LU501065B1

LU501065B1 - Carbon nitride-polyaniline nanocomposite and its preparation method as well as carbon nitride-polyaniline intumescent flame retardant coating and its preparation method

Info

Publication number: LU501065B1
Application number: LU501065A
Authority: LU
Inventors: Xilei Chen; Shaoxiang Li; Huixin Dong; Chuanmei Jiao
Original assignee: Qingdao Univ Of Science And Technology
Priority date: 2021-12-22
Filing date: 2021-12-22
Publication date: 2022-06-22

Abstract

The present invention provides a carbon nitride-polyaniline nanocomposite and its preparation method as well as carbon nitride-polyaniline intumescent flame retardant coating and its preparation method, and relates to the flame retardant coating field. This invention aims to solve the problem of easy modification of epoxy resin and to form the epoxy resin and other materials' compounds whose performance may be superior to that of each other. However, there is mutual effect of very strong VDW force between layers of carbon nitride, which makes it very likely to cake and very hard to disperse in epoxy resin. The present invention applies cheap raw materials, and the process is easy to control. Carbon nitride-polyaniline intumescent flame retardant coating prepared with carbon nitride-polyaniline nano materials is of extraordinary fire retardance performance and environment-friendly.

Description

Description Carbon nitride-polyaniline nanocomposite and its preparation method as well as carbon nitride- LUS01065 polyaniline intumescent flame retardant coating and its preparation method Technical Field The present invention relates to the flame retardant coating field, particularly to a carbon nitride-polyaniline nanocomposite and its preparation method as well as carbon nitride-polyaniline intumescent flame retardant coating and its preparation method.

Background of the Invention With the extraordinary mechanical property, good thermal stability and dielectric property, and good bondability of epoxy resin on the surface of other substances, epoxy resin-based coatings have been widely applied in construction, shipping, and petrochemical industries.

However, epoxy resin is flammable, and much smoke is generated during its combustion, bringing substantial fire hazards.

Thus, flame retardant processing should be applied to it before use to improve its fire safety performance to meet the fire safety requirement in the application environment.

Carbon nitride possesses a graphene-like two-dimensional layered structure, good chemical stability, thermal stability, and mechanical property, so it is widely applied in the environmental photocatalysis field.

Its surface is defective, and its ends contain rich amino, so it is easy to be modified, and this performance enables it to react with other materials to form compounds whose performance is superior to each of them.

However, there is a mutual effect of powerful VDW force between layers of carbon nitride, making it very likely to cake and very hard to disperse in epoxy resin.

Polyaniline has been widely researched due to its simple composition, low cost, controllable electrical conductivity, and environmental protection.

It has been verified that it can be used as corrosion protection packing in the epoxy resin system.

However, its research and application in flame retardant epoxy resin are still blank.

Content of the Invention To solve the above problem, the present invention provides a carbon nitride-polyaniline nanocomposite and its preparation method as well as carbon nitride-polyaniline intumescent flame retardant coating and its preparation method.

This flame retardant coating carbon nitride-polyaniline nanocomposite can be dispersed in epoxy resin well and can collaborate with the intumescent flame retardant system so as to improve the fire retardance performance of epoxy resin, inhibit survival and release of harmful and

Description poisonous gases in its combustion chamber and prepare a coating featured with good fire retardancy and LU501065 high fire safety.

In the carbon nitride-polyaniline nanocomposite in this invention, carbon nitride is sheet-like carbon nitride after heat peeling.

The particle size distribution of sheet-like carbon nitride after ball milling is 0.2~5um.

Preferentially, its particle size distribution is 0.2~2um.

In addition, said sheet-like carbon nitride is obtained in the following ways: (1) Melamine is put into an enclosed container, raise the temperature to 540°C~560°C at the rate of 15°C/min~18°C/min, preserve the temperature for 2h~4h, and then lower the temperature naturally to the ambient temperature to get the graphitic carbon nitride; (2) Put the graphitic carbon nitride obtained in step (1) into an open container, raise the temperature to 540°C~3560°C at the rate of 15°C/min~18°C/min in the system where there is flowing nitrogen gas, preserve the temperature for 2h~4h, and then lower the temperature naturally to the ambient temperature to get the carbon nitride after heat peeling; Preferentially, the input pressure of nitrogen is 0.1MPa~0.2MPa; (3) Conduct ball milling of carbon nitride obtained in step (2) after heat peeling to get said sheet-like carbon nitride.

