Modified epoxy heat-resistant flame-retardant coating and preparation method thereof

Abstract

The invention relates to the technical field of coatings, and discloses a modified epoxy heat-resistant flame-retardant coating and a preparation method thereof.The preparation method comprises the steps that flame-retardant modified halloysite nanotubes, deionized water, epoxy resin, boron phenolic resin, a defoaming agent and a flatting agent are mixed to be uniform and discharged, and the modified epoxy heat-resistant flame-retardant coating is obtained. Diethyl hypophosphorous acid ethylene oxide methyl ester and boric acid modified halloysite nanotubes react to obtain flame-retardant modified halloysite nanotubes, and the halloysite nanotubes and the organic flame retardant diethyl hypophosphorous acid ethylene oxide methyl ester have a synergistic effect, so that agglomeration of the halloysite nanotubes is avoided, migration of a small-molecule organic flame retardant is avoided, and the flame retardance of the halloysite nanotubes is improved. The boron phenolic resin, the flame-retardant modified halloysite nanotubes and the epoxy resin form a three-dimensional cross-linked thermosetting network structure, so that the hardness, wear resistance and impact resistance of the coating can be improved, and the obtained coating has excellent flame retardance and heat resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of paint, in particular to a modified epoxy heat-resistant and flame-retardant coating and a preparation method thereof. BACKGROUND

[0002] Epoxy resin is a kind of thermosetting resin with excellent adhesion, insulation, corrosion resistance and mechanical properties, and excellent process performance, which is widely used in chemical coatings, electronics and electrical and aerospace fields. With the rapid development of economy, the application of epoxy resin coating in life is becoming more and more widely. However, the flammability of epoxy resin is an inevitable defect, which has great safety hazards in use. In recent years, people have carried out a lot of in-depth research on improving the flame retardance of epoxy resin.

[0003] The fireproof effect of epoxy resin flame-retardant coating mainly comes from the flame-retardant additive therein, which delays the ignition time by adding flame retardant, thereby preventing the spread of fire. Chinese patent application CN112760009A discloses an epoxy coating with flame-retardant function, which is prepared by reacting chlorinated paraffin and p-hydroxy benzoic acid to obtain chlorinated paraffin containing carboxyl, then acylating to obtain hydroxyl isocyanurate modified chlorinated paraffin by esterification reaction with tris(2-hydroxyethyl) isocyanurate, reacting with trimellitic anhydride to obtain chlorinated paraffin diacid, and then reacting with epoxy chloropropane to obtain epoxy resin with flame-retardant function. The epoxy coating has excellent flame-retardant and heat-resistant properties, and the flame retardant is not easy to precipitate, and the flame-retardant property is durable. However, the halogen-containing flame retardant in the epoxy coating is easy to release a large amount of smoke and toxic gas during combustion, which is easy to cause environmental pollution and harm human health. Chinese patent application CN104449218A discloses a corrosion-resistant epoxy resin coating, which comprises: epoxy resin, phenolic resin, terpene resin, chlorobutyl rubber, hydroxymethyl cellulose, modified yttrium oxide, sepiolite powder, kaolin, nano aluminum nitride, organic bentonite, sodium lauryl sulfate, dimethyl phthalate, microcapsule red phosphorus, melamine phosphate, antimony trioxide, drier, pigment, toughening agent, defoaming agent, leveling agent and mildewcide. The epoxy resin coating has excellent corrosion resistance and excellent heat-resistant and flame-retardant properties. However, a large amount of inorganic nano materials are added, which is easy to agglomerate, greatly limiting the performance of the composite material, and the flame retardant is easy to precipitate.

[0004] Therefore, it is an urgent problem to develop an epoxy coating with excellent comprehensive performance of heat resistance and flame retardance. SUMMARY

[0005] (1) Technical problem solved

[0006] In view of the deficiencies of the prior art, the present application provides a modified epoxy heat-resistant and flame-retardant coating and a preparation method thereof, which solves the problems of poor flame retardance and heat resistance of epoxy resin coating.

