An enhanced high thermal conductive fire-retardant coating based on modified boron nitride and bio-based flame-retardant coating modified UiO-66

Abstract

The application discloses a kind of based on modified boron nitride and biological base fire-retardant coating modified UiO-66 enhanced high thermal conductivity fire-retardant coating, belongs to fire-retardant material field.The application is first by hydrolysis and condensation in BN surface coating polysilazane (PSZ) and silane, obtain surface treatment boron nitride (BN), then prepare UiO-66 again CS and PA two biological base materials are adsorbed on UiO-66 by electrostatic attraction, after and surface treatment boron nitride together with epoxy resin compounding obtains a kind of based on modified boron nitride and biological base modified UiO-66 enhanced fire-retardant coating, the strength of this fire-retardant resin expanded carbon layer is high and dense, and fire-retardant effect is remarkable, simultaneously, preparation method is simple, preparation process is green and environmental protection, is suitable in fire-retardant field widely applied and industrialized production.

Description

Technical Field

[0001] This invention relates to the field of fire-retardant coating technology, and in particular to an enhanced high thermal conductivity fire-retardant coating based on modified boron nitride and bio-based flame-retardant coating modified UiO-66. Background Technology

[0002] In recent years, nanotechnology for flame retardancy has attracted much attention and has been used to modify numerous materials. Metal-organic frameworks (MOFs) are porous nanomaterials with a periodic network skeleton formed by the combination of metal ions and organic ligands. Compared with traditional flame retardants, MOF-based flame retardants have advantages such as high thermal stability, good compatibility with the matrix, high porosity, strong structural designability, and minimal impact on the mechanical properties of the matrix. UiO-66, as a zirconium-based MOF material, possesses broad application potential due to its porosity, high specific surface area, chemical stability, and tunability. However, the flame retardant effect of using MOFs alone is usually limited due to the lack of flame-retardant elements (such as phosphorus, nitrogen, and silicon). Therefore, it is necessary to organically combine MOFs with compounds containing flame-retardant elements to further improve their flame-retardant efficiency through chemical modification.

[0003] Among the current technologies, CN 118878852 A discloses a metal-organic framework-based porous liquid functional flame retardant, but its peak heat release rate is only 45.2% lower than that of pure polyurea, and the effect can still be improved; patent CN 118562255 A discloses a polymer metal-organic framework modified flame-retardant epoxy resin, but its final measured PHRR value is greater than 600 kW·m 2 The effect can still be improved. Techniques related to chemical modification include those using chitosan and phytic acid. Patent CN 114703667 B discloses a method for preparing flame-retardant cotton fabrics based on attapulgite layer-by-layer self-assembly technology, and "The Influence of Chitosan / Sodium Phytate-Coated Ammonium Polyphosphate Composites on the Flame Retardant Properties of Polylactic Acid Composites." However, these techniques focus on the flame retardancy of fabrics, using fabric as the substrate rather than flowing liquids, and do not involve their use in flame-retardant coatings. Regarding the use of boron nitride modification, there is "Research on Boron Nitride Hybrid Modification of Environmentally Friendly Phenolic Resin Composites," but this article only explores the flame-retardant effect of silane coupling agents on the modification of boron nitride particles, without combining it with other substances. Furthermore, patent CN 118772683 A discloses a layer-by-layer self-assembled MOFs intumescent high-efficiency fire-retardant coating, mentioning the impregnation modification of MOFs nanomaterials, but the specific scheme does not involve the exploration of UiO-66 materials. Summary of the Invention

[0004] Technical issues

[0005] UiO-66, as a zirconium-based organometallic framework material, lacks flame-retardant elements (such as phosphorus, nitrogen, and silicon), so the flame-retardant effect of using MOF alone is usually limited. Therefore, it needs to be chemically modified to further improve its flame-retardant efficiency and broaden its application range.

[0006] Technical content

[0007] To address the aforementioned problems, this invention provides an enhanced fire-retardant coating based on modified boron nitride and bio-based modified UiO-66. The enhanced fire-retardant coating, by mass fraction, comprises 50-60% epoxy resin, 10-15% 4,4-diaminodiphenylmethane, 1-5% bio-based flame-retardant coating modified UiO-66 nanomaterials, and 25-35% modified boron nitride.

[0008] Preferably, the enhanced fire-retardant coating comprises, by mass fraction, 53-57% epoxy resin, 11-13% 4,4-diaminodiphenylmethane, 1-3% bio-based flame-retardant coating modified UiO-66 nanomaterial, and 27-32% modified boron nitride.

[0009] Specifically, the enhanced fire-retardant coating, by mass fraction, consists of 55.84% epoxy resin, 12.16% 4,4-diaminodiphenylmethane, 2% bio-based flame-retardant coating modified UiO-66 nanomaterials, and 30% modified boron nitride.