The preparation method of the above-mentioned carbon nitride-polyaniline nanocomposite includes the following steps: (1) Use phosphoric acid solution as the dispersant, put sheet-like carbon nitride into the phosphoric acid solution dispersant, mix them evenly and conduct ultrasonic processing for 30min; (2) Further add aniline into the carbon nitride dispersing solution, mix it for 10min to get solution A; (3) Add ammonium persulfate into another phosphoric acid solution, mix the liquid to make it dissolve completely to get the solution B; (4) Slowly add solution B into solution A, mix them at the ambient temperature for 30min and keep the mixture still for 24h.

Rinse the mixture until it is neutral, dry the mixture to get carbon nitride-polyaniline nanocomposite.

Preferentially, the concentration of phosphoric acid solution used in step (1) and step (3) is 0.5~1.5mol/L.

The total dosage of aniline and phosphoric acid used in steps (1) and (3) meets the following requirement: the mass ratio of aniline and phosphoric acid is 3:9.8~58.8.

Description In addition, the dosage of aniline in step (2) meets the following requirement: the mass ratio of aniline and LU501065 sheet-like carbon nitride added in step (1) is: 30: 1~3, and the mole ratio of aniline and ammonium persulfate added in step (3) is 1:1~1.3. The other purpose of the present invention 1s to provide an intumescent flame retardant coating containing carbon nitride-polyaniline nanocomposite and its preparation method. Said intumescent flame retardant coating contains the following components: carbon nitride-polyaniline nanocomposite, epoxy resin and intumescent flame retardant system, and the mass ratio of carbon nitride-polyaniline nanocomposite is

0.125~0.5%, that of the intumescent flame retardant system is 20-30%, and the rest is the epoxy resin. In addition, said intumescent flame retardant system is composed of dehydrator, carbon-forming agent and foaming agent. The mass ratio of the dehydrator, carbon-forming agent and the foaming agent is 3~5:1~ 3:1~3. Preferentially, said dehydrator is one or several types of ammonium polyphosphate, ammonium dihydrogen phosphate, melamine phosphate, dimelamine phosphate, melamine pyrophosphate and black phosphorus; said carbon-forming agent is one or several types of polyol like starch, chitosan, cellulose and derivatives, pentaerythritol and derivatives; said foaming agent is one or several types of poly-amino compounds like melamine, dicyandiamide, melamine phosphate, melamine phosphate, polyurea, urea, ammonium molybdate, poly-ammonium molybdate. In addition, the preparation method of said intumescent flame retardant coating includes the following steps: Carbon nitride-polyaniline nanocomposite is added into the epoxy resin, the intumescent flame retardant is added, they are mixed evenly, and then the mixture and the curing agent composition are mixed evenly to obtain the carbon nitride polyaniline intumescent flame retardant coating. Said curing agent is one or several types of the following ones: polyamide, liquid anhydride, aliphatic amine, cardanol modified amine curing agent. Said carbon nitride-polyaniline nanocomposite is prepared with the method as said in the present invention. Compared with the prior art, the present invention has the following benefits: © The raw materials are cheap and easy to get, and the composition process of carbon nitride-polyaniline nanocomposite is easy to control. 0 The epoxy resin system used in the present invention is solvent-free epoxy resin which is environment- friendly. [0 The carbon nitride-polyaniline nanocomposite can be dispersed well in the epoxy resin system to improve

Description fire retardance. Polyaniline can not only collaborate with the intumescent flame retardant system to enhance LU501065 the fire retardance performance of epoxy resin, but can also enable epoxy resin to have higher corrosion resistance performance. 00 The carbon nitride-polyaniline nanocomposite obtained can not only be dispersed well in the epoxy resin system to enable the epoxy resin to have good corrosion resistance performance but can also collaborate with the intumescent flame retardant system to improve the fire retardance performance and lower the heat release rate and inhibit the generation and release of poisonous and harmful gases. Thus, the coating prepared in the present invention is a genuine multi-functional environment-friendly coating. Brief Description of the Drawings Figure 1 is the SEM figure of block-shaped carbon nitride generated after primary calcination in example