[0007] (II) Technical Solution

[0008] In order to achieve the above-mentioned purpose, the application discloses a preparation method of modified epoxy heat-resistant flame-retardant coating, comprising the following steps:

[0009] S1, ultrasonic dispersion of halloysite nanotubes into an ethanol aqueous solution, after uniform ultrasonic dispersion, adjustment of pH to 5 by using acetic acid, addition of gamma-aminopropyl triethoxysilane, temperature increase, stirring and mixing, reaction, centrifugal separation after reaction end, washing of the product to neutral by using deionized water, vacuum drying at 80℃ for 12h, and obtaining of aminated halloysite nanotubes;

[0010] S2, ultrasonic dispersion of the aminated halloysite nanotubes into N,N-dimethylformamide, after uniform ultrasonic dispersion, addition of 4-aminobenzoic acid, temperature increase in a nitrogen atmosphere, stirring and mixing, reaction, suction filtration after reaction end, washing by using ethyl acetate, vacuum drying at 80℃ for 12h, and obtaining of borate-modified halloysite nanotubes;

[0011] S3, ultrasonic dispersion of the borate-modified halloysite nanotubes into anhydrous ethanol, after uniform dispersion, addition of diethyl hypophosphite oxymethylene methyl ester, stirring and mixing, reaction, centrifugal separation after reaction end, washing by using anhydrous ethanol after centrifugal separation, vacuum drying at 80℃ for 12h, and obtaining of flame-retardant modified halloysite nanotubes;

[0012] S4, ultrasonic dispersion of the flame-retardant modified halloysite nanotubes into deionized water, after uniform dispersion, addition of epoxy resin, dispersion in a high-speed dispersion machine at a dispersion rate of 1500-1600r / min for 5-8min, further addition of boron phenolic resin, defoaming agent and leveling agent, stirring and mixing at a stirring rate of 900-1200r / min for 10-12min, and obtaining of the modified epoxy heat-resistant flame-retardant coating after uniform mixing and discharging.

[0013] Preferably, the ethanol aqueous solution in S1 is mixed by anhydrous ethanol and deionized water in a volume ratio of 9:1, and the mass ratio of the halloysite nanotubes, the ethanol aqueous solution, and the gamma-aminopropyl triethoxysilane is 100:(3200-4000):(420-550).

[0014] Preferably, the temperature of the reaction in S1 is 75-85℃, and the reaction time is 5-8h.

[0015] Preferably, the mass ratio of the aminated halloysite nanotubes, the N,N-dimethylformamide, and the 4-aminobenzoic acid in S2 is 100:(1800-2000):(16-21).

[0016] Preferably, the temperature of the reaction in S2 is 95-105 DEG C, and the reaction time is 4-6h.

[0017] Preferably, the mass ratio of the borate modified halloysite nanotube, anhydrous ethanol and diethyl hypophosphite oxirane methyl ester in S3 is 100:(2500-3200):(60-85).

[0018] Preferably, the temperature of the reaction in S3 is 65-75 DEG C, and the reaction time is 6-9h.

[0019] Preferably, the mass ratio of the flame-retardant modified halloysite nanotube, deionized water, epoxy resin, boron phenolic resin, defoaming agent and leveling agent in S4 is (2-5):(120-150):100:(12-30):(0.5-1.2):(0.3-0.5).

[0020] Preferably, the leveling agent in S4 is polyether modified polysiloxane, and the defoaming agent is defoaming agent SPA202.

[0021] Preferably, the modified epoxy heat-resistant flame-retardant coating is prepared by the preparation method of the modified epoxy heat-resistant flame-retardant coating.

