mixture is washed with deionized water, the organic phase is dried with anhydrous magnesium sulfate for 48 hours, and the unreacted raw materials and solvents are removed to obtain the compound of the structure of formula (1) (nitrogen-phosphorus epoxy resin).

[0109] The three aspects of the present application provide a nitrogen-phosphorus epoxy resin prepared by the method described above.

[0110] The modified epoxy resin provided by the present application can be used as a flame retardant material alone, or can be used as a flame retardant material after modifying other resins.

[0111] The fourth aspect of the present application provides an epoxy resin composition containing a nitrogen-phosphorus epoxy resin, a bisphenol A type epoxy resin and an amine curing agent; wherein the nitrogen-phosphorus epoxy resin is the nitrogen-phosphorus epoxy resin described above.

[0112] The nitrogen-phosphorus epoxy resin is blended with the bisphenol A type epoxy resin, which can improve the flame retardant performance of the modified epoxy resin, and meanwhile, the modified epoxy resin has good mechanical properties.

[0113] In a preferred embodiment, the amount of the bisphenol A type epoxy resin can be 80-90 parts by weight, and the amount of the nitrogen-phosphorus epoxy resin can be 10-20 parts by weight, based on 100 parts by weight of the total amount of the bisphenol A type epoxy resin and the nitrogen-phosphorus epoxy resin. Limiting the amount ratio of the bisphenol A type epoxy resin and the nitrogen-phosphorus epoxy resin to an appropriate range can further improve the flame retardant performance of the modified epoxy resin, and meanwhile, the modified epoxy resin has good mechanical properties.

[0114] In the present application, the bisphenol A type epoxy resin can be a conventional selection in the art. In a specific embodiment, the bisphenol A type epoxy resin can be selected from one or more than two of E54, E51 and E44.

[0115] In the present application, the amount of the amine curing agent can be a conventional selection in the art. In a specific embodiment, the weight ratio of the total amount of the bisphenol A type epoxy resin and the nitrogen-phosphorus epoxy resin to the amount of the amine curing agent can be 100:10-30. Too slow curing speed affects the use, and too fast curing speed makes the resin have poor performance. In order to control the curing reaction speed, in a preferred embodiment, the weight ratio of the total amount of the bisphenol A type epoxy resin and the nitrogen-phosphorus epoxy resin to the amount of the amine curing agent is 100:15-25.

[0116] In a specific embodiment, the amine curing agent can be various selections well known in the art, for example, the amine curing agent can be selected from one or more than two of a polyamide curing agent, an aliphatic polyamine curing agent and an aromatic polyamine curing agent. In a preferred embodiment, the amine curing agent is curing agent 650 and / or curing agent 651.

[0117] The fifth aspect of the present application provides a method for preparing a modified epoxy resin, wherein the modified epoxy resin is prepared from the epoxy resin composition described above; the method comprises: mixing a bisphenol A type epoxy resin, a nitrogen-phosphorus epoxy resin and an amine curing agent, and then defoaming and curing.

[0118] The method of the present application can improve the flame retardant performance of the modified epoxy resin by blending the nitrogen-phosphorus epoxy resin with the bisphenol A type epoxy resin, and meanwhile, the modified epoxy resin has good mechanical properties.

[0119] In a specific embodiment, the temperature of the mixing can be 60-80℃, and the time of the mixing can be 0.5-3h.

[0120] In the preferred embodiment, the mixing step specifically comprises: preheating the bisphenol A type epoxy resin at 60-80℃, then adding the nitrogen-phosphorus epoxy resin and stirring for 0.3-2 hours, adding the amine curing agent after mixing evenly and stirring for 0.1-1 hour to obtain the resin prepolymer.

[0121] In the specific embodiment, the defoaming temperature can be 80-120℃, the defoaming time can be 0.5-2h, and the defoaming vacuum degree can be 0-10kPa.

[0122] In the present application, the defoaming process comprises: pouring the resin prepolymer into a mold and defoaming in a vacuum oven.

[0123] In the specific embodiment, the curing adopts a staged heating mode. In the preferred embodiment, the staged heating mode comprises: a first stage of curing at 110-130℃ for 0.5-1.5h; a second stage of curing at 150-170℃ for 1.5-2.5h; and a third stage of curing at 170-190℃ for 1.5-2.5h.

[0124] In the specific embodiment, the curing process can be carried out in an oven.

[0125] The sixth aspect of the present application provides a modified epoxy resin prepared by the method described above. The modified epoxy resin has excellent flame retardant performance and good mechanical properties.

[0126] The seventh aspect of the present application provides the use of the nitrogen-phosphorus epoxy resin described above and the modified epoxy resin described above as flame retardant materials. The nitrogen-phosphorus epoxy resin and the modified epoxy resin provided by the present application can be applied in the fields of petrochemical industry, automobile manufacturing, aerospace, etc.

[0127] The present application will be described in detail below through examples, but the protection scope of the present application is not limited to this.

[0128] Triethylamine, 3-diethylamino-1-propanol, 2-chloro-2-oxo-1,3,2-dioxaphospholane, tetrahydrofuran, stannous octoate, ethylene glycol, butanediol, hexanediol, benzyltriethylammonium chloride, sodium hydroxide, toluene, xylene and other chemical reagents are purchased from the Macklin Chemical Reagent Company.

[0129] The bisphenol A type epoxy resins E54, E44 and E51 are purchased from the Sino Blue Star Chemical Co., Ltd.

[0130] The curing agents 650 and 651 are purchased from the Macklin Chemical Reagent Company.