1. Figure 2 is the SEM figure of carbon nitride nanosheet generated after secondary calcination and heat peeling in example 1. Figure 3 is the SEM figure of carbon nitride-polyaniline nanocomposite obtained in example 1. Figure 4 is the TEM figure of carbon nitride nanosheet obtained in example 1. Figure 5 is the TEM figure of carbon nitride-polyaniline nanocomposite obtained in example 1. Figure 6 is the data about the heat release rate of carbon nitride-polyaniline intumescent flame retardant coating obtained in example 1 after testing with the cone calorimeter. Figure 7 is the data about the THR of carbon nitride-polyaniline intumescent flame retardant coating obtained in example 1 after testing with the cone calorimeter. Figure 8 is the data about the smoke release rate of carbon nitride-polyaniline intumescent flame retardant coating obtained in example 1 after testing with the cone calorimeter. Figure 9 is the data about the total smoke release of carbon nitride-polyaniline intumescent flame retardant coating obtained in example 1 after testing with the cone calorimeter. Figure 10 is the data about the CO release rate of carbon nitride-polyaniline intumescent flame retardant coating obtained in example 1 after testing with the cone calorimeter. Figure 11 is the data about the CO; release rate of carbon nitride-polyaniline intumescent flame retardant coating obtained in example 1 after testing with the cone calorimeter.

Description Figure 12 is the data about the quality loss of carbon nitride-polyaniline intumescent flame retardant coating LU501065 obtained in example 1 after testing with the cone calorimeter.

Figure 13 is the data about the heat release of carbon nitride-polyaniline intumescent flame retardant coating obtained in example 2 after testing with the cone calorimeter.

Figure 14 is the data about the THR of carbon nitride-polyaniline intumescent flame retardant coating obtained in example 2 after testing with the cone calorimeter.

Figure 15 is the data about the smoke release rate of carbon nitride-polyaniline intumescent flame retardant coating obtained in example 2 after testing with the cone calorimeter.

Figure 16 is the data about the total smoke release of carbon nitride-polyaniline intumescent flame retardant coating obtained in example 2 after testing with the cone calorimeter.

Figure 17 is the data about the CO release rate of carbon nitride-polyaniline intumescent flame retardant coating obtained in example 2 after testing with the cone calorimeter.

Figure 18 is the data about the CO; release rate of carbon nitride-polyaniline intumescent flame retardant coating obtained in example 2 after testing with the cone calorimeter.

Figure 19 is the data about the quality loss of carbon nitride-polyaniline intumescent flame retardant coating obtained in example 2 after testing with the cone calorimeter.

Detailed Description of Embodiments The present invention is further explained and described according to the attached drawings and examples.

Existing technologies are applied to all the examples, in addition to special descriptions.

Example 1 Put 30g melamine in a crucible, cover it with the cover, put the crucible inside the muffle furnace, rise the temperature at the rate of 18°C/min, preserve the temperature for 3h after the temperature rises to 550°C, reduce the temperature naturally to the ambient temperature, take it out to get the yellow block-shaped graphitic carbon nitride.

Put the yellow block-shaped graphitic carbon nitride into an uncovered crucible, put the crucible into the muffle furnace with nitrogen supplied (input pressure of 0.15MPa), raise the temperature to 550°C at the rate of 18°C/min, preserve the temperature for 3h, reduce the temperature naturally to the ambient temperature, take it out to get the dark yellow block-shaped graphitic carbon nitride after heat peeling.

Put the yellow solid into a ball mill for ball milling to get the carbon nitride nanosheet

Description whose particle size is 0.2-2 micrometer.

LU501065 Put 0.1g carbon nitride nanosheet generated in the last step into the 50ml 1mol/L phosphoric acid solution, mix it evenly and then conduct ultrasonic dispersion for 30min, add 3g aniline to get the solution A.

Put 9.86g ammonium persulfate into another 50ml1mol/L phosphoric acid solution, mix them evenly, conduct ultrasonic dispersion for 10min to get solution B.

Slowly add solution B into solution A, mix them for 30min at the ambient temperature, and then keep the mixture for 24h.