[0022] In the present application, the halloysite nanotube is modified by using gamma-aminopropyl triethoxysilane, the amino silane is introduced on the surface of the halloysite nanotube to obtain the aminated halloysite nanotube, the amino group on the surface of the halloysite nanotube reacts with the boron hydroxyl group on the 4-aminobenzene boronic acid to introduce the boronic acid on the surface of the halloysite nanotube, and meanwhile, the new amino group is introduced to obtain the borate modified halloysite nanotube, the amino group on the borate modified halloysite nanotube reacts with the diethyl hypophosphite oxirane methyl ester to introduce a large number of hydroxyl groups to obtain the flame-retardant modified halloysite nanotube, and the flame-retardant modified halloysite nanotube, the epoxy resin, the boron phenolic resin, the defoaming agent and the leveling agent are uniformly mixed to obtain the modified epoxy heat-resistant flame-retardant coating.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] (1) The halloysite nanotubes in the present application have excellent mechanical properties and flame retardant properties. During the combustion process, the crystal water in the structure can be released and converted into water vapor, absorbing heat. At the same time, the decomposition products can uniformly cover the surface of the epoxy resin matrix, slowing down the combustion reaction. After surface organic modification of halloysite nanotubes, agglomeration is effectively avoided, and they can be uniformly dispersed in the epoxy resin matrix to form a uniform mechanical network, improving the mechanical properties of the epoxy resin. The organic flame retardant diethyl hypophosphite oxymethylene methyl ester introduced during the reaction will produce acidic substances such as phosphoric acid during the combustion process, promoting the dehydration and carbonization of the matrix and the formation of a carbon layer on the matrix, improving the carbonization efficiency of the matrix and generating PO· free radicals that can quench the combustion chain reaction and prevent the combustion reaction from proceeding. The introduced silane can form a silicon carbon layer on the surface of the matrix during the combustion process, effectively improving the density of the carbon layer on the surface of the matrix, effectively blocking the transfer of heat and oxygen, and further delaying the combustion process. The nitrogen element introduced during the combustion process can produce non-combustible gases, diluting the oxygen concentration and smoke concentration required during the combustion process. The synergistic effect of halloysite nanotubes and organic flame retardants improves the flame retardant efficiency and ability, while solving the problem of easy migration of small molecule organic flame retardants. The boron element introduced in the halloysite nanotubes and the boron element on the boron phenolic resin can significantly reduce the heat release rate and total heat release of the epoxy resin during the combustion process, thereby slowing down the flame spread rate and improving the flame retardant properties of the matrix. At the same time, it improves the thermal stability of the epoxy resin, making it less likely to decompose at high temperatures.

[0025] (2) The boron phenolic resin added in the present application has excellent high temperature resistance, mechanical properties and chemical corrosion resistance, which can significantly improve the high temperature resistance, mechanical properties and corrosion resistance of the epoxy resin coating. The phenolic hydroxyl groups in the boron phenolic resin and the hydroxyl groups on the flame-retardant modified halloysite nanotubes can chemically react with the epoxy groups in the epoxy resin to form new chemical bonds, forming a three-dimensional cross-linked thermoset network structure between the raw materials. This structure helps to improve the overall strength and stability of the coating layer formed by the coating, forming a tougher and more durable coating, improving the hardness, wear resistance and impact resistance of the coating. The boron phenolic resin and the epoxy resin can produce a synergistic effect during the curing process, promoting the cross-linking reaction and helping to form a more dense and stable coating structure, effectively blocking the intrusion of external moisture, oxygen and corrosive media, thereby protecting the substrate from damage and improving the overall performance of the coating. Further, the thermal stability of the epoxy resin coating can be improved after the reaction, which helps to prolong the service life of the coating and protect the integrity of the substrate. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0027] Embodiment 1

[0028] A preparation method of a modified epoxy heat-resistant flame-retardant coating, comprising the following steps:

[0029] S1, mixing anhydrous ethanol and deionized water in a volume ratio of 9:1 to obtain an ethanol aqueous solution, ultrasonically dispersing halloysite nanotubes into the ethanol aqueous solution, after uniform ultrasonic dispersion, adjusting pH to 5 using acetic acid, adding γ-aminopropyl triethoxysilane, the mass ratio of halloysite nanotubes, the ethanol aqueous solution and γ-aminopropyl triethoxysilane being 100:3200:420, warming, stirring and mixing, reacting at 75℃ for 8h, after the reaction is completed, centrifugal separation, washing the product with deionized water until neutral, vacuum drying at 80℃ for 12h to obtain aminated halloysite nanotubes;

