Preparation of a green and environment-friendly epoxy intumescent fire-retardant coating of bio-based CS@SA@ZIF-67 nanohybrid material

Abstract

The application discloses a kind of green and environment-friendly biological base CS@SA@ZIF-67 nano hybrid material epoxy intumescent fire-retardant coating preparation, belong to fire-retardant coating technical field.The application is by using the interaction between active groups on biomass chitosan, sodium alginate and metal organic framework ZIF-67, based on electrostatic adsorption or coordination complex principle in situ loading chitosan and sodium alginate biomass fire-retardant layer on the surface of ZIF-67, and finally constructs green and environment-friendly biological base CS@SA@ZIF-67 core-shell structure nano hybrid material, meets sustainable green chemistry concept, and the method is also helpful to improve agglomeration, improve the dispersibility of metal organic framework nanomaterial, compatibility with matrix and fire-retardant efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fireproof coating, in particular to a preparation method of a green and environment-friendly bio-based CS@SA@ZIF-67 nano-hybrid material epoxy intumescent fireproof coating. BACKGROUND

[0002] Flame retardants are mainly used in the fields of plastics, rubber, textiles and coatings. There are many classifications of flame retardants, among which the representative ones are halogen-based, phosphorus-based, nitrogen-based, silicon-based, inorganic hydroxides and intumescent flame retardants. At the same time, bio-based flame retardant materials have become a hot spot in the field of flame retardation. Bio-based flame retardant materials have the characteristics of environmental friendliness, renewable raw materials and biodegradability. Bio-based flame retardant materials such as cellulose, starch, cyclodextrin and chitosan have high carbon content and excellent charring properties, and can act as carbon sources in intumescent flame retardants. They are currently a popular object of research as new flame-retardant materials. The flame-retardant elements of bio-based materials are mainly C and N, but the content of these elements is not enough to achieve the ideal flame-retardant effect in the matrix. Therefore, it is necessary to modify them to introduce other flame-retardant elements or to use them in combination with other flame retardants to achieve excellent synergistic flame-retardant effect.

[0003] Metal-Organic Frameworks (MOFs) are a kind of high-crystalline porous nanomaterials with periodic network framework formed by the combination of metal ions and organic ligands, which usually exhibit good catalytic oxidation and charring performance. Zeolitic imidazolate frameworks (ZIFs) are a subclass of Metal-Organic Frameworks (MOFs) composed of metal nodes and imidazole derivatives as linkers, which are usually used in polymer composites. The flame-retardant effect of ZIF-67 nanomaterials without flame-retardant modification is usually poor, so it is necessary to modify them to improve their flame-retardant performance.

[0004] At present, CN 118772683 A discloses a preparation and application of a layer-by-layer self-assembly MOFs intumescent high-efficiency fireproof coating, which specifically selects ZIF-67 micro-nano materials and polyethyleneimine (PEI) and sodium alginate for modification, and mixes them with ammonium polyphosphate / calcium gluconate salt system to obtain a fireproof composite material. However, the modification of ZIF-67 can be further expanded. In addition, in the technology related to the use of chitosan and sodium alginate, such as the research on the flame-retardant modification of polyester fabric and its combustion mechanism, a flame-retardant polyester fabric is obtained by using biomass polyelectrolyte chitosan, sodium alginate gel and one-dimensional inorganic nanomaterial sepiolite through layer-by-layer self-assembly technology. However, the research on fabric flame retardation uses fabric as the substrate, which is not a flowing liquid, and does not involve the use in flame-retardant coating, so the application is not wide enough. Therefore, further research can be carried out on the chemical modification of ZIF and its application in flame-retardant coating. SUMMARY

[0005] TECHNICAL PROBLEM

[0006] ZIF-67 is usually limited in its flame-retardant effect due to the lack of flame-retardant elements such as phosphorus, nitrogen and silicon, etc., so it needs to be chemically modified to further improve its flame-retardant efficiency and broaden its use.

[0007] TECHNICAL CONTENT

[0008] The present application utilizes the interaction between biomass and active groups on metal-organic framework ZIF-67, and based on the principle of electrostatic adsorption or coordination complex, loads a biomass flame-retardant layer on the surface of ZIF-67 in situ to modify the flame-retardant of ZIF-67 nanomaterials. Subsequently, the flame-retardant modified ZIF-67 nanomaterials are compounded with an epoxy resin system as fillers to obtain a composite fireproof system with enhanced flame-retardant effect.