[0010] Furthermore, the bio-based flame retardant coating modified UiO-66 nanomaterial is a UiO-66 nanomaterial that is wrapped with a chitosan layer and a phytic acid layer from the inside out; one chitosan layer and one phytic acid layer constitute one bio-based flame retardant coating, and there are a total of 1 to 5 bio-based flame retardant coatings, preferably 2 to 4 bio-based flame retardant coatings, and most preferably 3 bio-based flame retardant coatings.

[0011] Furthermore, the preparation of the UiO-66 nanomaterial is as follows:

[0012] Zirconium chloride was dissolved in N,N-dimethylformamide to obtain a zirconium chloride solution; 2-aminoterephthalic acid was dissolved in N,N-dimethylformamide to obtain a 2-aminoterephthalic acid solution; the two solutions were mixed and acetic acid was added and stirred, and then the reaction was carried out under sealed heating; after cooling, the solid was collected by centrifugation, and finally the UiO-66 nanomaterial was obtained by vacuum activation.

[0013] Furthermore, the concentration of zirconium chloride in the zirconium chloride solution is 0.75–2 wt%.

[0014] Furthermore, the concentration of 2-aminoterephthalic acid in the 2-aminoterephthalic acid solution is 0.35–1.5 wt%.

[0015] Furthermore, the total N,N-dimethylformamide volume ratio in the acetic acid, zirconium chloride solution, and 2-aminoterephthalic acid solution is 1:4 to 3:8;

[0016] Furthermore, the temperature of the sealed heating reaction is 100–200°C, and the time is 6–16 hours;

[0017] Furthermore, the vacuum activation conditions are a temperature of 20–180°C and an activation time of 1–12 h.

[0018] Further, the modified boron nitride is prepared as follows: boron nitride is added to ethanol and mixed to obtain a mixture, and the pH of the mixture is adjusted using ammonia water; a certain amount of 3-aminopropyltriethoxysilane is weighed and added to the above mixture for reaction, and after the reaction is completed, ethanol is added to the reaction solution for centrifugation and washing to remove unreacted ammonia and 3-aminopropyltriethoxysilane; the precipitate after centrifugation is collected, dried, and ground to obtain modified boron nitride.

[0019] Furthermore, the concentration of boron nitride in the mixture is 1–5 wt%.

[0020] Furthermore, the pH is adjusted to 7–12.

[0021] Furthermore, the mass ratio of 3-aminopropyltriethoxysilane to boron nitride is 1 to 5:1.

[0022] Furthermore, the reaction temperature is 55–70°C, and the reaction time is 3–6 hours.

[0023] Furthermore, the centrifugal washing is performed at 3500-6000 rpm for 4 times.

[0024] Furthermore, the drying temperature is 40–70°C, and the drying time is 36–60 hours.

[0025] The enhanced fire-retardant coating provided by this invention is applied in the fields of fire prevention or flame retardancy.

[0026] Furthermore, the application includes applying an enhanced fire-retardant coating to the surface of a building, furniture, equipment, or other material requiring fire protection, and then heating it to cure.

[0027] The present invention also provides an enhanced fireproof board based on modified boron nitride and bio-based modified UiO-66, wherein the enhanced fireproof board is obtained by heating and curing the above-mentioned enhanced fireproof coating after it is introduced into a mold.

[0028] Furthermore, the heat curing includes first drying at 100-150°C for 1-3 hours, and then drying at 150-200°C for 1-3 hours.

[0029] The present invention also provides a method for preparing the above-mentioned fire-retardant coating, the method comprising the following steps:

[0030] S1. Preparation of base material: Take epoxy resin and curing agent, mix them to obtain base material;

[0031] S2. Add boron nitride to ethanol and mix to obtain a mixture. Adjust the pH of the mixture with ammonia. Weigh a certain amount of 3-aminopropyltriethoxysilane and add it to the mixture to carry out the reaction. After the reaction is completed, add ethanol to the reaction solution and centrifuge to wash it to remove unreacted ammonia and 3-aminopropyltriethoxysilane. Collect the precipitate after centrifugation, dry it and grind it to obtain modified boron nitride.

[0032] S3. Preparation of bio-based flame retardant coating modified UiO-66 nanomaterials: UiO-66 nanomaterials were immersed in chitosan acetic acid aqueous solution, then the UiO-66 nanomaterials were taken out and immersed in phytic acid aqueous solution, and then the UiO-66 nanomaterials were taken out.

[0033] The UiO-66 nanomaterial after two impregnation steps is modified with one layer. Repeating the two impregnation steps again yields UiO-66 nanomaterial with multiple layers.