[0131] Flame retardant TCPP was purchased from Macklin Chemical Reagent Co., Ltd.

[0132] Unless otherwise specified, the reagents involved in the examples and comparative examples of the present application are commercially available products.

[0133] Example 1

[0134] Preparation of nitrogen-phosphorus epoxy resin:

[0135] 1) Synthesis of nitrogen-phosphorus small molecules

[0136] In a three-necked flask, 30 g of triethylamine, 12 g of 3-diethylamino-1-propanol (structure shown in formula (3), R1 is ethyl, R2 is ethyl, n is 3) and 100 g of anhydrous tetrahydrofuran were added, and the reaction device was placed in a circulating cold bath at -20°C. Under nitrogen protection, 15 g of 2-chloro-2-oxo-1,3,2-dioxaphospholane (structure shown in formula (2), R3 is chlorine) was slowly added to the reaction system through a dropping funnel, and the reaction was carried out for 6 h. After the reaction was completed, the insoluble substances were removed by filtration, and the solvent was removed using a rotary evaporator to obtain the nitrogen-phosphorus small molecule (structure shown in formula (4)).

[0137] 2) Synthesis of nitrogen-phosphorus oligomers

[0138] In a round-bottom flask, 1 g of ethylene glycol and 0.2 g of stannous octoate were added, and then 100 g of anhydrous tetrahydrofuran was added to dissolve, followed by the addition of 10 g of nitrogen-phosphorus small molecules of step 1). The round-bottom flask was moved to a 60°C oil bath under nitrogen, and the reaction was stirred for 4 hours. After the reaction was completed, the solvent was removed by rotary evaporation, and the reaction product was washed with a large amount of ice-n-hexane to remove unreacted raw materials. Then the product was dried to constant weight in a vacuum oven to obtain the nitrogen-phosphorus oligomer (structure shown in step (5), m is 1-3).

[0139] 3) Synthesis of nitrogen-phosphorus epoxy resin

[0140] After 10 g of nitrogen-phosphorus oligomers of step 2) were dissolved in 100 g of toluene and added to a round-bottom flask, 100 g of 50 wt% NaOH aqueous solution was added to the round-bottom flask, and then 5 g of benzyltriethylammonium chloride was added to the above homogeneous mixture. Under nitrogen, 12 g of epichlorohydrin (structure shown in formula (6), R4 is chlorine) was slowly added, and the reaction was carried out at room temperature (25°C) for 48 hours. Then, the temperature was raised to 80°C and the reaction was continued for 2 hours. The obtained mixture was washed with deionized water, and the organic phase was dried with anhydrous magnesium sulfate for 48 hours. The unreacted raw materials and solvents were removed by rotary evaporation to obtain the nitrogen-phosphorus epoxy resin (structure shown in formula (1)).

[0141] Preparation of modified epoxy resin:

[0142] 4) Modification of nitrogen-phosphorus epoxy resin with bisphenol A epoxy resin and its curing process

[0143] Preheat 80 g of bisphenol A epoxy resin E44 at 80 °C, then add 20 g of nitrogen phosphorus epoxy resin from step 3) and stir for 2 hours; after fully mixing and uniformity, continue to add 20 g of curing agent 650 and stir for 1 hour to obtain a resin prepolymer; pour it into a preheated mold, and deaerate in a vacuum oven at 100 °C for 2 h; then place it in an oven for staged temperature rise, and the curing process is: 120 °C for 1 h, 160 °C for 2 h, and 180 °C for 2 h; after cooling and demolding.

[0144] Example 2

[0145] Preparation of nitrogen phosphorus epoxy resin:

[0146] 1) Synthesis of nitrogen phosphorus small molecules

[0147] In a three-necked flask, add 27 g of triethylamine, 13.5 g of 3-dibutylamino-1-propanol (structure shown in formula (3), R1 is butyl, R2 is butyl, and n is 3), and 100 g of anhydrous tetrahydrofuran, and place the reaction device in a -10 °C circulating cold bath. Under nitrogen protection, slowly drop 15 g of 2-chloro-2-oxo-1,3,2-dioxaphospholane (structure shown in formula (2), R3 is chlorine) into the reaction system through a dropping funnel, and react for 7 h. After the reaction is completed, remove the insoluble material by filtration, and remove the solvent using a rotary evaporator to obtain nitrogen phosphorus small molecules (structure shown in formula (4)).

[0148] 2) Synthesis of nitrogen phosphorus oligomers

[0149] In a round-bottom flask, add 1 g of butanediol and 0.15 g of stannous octoate, then add 100 g of anhydrous dioxane to dissolve, and then add 15 g of nitrogen phosphorus small molecules from step 1). Under nitrogen conditions, move the round-bottom flask to a 50 °C oil bath and stir for 5 hours. After the reaction is completed, remove the solvent by rotary evaporation, wash the reaction product with a large amount of ice n-hexane to remove unreacted raw materials, and then dry the product in a vacuum oven to constant weight to obtain nitrogen phosphorus oligomers (structure shown in formula (5), m is 1-3).

[0150] 3) Synthesis of nitrogen phosphorus epoxy resin

[0151] After 11 g of the phosphorus-nitrogen oligomer of step 2) was dissolved in 100 g of toluene and added to a round bottom flask, 100 g of a 50 wt% aqueous KOH solution was added to the round bottom flask, and 5.5 g of tetrabutylammonium bromide was added to the above homogeneous mixture. 13.2 g of epichlorohydrin (structure shown in formula (6), R4 is chlorine) was slowly added under nitrogen, and the reaction was carried out at room temperature (25°C) for 48 hours. After that, the temperature was raised to 70°C and the reaction was continued for 2 hours. The resulting mixture was washed with deionized water, and the organic phase was dried with anhydrous magnesium sulfate for 48 hours. The unreacted raw materials and solvents were removed by rotary evaporation to obtain a phosphorus-nitrogen epoxy resin (structure shown in formula (1)).