[0009] The first aspect of the present application provides a preparation method of a bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material, comprising the following steps:

[0010] (1) ZIF-67 nanomaterials are immersed in a chitosan solution for a certain time, and the precipitate is collected by centrifugation;

[0011] (2) The precipitate obtained in (1) is immersed in a sodium alginate solution for a certain time, and the precipitate is collected by centrifugation to complete the loading modification, thereby obtaining a modified ZIF-67 sample;

[0012] (3) The modified ZIF-67 sample is dried to obtain a bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material.

[0013] In an embodiment of the present application, the ZIF-67 nanomaterials in step (1) are prepared by the following steps:

[0014] S1, dissolve 2-methylimidazole in a solvent and mix uniformly, add a transition metal compound solution drop by drop under stirring, and react at a certain temperature to obtain a suspension;

[0015] S2, collect the precipitate of the suspension in step S1 by centrifugation and wash with methanol;

[0016] S3, dry the washed solid in step S2 to obtain a metal-organic framework material.

[0017] Further, in the preparation of ZIF-67 nanomaterials, the solvent is one or more of deionized water, acetone, ethanol, anhydrous methanol or N,N-dimethylformamide.

[0018] Further, in the preparation of the ZIF-67 nanomaterial, the transition metal compound in step S1 is one or more of cobalt nitrate, cobalt sulfate, cobalt oxide and other metal cobalt salts.

[0019] Further, in the preparation of the ZIF-67 nanomaterial, the solvent in the transition metal compound solution in step S1 is one or more of deionized water, acetone, ethanol, anhydrous methanol or N,N-dimethylformamide.

[0020] Further, in the preparation of the ZIF-67 nanomaterial, the molar ratio of the transition metal compound to 2-methylimidazole in step S1 is 16:1 to 2:1.

[0021] Further, in the preparation of the ZIF-67 nanomaterial, the temperature in step S1 is 80 to 140°C.

[0022] Further, in the preparation of the ZIF-67 nanomaterial, the reaction time in step S1 is 2 to 14 hours.

[0023] In an embodiment of the present application, the concentration of chitosan in the chitosan solution in step (1) is 0.5 to 5 wt%.

[0024] In an embodiment of the present application, the concentration of chitosan in the chitosan solution in step (1) is 0.5 to 2 wt%.

[0025] In an embodiment of the present application, the concentration of chitosan in the chitosan solution in step (1) is 0.5 to 1 wt%.

[0026] In an embodiment of the present application, the concentration of chitosan in the chitosan solution in step (1) is 1 wt%.

[0027] In an embodiment of the present application, the concentration of sodium alginate in the sodium alginate solution in step (2) is 0.4 to 3 wt%.

[0028] In an embodiment of the present application, the concentration of sodium alginate in the sodium alginate solution in step (2) is 0.4 to 0.6 wt%.

[0029] In an embodiment of the present application, the concentration of sodium alginate in the sodium alginate solution in step (2) is 0.4 wt%.

[0030] In an embodiment of the present application, the immersion time in steps (1) and (2) is 3 to 20 minutes.

[0031] In an embodiment of the present application, the immersion time in step (1) is 3 to 10 minutes.

[0032] In one embodiment of the present application, the impregnation time in step (2) is 15-20 min.

[0033] The second aspect of the present application provides a preparation method of an epoxy intumescent fire-retardant coating based on a CS@SA@ZIF-67 core-shell structure nanohybrid material, comprising the following steps:

[0034] I. Mix the CS@SA@ZIF-67 core-shell structure nanohybrid material, acid source, gas source, and acetone solution, and stir to form a dispersion system;

[0035] II. Preheat the epoxy resin, and when the epoxy resin can flow, add it to the dispersion system obtained in step (I), stir until mixed uniformly, then volatilize the solvent under certain temperature conditions to obtain a mixed system;

[0036] III. Add the curing agent to the mixed system and stir to obtain an epoxy intumescent fire-retardant coating.

[0037] Further, the acid source in step I is one or several of ammonium polyphosphate, ammonium sulfate, ammonium chloride, or phytic acid.