[0034] S4. Preparation of flame retardant resin: Take the modified multilayer UiO-66 nanomaterial, modified boron nitride and base material, mix them, heat and stir to disperse evenly to obtain fire retardant coating.

[0035] Furthermore, the curing agent mentioned in step S1 includes one or a mixture of several of the following: polyamides, liquid anhydrides, aliphatic polyamines, cashew phenol-modified amines, and aromatic polyamine curing agents.

[0036] Furthermore, the mass ratio of epoxy resin to curing agent in step S1 is 2:1 to 5:1.

[0037] Furthermore, the concentration of boron nitride in the mixture in step S2 is 1–5 wt%.

[0038] Furthermore, the pH adjustment in step S2 is set to 7–12.

[0039] Furthermore, in step S2, the mass ratio of 3-aminopropyltriethoxysilane to boron nitride is 1 to 5:1.

[0040] Furthermore, the reaction in step S2 is carried out at a temperature of 55–70°C for 3–6 hours.

[0041] Furthermore, the centrifugal washing described in step S2 is performed at 3500-6000 rpm for 4 times.

[0042] Furthermore, the drying temperature in step S2 is 40–70°C, and the drying time is 36–60 h.

[0043] Furthermore, the preparation of the UiO-66 nanomaterial in step S3 is as follows:

[0044] Zirconium chloride was dissolved in N,N-dimethylformamide to obtain a zirconium chloride solution; 2-aminoterephthalic acid was dissolved in N,N-dimethylformamide to obtain a 2-aminoterephthalic acid solution; the two solutions were mixed and acetic acid was added and stirred, and then the reaction was carried out under sealed heating; after cooling, the solid was collected by centrifugation, and finally the UiO-66 nanomaterial was obtained by vacuum activation.

[0045] The concentration of zirconium chloride in the zirconium chloride solution is 0.75–2 wt%.

[0046] The concentration of 2-aminoterephthalic acid in the 2-aminoterephthalic acid solution is 0.35–1.5 wt%.

[0047] The total N,N-dimethylformamide volume ratio in the acetic acid, zirconium chloride solution, and 2-aminoterephthalic acid solution is 1:4 to 3:8.

[0048] The temperature of the sealed heating reaction is 100-150°C, and the time is 6-16 hours.

[0049] The vacuum activation conditions are a temperature of 20–140°C and an activation time of 1–12 h.

[0050] Furthermore, the concentration of chitosan in the chitosan-acetic acid aqueous solution in step S3 is 0.5–5 wt%.

[0051] Furthermore, the concentration of acetic acid in the chitosan-acetic acid aqueous solution in step S3 is 0.5–2 wt%.

[0052] Furthermore, the phytic acid concentration in the phytic acid aqueous solution in step S3 is 2-7 wt%.

[0053] Furthermore, the immersion time described in step S3 is 1 to 10 minutes.

[0054] Furthermore, the number of modification layers in the multilayered UiO-66 nanomaterial described in step S3 is 1 to 5.

[0055] Preferably, the number of modification layers in the multilayered UiO-66 nanomaterial described in step S3 is 2 to 4.

[0056] Most preferably, the number of modification layers of the multilayered UiO-66 nanomaterial described in step S3 is 3.

[0057] Furthermore, the fire-retardant coating described in step S4 contains 0.5 to 2 wt% of multilayered UiO-66 nanomaterials;

[0058] Furthermore, the modified boron nitride in the fire-retardant coating described in step S4 accounts for 10-30 wt%;

[0059] Furthermore, the base material in the fire-retardant coating described in step S4 accounts for 68% to 89.5 wt%.

[0060] Furthermore, the heating and stirring described in step S4 is performed at 60–105°C for 1.5–12 hours.

[0061] The present invention has the following beneficial effects:

[0062] (1) In this invention, the boron nitride nanomaterials grafted with silane coupling agents can effectively solve the problem of boron nitride dispersion in the matrix. Furthermore, the silane coupling agent modification of boron nitride also helps to reduce the interfacial thermal resistance between the boron nitride nanomaterials and the matrix, thereby improving its thermal conductivity. In addition, in this invention, UiO-66 is modified with a bio-based flame-retardant coating. This method is green, environmentally friendly, and low in toxicity. The resulting bio-based flame-retardant coating modified with UiO-66 is more efficient and safer, and it is also beneficial for constructing an intumescent flame-retardant coating.

[0063] (2) The boron nitride nanomaterials obtained in this invention have excellent heat resistance and sheet barrier effect. The bio-based flame retardant coating modified UiO-66 has the functions of porous adsorption, smoke suppression and toxicity reduction, catalytic char formation and expansion flame retardancy. The combination of the two will greatly improve the fire resistance of the matrix and reduce combustion toxicity, and achieve synergistic effect. Attached Figure Description

[0064] Figure 1 Infrared spectra of UiO-66 before and after bio-based flame retardant modification.

