Organophosphorus-nitrogen flame retardant @ halloysite nanotube hybrid / epoxy resin composite material and preparation method and application thereof

Abstract

The application relates to an organic phosphorus-nitrogen type flame retardant / halloysite nanotube hybrid / epoxy resin composite material and a preparation method and application thereof, wherein the composite material comprises the following components in percentage by weight: an organic phosphorus-nitrogen type flame retardant / halloysite nanotube hybrid 0.5-10%; a curing agent 18-22%; and a bisphenol A type epoxy resin 68-81.5%. Compared with the prior art, the application utilizes the synergistic effect between the organic phosphorus-nitrogen type flame retardant and the halloysite nanotube, obtains the epoxy resin composite material with high mechanical performance and high flame retardant performance, and has the advantages of rich raw material sources, simple process, high yield, low addition amount of the composite flame retardant, excellent flame retardant performance and excellent mechanical performance of the prepared epoxy resin / organic phosphorus-nitrogen type flame retardant / halloysite nanotube hybrid composite material, and the epoxy resin / organic phosphorus-nitrogen type flame retardant / halloysite nanotube hybrid composite material can be applied in industrialized fields such as advanced equipment, automobiles, electronic appliances and the like.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of materials, in particular to an organic phosphorus-nitrogen flame retardant-halloysite nanotube hybrid / epoxy resin composite material and a preparation method and application thereof. BACKGROUND

[0002] Epoxy resin (EP) is a typical thermosetting resin, which is widely used in the fields of communication, electronics, aerospace, engineering composites, etc. due to its excellent mechanical properties, electrical insulation properties, corrosion resistance, bonding properties and processing properties. However, the low limiting oxygen index (LOI) and flammability of EP limit its development and application. Therefore, the flame retardance of EP has attracted more and more attention. Although halogen-based flame retardants have high flame-retardant effect, they release a large amount of smoke and toxic and harmful corrosive gases during combustion, which can cause great damage to personnel and close instruments at the fire scene. Although the commonly used phosphorus-based flame retardants have good compatibility, flame retardance, plasticizing and other advantages, they also have defects such as poor thermal stability, easy hydrolysis and reduced mechanical properties.

[0003] Halloysite nanotubes (HNTs) are a kind of natural mineral material with a hollow nanotube structure, and its molecular formula is Al2SiO5(OH)4·nH2O (n=0 or 2). The outer surface of HNTs is mainly composed of Si-O-Si bonds, and the inner wall is mainly aluminum hydroxyl. There are a small amount of silicon / aluminum hydroxyl on the surface and end face of the nanotube. Due to its high specific surface area, large aspect ratio, high strength, high modulus and low cost, it is often used to improve the mechanical properties of polymer materials. However, HNTs also have the defect of low flame-retardant efficiency.

[0004] According to the literature [Lü Jiashuai, doctoral dissertation, Influence of phosphorus-based flame retardant compounded halloysite nanotubes on the performance of epoxy resin, 2021], compared with the blank epoxy resin, the epoxy resin composite material added with 10 parts of HNTs can reach UL 94V-1 level. Dong Yannao et al. [Polymer Materials Science and Engineering, 2020, 36(1): 75-82] synthesized zinc ammonium phosphate / halloysite nanotubes (ZAP / HNT) by adsorption-chemical precipitation method, and found that the epoxy resin composite material added with 15% ZAP / HNT still had no any level in the UL 94 test, and the epoxy resin composite material containing 20% ZAP / HNT could only reach UL 94V-2 level.

[0005] CN10997103A (phosphorus-containing nano flame retardant and preparation method thereof) discloses that after the surface of halloysite nanotubes is modified with an amino polymer, the halloysite nanotubes are reacted with phosphoric acid to load ammonium phosphate on the surface of the halloysite nanotubes, so as to improve the flame retardancy of the halloysite nanotubes, but the patent does not report the influence of the halloysite nanotubes loaded with ammonium phosphate on the flame retardant performance and mechanical properties of polymers (including epoxy resins). With the progress of science and technology, the performance requirements for materials are getting higher and higher, and in addition to meeting the flame retardant performance requirements, excellent mechanical properties and low addition amount of the flame retardant are often required.

[0006] Therefore, there is an urgent need to achieve low addition amount of the flame retardant and excellent mechanical properties of the epoxy resin composite material while meeting the flame retardant requirements of the epoxy resin. SUMMARY

[0007] The purpose of the present application is to provide an organic phosphorus-nitrogen flame retardant halloysite nanotube hybrid / epoxy resin composite material and a preparation method and application thereof to overcome the defects of the prior art, and the epoxy resin composite material prepared by adding the composite flame retardant to the epoxy resin has excellent flame retardant performance and excellent mechanical properties.