[0152] Preparation of modified epoxy resin:

[0153] 4) Modification of bisphenol A epoxy resin with phosphorus-nitrogen epoxy resin and its curing process

[0154] After 82 g of bisphenol A epoxy resin E51 was preheated at 70°C, 18 g of the phosphorus-nitrogen epoxy resin of step 3) was added and stirred for 0.5 hours; after being mixed evenly, 20 g of curing agent 651 was added and stirred for 0.5 hours to obtain a resin prepolymer; it was poured into a preheated mold and degassed in a vacuum oven at 110°C for 1.5 hours; then it was placed in an oven for staged temperature rise, and the curing process was as follows: 120°C for 1 hour, 160°C for 2 hours, and 180°C for 2 hours; and then it was cooled and demolded.

[0155] Example 3

[0156] Preparation of phosphorus-nitrogen epoxy resin:

[0157] 1) Synthesis of phosphorus-nitrogen small molecules

[0158] In a three-necked flask, 30.6 g of triethylamine, 17 g of 3-dimethylamino-1-propanol (structure shown in formula (3), R1 is methyl, R2 is methyl, and n is 3), and 100 g of anhydrous tetrahydrofuran were added, and the reaction device was placed in a circulating cold bath at -15°C. Under nitrogen protection, 17 g of 2-chloro-2-oxo-1,3,2-dioxaphospholane (structure shown in formula (2), R3 is chlorine) was slowly added to the reaction system through a dropping funnel, and the reaction was carried out for 8 hours. After the reaction was completed, the insoluble matter was removed by filtration, and the solvent was removed using a rotary evaporator to obtain phosphorus-nitrogen small molecules (structure shown in formula (4)).

[0159] 2) Synthesis of phosphorus-nitrogen oligomers

[0160] In a round bottom flask, 1 g of propylene glycol and 0.1 g of stannous octoate were added and dissolved in 100 g of anhydrous toluene, followed by the addition of 20 g of the nitrogen-phosphorus small molecule of step 1). The round bottom flask was then moved to a 40 °C oil bath under nitrogen and stirred for 6 hours. After the reaction was completed, the solvent was removed by rotary evaporation, the reaction product was washed with a large amount of ice and n-hexane to remove unreacted raw materials, and then the product was dried to constant weight in a vacuum oven to obtain a nitrogen-phosphorus oligomer (structure shown in step (5), m is 1-3).

[0161] 3) Synthesis of nitrogen-phosphorus epoxy resin

[0162] After 12 g of the nitrogen-phosphorus oligomer of step 2) was dissolved in 100 g of toluene and added to a round bottom flask, 100 g of a 50 wt% aqueous CaOH solution was added to the round bottom flask, and then 6 g of tetrabutylammonium chloride was added to the above homogeneous mixture. 16.8 g of epichlorohydrin (structure shown in formula (6), R4 is chlorine) was slowly added under nitrogen, and the reaction was carried out at room temperature (25 °C) for 48 hours. Then, the temperature was raised to 60 °C and the reaction was continued for 3 hours. The resulting mixture was washed with deionized water, and the organic phase was dried with anhydrous magnesium sulfate for 48 hours. The unreacted raw materials and solvents were removed by rotary evaporation to obtain a nitrogen-phosphorus epoxy resin (structure shown in formula (1)).

[0163] Preparation of modified epoxy resin:

[0164] 4) Nitrogen-phosphorus epoxy resin modified bisphenol A epoxy resin and its curing process

[0165] 84 g of bisphenol A type epoxy resin E54 was preheated at 60 °C, then 16 g of the nitrogen-phosphorus epoxy resin of step 3) was added and stirred for 1 hour; after being mixed evenly, 15 g of curing agent 650 was added and stirred for 1 hour to obtain a resin prepolymer; it was poured into a preheated mold and degassed in a vacuum oven at 90 °C for 1 h; then it was placed in an oven for staged heating, and the curing process was as follows: 120 °C for 1 h, 160 °C for 2 h, and 180 °C for 2 h; cooled and demolded.

[0166] Example 4

[0167] 1) Synthesis of nitrogen-phosphorus small molecule

[0168] Into a three-necked flask, 32 g of triethylamine, 28 g of 3-[ethyl(methyl)amino]propan-1-ol (structure shown in formula (3), R1 is ethyl, R2 is methyl, n is 3) and 100 g of anhydrous tetrahydrofuran were added, and the reaction device was placed in a circulating cooling bath at -20°C. Under nitrogen protection, 20 g of 2-bromo-2-oxo-1,3,2-dioxaphospholane (structure shown in formula (2), R3 is chlorine) was slowly added to the reaction system through a dropping funnel, and the reaction was carried out for 4 h. After the reaction was completed, the insoluble matter was removed by filtration, and the solvent was removed using a rotary evaporator to obtain a nitrogen-phosphorus small molecule (structure shown in formula (4)).

[0169] 2) Synthesis of nitrogen-phosphorus oligomers

[0170] Into a round-bottom flask, 1 g of ethylene glycol and 0.15 g of monobutyltin tris(isooctylate) were added, and then 100 g of anhydrous tetrahydrofuran was added for dissolution, followed by the addition of 15 g of the nitrogen-phosphorus small molecule of step 1). The round-bottom flask was then moved to an oil bath at 55°C under nitrogen protection, and the reaction was stirred for 5 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the reaction product was washed with a large amount of ice-n-hexane to remove unreacted raw materials. Then, the product was dried in a vacuum oven to a constant weight to obtain a nitrogen-phosphorus oligomer (structure shown in formula (5), m is 1-3).