[0030] S2, ultrasonically dispersing the aminated halloysite nanotubes into N,N-dimethylformamide, after uniform ultrasonic dispersion, adding 4-aminobenzoic acid, the mass ratio of the aminated halloysite nanotubes, N,N-dimethylformamide and 4-aminobenzoic acid being 100:1800:16, warming, stirring and mixing in a nitrogen atmosphere, reacting at 95℃ for 6h, after the reaction is completed, suction filtration, washing with ethyl acetate, vacuum drying at 80℃ for 12h to obtain boronic acid modified halloysite nanotubes;

[0031] S3, ultrasonically dispersing the boronic acid modified halloysite nanotubes into anhydrous ethanol, after uniform dispersion, adding diethyl hypophosphite oxymethylene methyl ester, the mass ratio of the boronic acid modified halloysite nanotubes, anhydrous ethanol and diethyl hypophosphite oxymethylene methyl ester being 100:2500:60, stirring and mixing, reacting at 65℃ for 9h, after the reaction is completed, centrifugal separation, after centrifugal separation, washing with anhydrous ethanol, vacuum drying at 80℃ for 12h to obtain flame-retardant modified halloysite nanotubes;

[0032] S4, the flame-retardant modified halloysite nanotube is ultrasonically dispersed into deionized water, after uniform dispersion, epoxy resin is added, the dispersion rate is 1500 r / min in a high-speed dispersion machine, the dispersion time is 8 min, boron phenolic resin, defoaming agent and leveling agent are added, stirring and mixing, the stirring rate is 900 r / min, the stirring time is 12 min, the mass ratio of the flame-retardant modified halloysite nanotube, deionized water, epoxy resin, boron phenolic resin, defoaming agent SPA202 and leveling agent polyether modified polysiloxane is 2:120:100:12:0.5:0.3, after uniform mixing, the material is discharged, and a modified epoxy heat-resistant flame-retardant coating is obtained.

[0033] Example 2

[0034] A preparation method of a modified epoxy heat-resistant flame-retardant coating comprises the following steps:

[0035] S1, anhydrous ethanol and deionized water with a volume ratio of 9:1 are mixed to obtain an ethanol aqueous solution, halloysite nanotubes are ultrasonically dispersed into the ethanol aqueous solution, after uniform ultrasonic dispersion, acetic acid is used to adjust the pH to 5, γ-aminopropyl triethoxysilane is added, the mass ratio of the halloysite nanotube, the ethanol aqueous solution and the γ-aminopropyl triethoxysilane is 100:3600:500, temperature is raised, stirring and mixing are performed, and the reaction is carried out at 80℃ for 6 hours; after the reaction is completed, centrifugal separation is performed, the product is washed to neutral with deionized water, and vacuum drying is performed at 80℃ for 12 hours to obtain aminated halloysite nanotubes;

[0036] S2, the aminated halloysite nanotubes are ultrasonically dispersed into N,N-dimethylformamide, after uniform ultrasonic dispersion, 4-aminobenzoic acid is added, the mass ratio of the aminated halloysite nanotube, the N,N-dimethylformamide and the 4-aminobenzoic acid is 100:1850:18, temperature is raised, stirring and mixing are performed in a nitrogen atmosphere, and the reaction is carried out at 100℃ for 5 hours; after the reaction is completed, suction filtration is performed, washing is performed with ethyl acetate, and vacuum drying is performed at 80℃ for 12 hours to obtain boronic acid modified halloysite nanotubes;

[0037] S3, the boronic acid modified halloysite nanotubes are ultrasonically dispersed into anhydrous ethanol, after uniform dispersion, diethyl hypophosphite oxymethylene methyl ester is added, the mass ratio of the boronic acid modified halloysite nanotube, the anhydrous ethanol and the diethyl hypophosphite oxymethylene methyl ester is 100:2700:70, stirring and mixing are performed, and the reaction is carried out at 70℃ for 7 hours; after the reaction is completed, centrifugal separation is performed, after centrifugation, washing is performed with anhydrous ethanol, and vacuum drying is performed at 80℃ for 12 hours to obtain flame-retardant modified halloysite nanotubes;