[0038] Further, the gas source in step I is one or several of ammonium polyphosphate, melamine, dicyandiamide, glycine, or ammonium borate.

[0039] Further, the mass fraction of the flame-retardant modified ZIF-67 nanomaterial in the epoxy intumescent fire-retardant coating is 0.5%-6%.

[0040] Preferably, the mass fraction of the flame-retardant modified ZIF-67 nanomaterial in the epoxy intumescent fire-retardant coating is 0.5%-2%.

[0041] Most preferably, the mass fraction of the flame-retardant modified ZIF-67 nanomaterial in the epoxy intumescent fire-retardant coating is 1%.

[0042] Further, the mass fraction of the acid source in the epoxy intumescent fire-retardant coating is 0.01%-6%.

[0043] Further, the mass fraction of the gas source in the epoxy intumescent fire-retardant coating is 0.01%-8%.

[0044] Specifically, the acid source and the gas source in step I are ammonium polyphosphate.

[0045] Specifically, the mass fraction of ammonium polyphosphate in the epoxy intumescent fire-retardant coating is 0.5-1.5%.

[0046] Further, the mass fraction of the epoxy resin in the epoxy intumescent fire-retardant coating is 80-85%.

[0047] Further, the temperature in step II is 60-100 DEG C; the volatilization time is 1-3h.

[0048] Further, the curing agent in step III is one or more of 4,4-diaminodiphenyl methane, 4,4-diaminodiphenyl ether, diaminodiphenyl sulfone, methyl tetrahydrophthalic anhydride, diethylenetriamine and ethylenediamine.

[0049] Further, the mass ratio of the curing agent in the epoxy intumescent fire-retardant coating is 15-20%.

[0050] The third aspect of the application provides the application of the epoxy intumescent fire-retardant coating obtained by the preparation method in the field of fire prevention and fireproof product preparation.

[0051] The application has the following beneficial effects:

[0052] (1) The application utilizes the interaction between the active groups on the biomass chitosan, sodium alginate and metal organic framework ZIF-67, and based on the electrostatic adsorption or coordination complex principle, loads the chitosan and sodium alginate biomass fire-retardant layer on the surface of ZIF-67 in situ, and finally constructs the green and environment-friendly bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material, which meets the sustainable green chemical concept; in addition, the method also helps to improve the agglomeration, and improve the dispersibility, compatibility with the matrix and fire-retardant efficiency of the metal organic framework nanomaterial.

[0053] (2) The CS@SA@ZIF-67 core-shell structure nanohybrid material has excellent catalytic charring, smoke suppression and toxicity reduction and heat resistance, and can act as a carbon source, and combines with the acid source / gas source of the traditional intumescent fire-retardant system such as ammonium polyphosphate, plays a synergistic fire-retardant effect, improves the intumescent fire-retardant performance of the fire-retardant coating, promotes the expansion of the coating into a protective intumescent carbon layer at high temperature, can block heat and effectively control the fire spread, and then helps to prolong the valuable rescue time. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 The XRD graphs of ZIF-67 before and after modification;

[0055] Figure 2 The FTIR graphs of ZIF-67 before and after modification;

[0056] Figure 3 The SEM graphs of ZIF-67 before and after modification, wherein a is the SEM graph of ZIF-67 before modification, and b is the SEM graph of ZIF-67 after modification. DETAILED DESCRIPTION

[0057] The application will be further explained and described below in combination with the attached table and examples, but the protection scope of the application is not limited to the following examples.

[0058] Raw material source

[0059] The ammonium polyphosphate (APP) used in the following examples has a purity of 99.8% and is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0060] Example 1

[0061] The preparation method of the epoxy intumescent fireproof coating based on the bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material comprises the following steps:

[0062] 1. Preparation of ZIF-67 nanomaterial

[0063] (1) 6.552 g of cobalt nitrate and 3.696 g of 2-methylimidazole were respectively dissolved in 60 mL of methanol to form a cobalt nitrate solution and a 2-methylimidazole solution, and then the 2-methylimidazole solution was added dropwise into the cobalt nitrate solution under stirring, and a suspension was obtained after reaction at 120°C for 4 h;

[0064] (2) The suspension in step (1) was collected by centrifugation at a speed of 6000 r / min for 8 min, and the precipitate was washed with methanol for 3 times;

[0065] (3) The washed solid in step (2) was dried in an oven at 80°C for 12 h to obtain the ZIF-67 nanomaterial.