[0171] 3) Synthesis of nitrogen-phosphorus epoxy resin

[0172] After 14 g of the nitrogen-phosphorus oligomer of step 2) was dissolved in 100 g of toluene and added to a round-bottom flask, 100 g of a 50 wt% aqueous KOH solution was added to the round-bottom flask, and then 7 g of tetrabutylammonium bromide was added to the above homogeneous mixture. Under nitrogen protection, 16.8 g of epichlorohydrin (structure shown in formula (6), R4 is chlorine) was slowly added, and the reaction was carried out at room temperature (25°C) for 48 h. Then, the temperature was increased to 65°C, and the reaction was continued for 3 h. The obtained mixture was washed with deionized water, and the organic phase was dried with anhydrous magnesium sulfate for 48 h. The unreacted raw materials and solvents were removed by rotary evaporation to obtain a nitrogen-phosphorus epoxy resin (structure shown in formula (1)).

[0173] Preparation of modified epoxy resin:

[0174] 4) Nitrogen-phosphorus epoxy resin modified bisphenol A epoxy resin and its curing process

[0175] Preheat 88 g of bisphenol A epoxy resin E51 at 65 °C, then add 12 g of the nitrogen phosphorus epoxy resin of step 3) and stir for 1.5 hours; after the mixture is well mixed and uniform, continue to add 15 g of curing agent 650 and stir for 0.2 hours to obtain a resin prepolymer; pour it into a preheated mold and deaerate in a vacuum oven at 110 °C for 2 hours; then place it in an oven for staged temperature increase, and the curing process is: 120 °C for 1 hour, 160 °C for 2 hours, and 180 °C for 2 hours; cool and demold.

[0176] Example 5

[0177] 1) Synthesis of nitrogen phosphorus small molecules

[0178] In a three-necked flask, add 30 g of triethylamine, 30 g of dimethylaminobutanol (structure shown in formula (3), R1 is methyl, R2 is methyl, n is 4), and 100 g of anhydrous tetrahydrofuran, and place the reaction device in a circulating cold bath at -20 °C. Under nitrogen protection, slowly drop 20 g of 2-chloro-2-oxo-1,3,2-dioxaphospholane (structure shown in formula (2), R3 is chlorine) into the reaction system through a dropping funnel, and react for 6 hours. After the reaction is completed, remove the insoluble substances by filtration, and remove the solvent using a rotary evaporator to obtain a nitrogen phosphorus small molecule (structure shown in formula (4)).

[0179] 2) Synthesis of nitrogen phosphorus oligomers

[0180] In a round-bottom flask, add 1 g of ethylene glycol and 0.2 g of monobutyltin tris isooctanoate, then add 100 g of anhydrous tetrahydrofuran to dissolve, and then add 20 g of the nitrogen phosphorus small molecule of step 1). Under nitrogen conditions, move the round-bottom flask to a 60 °C oil bath and stir for 5 hours. After the reaction is completed, remove the solvent by rotary evaporation, wash the reaction product with a large amount of ice n-hexane to remove unreacted raw materials, and then dry the product in a vacuum oven to constant weight to obtain a nitrogen phosphorus oligomer (structure shown in step (5), m is 1-3).

[0181] 3) Synthesis of nitrogen phosphorus epoxy resin

[0182] Dissolve 15 g of the nitrogen phosphorus oligomer of step 2) in 100 g of toluene and add it to a round-bottom flask, then add 100 g of a 50 wt% NaOH aqueous solution to the round-bottom flask, and then add 7.5 g of tetrabutylammonium chloride to the above homogeneous mixture. Slowly add 18 g of epichlorohydrin (structure shown in formula (6), R4 is chlorine) under nitrogen conditions, and react for 48 hours at room temperature (25 °C). Then, continue to react at 80 °C for 2 hours. The obtained mixture is washed with deionized water, the organic phase is dried with anhydrous magnesium sulfate for 48 hours, and the unreacted raw materials and solvents are removed by rotary evaporation to obtain a nitrogen phosphorus epoxy resin (structure shown in formula (1)).

[0183] Preparation of modified epoxy resin:

[0184] 4) Nitrogen-phosphorus epoxy resin modified bisphenol A epoxy resin and its curing process

[0185] Preheat 90 g of bisphenol A type epoxy resin E54 at 80°C, then add 10 g of nitrogen-phosphorus epoxy resin of step 3) and stir for 1.5 hours; after being fully mixed and uniform, continue to add 25 g of curing agent 651 and stir for 1 hour to obtain a resin prepolymer; pour it into a preheated mold and deaerate in a vacuum oven at 90°C for 1.5 h; then place it in an oven for staged temperature rise, and the curing process is: 120°C for 1 h, 160°C for 2 h, and 180°C for 2 h; cool and demold.

[0186] Example 6

[0187] Preparation of nitrogen-phosphorus epoxy resin:

[0188] 1) Synthesis of nitrogen-phosphorus small molecules

[0189] Add 18 g of diisopropylethylamine, 10 g of 2-(dimethylamine)butan-1-ol (structure shown in formula (3), R1 is methyl, R2 is methyl, and n is 4), and 100 g of anhydrous ethyl acetate to a three-necked flask, and place the reaction device in a -10°C circulating cold bath. Under nitrogen protection, slowly drop 10 g of 2-chloro-2-oxo-1,3,2-dioxaphospholane (structure shown in formula (2), R3 is chlorine) into the reaction system through a dropping funnel, and react for 6 h. After the reaction is completed, remove the insoluble substances by filtration, and remove the solvent using a rotary evaporator to obtain nitrogen-phosphorus small molecules (structure shown in formula (4)).