[0038] S4, the flame-retardant modified halloysite nanotube is ultrasonically dispersed into deionized water, after uniform dispersion, epoxy resin is added, the dispersion rate is 1550 r / min in a high-speed dispersion machine, the dispersion time is 6 min, boron phenolic resin, defoaming agent and leveling agent are added, stirring and mixing, the stirring rate is 1000 r / min, the stirring time is 11 min, the mass ratio of the flame-retardant modified halloysite nanotube, deionized water, epoxy resin, boron phenolic resin, defoaming agent SPA202 and leveling agent polyether modified polysiloxane is 3:130:100:18:1:0.4, after uniform mixing, the material is discharged, and a modified epoxy heat-resistant flame-retardant coating is obtained.

[0039] Example 3

[0040] A preparation method of a modified epoxy heat-resistant flame-retardant coating, comprising the following steps:

[0041] S1, anhydrous ethanol and deionized water with a volume ratio of 9:1 are mixed to obtain an ethanol aqueous solution, halloysite nanotubes are ultrasonically dispersed into the ethanol aqueous solution, after uniform ultrasonic dispersion, acetic acid is used to adjust the pH to 5, γ-aminopropyl triethoxysilane is added, the mass ratio of the halloysite nanotube, the ethanol aqueous solution and the γ-aminopropyl triethoxysilane is 100:3600:500, temperature is raised, stirring and mixing are carried out, and the reaction is carried out at 80℃ for 6 hours; after the reaction is completed, centrifugal separation is carried out, the product is washed to neutral with deionized water, and vacuum drying is carried out at 80℃ for 12 hours, so as to obtain aminated halloysite nanotubes;

[0042] S2, the aminated halloysite nanotubes are ultrasonically dispersed into N,N-dimethylformamide, after uniform ultrasonic dispersion, 4-aminobenzoic acid is added, the mass ratio of the aminated halloysite nanotube, the N,N-dimethylformamide and the 4-aminobenzoic acid is 100:1950:20, temperature is raised, stirring and mixing are carried out in a nitrogen atmosphere, and the reaction is carried out at 100℃ for 5 hours; after the reaction is completed, suction filtration is carried out, washing is carried out with ethyl acetate, and vacuum drying is carried out at 80℃ for 12 hours, so as to obtain boronic acid modified halloysite nanotubes;

[0043] S3, the boronic acid modified halloysite nanotubes are ultrasonically dispersed into anhydrous ethanol, after uniform dispersion, diethyl hypophosphite oxymethylene methyl ester is added, the mass ratio of the boronic acid modified halloysite nanotube, the anhydrous ethanol and the diethyl hypophosphite oxymethylene methyl ester is 100:3000:80, stirring and mixing are carried out, the reaction is carried out at 70℃ for 8 hours, after the reaction is completed, centrifugal separation is carried out, after centrifugal separation, washing is carried out with anhydrous ethanol, and vacuum drying is carried out at 80℃ for 12 hours, so as to obtain flame-retardant modified halloysite nanotubes;

[0044] S4, the flame-retardant modified halloysite nanotube is ultrasonically dispersed into deionized water, after uniform dispersion, epoxy resin is added, the dispersion rate is 1550 r / min in a high-speed dispersion machine, the dispersion time is 7 min, boron phenolic resin, defoaming agent and leveling agent are added, stirring and mixing, the stirring rate is 1100 r / min, the stirring time is 11 min, the mass ratio of the flame-retardant modified halloysite nanotube, deionized water, epoxy resin, boron phenolic resin, defoaming agent SPA202 and leveling agent polyether modified polysiloxane is 4:140:100:25:1:0.4, after uniform mixing, the material is discharged, and a modified epoxy heat-resistant flame-retardant coating is obtained.