Rinse the mixture in a filter device with ionized water or ethyl alcohol, dry the product, conduct ball milling to get carbon nitride-polyaniline nanocomposite.

Mix ammonium polyphosphate, pentaerythritol, and melamine at the ratio of 3:1:1, conduct ball milling to get the intumescent flame retardant system.

Comparison example 0-1: Add 75% E-44 epoxy resin into the high-speed mixing and grinding dispenser at the mass proportion, add 25% solvent-free cardanol modified curing agent, combine them for 6min at the rate of 800r/min, take 50g mixture, pour it into a 10cm* 10cm* 1cm aluminum mold, conduct curing at the ambient temperature for 3 days, and conduct testing with a cone calorimeter after 7 days of maintenance.

Comparison example 0-2: Add 52.5% E-44 epoxy resin into the high-speed mixing and grinding dispenser at the mass proportion, add 30% intumescent flame retardant system, combine them for 30min at the rate of 800r/min, add 17.5% solvent-free cardanol modified curing agent, combine them for 6min at the rate of 800r/min, take 50g mixture, pour it into a 10cm* 10cm* 1cm aluminum mold, conduct curing at the ambient temperature for 3 days, and conduct testing with a cone calorimeter after 7 days of maintenance.

Example 1-1: Add 52.5% E-44 epoxy resin into the high-speed mixing and grinding dispenser at the mass proportion, add 0.125% carbon nitride-polyaniline nanocomposite, combine them for 30min at the rate of 800r/min, add 29.875% intumescent flame retardant system, mix them for 30min at the rate of 800r/min, add 17.5% solvent-free cardanol modified curing agent, mix them for 6min at the rate of 800r/min, take 50g mixture, pour it into a 10cm* 10cm* lem aluminum mold, conduct curing at the ambient temperature for 3 days, and conduct testing with a cone calorimeter after 7 days of maintenance.

Example 1-2: Add 52.5% E-44 epoxy resin into the high-speed mixing and grinding dispenser at the mass proportion, add 0.188% carbon nitride-polyaniline nanocomposite, mix them for 30min at the rate of 800r/min, add 29.812% intumescent flame retardant system, mix them for 30min at the rate of 800r/min, add 17.5% solvent-free cardanol modified curing agent, combine them for 6min at the rate of 800r/min, take 50g mixture, pour it into a 10cm*10cm* lem aluminum mold, conduct curing at the ambient temperature for 3 days, and conduct testing with a cone calorimeter after 7 days of maintenance.

Description Example 1-3: Add 52.5% E-44 epoxy resin into the high-speed mixing and grinding dispenser at the mass LU501065 proportion, add 0.25% carbon nitride-polyaniline nanocomposite, mix them for 30min at the rate of 800r/min, add 29.75% intumescent flame retardant system, mix them for 30min at the rate of 800r/min, add

17.5% solvent-free cardanol modified curing agent, mix them for 6min at the rate of 800r/min, take 50g mixture, pour it into a 10cm* 10cm* lem aluminum mold, conduct curing at the ambient temperature for 3 days, and conduct testing with a cone calorimeter after 7 days of maintenance. Example 1-4: Add 52.5% E-44 epoxy resin into the high-speed mixing and grinding dispenser at the mass proportion, add 0.5% carbon nitride-polyaniline nanocomposite, combine them for 30min at the rate of 800r/min, add 29.5% intumescent flame retardant system and continue stirring at 800r/min for 30min, add

17.5% solvent-free cardanol modified curing agent, mix them for 6min at the rate of 800r/min, take 50g mixture, pour it into a 10cm* 10cm* lem aluminum mold, conduct curing at the ambient temperature for 3 days, and conduct testing with a cone calorimeter after 7 days of maintenance. Table 1 Sample Formula of Comparison Examples 0-1 - 0-2 and Examples 1-1 - 1-4 E-44 Cardanol modified | Intumescent Carbon nitride- curing agent flame retardant | polyaniline (wt%6) system (wt%) Y (wt%) (wt%) Comparison 75 25 example 0-1 Comparison 52.5 17.5 30 example 0-2 Table 2 Cone Calorimeter Testing Data of Comparison Examples 0-1 - 0-2 and Examples 1-1 - 1-4 in Table 1 pHRR THR Co CO2 TSR MASS (kW-m?) | (MJ-m?) (gs) (gs?) (m?) (%)