[0190] 2) Synthesis of nitrogen-phosphorus oligomers

[0191] Add 1 g of butanediol and 0.2 g of monobutyltin tris isooctoate to a round-bottom flask, then add 100 g of anhydrous tetrahydrofuran for dissolution, and then add 5 g of nitrogen-phosphorus small molecules of step 1). Under nitrogen conditions, move the round-bottom flask to a 50°C oil bath and stir for 5 hours. After the reaction is completed, remove the solvent by rotary evaporation, wash the reaction product with a large amount of ice n-hexane to remove unreacted raw materials, and then dry the product in a vacuum oven to constant weight to obtain nitrogen-phosphorus oligomers (structure shown in step (5), m is 1-3).

[0192] 3) Synthesis of nitrogen-phosphorus epoxy resin

[0193] The 12 g of nitrogen phosphorus oligomer of step 2) was dissolved in 100 g of toluene and added to a round bottom flask, 100 g of 50 wt% NaOH aqueous solution was added to the round bottom flask, and 2.4 g of benzyl triethyl ammonium chloride was added to the above homogeneous mixture. 12 g of epichlorohydrin (structure shown in formula (6), R4 is chlorine) was slowly added under nitrogen atmosphere, and the reaction was carried out at room temperature (25°C) for 48 hours. Then, the temperature was raised to 80°C and the reaction was continued for 2 hours. The obtained mixture was washed with deionized water, and the organic phase was dried with anhydrous magnesium sulfate for 48 hours. The unreacted raw materials and solvents were removed by rotary evaporation to obtain a nitrogen phosphorus epoxy resin (structure shown in formula (1)).

[0194] Preparation of modified epoxy resin:

[0195] 4) Nitrogen phosphorus epoxy resin modified bisphenol A epoxy resin and its curing process

[0196] 86 g of bisphenol A type epoxy resin E44 was preheated at 80°C, then 14 g of nitrogen phosphorus epoxy resin of step 3) was added and stirred for 0.3 hours; after uniform mixing, 10 g of curing agent 650 was added and stirred for 1 hour to obtain a resin prepolymer; it was poured into a preheated mold and degassed in a vacuum oven at 80°C for 1 h; then placed in an oven for staged temperature rise, the curing process was: 120°C for 1 h, 160°C for 2 h, 180°C for 2 h; cooled and demolded.

[0197] Example 7

[0198] 1) Synthesis of nitrogen phosphorus small molecules

[0199] In a three-necked flask, 40 g of diisopropylethylamine, 30 g of 1-diethylamino-2-propanol (structure shown in formula (3), R1 is ethyl, R2 is ethyl, n is 3) and 100 g of anhydrous dioxane were added, and the reaction device was placed in a -10°C circulating cold bath. Under nitrogen protection, 25 g of 2-chloro-2-oxo-1,3,2-dioxaphospholane (structure shown in formula (2), R3 is chlorine) was slowly added to the reaction system through a dropping funnel, and the reaction was carried out for 6 h. After the reaction was completed, the insoluble material was removed by filtration, and the solvent was removed using a rotary evaporator to obtain a nitrogen phosphorus small molecule (structure shown in formula (4)).

[0200] 2) Synthesis of nitrogen phosphorus oligomer

[0201] In a round bottom flask, 1 g of propylene glycol and 0.1 g of monobutyl tin triisooctoate were added and dissolved in 100 g of anhydrous dioxane, followed by the addition of 8 g of the nitrogen phosphorus small molecule of step 1). The round bottom flask was then moved to a 50 °C oil bath under nitrogen and stirred for 5 hours. After the reaction was completed, the solvent was removed by rotary evaporation, and the reaction product was washed with a large amount of ice and n-hexane to remove unreacted raw materials. The product was then dried to constant weight in a vacuum oven to obtain a nitrogen phosphorus oligomer (structure shown in step (5), m is 1-3).

[0202] 3) Synthesis of nitrogen phosphorus epoxy resin

[0203] After 12 g of the nitrogen phosphorus oligomer of step 2) was dissolved in 100 g of xylene and added to a round bottom flask, 100 g of a 50 wt% NaOH aqueous solution was added to the round bottom flask, and then 3.6 g of benzyl triethyl ammonium chloride was added to the above homogeneous mixture. Under nitrogen, 13.2 g of epichlorohydrin (structure shown in formula (6), R4 is chlorine) was slowly added, and the reaction was carried out at room temperature (25 °C) for 48 hours. After that, the temperature was raised to 80 °C and the reaction was continued for 2 hours. The obtained mixture was washed with deionized water, and the organic phase was dried with anhydrous magnesium sulfate for 48 hours. The unreacted raw materials and solvents were removed by rotary evaporation to obtain a nitrogen phosphorus epoxy resin (structure shown in formula (1)).

[0204] Preparation of modified epoxy resin:

[0205] 4) Nitrogen phosphorus epoxy resin modified bisphenol A epoxy resin and its curing process

[0206] After 87 g of bisphenol A type epoxy resin E51 was preheated at 80 °C, 13 g of the nitrogen phosphorus epoxy resin of step 3) was added and stirred for 1 hour; after being fully mixed and uniform, 30 g of curing agent 651 was added and stirred for 1 hour to obtain a resin prepolymer; it was poured into a preheated mold and degassed in a vacuum oven at 80 °C for 0.5 h; then placed in an oven for staged temperature rise, and the curing process was: 120 °C for 1 h, 160 °C for 2 h, and 180 °C for 2 h; cooled and demolded.