[0065] Figure 2 XRD patterns of UiO-66 before and after bio-based flame retardant modification.

[0066] Figure 3 The image shows the SEM image of the unmodified UiO-66 in Comparative Example 2.

[0067] Figure 4 This is a SEM image of the modified UiO-66-3 in Example 2.

[0068] Figure 5 This is a photograph of the fire-retardant coating obtained in Comparative Example 1 after a cone calorimetry test.

[0069] Figure 6 This is a photograph of the fire-retardant coating obtained in Example 4 after a cone calorimetry test. Detailed Implementation

[0070] The present invention will be further explained and described below with reference to the appendix and embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0071] Example 1

[0072] A fire-retardant coating comprising the following steps:

[0073] 1. Preparation of base material

[0074] Weigh out 40.24g of epoxy resin and 8.76g of 4,4-diaminodiphenylmethane to obtain the base material;

[0075] 2. Preparation of bio-based flame-retardant coating modified UiO-66 nanomaterials

[0076] (1) Preparation of UiO-66 nanomaterials

[0077] 0.714 g of zirconium chloride (ZrCl4) was dissolved in 80 mL of N,N-dimethylformamide (DMF); 0.5075 g of 2-aminoterephthalic acid was dissolved in 80 mL of DMF; the two solutions were poured into a beaker and 42 mL of acetic acid was added and ultrasonically stirred. The mixture was then poured into a polytetrafluoroethylene beaker and sealed. The reaction was carried out at 120 °C in an oven for 12 h. After cooling, the product was collected by centrifugation and washed 3 times with DMF and 2 times with methanol. Finally, the product was activated under vacuum at 120 °C for 2 h to obtain UiO-66 nanomaterials.

[0078] (2) Preparation and modification of bio-based solutions for UiO-66 nanomaterials

[0079] 1 g of chitosan (CS) powder was dissolved in 100 mL of 1% acetic acid solution to form bio-based solution 1; 7.17 g of 70% phytic acid (PA) solution was dissolved in 92.83 mL of deionized water by ultrasonic stirring to form bio-based solution 2.

[0080] 1 g of UiO-66 nanomaterial was weighed and impregnated in bio-based solution 1. After impregnation for 5 min, the solid was centrifuged at 6000 r / min for 8 min and the solid was retained. The obtained solid was impregnated in bio-based solution 2. After impregnation for 5 min, the solid was centrifuged at 6000 r / min for 8 min and the solid was retained, completing the first layer after electrostatic adsorption. The solid after centrifugation in bio-based solution 2 was vacuum dried at 80 °C for 2 h to obtain bio-based modified UiO-66-1 nanomaterial.

[0081] 3. Preparation of fire-retardant coatings

[0082] Weigh 1g of bio-based modified UiO-66-1 nanomaterial and mix it with the base material. Then heat it in an oil bath at 105℃ and stir it at a stirring speed of 350r / min for 3h to obtain the fireproof coating.

[0083] Example 2

[0084] A fire-retardant coating comprising the following steps:

[0085] 1. Preparation of base material: Refer to step 1 in Example 1;

[0086] 2. Preparation of bio-based flame-retardant coating modified UiO-66 nanomaterials

[0087] (1) Preparation of UiO-66 nanomaterials: The preparation was carried out according to the corresponding steps in Example 1;

[0088] (2) Preparation and modification of bio-based solutions for UiO-66 nanomaterials

[0089] 1 g of chitosan (CS) powder was dissolved in 100 mL of 1% acetic acid solution to form bio-based solution 1; 7.17 g of 70% phytic acid (PA) solution was dissolved in 92.83 mL of deionized water by ultrasonic stirring to form bio-based solution 2.

[0090] Weigh 1g of UiO-66 nanomaterial and immerse it in bio-based solution 1. After immersion for 5min, centrifuge at 6000r / min for 8min to retain the solid. Immerse the obtained solid in bio-based solution 2. After immersion for 5min, centrifuge at 6000r / min for 8min to retain the solid, thus completing the first layer after electrostatic adsorption.

[0091] Repeat the above two impregnation steps twice, shortening the impregnation time to 1 minute each time; dry the solid obtained after centrifugation at 80°C under vacuum for 2 hours to obtain bio-based modified UiO-66-3 nanomaterials.

[0092] 3. Preparation of fire-retardant coatings

[0093] Weigh 1g of bio-based modified UiO-66-3 nanomaterial and mix it with the base material. Then heat it in an oil bath at 105℃ and stir it at a stirring speed of 350r / min for 3h to obtain the fireproof coating.