Description Comparison | 1071.8 | 155.28 0.05083 | 0.55 36.896 6.194 LU501065 example 0-1 Comparison 260.54 99.165 0.0251 0.133 23.643 26.223 example 0-2 Example 1-1 229.82 92.039 0.013 0.133 17.989 37.236 Example 1-2 245.26 87.139 0.0151 0.121 19.448 39.964 Example 1-3 254.85 92.027 0.0127 0.142 15.473 39.477 Example 1-4 266.00 91.950 0.0137 0.147 16.307 38.362 In combination with table 1, the cone calorimetric test data of comparison example 0-1 to 0-2 and examples 1-1 - 1-4 in Table 2 are compared. By comparing the heat release data (PHRR and THR) of each sample, the peak of heat release rate (PHRR) of the sample (comparison example 0-2) where only intumescent flame retardant system was added reduced by 75.69% compared with the pure sample (comparison example 0-1), the PHRR reduced by 78.56% after adding 0.125% carbon nitride-polyaniline, and the PHRR of samples (i.e., examples 1-1 - 1-3) were 0.125%,

0.188% and 0.25% carbon nitride-polyaniline was added was lower than that of the comparison example 0-2 where only intumescent flame retardant system was added. The total heat release (THR) of examples 1-1 - 1-4 was lower than comparison examples, especially when the additive amount of carbon nitride- polyaniline was up to 0.188%, the THR reduced by 43.88% compared with that of the pure epoxy resin (comparison example 0-1). This reveals that a certain amount of carbon nitride-polyaniline can collaborate with the intumescent flame retardant system where ammonium polyphosphate as dehydrator will be decomposed at a low temperature to promote dehydration of pentaerythritol (carbon-forming agent) into carbon and to generate a lot of non-flammable vapor. In the meanwhile, foaming agent melamine is decomposed to generate a lot of non-flammable ammonia gas, which promotes foaming of molten epoxy resin system to form expanded carbon layers with cellular inside. Carbon nitride-polyaniline collaborates with expanded carbon layers. Microscopically, long-chain secondary amine after polymerization, can promote ring opening of epoxy groups and conduct crosslinking to form more stable long-chain polymer; macroscopically, expanded carbon layers are denser and stronger and not easy to be oxidized, so they can protect polymers under them and the substrate effectively. Thus, carbon forming is accelerated, and it is mitigated that epoxy resin is pyrolyzed into flammable gases, and PHRR and THR are reduced effectively. By comparing data of release of CO and CO; and total smoke release (TSR), the release peak of CO of the sample (comparison example 0-2) where intumescent flame retardant system was added reduced by 44.08% compared with the pure sample (comparison example 0-1), the release peak of CO reduced by 64.83% after

Description adding 0.125% carbon nitride-polyaniline, and the release peak of samples (i.e. examples 1-1 - 1-4) where LU501065 carbon nitride-polyaniline was added was lower than that of the comparison example 0-2 where only intumescent flame retardant system was added. The release peak of CO, of examples 1-1 - 1-4 reduced by over 70% than that of comparison example 0-1, especially when the quantity of carbon nitride-polyaniline added was up to 0.188%, the release peak of COz was reduced by 78% than that of pure epoxy resin (comparison example 0-1). The release peak of THR of examples 1-1 - 1-4 reduced by over 35% than that of comparison example 0-1, especially when the quantity of carbon nitride-polyaniline added was up to