[0207] Example 8

[0208] 1) Synthesis of nitrogen phosphorus small molecule

[0209] Into a three-necked flask, 45 g of diisopropylethylamine, 25 g of 3- diethylamino-1-propanol (structure shown in formula (3), R1 is ethyl, R2 is ethyl, n is 3) and 100 g of anhydrous toluene were added, and the reaction device was placed in a circulating cooling bath at -10°C. Under nitrogen protection, 25 g of 2-chloro-2-oxo-1,3,2-dioxaphospholane (structure shown in formula (2), R3 is chlorine) was slowly added to the reaction system through a dropping funnel, and the reaction was carried out for 6 h. After the reaction was completed, the insoluble substances were removed by filtration, and the solvent was removed using a rotary evaporator to obtain a nitrogen-phosphorus small molecule (structure shown in formula (4)).

[0210] 2) Synthesis of nitrogen-phosphorus oligomers

[0211] Into a round-bottom flask, 1 g of ethylene glycol and 0.1 g of stannous octoate were added, and then 100 g of anhydrous toluene was added to dissolve, followed by the addition of 25 g of the nitrogen-phosphorus small molecule of step 1). The round-bottom flask was moved to a 50°C oil bath under nitrogen, and the reaction was stirred for 5 hours. After the reaction was completed, the solvent was removed by rotary evaporation, and the reaction product was washed with a large amount of ice-n-hexane to remove unreacted raw materials. The product was then dried in a vacuum oven to a constant weight to obtain a nitrogen-phosphorus oligomer (structure shown in step (5), m is 1-3).

[0212] 3) Synthesis of nitrogen-phosphorus epoxy resin

[0213] After 12 g of the nitrogen-phosphorus oligomer of step 2) was dissolved in 100 g of N,N-dimethylformamide, it was added to a round-bottom flask, and then 100 g of a 50 wt% NaOH aqueous solution was added to the round-bottom flask. Then, 4.8 g of benzyltriethylammonium chloride was added to the above homogeneous mixture. Under nitrogen, 12 g of epichlorohydrin (structure shown in formula (6), R4 is chlorine) was slowly added, and the reaction was carried out at room temperature (25°C) for 48 hours. Then, the temperature was raised to 80°C and the reaction was continued for 2 hours. The obtained mixture was washed with deionized water, and the organic phase was dried with anhydrous magnesium sulfate for 48 hours. The unreacted raw materials and solvents were removed by rotary evaporation to obtain a nitrogen-phosphorus epoxy resin (structure shown in formula (1)).

[0214] Preparation of modified epoxy resin:

[0215] 4) Nitrogen-phosphorus epoxy resin modified bisphenol A epoxy resin and its curing process

[0216] Preheat 88 g of bisphenol A epoxy resin E54 at 80 °C, then add 12 g of the nitrogen phosphorus epoxy resin of step 3) and stir for 1 hour; after the mixture is well mixed and uniform, continue to add 10 g of curing agent 651 and stir for 1 hour to obtain a resin prepolymer; pour it into a preheated mold and deaerate in a vacuum oven at 120 °C for 1.5 h; then place it in an oven for staged temperature rise, and the curing process is: 1 h at 120 °C, 2 h at 160 °C, and 2 h at 180 °C; cool and demold.

[0217] Example 9

[0218] 1) Synthesis of nitrogen phosphorus small molecules

[0219] In a three-necked flask, add 54 g of diisopropylethylamine, 45 g of 3-diethylamino-2-propanol (structure shown in formula (3), R1 is ethyl, R2 is ethyl, and n is 3), and 100 g of anhydrous dioxane, and place the reaction device in a -10 °C circulating cold bath. Under nitrogen protection, slowly drop 30 g of 2-chloro-2-oxo-1,3,2-dioxaphospholane (structure shown in formula (2), R3 is chlorine) into the reaction system through a dropping funnel, and react for 6 h. After the reaction is completed, remove the insoluble substances by filtration, and remove the solvent using a rotary evaporator to obtain a nitrogen phosphorus small molecule (structure shown in formula (4)).

[0220] 2) Synthesis of nitrogen phosphorus oligomers

[0221] In a round-bottom flask, add 1 g of butanediol and 0.2 g of monobutyltin tris(isooctanoate), then add 100 g of anhydrous tetrahydrofuran for dissolution, and then add 30 g of the nitrogen phosphorus small molecule of step 1). Under nitrogen conditions, move the round-bottom flask to a 50 °C oil bath and stir for 5 hours. After the reaction is completed, remove the solvent by rotary evaporation, wash the reaction product with a large amount of ice n-hexane to remove unreacted raw materials, and then dry the product in a vacuum oven to constant weight to obtain a nitrogen phosphorus oligomer (structure shown in step (5), m is 1-3).

[0222] 3) Synthesis of nitrogen phosphorus epoxy resin

[0223] Dissolve 12 g of the nitrogen phosphorus oligomer of step 2) in 100 g of toluene and add it to a round-bottom flask, then add 100 g of a 50 wt% NaOH aqueous solution to the round-bottom flask, and then add 7.2 g of benzyltriethylammonium chloride to the above homogeneous mixture. Slowly add 18 g of epichlorohydrin (structure shown in formula (6), R4 is chlorine) under nitrogen conditions, and react for 48 hours at room temperature (25 °C). Then, continue to react at 80 °C for 2 hours. Wash the obtained mixture with deionized water, dry the organic phase with anhydrous magnesium sulfate for 48 hours, remove the unreacted raw materials and solvent by rotary evaporation, and obtain a nitrogen phosphorus epoxy resin (structure shown in formula (1)).