[0094] Example 3

[0095] A fire-retardant coating comprising the following steps:

[0096] 1. Preparation of base material: Refer to step 1 in Example 1;

[0097] 2. Preparation of bio-based flame-retardant coating modified UiO-66 nanomaterials

[0098] (1) Preparation of UiO-66 nanomaterials: The preparation was carried out according to the corresponding steps in Example 1;

[0099] (2) Preparation and modification of bio-based solutions for UiO-66 nanomaterials

[0100] 1 g of chitosan (CS) powder was dissolved in 100 mL of 1% acetic acid solution to form bio-based solution 1; 7.17 g of 70% phytic acid (PA) solution was dissolved in 92.83 mL of deionized water by ultrasonic stirring to form bio-based solution 2.

[0101] Weigh 1g of UiO-66 nanomaterial and immerse it in bio-based solution 1. After immersion for 5min, centrifuge at 6000r / min for 8min to retain the solid. Immerse the obtained solid in bio-based solution 2. After immersion for 5min, centrifuge at 6000r / min for 8min to retain the solid, thus completing the first layer after electrostatic adsorption.

[0102] Repeat the above two impregnation steps 4 times, shortening the impregnation time to 1 minute each time; dry the solid obtained after centrifugation at 80°C under vacuum for 2 hours to obtain bio-based modified UiO-66-5 nanomaterials.

[0103] 3. Preparation of fire-retardant coatings

[0104] Weigh 1g of bio-based modified UiO-66-5 nanomaterial and mix it with the base material. Then heat it in an oil bath at 105℃ and stir it at a stirring speed of 350r / min for 3h to obtain the fireproof coating.

[0105] Example 4

[0106] A fire-retardant coating comprising the following steps:

[0107] 1. Preparation of base material

[0108] Weigh out 27.92g of epoxy resin and 6.08g of 4,4-diaminodiphenylmethane to obtain a uniformly mixed base material;

[0109] 2. Preparation of modified boron nitride

[0110] 5g of boron nitride was added to 100mL of ethanol to obtain a 5wt% mixture, which was then dispersed using ultrasound. The pH of the mixture was then adjusted to 10 using ammonia. 20g of 3-aminopropyltriethoxysilane was weighed and slowly added to the mixture. After the addition was complete, the mixture was placed in a water bath at 70℃ for 3 hours. The solution was then transferred to a centrifuge tube and washed four times with ethanol at 4500rpm to remove unreacted ammonia and 3-aminopropyltriethoxysilane. The collected precipitate was dried in a vacuum oven at 50℃ for 48 hours. After drying, it was gently ground in an agate mortar to disperse it evenly and prevent agglomeration for later use.

[0111] 3. Preparation of bio-based flame-retardant coating modified UiO-66 nanomaterials

[0112] (1) Preparation of UiO-66 nanomaterials: The preparation was carried out according to the corresponding steps in Example 1;

[0113] (2) Preparation of bio-based solution and modification of UiO-66 nanomaterials: Refer to the corresponding steps in Example 2;

[0114] 4. Preparation of fire-retardant coatings

[0115] Weigh 1g of bio-based flame-retardant modified UiO-66-3 nanomaterial and 15g of modified boron nitride and mix them with the base material. Then heat the mixture in an oil bath at 105℃ and stir at a stirring speed of 350r / min for 3h to obtain the fireproof coating.

[0116] Comparative Example 1

[0117] A fire-retardant coating comprising the following steps:

[0118] 1. Preparation of base material

[0119] Weigh 41.06g of epoxy resin and 8.94g of 4,4-diaminodiphenylmethane to obtain a uniformly mixed base material;

[0120] 2. Resin Preparation

[0121] After the base material is mixed evenly, it is poured into the mold and dried at 100℃ for 2 hours, then dried at 150℃ for 2 hours; after it is completely cooled, it is demolded.

[0122] Comparative Example 2

[0123] A fire-retardant coating comprising the following steps:

[0124] 1. Preparation of base material: Refer to step 1 in Example 1;

[0125] 2. Preparation of UiO-66 nanomaterials: Follow the steps outlined in Example 1.

[0126] 3. Preparation of fire-retardant coatings

[0127] Weigh 1g of UiO-66 nanomaterial and mix it with the base material. Then heat it in an oil bath at 105℃ and stir it at a stirring speed of 350r / min for 3h to obtain the fireproof coating.