[0008] The applicant believes that the halloysite nanotubes need to be modified with a flame retardant to enhance their flame retardant performance during the conception process. The organic phosphorus-nitrogen flame retardant is a safe and environmentally friendly flame retardant that does not contain halogen elements and does not require the addition of organic solvents during the synthesis process. The organic phosphorus-nitrogen flame retardant has excellent flame retardant performance. The organic phosphorus-nitrogen flame retardant loaded on the halloysite nanotubes can improve the poor flame retardant performance of the halloysite nanotubes, and can also take advantage of the excellent mechanical properties of the high aspect ratio of the surface of the halloysite nanotubes and the easy surface modification of the organic groups on the surface of the halloysite nanotubes to improve the compatibility of the resin. The raw materials involved in the present application are abundant and inexpensive, the preparation process is simple, and the preparation process is green and environmentally friendly. The prepared epoxy composite material has excellent flame retardant performance, high mechanical properties, and low addition amount of the flame retardant.

[0009] The purpose of the present application can be achieved by the following technical solutions:

[0010] The present application provides an organic phosphorus-nitrogen flame retardant halloysite nanotube hybrid / epoxy resin composite material, which comprises the following components by weight percentage:

[0011] Organic phosphorus-nitrogen flame retardant halloysite nanotube hybrid 0.5% to 10%;

[0012] Curing agent 18% to 22%;

[0013] Bisphenol A type epoxy resin 68% to 81.5%.

[0014] Further, the organic phosphorus-nitrogen flame retardant / halloysite nanotube hybrid is prepared by sequentially performing hydroxylation modification and amination modification on halloysite nanotubes, and then respectively reacting with an aqueous organic phosphonic acid solution and an aqueous melamine solution.

[0015] Further, the curing agent is selected from one or more of a heterocyclic amine curing agent, an aromatic amine curing agent, an acid anhydride curing agent, and an alicyclic amine curing agent.

[0016] The second aspect of the present application provides a preparation method of the organic phosphorus-nitrogen flame retardant / halloysite nanotube hybrid / epoxy resin composite material, comprising the following steps:

[0017] S1: hydroxylation modification of halloysite nanotubes is performed using an alcohol alkali solution to obtain material A;

[0018] S2: aminosiloxane is used to perform amination modification on the material A to obtain material B;

[0019] S3: the material B is added to an aqueous organic phosphonic acid solution, and a temperature is raised for reaction, and then an aqueous melamine solution is slowly added dropwise, and the reaction is performed under continuous stirring, and then the obtained product is filtered, washed with water, and dried to prepare the organic phosphorus-nitrogen flame retardant / halloysite nanotube hybrid;

[0020] S4: mixing and curing to obtain the organic phosphorus-nitrogen flame retardant / halloysite nanotube hybrid / epoxy resin composite material.

[0021] Further, in S3, the organic phosphonic acid is selected from one or more of aminotri(methylene) phosphonic acid, phenyl phosphonic acid, phytic acid, diethylene triamine penta(methylene) phosphonic acid, hexanediamine tetra(methylene) phosphonic acid, and ethylenediamine tetra(methylene) phosphonic acid;

[0022] In S3, the molar ratio of the organic phosphonic acid to melamine is 1:3 to 3:1.

[0023] In S3, the temperature of the temperature-raising reaction is 80-120 DEG C, and the reaction time is 1-24 h.

[0024] Further, in S1, the alcohol in the alcohol alkali solution is a saturated aliphatic alcohol, and is at least one of methanol, ethanol, n-propanol, and isopropanol.

[0025] The base in the alcohol alkali solution is at least one of a sodium hydroxide aqueous solution and a potassium hydroxide aqueous solution.

[0026] Further, in S2, the aminosiloxane is selected from one or more of gamma-aminopropyltriethoxysilane, gamma-aminopropyltrimethoxysilane, N-(beta-aminoethyl)-gamma-aminopropyltriethoxysilane, N-(beta-aminoethyl)-gamma-aminopropyltrimethoxysilane, N-(beta-aminoethyl)-gamma-aminopropylmethyldimethoxysilane, N-(beta-aminoethyl)-gamma-aminopropylmethyldiethoxysilane, gamma-aminopropylmethyldiethoxysilane, gamma-aminopropylmethyldimethoxysilane, gamma-aminopropylethoxydimethylsilane.

[0027] Further, in S4, the bisphenol A type epoxy resin, the organic phosphorus-nitrogen type flame retardant@halloysite nanotube hybrid and the curing agent are weighed according to the ratio, stirred uniformly and then placed into a polytetrafluoroethylene mold, and curing is performed in different temperature and time sections, the curing temperature is 100-150 DEG C, and the curing time is 2-8 h.