[0224] Preparation of modified epoxy resin:

[0225] 4) Nitrogen-phosphorus epoxy resin modified bisphenol A epoxy resin and its curing process

[0226] 89 g of bisphenol A epoxy resin E44 was preheated at 80° C., and then 11 g of the nitrogen-phosphorus epoxy resin prepared in step 3) was added and stirred for 1 hour. After thorough mixing, 30 g of curing agent 651 was added and stirred for 1 hour to obtain a resin prepolymer. The prepolymer was poured into a preheated mold and degassed in a vacuum oven at 120° C. for 1.5 hours. The prepolymer was then placed in an oven for staged heating. The curing process was as follows: reaction at 120° C. for 1 hour, reaction at 160° C. for 2 hours, and reaction at 180° C. for 2 hours. The prepolymer was then cooled and demolded.

[0227] Comparative Example 1

[0228] 100 g of bisphenol A epoxy resin E44 was preheated at 80° C., and 20 g of curing agent 650 was added and stirred for 1 hour to obtain a resin prepolymer. The prepolymer was poured into a preheated mold and degassed in a vacuum oven at 100° C. for 2 hours. The prepolymer was then placed in an oven for staged heating. The curing process was as follows: reaction at 120° C. for 1 hour, reaction at 160° C. for 2 hours, and reaction at 180° C. for 2 hours. After cooling and demolding, a cured epoxy resin was obtained.

[0229] Comparative Example 2

[0230] 80g of bisphenol A epoxy resin E44 was preheated at 80°C, and then 20g of flame retardant TCPP was added and stirred to mix thoroughly; 20g of curing agent 650 was further added and stirred to obtain a resin prepolymer; the prepolymer was poured into a preheated mold and degassed in a vacuum oven at 100°C for 2h; the prepolymer was then placed in an oven for staged heating, and the curing process was as follows: reaction at 120°C for 1h, reaction at 160°C for 2h, and reaction at 180°C for 2h; and the prepolymer was cooled and demolded.

[0231] Test Case

[0232] The flame retardant properties and mechanical properties of the products prepared in the examples and comparative examples were tested, and the results are shown in Table 1.

[0233] The tensile strength test method refers to the standard GB / T 1447;

[0234] Toughness test method reference standard GB / T 1447;

[0235] Oxygen index test method reference standard GB / T 2406;

[0236] UL94 test method refers to standard UL94.

[0237] Table 1

[0238]

[0239]

[0240] As can be seen from Table 1, the nitrogen-phosphorus epoxy resin can significantly improve the oxygen index and UL-94 flame retardant grade of the material, and the nitrogen-phosphorus epoxy resin can increase the toughness of the material, and will not reduce the tensile strength of the material like traditional flame retardant TCPP. Therefore, the nitrogen-phosphorus epoxy resin has obvious technical effect advantage.

[0241] As can be seen from Table 1, the nitrogen-phosphorus epoxy resin can improve the toughness of the material, and the elongation at break of the material is all above 5%. Figure 1 As can be seen from Table 1, the nitrogen-phosphorus epoxy resin can improve the toughness of the material, and the elongation at break of the material is all above 5%. -1 As can be seen from Table 1, the nitrogen-phosphorus epoxy resin can improve the toughness of the material, and the elongation at break of the material is all above 5%. -1 As can be seen from Table 1, the nitrogen-phosphorus epoxy resin can improve the toughness of the material, and the elongation at break of the material is all above 5%. -1 As can be seen from Table 1, the nitrogen-phosphorus epoxy resin can improve the toughness of the material, and the elongation at break of the material is all above 5%.

[0242] As can be seen from Table 1, the nitrogen-phosphorus epoxy resin can improve the toughness of the material, and the elongation at break of the material is all above 5%. Figure 2 As can be seen from Table 1, the nitrogen-phosphorus epoxy resin can improve the toughness of the material, and the elongation at break of the material is all above 5%.

[0243] The above is only an embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent transformation or direct or indirect application in other related technical fields using the content of the present application is also included in the patent protection scope of the present application.

Claims

1. A nitrogen-phosphorus epoxy resin, characterized in that The nitrogen-phosphorus epoxy resin contains a compound having a structure represented by formula (1), Wherein, R1 and R2 are each independently selected from hydrogen or alkyl, m is an integer of 1-6, and n is an integer of 1-10.

2. The nitrogen-phosphorus epoxy resin according to claim 1, characterized in that R1 and R2 are each independently selected from hydrogen or C1-C5 alkyl; Preferably, R1 and R2 are each independently selected from hydrogen, methyl, ethyl or butyl.

3. A method for preparing a nitrogen-phosphorus epoxy resin, characterized in that: The method comprises the following steps: (1) reacting a compound having a structure represented by formula (2) with an alcoholamine compound having a structure represented by formula (3) in the presence of an organic amine and a first solvent to obtain a compound having a structure represented by formula (4); (2) reacting the compound of formula (4) with a diol in the presence of an organotin catalyst and a second solvent to obtain a compound of formula (5); (3) reacting the compound of formula (5) with the compound of formula (6) in the presence of an organic salt catalyst, a third solvent, and a base to obtain a compound of formula (1); Wherein, R1, R2, m, and n are the same as those defined in claim 1 or 2; R3 is chlorine or bromine; and R4 is chlorine or bromine.