[0128] Comparative Example 3

[0129] A fire-retardant coating comprising the following steps:

[0130] 1. Preparation of base material: Refer to step 1 in Example 1;

[0131] 2. Preparation of bio-based flame-retardant coating modified UiO-66 nanomaterials

[0132] (1) Preparation of UiO-66 nanomaterials: The preparation was carried out according to the corresponding steps in Example 1;

[0133] (2) Preparation and modification of bio-based solutions for UiO-66 nanomaterials

[0134] 1g of chitosan (CS) powder was dissolved in 100mL of 1% acetic acid solution to form bio-based solution 1;

[0135] 1 g of UiO-66 nanomaterial was weighed and immersed in bio-based solution 1. After immersion for 5 min, the solid was centrifuged at 6000 r / min for 8 min and the solid was retained. The solid was vacuum dried at 80 °C for 2 h to obtain bio-based modified CS@UiO-66-1 nanomaterial.

[0136] 3. Preparation of fire-retardant coatings

[0137] Weigh 1g of CS@UiO-66-1 nanomaterial and mix it with the base material. Then heat it in an oil bath at 105℃ and stir it at a stirring speed of 350r / min for 3h to obtain the fireproof coating.

[0138] Comparative Example 4

[0139] A fire-retardant coating comprising the following steps:

[0140] 1. Preparation of base material: Refer to step 1 in Example 1;

[0141] 2. Preparation of bio-based flame-retardant coating modified UiO-66 nanomaterials

[0142] (1) Preparation of UiO-66 nanomaterials: The preparation was carried out according to the corresponding steps in Example 1;

[0143] (2) Preparation and modification of bio-based solutions for UiO-66 nanomaterials

[0144] A 70% phytic acid solution (7.17 g) was ultrasonically stirred and dissolved in 92.83 mL of deionized water to form bio-based solution 2.

[0145] 1 g of UiO-66 nanomaterial was weighed and immersed in bio-based solution 2. After immersion for 5 min, the solid was centrifuged at 6000 r / min for 8 min and the solid was retained. The solid was vacuum dried at 80 °C for 2 h to obtain bio-based modified PA@UiO-66-1 nanomaterial.

[0146] 3. Preparation of fire-retardant coatings

[0147] Weigh 1g of PA@UiO-66-1 nanomaterial and mix it with the base material. Then heat it in an oil bath at 105℃ and stir it at a stirring speed of 350r / min for 3h to obtain the fireproof coating.

[0148] Comparative Example 5

[0149] A fire-retardant coating comprising the following steps:

[0150] 1. Preparation of base material: Refer to step 1 in Example 1;

[0151] 2. Preparation of bio-based flame-retardant coating modified UiO-66 nanomaterials

[0152] (1) Preparation of UiO-66 nanomaterials: The preparation was carried out according to the corresponding steps in Example 1;

[0153] (2) Preparation of blended nanomaterials

[0154] 0.6 g UiO-66 was dispersed in 20 mL of pure water and sonicated for 30 min to form a well-dispersed suspension. 0.07 g chitosan (CS) was added to the suspension and stirred until the mixture was homogeneous. While stirring, 0.33 g phytic acid (PA) was added dropwise to the suspension, and the mixture was magnetically stirred at room temperature for 24 h. After stirring, the mixture was centrifuged at 6000 r / min for 8 min to retain the solid. The obtained solid was vacuum dried at 80 °C for 2 h to obtain the blended nanomaterials.

[0155] 3. Preparation of fire-retardant coatings

[0156] Weigh 1g of blended nanomaterials (of which chitosan accounts for 7wt%, phytic acid accounts for 33wt%, and UiO-66 accounts for 60wt%) and mix them with the base material. Then heat the mixture in an oil bath at 105℃ and stir at a stirring speed of 350r / min for 3h to obtain the fireproof coating.

[0157] Comparative Example 6

[0158] A fire-retardant coating comprising the following steps:

[0159] 1. Preparation of base material

[0160] Weigh out 28.92g of epoxy resin and 6.08g of 4,4-diaminodiphenylmethane to obtain a uniformly mixed base material;

[0161] 2. Preparation of modified boron nitride

[0162] 5g of boron nitride was added to 100mL of ethanol to obtain a 5wt% mixture, which was then dispersed using ultrasound. The pH of the mixture was then adjusted to 10 using ammonia. 20g of 3-aminopropyltriethoxysilane was weighed and slowly added to the mixture. After the addition was complete, the mixture was placed in a water bath at 70℃ for 3 hours. The solution was then transferred to a centrifuge tube and washed four times with ethanol at 4500rpm to remove unreacted ammonia and 3-aminopropyltriethoxysilane. The collected precipitate was dried in a vacuum oven at 50℃ for 48 hours. After drying, it was gently ground in an agate mortar to disperse it evenly and prevent agglomeration for later use.

[0163] 3. Preparation of fire-retardant coatings

[0164] Weigh 15g of modified boron nitride and mix it with the base material. Then heat the mixture in an oil bath at 105℃ and stir at a stirring speed of 350r / min for 3h to obtain the fireproof coating.