[0045] Example 4

[0046] A preparation method of a modified epoxy heat-resistant flame-retardant coating, comprising the following steps:

[0047] S1, anhydrous ethanol and deionized water with a volume ratio of 9:1 are mixed to obtain an ethanol aqueous solution, halloysite nanotubes are ultrasonically dispersed into the ethanol aqueous solution, after uniform ultrasonic dispersion, acetic acid is used to adjust the pH to 5, γ-aminopropyl triethoxysilane is added, the mass ratio of the halloysite nanotube, the ethanol aqueous solution and the γ-aminopropyl triethoxysilane is 100:4000:550, temperature is raised, stirring and mixing are carried out, and the reaction is carried out at 85℃ for 5h; after the reaction is completed, centrifugal separation is carried out, the product is washed to neutral with deionized water, and vacuum drying is carried out at 80℃ for 12h to obtain aminated halloysite nanotubes;

[0048] S2, the aminated halloysite nanotubes are ultrasonically dispersed into N,N-dimethylformamide, after uniform ultrasonic dispersion, 4-aminobenzoic acid is added, the mass ratio of the aminated halloysite nanotube, the N,N-dimethylformamide and the 4-aminobenzoic acid is 100:2000:21, temperature is raised, stirring and mixing are carried out in a nitrogen atmosphere, and the reaction is carried out at 105℃ for 4h; after the reaction is completed, suction filtration is carried out, washing is carried out with ethyl acetate, and vacuum drying is carried out at 80℃ for 12h to obtain boronic acid modified halloysite nanotubes;

[0049] S3, the boronic acid modified halloysite nanotubes are ultrasonically dispersed into anhydrous ethanol, after uniform dispersion, diethyl hypophosphite oxymethylene methyl ester is added, the mass ratio of the boronic acid modified halloysite nanotube, the anhydrous ethanol and the diethyl hypophosphite oxymethylene methyl ester is 100:3200:85, stirring and mixing are carried out, and the reaction is carried out at 75℃ for 6h; after the reaction is completed, centrifugal separation is carried out, after centrifugation, washing is carried out with anhydrous ethanol, and vacuum drying is carried out at 80℃ for 12h to obtain flame-retardant modified halloysite nanotubes;

[0050] S4, the flame-retardant modified halloysite nanotube is ultrasonically dispersed into deionized water, after uniform dispersion, epoxy resin is added, dispersion is carried out in a high-speed dispersion machine, the dispersion rate is 1600 r / min, the dispersion time is 5 min, then boron phenolic resin, defoaming agent and leveling agent are added, stirring and mixing are carried out, the stirring rate is 1200 r / min, the stirring time is 10 min, wherein the mass ratio of the flame-retardant modified halloysite nanotube, deionized water, epoxy resin, boron phenolic resin, defoaming agent SPA202 and leveling agent polyether modified polysiloxane is 5:150:100:30:1.2:0.5, after uniform mixing, the material is discharged, and a modified epoxy heat-resistant flame-retardant coating is obtained.

[0051] Comparative example 1

[0052] A preparation method of a modified epoxy heat-resistant flame-retardant coating comprises the following steps:

[0053] S1, anhydrous ethanol and deionized water are mixed in a volume ratio of 9:1 to obtain an ethanol aqueous solution, halloysite nanotubes are ultrasonically dispersed into the ethanol aqueous solution, after uniform ultrasonic dispersion, acetic acid is used to adjust the pH to 5, γ-aminopropyl triethoxysilane is added, the mass ratio of the halloysite nanotube, the ethanol aqueous solution and the γ-aminopropyl triethoxysilane is 100:3600:500, temperature is raised, stirring and mixing are carried out, the reaction is carried out at 80℃ for 6 h, after the reaction is completed, centrifugal separation is carried out, the product is washed to neutral with deionized water, and vacuum drying is carried out at 80℃ for 12 h, to obtain amino-modified halloysite nanotubes;

[0054] S2, the amino-modified halloysite nanotubes are ultrasonically dispersed into N,N-dimethylformamide, after uniform ultrasonic dispersion, 4-aminobenzoic acid is added, the mass ratio of the amino-modified halloysite nanotube, N,N-dimethylformamide and 4-aminobenzoic acid is 100:1950:20, temperature is raised, stirring and mixing are carried out in a nitrogen atmosphere, the reaction is carried out at 100℃ for 5 h, after the reaction is completed, suction filtration is carried out, washing is carried out with ethyl acetate, and vacuum drying is carried out at 80℃ for 12 h, to obtain boronic acid-modified halloysite nanotubes;