0.25%, the release peak of CO, was reduced by 58.05% than that of pure epoxy resin (comparison example 0-1). This reveals that a certain amount of carbon nitride-polyaniline can collaborate with the intumescent flame retardant system where ammonium polyphosphate as dehydrator will be decomposed at a low temperature to promote dehydration of pentaerythritol (carbon-forming agent) into carbon and to generate a lot of non-flammable vapor. In the meanwhile, foaming agent melamine 1s decomposed to generate a lot of non-flammable ammonia gas which promotes foaming of molten epoxy resin system to form expanded carbon layers with cellular inside. Carbon nitride-polyaniline collaborates with expanded carbon layers. Microscopically, long-chain secondary amine after polymerization can promote ring opening of epoxy groups and conduct crosslinking to form more stable long-chain polymer; thus, the cracking of low polymerization degree small molecular polymer into combustible gas and flue gas and combustion into toxic gases such as CO and CO: is reduced, to mitigate THR, CO and CO2 effectively. By comparing the residual mass of each sample, the residual mass of sample (comparison example 0-2) where only intumescent flame retardant system was added increased by 3.37 times than that of the pure sample (comparison example 0-1), especially when 0.125% carbon nitride-polyaniline was added, the residual mass increased by 5.2 times, and the residual mass of examples 1-1 - 1-4 was higher than that comparison example 0-1 where only intumescent flame retardant system was added. This reveals that a certain amount of carbon nitride-polyaniline can collaborate with the intumescent flame retardant system where ammonium polyphosphate as dehydrator will be decomposed at a low temperature to promote dehydration of pentaerythritol (carbon-forming agent) into carbon and to generate a lot of non-flammable vapor. In the meanwhile, foaming agent melamine 1s decomposed to generate a lot of non-flammable ammonia gas which promotes foaming of molten epoxy resin system to form expanded carbon layers with cellular inside. Carbon nitride-polyaniline collaborates with expanded carbon layers. Microscopically, long- chain secondary amine, after polymerization, can promote ring opening of epoxy groups and conduct crosslinking to form a more stable long-chain polymer; macroscopically, expanded carbon layers are denser and more robust not easy to be oxidized, so they can protect polymers under them and the substrate effectively. Thus, carbon forming is accelerated, it is mitigated that epoxy resin is pyrolyzed into flammable gases, and the mass of carbon residue is improved.

Description In conclusion, it is known by comparing data of examples and comparison examples that the fire retardance LU501065 performance of the present invention, i.e. carbon nitride-polyaniline intumescent flame retardant coating, is improved, and the present invention has outstanding performance in terms of lowering the heat release, smoke release and generation of poisonous gas CO as well as promoting carbon-forming and improving the mass of carbon residue.

Example 2 Put 30g melamine in a crucible, cover it with the cover, put the crucible inside the muffle furnace, rise the temperature at the rate of 15°C/min, preserve the temperature for 3h after the temperature rises to 550°C, reduce the temperature naturally to the ambient temperature, take it out to get the yellow block-shaped graphitic carbon nitride.

Put the yellow block-shaped graphitic carbon nitride into an uncovered crucible, put the crucible into the muffle furnace with nitrogen supplied (input pressure of 0.2MPa), rise the temperature to 540°C at the rate of 15°C/min, preserve the temperature for 2h, reduce the temperature naturally to the ambient temperature, take it out to get the dark yellow block-shaped graphitic carbon nitride after heat peeling.

Put the yellow solid into a ball mill for ball milling to get the carbon nitride nanosheet whose particle size is 0.2-2 micrometer.

Put 0.1g carbon nitride nanosheet generated in the last step into the 100m10.5mol/L phosphoric acid solution, mix it evenly and then conduct ultrasonic dispersion for 30min, add 3g aniline to get the solution A.

Put 7.65g ammonium persulfate into another 100m10.5mol/L phosphoric acid solution, mix them evenly, conduct ultrasonic dispersion for 10min to get solution B.

Comparison example 0-1: Add 75% E-44 epoxy resin into the high-speed mixing and grinding dispenser at the mass proportion, add 25% solvent-free cardanol modified curing agent, mix them for 6min at the rate of 800r/min, take 50g mixture, pour it into a 10cm*10cm*1cm aluminum mold, conduct curing at the ambient temperature for 3 days, and conduct testing with a cone calorimeter after 7 days of maintenance.

Comparison example 0-2: Add 52.5% E-44 epoxy resin into the high-speed mixing and grinding dispenser

Description at the mass proportion, add 30% intumescent flame retardant system, mix them for 30min at the rate of LU501065 800r/min, add 17.5% solvent-free cardanol modified curing agent, mix them for 6min at the rate of 800r/min, take 50g mixture, pour it into a 10cm*10em*1cm aluminum mold, conduct curing at the ambient temperature for 3 days, and conduct testing with a cone calorimeter after 7 days of maintenance.