[0165] Comparative Example 7

[0166] A fire-retardant coating comprising the following steps:

[0167] 1. Preparation of base material: Refer to step 1 in Example 1;

[0168] 2. Preparation of bio-based flame-retardant coating modified UiO-66 nanomaterials

[0169] (1) Preparation of UiO-66 nanomaterials: The preparation was carried out according to the corresponding steps in Example 1;

[0170] (2) Preparation and modification of bio-based solutions for UiO-66 nanomaterials

[0171] 1 g of chitosan (CS) powder was dissolved in 100 mL of 1% acetic acid solution to form bio-based solution 1; 7.17 g of 70% phytic acid (PA) solution was dissolved in 92.83 mL of deionized water by ultrasonic stirring to form bio-based solution 2.

[0172] Weigh 1g of UiO-66 nanomaterial and immerse it in bio-based solution 1. After immersion for 5min, centrifuge at 6000r / min for 8min to retain the solid. Immerse the obtained solid in bio-based solution 2. After immersion for 5min, centrifuge at 6000r / min for 8min to retain the solid, thus completing the first layer after electrostatic adsorption.

[0173] Repeat the above two impregnation steps 6 times, shortening the impregnation time to 1 minute each time; dry the solid obtained after centrifugation at 80°C under vacuum for 2 hours to obtain bio-based modified UiO-66-7 nanomaterials.

[0174] However, due to the 7-layer self-assembly modification, the UiO-66-7 nanomaterials have agglomerated and clump together, making them unsuitable for further applications.

[0175] Table 1. Sample formulations of Comparative Examples 1-6 and Examples 1-4

[0176]

[0177]

[0178] Cone calorimetry test procedure:

[0179] Composite material samples prepared in Examples 1-4 and Comparative Examples 1-6 were respectively installed on the test apparatus. The power of the radiation cone was set to 35 kW. The cone calorimeter was started to perform thermal radiation and collect test data in real time. Parameters such as the heat release rate, total heat release, and carbon monoxide release rate of the material were calculated. After the preset test time was reached, the thermal radiation of the radiation cone was stopped. The test results are shown in the table below:

[0180] Table 2. Cone calorimetry test data for Comparative Examples 1-6 and Examples 1-4

[0181]

[0182] Peak heat release rate (PHRR) is an important fire characteristic parameter of a material, with the initial maximum peak representing the typical combustion characteristics of the material; total heat release (THR) refers to the total heat released by the material from ignition to flame extinction, and the higher the value, the more intense the combustion reaction; total smoke production (TSR) refers to the total cumulative smoke produced per unit sample area during combustion, and the higher the value, the more smoke is produced during combustion; real-time mass (MASS) reflects the trend of material decomposition and weight loss during combustion, and the greater the weight loss, the more intense the combustion reaction.

[0183] The results show that the PHRR values ​​of Examples 1-4 are lower than those of pure epoxy resin (Comparative Example 1), proving that the flame retardant performance can be improved by adding the bio-based flame retardant modified UiO-66 nano flame retardant system and the modified boron nitride (BN).

[0184] In Examples 1-3, the PHRR value showed a trend of first increasing and then decreasing with the increase of the number of bio-based flame-retardant modified UiO-66 layers. This demonstrates that within a certain range, the flame-retardant performance first increases and then decreases with the increase of the number of bio-based flame-retardant modified UiO-66 layers. When the number of bio-based flame-retardant modified UiO-66 layers reaches five (Example 3), the flame-retardant performance deteriorates, possibly due to the aggregation of nanomolecules caused by excessive layers, resulting in internal blockage. Furthermore, when the number of layers reaches seven, severe aggregation of nanomolecules occurs, directly affecting subsequent use. Therefore, the number of layers in the layer-by-layer self-assembly modification should be controlled between 1 and 5, preferably 3 layers.

[0185] Compared with Comparative Example 2, Examples 1-3 and Comparative Examples 3-5 all showed improved flame retardant performance with the addition of the same proportion of nanomaterials, demonstrating the necessity of bio-based modification. Meanwhile, Example 2 showed better results than Comparative Examples 3-5, indicating that simply using chitosan or phytic acid, or using blending without layer-by-layer modification, cannot achieve a superior improvement in flame retardant performance.

[0186] Furthermore, compared to Examples 2 and 6, Example 4 is significantly superior, achieving a synergistic effect of modified BN and UiO-66-3, where "one plus one is greater than two." Specifically, regarding PHRR, Example 2, with only the addition of UiO-66-3 compared to Comparative Example 1, resulted in a PHRR decrease of 329.04 kW·m. 2 The decline rate was 25.4% (E A Comparative Example 6, compared to Comparative Example 1, only added the use of modified boron nitride, and its PHRR value decreased by 412.808 kW·m. 2 The decline rate was 31.9% (E B Example 4, compared to Comparative Example 1, incorporated the combined use of UiO-66-3 and modified boron nitride, resulting in a PHRR value decrease of 789.64 kW·m. 2 The decline rate was 61.0% (E A+B Applying the formula for calculating the Q value of Jin Zhengjun, we can obtain Q > 1.15. Therefore, a synergistic effect was achieved in Example 4.