4. The method according to claim 3, characterized in that In step (1), the alcoholamine compound of the structure shown in formula (3) is selected from one or more of 3-diethylamino-1-propanol, 3-dibutylamino-1-propanol, 3-dimethylamino-1-propanol, 3-[ethyl(methyl)amino]propan-1-ol, dimethylaminobutanol, 2-(dimethylamino)butan-1-ol and 1-diethylamino-2-propanol; Preferably, in step (1), the organic amine is triethylamine and / or diisopropylethylamine; Preferably, in step (1), the first solvent is selected from one or more of tetrahydrofuran, ethyl acetate, dioxane and toluene.

5. The method according to any one of claims 3 to 4, characterized in that In step (1), the weight ratio of the organic amine, the amine compound of the structure represented by formula (3) and the compound of the structure represented by formula (2) is 15-20:8-15:10; Preferably, the weight ratio of the compound having the structure represented by formula (2) to the first solvent is 10-30:100, preferably 15-20:

100.

6. The method according to any one of claims 3 to 5, characterized in that In step (1), the reaction conditions include: temperature of -20 to 0°C and time of 4 to 8 hours.

7. The method according to any one of claims 3 to 6, characterized in that In step (2), the organotin catalyst is selected from stannous octoate and / or monobutyl octyltin triisoate; Preferably, in step (2), the diol has 2 to 8 carbon atoms, and is preferably one or more of ethylene glycol, butanediol, and propylene glycol; Preferably, in step (2), the second solvent is selected from one or more of tetrahydrofuran, dioxane and toluene.

8. The method according to any one of claims 3 to 7, characterized in that: In step (2), the weight ratio of the organotin catalyst to the diol is 0.1-0.2:1; Preferably, the weight ratio of the compound of formula (4) to the diol is 5-30:1, preferably 10-20:1; Preferably, the weight ratio of the total amount of the compound of the structure represented by formula (4) and the diol to the amount of the second solvent is 5-35:

100.

9. The method according to any one of claims 3 to 8, characterized in that In step (2), the reaction conditions include: temperature of 40-60° C. and time of 4-6 h.

10. The method according to any one of claims 3 to 9, characterized in that In step (3), the organic salt catalyst is selected from one or more of benzyltriethylammonium chloride, tetrabutylammonium bromide and tetrabutylammonium chloride; Preferably, in step (3), the base is selected from one or more of sodium hydroxide, potassium hydroxide and calcium hydroxide; Preferably, in step (3), the third solvent is selected from one or more of toluene, xylene and N,N-dimethylformamide.

11. The method according to any one of claims 3 to 10, characterized in that: In step (3), the weight ratio of the compound of formula (6) to the compound of formula (5) is 1-1.5:1, preferably 1.2-1.4; Preferably, the weight ratio of the organic salt catalyst to the compound of the structure of formula (5) is 0.2-0.6:1; Preferably, the weight ratio of the compound of formula (5) to the third solvent is 10-15:

100.

12. The method according to any one of claims 3 to 11, characterized in that: In step (3), the reaction conditions include: reacting at 10-40° C. for 30-60 hours, and then reacting at 60-80° C. for 2-3 hours.

13. A nitrogen-phosphorus epoxy resin prepared by the method according to any one of claims 3 to 12.

14. An epoxy resin composition, characterized in that The epoxy resin composition contains nitrogen-phosphorus epoxy resin, bisphenol A epoxy resin and amine curing agent; Wherein, the nitrogen-phosphorus epoxy resin is the nitrogen-phosphorus epoxy resin according to any one of claims 1, 2 and 13.

15. The epoxy resin composition according to claim 14, characterized in that Based on the total amount of the bisphenol A epoxy resin and the nitrogen-phosphorus epoxy resin as 100 parts by weight, the amount of the bisphenol A epoxy resin is 80-90 parts by weight, and the amount of the nitrogen-phosphorus epoxy resin is 10-20 parts by weight; Preferably, the weight ratio of the total amount of the bisphenol A epoxy resin and the nitrogen-phosphorus epoxy resin to the amount of the amine curing agent is 100:10-30, preferably 100:15-25.

16. The epoxy resin composition according to claim 14 or 15, characterized in that The bisphenol A epoxy resin is selected from one or more of E54, E51 and E44; Preferably, the amine curing agent is selected from one or more of a polyamide curing agent, an aliphatic polyamine curing agent and an aromatic polyamine curing agent.

17. A method for preparing a modified epoxy resin, characterized in that: The modified epoxy resin is prepared from the epoxy resin composition according to any one of claims 14 to 16; The method comprises: mixing bisphenol A epoxy resin, nitrogen-phosphorus epoxy resin and amine curing agent, and then performing degassing and curing.

18. The method according to claim 17, wherein the mixing conditions include: The temperature is 60-80℃ and the time is 0.5-3h; Preferably, the degassing conditions include: temperature of 80-120° C., time of 0.5-2 h, and vacuum degree of 0-10 kPa.

19. The method according to claim 17 or 18, wherein the curing is carried out by heating in stages; Preferably, the stage heating method includes: The first stage: curing at 110-130℃ for 0.5-1.5h; The second stage: curing at 150-170℃ for 1.5-2.5h; the third stage: curing at 170-190℃ for 1.5-2.5h.

20. The modified epoxy resin prepared by the method according to any one of claims 17 to 19.

21. Use of the nitrogen-phosphorus epoxy resin according to any one of claims 1, 2 or 13 and the modified epoxy resin according to claim 20 as flame retardant materials.

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