[0028] The third aspect of the application provides a kind of organic phosphorus-nitrogen type flame retardant@halloysite nanotube hybrid / epoxy resin composite material in special epoxy resin material.

[0029] Further, the organic phosphorus-nitrogen type flame retardant in the organic phosphorus-nitrogen type flame retardant@halloysite nanotube hybrid / epoxy resin composite material can promote carbonization of the matrix material to generate carbon layer when heated, and the non-combustible gas generated at the same time has dilution air and combustible gas concentration, and the halloysite nanotube therein plays a physical shielding effect, which together improves the flame retardant performance of the epoxy resin, and the surface-loaded organic phosphorus-nitrogen type flame retardant promotes the compatibility between the halloysite nanotube and the epoxy resin, thereby improving the mechanical properties of the epoxy resin.

[0030] Compared with the prior art, the application has the following technical advantages:

[0031] 1) The organic phosphorus-nitrogen type flame retardant@halloysite nanotube hybrid is added to the epoxy resin, the reaction conditions are controlled, and the mass ratio of the organic phosphorus-nitrogen type flame retardant and the halloysite nanotube is adjusted, so that the prepared epoxy resin composite material has excellent flame retardant performance and mechanical properties. The organic phosphorus-nitrogen type flame retardant is prepared from an organic polybasic phosphonic acid and melamine. The organic phosphorus-nitrogen type flame retardant can promote carbonization of the matrix material to generate carbon layer when heated, and the non-combustible gas generated at the same time has dilution air and combustible gas concentration to produce a flame retardant effect.

[0032] 2) The halloysite nanotube used in the application is a multi-walled hollow nanotube with high aspect ratio and high temperature resistance, which can play a certain physical shielding effect and also has a certain flame retardant effect in the epoxy resin system. The surface-loaded organic phosphorus-nitrogen type flame retardant improves the compatibility between the halloysite nanotube and the epoxy resin, thereby improving the mechanical properties of the epoxy resin. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Transmission electron micrograph of unmodified halloysite nanotubes;

[0034] Figure 2 Transmission electron micrograph of melamine aminotrimethylene phosphonate loaded halloysite nanotubes (mass ratio of melamine aminotrimethylene phosphonate to halloysite nanotubes is 1:1);

[0035] Figure 3 Infrared spectrum of melamine aminotrimethylene phosphonate loaded halloysite nanotubes (mass ratio of melamine aminotrimethylene phosphonate to halloysite nanotubes is 1:1);

[0036] Figure 4 Thermogravimetric curve of epoxy resin and melamine aminotrimethylene phosphonate loaded halloysite nanotubes (mass ratio of melamine aminotrimethylene phosphonate to halloysite nanotubes is 1:1) / epoxy resin composite (nitrogen atmosphere, heating rate is 10℃ / min). DETAILED DESCRIPTION

[0037] Overall, the present application relates to an organic phosphorus-nitrogen flame retardant@halloysite nanotube hybrid / epoxy resin composite and a preparation method thereof. Specifically, the method comprises the following steps: aminating the surface of halloysite nanotubes, reacting the aminated halloysite nanotubes with aminotrimethylene phosphonic acid, then slowly adding an aqueous solution of melamine, synthesizing an organic phosphorus-nitrogen flame retardant loaded halloysite nanotube, applying it to an epoxy resin, and preparing an epoxy resin / organic phosphorus-nitrogen flame retardant@halloysite nanotube hybrid composite. By utilizing the synergistic effect between the organic phosphorus-nitrogen flame retardant and the halloysite nanotube, an epoxy resin composite with high mechanical properties and high flame retardant properties is obtained. The raw materials of the present application are abundant, the process is simple, the yield is high, the addition amount of the composite flame retardant is low, and the prepared epoxy resin / organic phosphorus-nitrogen flame retardant@halloysite nanotube hybrid composite not only has excellent flame retardant properties, but also has good mechanical properties, and can be applied in advanced equipment, automobiles, electronic appliances and other industrial fields.

[0038] Specifically, the organic phosphorus-nitrogen flame retardant@halloysite nanotube hybrid / epoxy resin composite of the present application comprises the following raw materials by weight percentage: 0.5% to 10% of the organic phosphorus-nitrogen flame retardant@halloysite nanotube hybrid, 18% to 22% of the curing agent, and 68% to 81.5% of the bisphenol A type epoxy resin. Preferably, the mass percentage of the organic phosphorus-nitrogen flame retardant@halloysite nanotube hybrid is 1% to 2%.