Example 2-1: Add 56% E-44 epoxy resin into the high-speed mixing and grinding dispenser at the mass proportion, add 0.125% carbon nitride-polyaniline nanocomposite, mix them for 30min at the rate of 800r/min, add 29.875% intumescent flame retardant system, mix them for 30min at the rate of 800r/min, add 14% solvent-free cardanol modified curing agent, mix them for 6min at the rate of 800r/min, take 50g mixture, pour it into a 10cm* 10cm* lem aluminum mold, conduct curing at the ambient temperature for 3 days, and conduct testing with a cone calorimeter after 7 days of maintenance.

Example 2-2: Add 56% E-44 epoxy resin into the high-speed mixing and grinding dispenser at the mass proportion, add 0.188% carbon nitride-polyaniline nanocomposite, mix them for 30min at the rate of 800r/min, add 29.812% intumescent flame retardant system, mix them for 30min at the rate of 800r/min, add 14% solvent-free cardanol modified curing agent, mix them for 6min at the rate of 800r/min, take 50g mixture, pour it into a 10cm* 10cm* lem aluminum mold, conduct curing at the ambient temperature for 3 days, and conduct testing with a cone calorimeter after 7 days of maintenance.

Example 2-3: Add 56% E-44 epoxy resin into the high-speed mixing and grinding dispenser at the mass proportion, add 0.25% carbon nitride-polyaniline nanocomposite, mix them for 30min at the rate of 800r/min, add 29.75% intumescent flame retardant system, mix them for 30min at the rate of 800r/min, add 14% solvent-free cardanol modified curing agent, mix them for 6min at the rate of 800r/min, take 50g mixture, pour it into a 10cm* 10cm* lem aluminum mold, conduct curing at the ambient temperature for 3 days, and conduct testing with a cone calorimeter after 7 days of maintenance.

Example 2-4: Add 56% E-44 epoxy resin into the high-speed mixing and grinding dispenser at the mass proportion, add 0.5% carbon nitride-polyaniline nanocomposite, mix them for 30min at the rate of 800r/min, add 29.5% intumescent flame retardant system, mix them for 30min at the rate of 800r/min, add 14% solvent-free cardanol modified curing agent, mix them for 6min at the rate of 800r/min, take 50g mixture, pour it into a 10cm*10cm* 1cm aluminum mold, conduct curing at the ambient temperature for 3 days, and conduct testing with a cone calorimeter after 7 days of maintenance.

Table 3 Sample Formula of Comparison Examples 0-1 - 0-2 and Examples 2-1 - 2-4

Description E-44 Cardanol modified | Intumescent flame | Carbon nitride- | 4501065 curing agent retardant system polyaniline (wt%) (wt%) (wt%) (wt%) Comparison 75 25 example 0-1 Comparison 52.5 17.5 30 example 0-2 Table 4 Cone Calorimeter Testing Data of Comparison Examples 0-1 - 0-2 and Examples 2-1 - 2-4 in Table 1 PHRR THR co CO2 TSR MASS (kW-m2) | (MJ-m2) (g-s-1) (g-s-1) (m2) (%) Comparison 1071.8 155.28 0.05083 0.55 36.896 6.194 example 0-1 Comparison 260.54 99.165 0.0251 0.133 23.643 26.223 example 0-2 Example 1-4 | 342.7 699 | 0.015 10.15 42.29 It is proven through comparing comparison examples 0-1 - 0-2 and examples 2-1 - 2-4 that the fire retardance performance of the present invention, i.e. carbon nitride-polyaniline intumescent flame retardant coating, is improved, and the present invention has outstanding performance in terms of lowering the heat release, smoke release and generation of poisonous gas CO as well as promoting carbon-forming and improving the mass of carbon residue

Claims

1. A carbon nitride-polyaniline nanocomposite, characterized in that carbon nitride is sheet-like LU501065 after heat peeling, and the particle size distribution of sheet-like carbon nitride is 0.2~5um.