[0055] S3, the boronic acid-modified halloysite nanotubes are ultrasonically dispersed into deionized water, after uniform dispersion, epoxy resin is added, dispersion is carried out in a high-speed dispersion machine, the dispersion rate is 1550 r / min, the dispersion time is 7 min, then boron phenolic resin, defoaming agent and leveling agent are added, the stirring rate is 1100 r / min, the stirring time is 11 min, wherein the mass ratio of the boronic acid-modified halloysite nanotube, deionized water, epoxy resin, boron phenolic resin, defoaming agent SPA202 and leveling agent polyether modified polysiloxane is 4:140:100:25:1:0.4, after uniform mixing, the material is discharged, to obtain a modified epoxy heat-resistant flame-retardant coating.

[0056] Comparative example 2

[0057] A preparation method of a modified epoxy heat-resistant flame-retardant coating, comprising the following steps:

[0058] S1, ultrasonic dispersion of halloysite nanotubes and diethyl hypophosphite oxirane methyl ester into deionized water, after uniform dispersion, add epoxy resin, disperse in a high-speed disperser, the dispersion rate is 1550r / min, the dispersion time is 7min, then add boron phenolic resin, defoaming agent and leveling agent, the stirring rate is 1100r / min, the stirring time is 11min, wherein the mass ratio of halloysite nanotubes, diethyl hypophosphite oxirane methyl ester, deionized water, epoxy resin, boron phenolic resin, defoaming agent SPA202, leveling agent polyether modified polysiloxane is 2.2:1.8:140:100:25:1:0.4, after uniform mixing, discharge, to obtain a modified epoxy heat-resistant flame-retardant coating.

[0059] The halloysite nanotubes used in the examples and comparative examples of the present application are purchased from Guangzhou Runwo Material Technology Co., Ltd., with a diameter of 50nm; the CAS number of diethyl hypophosphite oxirane methyl ester is 2640342-38-5; the epoxy resin is epoxy resin E-51, purchased from Wuxi Qian Guang Chemical Raw Materials Co., Ltd.; the boron phenolic resin is purchased from Shaanxi Taihang Fire-Resistant Polymer Co., Ltd., with a model number of THC-400; and the rest of the reagents are commercially available.

[0060] The modified epoxy heat-resistant flame-retardant coatings in Examples 1-4 and Comparative Examples 1-2 are subjected to relevant performance tests, and the specific tests are as follows:

[0061] (1) Adhesion test: the adhesion is tested according to the test standard of GB / T 9286-2021 "Paint and Varnish Crosshatch Test";

[0062] (2) Flame-retardant performance test: the modified epoxy heat-resistant flame-retardant coating is poured into a polytetrafluoroethylene mold at room temperature, dried and cured, demolded, and then cut into a square sample, and the flame-retardant performance is tested on a K-R2406S oxygen index analyzer, vertically placed, and the oxygen concentration is measured after ignition, and the limiting oxygen index is recorded;

[0063] (3) Heat resistance test: the heat resistance is tested by DSC according to ASTM 3418-82, and the temperature rising rate is 10℃ / min;

[0064] (4) Impact strength test: the impact strength is tested according to the test standard of ASTM D256-81;

[0065] The above test results are shown in Table 1:

[0066] Table 1

[0067]

[0068] According to the test results of Table 1, it can be seen that the coatings corresponding to Examples 1-4 of the present application have excellent adhesion, flame retardant performance, heat resistance and impact strength. In Comparative Example 1, boric acid modified halloysite nanotubes are used instead of flame-retardant modified halloysite nanotubes to be added to the epoxy resin matrix, which has a greater impact on the flame retardant performance and a smaller impact on the adhesion and impact strength. In Comparative Example 2, halloysite nanotubes and diethyl hypophosphite oxirane methyl ester are directly added, and the comprehensive performance of the coating is greatly reduced, the adhesion is poor, and the flame retardant performance, heat resistance and impact strength are greatly reduced.