[0039] The organic phosphorus-nitrogen flame retardant@halloysite nanotube hybrid is prepared by the following method: first, hydroxyl modification of halloysite nanotubes is carried out by using alcohol alkali solution, then amino modification is carried out by using amino siloxane, the modified halloysite tubes are added into aqueous solution of organic phosphonic acid, the temperature is raised to a specified temperature and the reaction is carried out for a certain time, then aqueous solution of melamine is slowly added dropwise under continuous stirring, the obtained product is filtered, washed with water and dried, thereby the organic phosphorus-nitrogen flame retardant@halloysite nanotube hybrid is prepared.

[0040] The organic phosphonic acid is selected from one or more of aminotri(methylene)phosphonic acid, phenylphosphonic acid, phytic acid, diethylenetriamine penta(methylene)phosphonic acid, hexanediamine tetra(methylene)phosphonic acid, and ethylenediamine tetra(methylene)phosphonic acid. The molar ratio of the organic phosphonic acid to melamine is 1:3-3:1. The mass ratio of the organic phosphorus-nitrogen flame retardant to halloysite nanotubes is 1:3-3:1.

[0041] The curing agent is one or more of a heterocyclic amine curing agent, an aromatic amine curing agent, an acid anhydride curing agent, or an alicyclic amine curing agent.

[0042] The halloysite nanotubes are treated by alcohol alkali solution, the alcohol of the alcohol alkali solution is at least one of saturated aliphatic alcohol, such as methanol, ethanol, n-propanol, and isopropanol, and is preferably ethanol; and the base of the alcohol alkali solution is at least one of an alkaline solution, such as aqueous sodium hydroxide solution and aqueous potassium hydroxide solution.

[0043] The specified temperature of the reaction is 80-120℃, and the reaction time is 1-24h.

[0044] The amino siloxane is one or more of γ-aminopropyl triethoxysilane, γ-aminopropyl trimethoxysilane, N-(β-aminoethyl)-γ-aminopropyl triethoxysilane, N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane, N-(β-aminoethyl)-γ-aminopropyl methyl dimethoxysilane, N-(β-aminoethyl)-γ-aminopropyl methyl diethoxysilane, γ-aminopropyl methyl diethoxysilane, γ-aminopropyl methyl dimethoxysilane, and γ-aminopropyl ethoxydimethylsilane, and is preferably γ-aminopropyl triethoxysilane.

[0045] Finally, bisphenol A type epoxy resin, organic phosphonic acid metal salt@halloysite nanotube hybrid, and curing agent are weighed according to the ratio, stirred uniformly, and then placed into a polytetrafluoroethylene mold, and cured at different temperature and time segments, with the curing temperature being 100-150℃ and the curing time being 2-8h.

[0046] The present application is described in detail below in combination with the drawings and specific examples. If the preparation methods, materials, structures, or component ratios of features not explicitly described in the technical solution are considered as common technical features disclosed in the prior art.

[0047] Example 1

[0048] A 250 mL aqueous solution with pH value of 10 was prepared by using 0.1 mol / L NaOH solution, 250 mL base solution was mixed with 250 mL ethanol solution; 50 g of halloysite nanotubes were added to the above alcohol-base solution mixture and ultrasonic for 5 min, then stirred at room temperature for 2-5 h, then centrifugal separation or suction filtration, washed with deionized water until neutral, to obtain hydroxylated halloysite nanotubes. 50 g of hydroxylated halloysite nanotubes were added to the amino siloxane solution system, and the mixed system was refluxed at 80℃ for 4-6 h; after the reaction was completed, it was washed with deionized water until neutral, and dried at 80℃ for 24 h to obtain aminated halloysite nanotubes.

[0049] 11.94 g of 50% aminotrimethylene phosphonic acid aqueous solution, 10 g of aminated halloysite nanotubes, and 200 mL of deionized water were weighed into a reaction vessel with a stirrer, heated to 100℃, and stirred for 2 h, then 4.57 g of melamine and 100 mL of deionized water were added to the reactor, and the stirring reaction was continued at 100℃ for 2 h, then the product was filtered and dried to obtain melamine aminotrimethylene phosphonate loaded halloysite nanotubes (ATMP-MEL@HNTs, where the molar ratio of ATMP to MEL is 1.1:2, and the mass ratio of ATMP-MEL to HNTs is 1:1).

[0050] Figure 1 The transmission electron micrograph of unmodified halloysite nanotubes; Figure 2 The transmission electron micrograph of melamine aminotrimethylene phosphonate loaded halloysite nanotubes (the mass ratio of melamine aminotrimethylene phosphonate to halloysite nanotubes is 1:1). From the transmission electron micrograph, it can be seen that the inner cavity and outer surface of the halloysite nanotubes are attached with particulate matter.