[0066] 2. Preparation of biomass modification solution

[0067] 1 g of chitosan was dissolved in 100 mL of 1% acetic acid solution to prepare a chitosan solution with a concentration of 1 wt%; 0.4 g of sodium alginate was dissolved in 100 mL of deionized water to prepare a sodium alginate solution with a concentration of 0.4 wt%.

[0068] 3. Preparation of CS@SA@ZIF-67 core-shell structure nanohybrid material

[0069] (1) The ZIF-67 nanomaterial was immersed in the prepared 1 wt% chitosan solution for 5 min, and the precipitate was collected by centrifugation;

[0070] (2) The precipitate obtained in (1) was immersed in the prepared 0.4 wt% sodium alginate solution for 20 min, and the precipitate was collected by centrifugation to complete the loading modification;

[0071] (3) The ZIF-67 sample after loading modification was dried in an oven at 90°C for 12 h to obtain the CS@SA@ZIF-67 core-shell structure nanohybrid material.

[0072] 4. Preparation of epoxy intumescent fireproof coating

[0073] (1) 0.5 g of the bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material, 5 mL of an APP aqueous solution (containing 0.5 g of APP), and 60 mL of an acetone solution were mixed in a three-necked flask, and a modified ZIF-67 uniform dispersion system was formed by ultrasonic stirring;

[0074] (2) 40.2365 g of an epoxy resin (EP) was preheated in an 80°C oven for 10 min; when the epoxy resin could flow, it was added to the dispersion system described in step (1), and stirring was performed for 35 min;

[0075] (3) The mixed system in (2) was placed in an oil pot, and volatilization was performed at 105°C for 3 h;

[0076] (4) 8.7635 g of 4,4-diaminodiphenyl methane was added, and stirring was continuously performed for 2 min, to obtain an epoxy intumescent fireproof coating based on the CS@SA@ZIF-67 core-shell structure nanohybrid material.

[0077] Example 2

[0078] A preparation method of an epoxy intumescent fireproof coating based on a bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material, comprising the following steps:

[0079] Steps 1-3 were prepared by referring to steps in Example 1.

[0080] 4. Preparation of an epoxy intumescent fireproof coating

[0081] (1) 0.5 g of the bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material and 60 mL of an acetone solution were mixed in a three-necked flask, and a modified ZIF-67 uniform dispersion system was formed by ultrasonic stirring;

[0082] (2) 40.6471 g of an epoxy resin (EP) was preheated in an 80°C oven for 10 min; when the epoxy resin could flow, it was added to the dispersion system described in step (1), and stirring was performed for 35 min;

[0083] (3) The mixed system in (2) was placed in an oil pot, and volatilization was performed at 105°C for 3 h;

[0084] (4) 8.8529 g of 4,4-diaminodiphenyl methane was added, and stirring was continuously performed for 2 min, to obtain an epoxy intumescent fireproof coating based on the CS@SA@ZIF-67 core-shell structure nanohybrid material.

[0085] Example 3

[0086] A preparation method of an epoxy intumescent fireproof coating based on a bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material, comprising the following steps:

[0087] Steps 1-3 were prepared by referring to the steps in Example 1.

[0088] 4. Preparation of epoxy intumescent fire retardant coating

[0089] (1) 0.25 g of bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material and 60 mL of acetone solution were mixed in a three-necked flask, and ultrasonic stirring was performed to form a modified ZIF-67 uniform dispersion system;

[0090] (2) 40.8524 g of epoxy resin (EP) was preheated in an 80°C oven for 10 min; when the epoxy resin could flow, it was added to the dispersion system described in step (1), and stirred for 35 min;

[0091] (3) The mixed system in (2) was placed in an oil pot and volatilized at 105°C for 3 h;

[0092] (4) 8.8976 g of 4,4-diamino diphenyl methane was added and stirred for 2 min to obtain an epoxy intumescent fire retardant coating based on CS@SA@ZIF-67 core-shell structure nanohybrid material.

[0093] Example 4

[0094] The preparation method of the epoxy intumescent fire retardant coating based on bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material comprises the following steps:

[0095] Steps 1-3 were prepared by referring to the steps in Example 1.