[0069] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and any equivalent changes and improvements made within the scope of the present application should still fall within the scope of the present application.

Claims

1. A process for the preparation of a modified epoxy heat resistant flame retardant coating characterized by: It comprises the following steps: S1, ultrasonic dispersion of halloysite nanotubes into an aqueous ethanol solution, after uniform ultrasonic dispersion, adjust the pH to 5 using acetic acid, add γ-aminopropyl triethoxysilane, heat, stir and mix, reaction occurs, after the reaction is completed, centrifugal separation, wash the product with deionized water until neutral, vacuum drying at 80℃ for 12h, to obtain aminated halloysite nanotubes; S2, ultrasonic dispersion of aminated halloysite nanotubes into N,N-dimethylformamide, after uniform ultrasonic dispersion, add 4-aminobenzoic acid, heat, stir and mix in a nitrogen atmosphere, reaction occurs, after the reaction is completed, suction filtration, wash with ethyl acetate, vacuum drying at 80℃ for 12h, to obtain borate modified halloysite nanotubes; S3, ultrasonic dispersion of borate modified halloysite nanotubes into anhydrous ethanol, after uniform dispersion, add diethyl phosphinic acid oxirane methyl ester, stir and mix, reaction occurs, after the reaction is completed, centrifugal separation, after centrifugation, wash with anhydrous ethanol, vacuum drying at 80℃ for 12h, to obtain flame-retardant modified halloysite nanotubes; S4, ultrasonic dispersion of flame-retardant modified halloysite nanotubes into deionized water, after uniform dispersion, add epoxy resin, disperse in a high-speed disperser, the dispersion rate is 1500-1600r / min, the dispersion time is 5-8min, then add boron phenolic resin, defoaming agent and leveling agent, stir and mix, the stirring rate is 900-1200r / min, the stirring time is 10-12min, after uniform mixing, discharge, to obtain modified epoxy heat-resistant flame-retardant coating.

2. The process for the preparation of a modified epoxy heat resistant fire retardant coating as claimed in claim 1, wherein: The aqueous ethanol solution in S1 is mixed by anhydrous ethanol and deionized water in a volume ratio of 9:1, the mass ratio of halloysite nanotubes, aqueous ethanol solution, γ-aminopropyl triethoxysilane is 100:(3200-4000):(420-550), the reaction temperature is 75-85℃, and the reaction time is 5-8h.

3. The method of preparing a modified epoxy heat resistant flame retardant coating according to claim 1, characterized in that: The mass ratio of aminated halloysite nanotubes, N,N-dimethylformamide, 4-aminobenzoic acid in S2 is 100:(1800-2000):(16-21).

4. The method of preparing a modified epoxy heat resistant flame retardant coating according to claim 1, characterized in that: The reaction temperature in S2 is 95-105℃, and the reaction time is 4-6h.

5. The method of preparing a modified epoxy heat resistant fire-retardant coating as claimed in claim 1, wherein: The mass ratio of borate modified halloysite nanotubes, anhydrous ethanol, diethyl phosphinic acid oxirane methyl ester in S3 is 100:(2500-3200):(60-85).

6. The method of preparing a modified epoxy heat resistant flame retardant coating as claimed in claim 1, wherein: The reaction temperature in S3 is 65-75℃, and the reaction time is 6-9h.

7. The process for the preparation of modified epoxy heat resistant fire retardant coating as claimed in claim 1, wherein the process comprises of: The mass ratio of flame-retardant modified halloysite nanotubes, deionized water, epoxy resin, boron phenolic resin, defoaming agent, leveling agent in S4 is (2-5):(120-150):100:(12-30):(0.5-1.2):(0.3-0.5).

8. The method of preparing a modified epoxy heat resistant flame retardant coating as claimed in claim 1, wherein: The leveling agent in S4 is polyether modified polysiloxane, and the defoaming agent is defoaming agent SPA202. 9.A modified epoxy heat-resistant flame-retardant coating prepared by the preparation method of the modified epoxy heat-resistant flame-retardant coating according to any one of claims 1-8.

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