[0051] Figure 3 The infrared spectrum of melamine aminotrimethylene phosphonate loaded halloysite nanotubes (the mass ratio of melamine aminotrimethylene phosphonate to halloysite nanotubes is 1:1). From the infrared spectrum, it can be seen that the synthesis of melamine aminotrimethylene phosphonate is successful.

[0052] Figure 4 The thermogravimetric analysis (TGA) curve of epoxy resin and melamine aminotrimethylene phosphonate loaded halloysite nanotubes (the mass ratio of melamine aminotrimethylene phosphonate to halloysite nanotubes is 1:1) / epoxy resin composite (nitrogen atmosphere, heating rate of 10℃ / min). From the TGA curve, it can be seen that the addition of the flame retardant improves the carbon residue of the composite, and the starting decomposition temperature (5% mass loss) of the composite with 2% flame retardant@halloysite nanotube hybrid is reduced by 15.8℃ compared with pure epoxy resin.

[0053] Take 47.4 g of epoxy resin in a 200 mL stainless steel container, place it on a heating type magnetic stirrer to stir at an appropriate speed and warm up to 90°C, take 0.3 g of melamine aminotri methylene phosphonate loaded halloysite nanotube powder in a 50 mL container, stir for 10 min, then add 12.3 g of 4,4'-diaminodiphenylmethane curing agent and continue stirring for 3 min, then vacuum at 90°C for 5 min, and finally pour into the corresponding polytetrafluoroethylene mold, cure at 120°C for 2 h, and cure at 140°C for 2 h. Finally, the epoxy resin composite (the addition amount of melamine aminotri methylene phosphonate loaded modified halloysite nanotube is 0.5 wt%) is obtained. The composition of the epoxy resin composite, the flame retardant test results, and the mechanical test results are shown in Tables 1, 2, and 3.

[0054] Example 2

[0055] The preparation of melamine aminotri methylene phosphonate loaded modified halloysite nanotubes (ATMP-MEL@HNTs) is consistent with Example 1.

[0056] Take 47.2 g of epoxy resin in a 200 mL stainless steel container, place it on a heating type magnetic stirrer to stir at an appropriate speed and warm up to 90°C, take 0.6 g of melamine aminotri methylene phosphonate loaded modified halloysite nanotube powder in a 50 mL container, stir for 10 min, then add 12.2 g of 4,4'-diaminodiphenylmethane curing agent and continue stirring for 3 min, then vacuum at 90°C for 5 min, and finally pour into the corresponding polytetrafluoroethylene mold, cure at 120°C for 2 h, and cure at 140°C for 2 h. Finally, the epoxy resin composite (the addition amount of melamine aminotri methylene phosphonate loaded modified halloysite nanotube is 1 wt%) is obtained. The composition of the epoxy resin composite, the flame retardant test results, and the mechanical test results are shown in Tables 1, 2, and 3.

[0057] Example 3

[0058] The preparation of melamine aminotri methylene phosphonate loaded modified halloysite nanotubes (ATMP-MEL@HNTs) is consistent with Example 1.

[0059] Take 46.7 g of epoxy resin in a 200 mL stainless steel container, place it on a heating type magnetic stirrer to stir at an appropriate speed and heat to 90°C, take 1.2 g of melamine aminotri methylene phosphonate modified halloysite nanotube powder in a 50 mL container, stir for 10 min, then add 12.1 g of 4,4'-diaminodiphenylmethane curing agent and continue to stir for 3 min, then vacuum at 90°C for 5 min, and finally pour into the corresponding polytetrafluoroethylene mold, and cure at 120°C for 2 h and at 140°C for 2 h. Finally, an epoxy resin composite (the addition amount of melamine aminotri methylene phosphonate modified halloysite nanotube is 2wt%) is obtained. The composition of the epoxy resin composite, the flame retardant test results, and the mechanical test results are shown in Tables 1, 2, and 3.

[0060] Example 4

[0061] Take 11.94 g of 50% aminotri methylene phosphonic acid aqueous solution, 20 g of aminated halloysite nanotubes, and 200 mL of deionized water into a reaction container with a stirrer, heat to 100°C, and react for 2 h under stirring, then add 4.57 g of melamine and 100 mL of deionized water to the reactor, continue to stir and react at 100°C for 2 h, then filter, boil water wash, and dry the product to obtain melamine aminotri methylene phosphonate modified halloysite nanotubes (ATMP-MEL@HNTs, where the molar ratio of ATMP to MEL is 1.1:2, and the mass ratio of ATMP-MEL to HNTs is 1:2).