[0096] 4. Preparation of epoxy intumescent fire retardant coating

[0097] (1) 1.0 g of bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material and 60 mL of acetone solution were mixed in a three-necked flask, and ultrasonic stirring was performed to form a modified ZIF-67 uniform dispersion system;

[0098] (2) 40.2365 g of epoxy resin (EP) was preheated in an 80°C oven for 10 min; when the epoxy resin could flow, it was added to the dispersion system described in step (1), and stirred for 35 min;

[0099] (3) The mixed system in (2) was placed in an oil pot and volatilized at 105°C for 3 h;

[0100] (4) 8.7635 g of 4,4-diamino diphenyl methane was added and stirred for 2 min to obtain an epoxy intumescent fire retardant coating based on CS@SA@ZIF-67 core-shell structure nanohybrid material.

[0101] Comparative Example 1

[0102] Preheat 41.0577 g of epoxy resin (EP) in an 80°C oven for 10 min, and add to the flask when the epoxy resin can flow. Continuously stir 8.9423 g of 4,4-diaminodiphenyl methane for 2 min to obtain an epoxy fireproof coating.

[0103] Comparative Example 2

[0104] Mix 0.5 g of ZIF-67 nanomaterial and 60 mL of acetone solution in a three-necked flask, and ultrasonically stir to form a uniform dispersion system of ZIF-67; preheat 40.6471 g of epoxy resin (EP) in an 80°C oven for 10 min, and add to the flask when the epoxy resin can flow. Continuously stir 8.8529 g of 4,4-diaminodiphenyl methane for 2 min to obtain an epoxy intumescent fireproof coating.

[0105] Comparative Example 3

[0106] Steps 1-2 are prepared according to the steps in Example 1.

[0107] 3. Preparation of CS@ZIF-67 core-shell structure nanohybrid material

[0108] Immerse the ZIF-67 nanomaterial in the prepared 1wt% chitosan solution for 5 min, and collect the precipitate by centrifugation; dry the ZIF-67 sample with completed loading modification in a 90°C oven for 12 h to obtain a CS@SA@ZIF-67 core-shell structure nanohybrid material;

[0109] 4. Preparation of epoxy intumescent fireproof coating

[0110] (1) Mix 0.5 g of bio-based CS@ZIF-67 core-shell structure nanohybrid material and 60 mL of acetone solution in a three-necked flask, and ultrasonically stir to form a uniform dispersion system of modified ZIF-67;

[0111] (2) Preheat 40.6471 g of epoxy resin (EP) in an 80°C oven for 10 min, and add to the flask when the epoxy resin can flow;

[0112] (3) Place the mixed system in (2) in an oil pot and volatilize at 105°C for 3 h;

[0113] (4) Add 8.8529 g of 4,4-diaminodiphenyl methane and continuously stir for 2 min to obtain an epoxy intumescent fireproof coating based on the CS@SA@ZIF-67 core-shell structure nanohybrid material.

[0114] Comparative Example 4

[0115] Steps 1-2 are prepared according to the steps in Example 1.

[0116] 3. Preparation of SA@ZIF-67 core-shell structure nanohybrid material

[0117] The ZIF-67 nanomaterial was immersed in the prepared 0.4wt% sodium alginate solution for 20 min, and the precipitate was collected by centrifugation to complete the loading modification; the ZIF-67 sample after loading modification was placed in a 90°C oven for drying for 12 h to prepare the SA@ZIF-67 core-shell structure nanohybrid material;

[0118] 4. Preparation of epoxy intumescent fireproof coating

[0119] (1) 0.5 g of bio-based SA@ZIF-67 core-shell structure nanohybrid material and 60 mL of acetone solution were mixed in a three-necked flask, and ultrasonic stirring was performed to form a modified ZIF-67 uniform dispersion system;

[0120] (2) 40.6471 g of epoxy resin (EP) was preheated in an 80°C oven for 10 min, and then added to the flask when the epoxy resin could flow;

[0121] (3) The mixed system in (2) was placed in an oil pot and volatilized at 105°C for 3 h;

[0122] (4) 8.8529 g of 4,4-diamino diphenyl methane was added and stirred for 2 min to obtain an epoxy intumescent fireproof coating based on CS@SA@ZIF-67 core-shell structure nanohybrid material.