2. The carbon nitride-polyaniline nanocomposite of claim 1, characterized in that said sheet- like carbon nitride is obtained in the following ways: (1) Put melamine into an enclosed container, raise the temperature to 540°C —560°C at the rate of 15°C/min~18°C/min, preserve the temperature for 2h~4h, and then lower the temperature naturally to the ambient temperature to get the graphitic carbon nitride; (2) Put the graphitic carbon nitride obtained in step (1) into an open container, raise the temperature to 540°C —560°C at the rate of 15°C/min~18°C/min in the system where there is flowing nitrogen gas, preserve the temperature for 2h~4h, and then lower the temperature naturally to the ambient temperature to get the carbon nitride after heat peeling; (3) Conduct ball milling of carbon nitride obtained in step (2) after heat peeling to get said sheet-like carbon nitride.

3. The carbon nitride-polyaniline nanocomposite of claim 2, characterized in that the input pressure of nitrogen in step (2) is 0.1MPa~0.2MPa.

4. A preparation method of the carbon nitride-polyaniline nanocomposite of claim 1, 2 or 3, characterized in that the following steps are involved: (1) Use phosphoric acid solution as the dispersant, put sheet-like carbon nitride into the phosphoric acid solution dispersant, mix them evenly and conduct ultrasonic processing for 30min; (2) Further add aniline into the carbon nitride dispersing solution, mix it for 10min to get solution A; (3) Add ammonium persulfate into another phosphoric acid solution, mix the liquid to make it dissolve completely to get the solution B; (4) Slowly add solution B into solution A, mix them at the ambient temperature for 30min and keep the mixture still for 24h. Rinse the mixture until it is neutral, dry the mixture to get carbon

Claims nitride-polyaniline nanocomposite. LU501065

5. The preparation method of carbon nitride-polyaniline nanocomposite of claim 4, characterized in that in steps (1) and (3), the concentration of the used phosphoric acid solution is 0.5—1.5mol/L, the total dosage of aniline and phosphoric acid used in step (1) meets the following requirement: the mass ratio of aniline and phosphoric acid is 3:4.9~29.4, and the total dosage of aniline and phosphoric acid used in step (3) meets the following requirement: the mass ratio of aniline and phosphoric acid is 3:4.9~29.4.

6. The preparation method of carbon nitride-polyaniline nanocomposite of claim 4, characterized in that the dosage of aniline used in step (2) is: the mass ratio of aniline and sheet- like carbon nitride added in step (1) is: 30: 1~3, and the mole ratio of aniline and ammonium persulfate added in step (3) is 1:1~1.3.

7. An intumescent flame retardant coating containing the carbon nitride-polyaniline nanocomposite of claim 1, 2 or 3, characterized in that said coating includes the following components: carbon nitride-polyaniline nanocomposite, epoxy resin, and intumescent flame retardant system, and the mass ratio of carbon nitride-polyaniline nanocomposite is 0.125~

0.5%, that of the intumescent flame retardant system is 20-30%, and the rest is the epoxy resin.

8. The intumescent flame retardant coating of claim 7, characterized by said intumescent flame retardant system, is composed of dehydrator, carbon-forming agent, and foaming agent.

9. The intumescent flame retardant coating of claim 8, characterized in that the mass ratio of dehydrator, carbon-forming agent, and foaming agent in the intumescent flame retardant system is 3~5:1~3:1~3.

10. The intumescent flame retardant coating of claim 8, characterized in that said dehydrator is one or several types of ammonium polyphosphate, ammonium dihydrogen phosphate, melamine phosphate, dimelamine phosphate, melamine pyrophosphate, and black phosphorus; Said carbon-forming agent is one or several types of polyol like starch, chitosan, cellulose and derivatives, pentaerythritol and derivatives; Said foaming agent is one or several types of poly-amino compounds like melamine,

Claims dicyandiamide, melamine phosphate, melamine phosphate, polyurea, urea, ammonium LU501065 molybdate, poly-ammonium molybdate.

11. À preparation method of intumescent flame retardant of claim 7, characterized in that the following steps are involved: Carbon nitride-polyaniline nanocomposite 1s added into the epoxy resin, intumescent flame retardant is added, they are mixed evenly, and then the mixture and the curing agent composition are mixed evenly to obtain the carbon nitride polyaniline intumescent flame retardant coating.

12. The preparation method of intumescent flame retardant of claim 7, characterized in that said curing agent is one or several types of the following ones: polyamide, liquid anhydride, aliphatic amine, cardanol modified amine curing agent.