[0062] Take 47.4 g of epoxy resin in a 200 mL stainless steel container, place it on a heating type magnetic stirrer to stir at an appropriate speed and heat to 90°C, take 0.3 g of melamine aminotri methylene phosphonate modified halloysite nanotube powder in a 50 mL container, stir for 10 min, then add 12.3 g of 4,4'-diaminodiphenylmethane curing agent and continue to stir for 3 min, then vacuum at 90°C for 5 min, and finally pour into the corresponding polytetrafluoroethylene mold, and cure at 120°C for 2 h and at 140°C for 2 h. Finally, an epoxy resin composite (the addition amount of melamine aminotri methylene phosphonate modified halloysite nanotube is 0.5wt%) is obtained. The composition of the epoxy resin composite, the flame retardant test results, and the mechanical test results are shown in Tables 1, 2, and 3.

[0063] Example 5

[0064] The method for preparing melamine aminotri methylene phosphonate modified halloysite nanotubes (ATMP-MEL@HNTs) is consistent with Example 4.

[0065] Take 47.2 g of epoxy resin in a 200 mL stainless steel container, place it on a heating type magnetic stirrer to stir at an appropriate speed and heat to 90°C, take 0.6 g of melamine aminotrimethylene phosphonate loaded modified halloysite nanotube powder in a 50 mL container, stir for 10 min, then add 12.2 g of 4,4'-diaminodiphenyl methane curing agent and continue to stir for 3 min, then vacuum at 90°C for 5 min, and finally pour into the corresponding polytetrafluoroethylene mold, and cure at 120°C for 2 h and at 140°C for 2 h. Finally, an epoxy resin composite material (the addition amount of melamine aminotrimethylene phosphonate loaded modified halloysite nanotube is 1 wt%) is obtained. The composition of the epoxy resin composite material, the flame retardant test results, and the mechanical test results are shown in Tables 1-3.

[0066] Example 6

[0067] The preparation of melamine aminotrimethylene phosphonate loaded modified halloysite nanotubes (ATMP-MEL@HNTs) is consistent with Example 4.

[0068] Take 47.2 g of epoxy resin in a 200 mL stainless steel container, place it on a heating type magnetic stirrer to stir at an appropriate speed and heat to 90°C, take 0.6 g of melamine aminotrimethylene phosphonate loaded modified halloysite nanotube powder in a 50 mL container, stir for 10 min, then add 12.2 g of 4,4'-diaminodiphenyl methane curing agent and continue to stir for 3 min, then vacuum at 90°C for 5 min, and finally pour into the corresponding polytetrafluoroethylene mold, and cure at 120°C for 2 h and at 140°C for 2 h. Finally, an epoxy resin composite material (the addition amount of melamine aminotrimethylene phosphonate loaded modified halloysite nanotube is 1 wt%) is obtained. The composition of the epoxy resin composite material, the flame retardant test results, and the mechanical test results are shown in Tables 1-3.

[0069] Comparative Example 1

[0070] Take 47.2 g of epoxy resin in a 200 mL stainless steel container, place it on a heating type magnetic stirrer to stir at an appropriate speed and heat to 90°C, take 0.6 g of melamine aminotrimethylene phosphonate loaded modified halloysite nanotube powder in a 50 mL container, stir for 10 min, then add 12.2 g of 4,4'-diaminodiphenyl methane curing agent and continue to stir for 3 min, then vacuum at 90°C for 5 min, and finally pour into the corresponding polytetrafluoroethylene mold, and cure at 120°C for 2 h and at 140°C for 2 h. Finally, an epoxy resin composite material (the addition amount of melamine aminotrimethylene phosphonate loaded modified halloysite nanotube is 1 wt%) is obtained. The composition of the epoxy resin composite material, the flame retardant test results, and the mechanical test results are shown in Tables 1-3.

[0071] Comparative Example 2

[0072] Take 47.2 g of epoxy resin in a 200 mL stainless steel container, place it on a heating type magnetic stirrer to stir at an appropriate speed and heat to 90°C, take 0.6 g of amino-eriochite nanotube powder (preparation method refer to example 1) in a 50 mL container, stir for 10 min, then add 12.3 g of 4,4'-diaminodiphenyl methane curing agent and continue to stir for 3 min, then vacuum at 90°C for 5 min, finally pour into the corresponding polytetrafluoroethylene mold, cure at 120°C for 2h, 140°C for 2h. Finally, the epoxy resin composite (eriochite addition amount is 1wt%) is obtained. The composition of the epoxy resin composite, the flame retardant test results, the mechanical test results are shown in Tables 1-3.