[0123] Comparative Example 5

[0124] 0.5 g of ZIF-67 nanomaterial, 5 mL of APP aqueous solution (containing 0.5 g of APP), and 60 mL of acetone solution were mixed in a three-necked flask, and ultrasonic stirring was performed to form a ZIF-67 uniform dispersion system; 40.2365 g of epoxy resin (EP) was preheated in an 80°C oven for 10 min, and then added to the flask when the epoxy resin could flow. 8.7635 g of 4,4-diamino diphenyl methane was added to the flask, and after stirring for 2 min, it was poured into a mold and dried at 100°C for 2 h and at 150°C for 2 h, and after cooling, the mold was removed to obtain an epoxy fireproof coating.

[0125] Comparative Example 6

[0126] Mix 0.5 g of ZIF-67 nanomaterial, 5 mL of APP and calcium gluconate salt mixed aqueous solution (ammonium polyphosphate: calcium gluconate salt = 4:1, total 0.5 g) and 60 mL of acetone solution in a three-necked flask, ultrasonic stirring to form a uniform dispersion system of ZIF-67; 40.2365 g of epoxy resin (EP) is preheated in an oven at 80°C for 10 min, and then added into the flask when the epoxy resin can flow. 8.7635 g of 4,4-diaminodiphenyl methane is added into the flask, and after continuous stirring for 2 min, it is poured into the mold and dried at 100°C for 2 h and at 150°C for 2 h, and then demolded after cooling to obtain an epoxy fireproof coating.

[0127] Comparative Example 7

[0128] Step 1 is prepared by referring to the step in Example 1.

[0129] 2. Preparation of biomass modification solution

[0130] Take 1 g of polyethyleneimine (PEI) in 100 mL of deionized water to prepare a polyethyleneimine solution with a concentration of 1 wt%; 0.4 g of sodium alginate is dissolved in 100 mL of deionized water to prepare a sodium alginate solution with a concentration of 0.4 wt%.

[0131] 3. Preparation of PEI@SA@ZIF-67 core-shell structure nanohybrid material

[0132] (1) ZIF-67 nanomaterial is immersed in the prepared 1 wt% polyethyleneimine solution for 5 min, and the precipitate is collected by centrifugation;

[0133] (2) The precipitate obtained in (1) is immersed in the prepared 0.4 wt% sodium alginate solution for 20 min, and the precipitate is collected by centrifugation to complete the loading modification;

[0134] (3) The ZIF-67 sample after loading modification is placed in a 90°C oven for drying for 12 h to prepare a PEI@SA@ZIF-67 core-shell structure nanohybrid material.

[0135] 4. Preparation of epoxy intumescent fireproof coating

[0136] (1) Mix 0.5 g of bio-based PEI@SA@ZIF-67 nanohybrid material, 5 mL of APP aqueous solution (containing 0.5 g of APP) and 60 mL of acetone solution in a three-necked flask, and ultrasonic stirring to form a uniform dispersion system of modified ZIF-67;

[0137] (2) 40.2365 g of epoxy resin (EP) is preheated in an oven at 80°C for 10 min; when the epoxy resin can flow, it is added into the dispersion system in step (1) and stirred for 35 min;

[0138] (3) Put the mixed system in (2) into an oil pot, and volatilize at 105 °C for 3 h;

[0139] (4) Add 8.7635 g of 4,4-diaminodiphenyl methane, continuously stir for 2 min, and obtain an epoxy intumescent fireproof coating based on the PEI@SA@ZIF-67 core-shell structure nano hybrid material.

[0140] Comparative Example 8

[0141] Mix ZIF-67 nanomaterial, 1wt% ZIF-67 / CS / SA blended solution (ZIF-67 nanomaterial: chitosan solution: sodium alginate solution = 2.5:2.5:1, total 0.5 g) and 60 mL of acetone solution in a three-necked flask, and ultrasonically stir to form a ZIF-67 uniform dispersion system; 40.6471 g of epoxy resin (EP) is preheated in an 80 °C oven for 10 min, and then added into the flask when the epoxy resin can flow. 8.8529 g of 4,4-diaminodiphenyl methane is added into the flask, and after continuously stirring for 2 min, it is poured into a mold and dried at 100 °C for 2 h and at 150 °C for 2 h, and after cooling, the mold is removed, to obtain an epoxy fireproof coating.

[0142] Comparative Example 9

[0143] Preparation is carried out according to the steps and parameters in Comparative Example 1, wherein only the concentration of the sodium alginate solution in step 2 is adjusted to 1wt%, and then impregnation is carried out, and finally the nanoparticles disintegrate, and the subsequent preparation cannot be carried out.

[0144] Comparative Example 10

[0145] Preparation is carried out according to the steps and parameters in Comparative Example 1, wherein only the concentration of the sodium alginate solution in step 2 is adjusted to 2wt%, and then impregnation is carried out, and finally the nanoparticles disintegrate, and the subsequent preparation cannot be carried out.

[0146] Comparative Example 11

[0147] Preparation is carried out according to the steps and parameters in Comparative Example 1, wherein only steps (1) and (2) in step 2 are repeated once, and a ZIF-67 sample loaded with a modified 2-layer is obtained, and finally the nanoparticles disintegrate, and the subsequent preparation cannot be carried out.

[0148] Comparative Example 12

[0149] Preparation is carried out according to the steps and parameters in Comparative Example 1, wherein only steps (1) and (2) in step 2 are repeated twice, and a ZIF-67 sample loaded with a modified 3-layer is obtained, and finally the nanoparticles disintegrate, and the subsequent preparation cannot be carried out.

[0150] Table 1 Sample formulation table of examples 1-4 and comparative examples 1-8

[0151]

[0152]

[0153] The fireproof coating prepared in examples 1-4 and comparative examples 1-8 was poured into a mold and heated and cured (baked at 100℃ for 2h, baked at 150℃ for 2h) to obtain a composite material sample, and then the composite material sample was subjected to a cone calorimeter test. The sample was installed on the test device, the power of the radiant cone was set to 35kw, the cone calorimeter was started, heat radiation was carried out and test data were collected in real time, the heat release rate, total heat release and other parameters of the material were calculated, and the heat radiation of the radiant cone was stopped after reaching the preset test time.

[0154] The test results are shown in the following table:

[0155] Table 2 Cone calorimeter test data table of examples 1-4 and comparative examples 1-8

[0156]

[0157]

[0158] Among them, the peak heat release rate (PHRR) is an important fire characteristic parameter of the material, the initial maximum peak value represents the typical combustion characteristics of the material, the total heat release (THR) refers to the total heat released from ignition to flame extinguishment, the larger the value, the more intense the combustion reaction; the real-time mass (MASS) reflects the trend of weight loss during the combustion process of the material, the greater the weight loss, the more intense the combustion reaction. From the THR and MASS, the same conclusion as above can be obtained.

[0159] The results show that compared with the pure epoxy resin (comparative example 1), the PHRR of the unmodified intumescent nano fireproof coating (comparative example 2) is reduced, which indicates that the addition of nano materials improves the flame retardant performance of the epoxy resin. Compared with the pure epoxy resin (comparative example 1) and the unmodified intumescent nano fireproof coating (comparative example 2), the PHRR of the epoxy intumescent fireproof coating based on the bio-based CS@SA@ZIF-67 core-shell structure nano hybrid material (examples 2-4) is significantly reduced, which proves that the flame retardant performance of the modified ZIF-67 is enhanced.

[0160] For examples 2-4, the more the content of CS@SA@ZIF-67, the better the flame retardant performance. But the performance of example 2 is similar to that of example 4, which has reached the ideal effect. In order to reduce the cost, the mass fraction of the bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material prepared by the application in the intumescent fire retardant coating should be 1.0%. Compared with example 2, APP in this flame retardant system acts as an acid source and a gas source, which improves the flame retardance of the composite material, and the PHRR is significantly reduced.

[0161] Compared with pure epoxy resin (comparative example 1), the PHRR of the epoxy resin composite material modified by CS modified ZIF-67, SA modified ZIF-67, APP modified ZIF-67, and APP / glucose acid calcium salt modified ZIF-67 (comparative examples 3-6) is reduced, but the PHRR is still at a high level compared with example 1, and the flame retardant performance is poor.

[0162] Comparative example 7 is modified by PEI and SA modified ZIF-67, and APP is added on the basis of flame retardant modification, and the PHRR is significantly increased compared with example 1, and the flame retardant performance is poor.