[0073] Comparative example 3

[0074] Preparation of melamine powder aminotri (methylene) phosphonate flame retardant (preparation method refer to CN 104497041A.

[0075] Take 47.2 g of epoxy resin in a 200 mL stainless steel container, place it on a heating type magnetic stirrer to stir at an appropriate speed and heat to 90°C, take 0.6 g of melamine powder aminotri (methylene) phosphonate flame retardant in a 50 mL container, stir for 10 min, then add 12.3 g of 4,4'-diaminodiphenyl methane curing agent and continue to stir for 3 min, then vacuum at 90°C for 5 min, finally pour into the corresponding polytetrafluoroethylene mold, cure at 120°C for 2h, 140°C for 2h. Finally, the epoxy resin composite (melamine powder aminotri (methylene) phosphonate flame retardant addition amount is 1wt%) is obtained. The composition of the epoxy resin composite, the flame retardant test results, the mechanical test results are shown in Tables 1, 2, 3.

[0076] As can be seen from Table 2, the melamine aminotri (methylene) phosphonate@eriochite nanotube hybrid added to the epoxy resin has obvious improvement in flame retardant effect, which proves that melamine aminotri (methylene) phosphonate and eriochite nanotube can synergistically flame retardant. When the addition amount is 1wt% and 2wt%, melamine aminotri (methylene) phosphonate@eriochite nanotube loaded at a mass ratio of 1:2, 1:1 can improve the flame retardant performance of epoxy composite the most, and the LOI and flame retardant grade are obviously improved, among which the flame retardant performance of melamine aminotri (methylene) phosphonate loaded eriochite nanotube at a ratio of 1:1 is the best.

[0077] From Table 3, it can be seen that the two different load ratios of the same 1 wt% addition amount of melamine aminotri (methylenephosphonate) @ halloysite nanotube hybrid / epoxy resin composite samples, namely Example 2 and Example 5, have load ratios of 1:1 and 1:2, respectively. It can be seen that, as the load ratio of melamine aminotri (methylenephosphonate) to halloysite nanotubes decreases, i.e. the content of halloysite nanotubes increases, the impact performance of the material increases between 34-37 kJ / m 2 The melamine aminotri (methylenephosphonate) @ halloysite nanotube hybrid / epoxy resin composite sample can obviously improve the mechanical properties while ensuring the best UL-94 rating V-0, and compared with pure epoxy resin, the tensile strength can be increased by 17.1% and the impact strength can be increased by 42.3%. This can improve the mechanical properties of epoxy resin, has high flame retardant efficiency, and is expected to be applied in the industrialization fields of advanced equipment, automobiles, electronics and electrical appliances, etc.

[0078] Table 1 Composition of epoxy resin composite prepared in each example and control example

[0079]

[0080]

[0081] Note: ATMP-MEL@HNTs = 1:1 indicates that melamine aminotri (methylenephosphonate) is loaded on halloysite nanotubes, the molar ratio of aminotri (methylenephosphonate) to melamine is 1.1:2, and the mass ratio of melamine aminotri (methylenephosphonate) to halloysite nanotubes is 1:1; ATMP-MEL@HNTs = 1:2 indicates that melamine aminotri (methylenephosphonate) is loaded on halloysite nanotubes, the molar ratio of aminotri (methylenephosphonate) to melamine is 1.1:2, and the mass ratio of melamine aminotri (methylenephosphonate) to halloysite nanotubes is 1:2; ATMP-MEL@HNTs = 1:3 indicates that melamine aminotri (methylenephosphonate) is loaded on halloysite nanotubes, the molar ratio of aminotri (methylenephosphonate) to melamine is 1.1:2, and the mass ratio of melamine aminotri (methylenephosphonate) to halloysite nanotubes is 1:3; N-HNTs indicates aminated halloysite nanotubes; ATMP-MEL indicates melamine aminotri (methylenephosphonate), the molar ratio of aminotri (methylenephosphonate) to melamine is 1:2; EP indicates bisphenol A type epoxy resin; and DDM indicates 4,4'-diaminodiphenylmethane.

[0082] Table 2 Flame retardant properties of epoxy resin composite prepared in each example and control example

[0083]

[0084] Table 3: Mechanical properties of epoxy resin composite materials prepared in each example and control example

[0085]

[0086]

[0087] The foregoing description of the examples has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed, and various modifications and variations are possible in light of the above teachings or can be acquired from practice of the application. The examples were chosen and described in order to explain the principles of the application and its practical application and to enable others skilled in the art to understand the application for various embodiments and with various modifications as are suited to the particular use contemplated. Accordingly, the patentable scope of the application should be defined by the following claims.

Claims

1. An organophosphorus-nitrogen based flame retardant-halloysite nanotube hybrid / epoxy resin composite material, characterized by, The following components are included by weight percentage: Organic phosphorus-nitrogen type flame retardant@halloysite nanotube hybrid 1%~2%; Curing agent 18%~22%; Bisphenol A type epoxy resin 68%~81.5%; The sum of the above components is 100%; The curing agent is selected from one or more of the following: heterocyclic amine curing agent, aromatic amine curing agent, acid anhydride curing agent, alicyclic amine curing agent; The organic phosphonic acid is selected from one or more of the following: aminotri(methylene) phosphonic acid, diethylene triamine penta(methylene) phosphonic acid, hexanediamine tetra(methylene) phosphonic acid, ethylenediamine tetra(methylene) phosphonic acid; The preparation method of the organic phosphorus-nitrogen type flame retardant@halloysite nanotube hybrid / epoxy resin composite material includes the following steps: S1: hydroxyl modification of halloysite nanotubes using an alcohol alkali solution to obtain material A; S2: aminization modification of material A using amino siloxane to obtain material B; S3: adding material B to an aqueous organic phosphonic acid solution, warming and reacting, then slowly adding an aqueous melamine solution, and reacting under constant stirring, then filtering, washing with water, and drying the obtained product to prepare an organic phosphorus-nitrogen type flame retardant@halloysite nanotube hybrid; S4: mixing and curing to obtain an organic phosphorus-nitrogen type flame retardant@halloysite nanotube hybrid / epoxy resin composite material.

2. A method for preparing an organophosphorus-nitrogen flame retardant-halloysite nanotube hybrid / epoxy resin composite as claimed in claim 1, characterized in that, The following steps are included: S1: hydroxyl modification of halloysite nanotubes using an alcohol alkali solution to obtain material A; S2: aminization modification of material A using amino siloxane to obtain material B; S3: adding material B to an aqueous organic phosphonic acid solution, warming and reacting, then slowly adding an aqueous melamine solution, and reacting under constant stirring, then filtering, washing with water, and drying the obtained product to prepare an organic phosphorus-nitrogen type flame retardant@halloysite nanotube hybrid; S4: mixing and curing to obtain an organic phosphorus-nitrogen type flame retardant@halloysite nanotube hybrid / epoxy resin composite material.

3. The method for preparing an organophosphorus-nitrogen flame retardant-halloysite nanotube hybrid / epoxy resin composite material according to claim 2, characterized in that, In S3, the molar ratio of the organic phosphonic acid to melamine is 1:3~3:1; In S3, the temperature of the warming reaction is 80~120 ℃, and the reaction time is 1~24 h.

4. The method for preparing an organophosphorus-nitrogen flame retardant-halloysite nanotube hybrid / epoxy resin composite material according to claim 2, characterized in that, In S1, the alcohol in the alcohol alkali is a saturated aliphatic alcohol, and the base in the alcohol alkali is selected from at least one of the following: aqueous sodium hydroxide solution, aqueous potassium hydroxide solution.

5. The method for preparing an organophosphorus-nitrogen flame retardant-halloysite nanotube hybrid / epoxy resin composite material according to claim 4, characterized in that, The alcohol in the alcohol alkali is selected from at least one of the following: methanol, ethanol, n-propanol, isopropanol.

6. The method for preparing an organophosphorus-nitrogen flame retardant-halloysite nanotube hybrid / epoxy resin composite material according to claim 2, characterized by, In S2, the amino siloxane is selected from one or more of the following: γ-aminopropyl triethoxysilane, γ-aminopropyl trimethoxysilane, N-(β-aminoethyl)-γ-aminopropyl triethoxysilane, N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane, N-(β-aminoethyl)-γ-aminopropyl methyl dimethoxysilane, N-(β-aminoethyl)-γ-aminopropyl methyl diethoxysilane, γ-aminopropyl methyl diethoxysilane, γ-aminopropyl methyl dimethoxysilane, γ-aminopropyl ethoxydimethylsilane.

7. The method for preparing an organophosphorus-nitrogen flame retardant-halloysite nanotube hybrid / epoxy resin composite material according to claim 2, characterized by, In S4, bisphenol A type epoxy resin, organic phosphonic acid metal salt@halloysite nanotube hybrid and curing agent are weighed according to the proportion, uniformly stirred and then put into a polytetrafluoroethylene mold, and cured in different temperature and time sections, with a curing temperature of 100~150 ℃ and a curing time of 2~8 h.

8. Application of the organic phosphorus-nitrogen flame retardant@halloysite nanotube hybrid / epoxy resin composite material as claimed in claim 1 in special epoxy resin materials.

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