[0163] Comparative example 8 is a blend of ZIF-67, CS, and SA (ZIF-67:CS:SA=2.5:2.5:1), and forms a composite material with epoxy resin, and the PHRR is increased compared with the epoxy intumescent fire retardant coating based on the bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material (example 2), which proves that the flame retardant effect of flame retardant modification of nanomaterials is better than that of direct physical blending, and the flame retardant performance of the fire retardant coating prepared by the application is improved due to the modification of the nanomaterials.

[0164] Comparative examples 9-12 show that the concentration of sodium alginate solution and the number of impregnation of biomass modification solution in the preparation of CS@ZIF-67 core-shell structure nanohybrid material have important influence on the structure of the core-shell structure nanohybrid material, among which the concentration of sodium alginate solution should not be too high and should be kept at 0.4wt%, and the number of impregnation modification should not be too much, and only one impregnation modification is needed.

[0165] The above examples provided are not intended to limit the scope covered by the application, and the described steps are not intended to limit the execution order. Those skilled in the art can make obvious improvements to the application in combination with existing common knowledge, which also falls within the protection scope defined by the claims of the application.

Claims

1. A preparation method of a bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material, characterized in that, The preparation method is the following steps: (1) ZIF-67 nanomaterial is immersed in a 0.5-1wt% chitosan solution, and the precipitate is collected by centrifugation; (2) The precipitate obtained in (1) is immersed in a 0.4-0.6wt% sodium alginate solution, and the precipitate is collected by centrifugation to complete the loading modification, thereby obtaining a modified ZIF-67 sample; (3) The modified ZIF-67 sample is dried to obtain a bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material; In step (1), the ZIF-67 nanomaterial is prepared by the following steps: S1, 2-methylimidazole is dissolved in a solvent and mixed uniformly, and under stirring, a cobalt nitrate solution is added dropwise to obtain a suspension under certain temperature conditions; S2, the suspension in step S1 is centrifuged to collect the precipitate, which is then washed with methanol; S3, the washed solid in step S2 is dried to obtain ZIF-67 nanomaterial.

2. The production method according to claim 1, characterized by, In the preparation of ZIF-67 nanomaterial, the molar ratio of cobalt nitrate to 2-methylimidazole in step S1 is 16:1-2:1; the certain temperature in step S1 is 80-140℃; and the reaction time in step S1 is 2-14h.

3. The production method according to claim 1, characterized by, The immersion time in step (1) is 3-10min.

4. The production method as claimed in claim 1, characterized in that, The immersion time in step (2) is 15-20min.

5. A method for preparing an epoxy intumescent fire-retardant coating based on the bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material prepared according to any one of claims 1-4, characterized in that, The following steps are included: Ⅰ, mixing bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material, ammonium polyphosphate and acetone solution to form a dispersion system; Ⅱ, preheat the epoxy resin; when the epoxy resin can flow, add it to the dispersion system obtained in step (Ⅰ), stir until mixed uniformly, then volatilize the solvent under certain temperature conditions to obtain a mixed system; Ⅲ, add a curing agent to the mixed system and stir to obtain an epoxy intumescent fireproof coating.

6. The production method according to claim 5, characterized by, The mass fraction of bio-based CS@SA@ZIF-67 core-shell structure nanohybrid material in the epoxy intumescent fireproof coating is 0.5%-2%.

7. The preparation method according to claim 5, characterized in that, The mass fraction of ammonium polyphosphate in the epoxy intumescent fireproof coating is 0.5-1.5%.

8. The preparation method according to claim 5, characterized in that, The mass fraction of epoxy resin in the epoxy intumescent fireproof coating is 80-85%.

9. The preparation method according to claim 5, characterized in that, The curing agent in step Ⅲ is one or more of 4,4-diaminodiphenyl methane, 4,4-diaminodiphenyl ether, diamino diphenyl sulfone, methyl tetrahydrophthalic anhydride, diethylenetriamine and ethylenediamine; the mass fraction of the curing agent in the epoxy intumescent fireproof coating is 15-20%.

10. The use of the epoxy intumescent fireproof coating prepared by the preparation method of any one of claims 5-9 in the field of fire prevention and fireproof product preparation.

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