[0187]

[0188] E A E B E represents the effect of A and B acting alone. A+B The combined effect of A and B is given. Q < 0.85 indicates an antagonistic effect between A and B; 0.85 ≤ Q ≤ 1.15 indicates an additive effect between A and B; and Q ≥ 1.15 indicates a synergistic effect between A and B.

[0189] The UiO-66 nano flame retardant with added bio-based flame retardant modification forms an integrated bio-based flame retardant system, and the composite material's expansion effect is as follows: Figure 6 As shown, the system works synergistically as a dehydrating agent / foaming agent to form a stable expanded carbon layer, protecting the matrix material from the continuous impact of flame and heat.

[0190] In summary, the composite material of UiO-66-3 nanomaterials with added bio-based flame retardant modification and modified boron nitride (BN) exhibits excellent flame retardant properties.

[0191] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A reinforced fire-retardant coating based on modified boron nitride and bio-based modified UiO-66, characterized in that, The enhanced fire-retardant coating, by mass fraction, consists of 50-60% epoxy resin, 10-15% 4,4-diaminodiphenylmethane, 1-5% bio-based flame-retardant coating modified UiO-66 nanomaterials, and 25-35% modified boron nitride. The bio-based flame retardant coating modified UiO-66 nanomaterial is a UiO-66 nanomaterial that is wrapped with a chitosan layer and a phytic acid layer from the inside out; one chitosan layer and one phytic acid layer are counted as one bio-based flame retardant coating, and there are a total of 1 to 5 bio-based flame retardant coatings. Preparation of the modified boron nitride: Boron nitride is added to ethanol and mixed to obtain a mixture. The pH of the mixture is adjusted using ammonia. A certain amount of 3-aminopropyltriethoxysilane is weighed and added to the mixture for reaction. After the reaction is completed, ethanol is added to the reaction solution for centrifugation and washing to remove unreacted ammonia and 3-aminopropyltriethoxysilane. The precipitate after centrifugation is collected, dried, and ground to obtain modified boron nitride.

2. The enhanced fire-retardant coating based on modified boron nitride and bio-based modified UiO-66 as described in claim 1, characterized in that, The enhanced fire-retardant coating, by mass fraction, consists of 53-57% epoxy resin, 11-13% 4,4-diaminodiphenylmethane, 1-3% bio-based flame-retardant coating modified UiO-66 nanomaterials, and 27-32% modified boron nitride.

3. The enhanced fire-retardant coating based on modified boron nitride and bio-based modified UiO-66 as described in claim 1, characterized in that, The bio-based flame-retardant coating has a total of 2 to 4 layers.

4. The application of the enhanced fire-retardant coating based on modified boron nitride and bio-based modified UiO-66 as described in any one of claims 1 to 3 in the field of fire prevention or flame retardancy.

5. A reinforced fireproof board based on modified boron nitride and bio-based modified UiO-66, characterized in that, The enhanced fireproof board is prepared by heating and curing the enhanced fireproof coating based on modified boron nitride and bio-based modified UiO-66 as described in any one of claims 1 to 3 after it is introduced into a mold.

6. A method for preparing the fire-retardant coating based on modified boron nitride and bio-based modified UiO-66 as described in any one of claims 1 to 3, characterized in that, The preparation method includes the following steps: S1. Preparation of the base material: Take epoxy resin and 4,4-diaminodiphenylmethane and mix them to obtain the base material; S2. Preparation of modified boron nitride: Boron nitride was added to ethanol and mixed to obtain a mixture. The pH of the mixture was adjusted using ammonia. A certain amount of 3-aminopropyltriethoxysilane was weighed and added to the mixture for reaction. After the reaction was completed, ethanol was added to the reaction solution and centrifuged to remove unreacted ammonia and 3-aminopropyltriethoxysilane. The precipitate after centrifugation was collected, dried, and ground to obtain modified boron nitride. S3. Preparation of bio-based flame retardant coating modified UiO-66 nanomaterials: UiO-66 nanomaterials were immersed in chitosan acetic acid aqueous solution, then the UiO-66 nanomaterials were taken out and immersed in phytic acid aqueous solution, and then the UiO-66 nanomaterials were taken out. The UiO-66 nanomaterial after two impregnation steps is modified with one layer. Repeating the two impregnation steps again yields UiO-66 nanomaterial with multiple layers. S4. Preparation of flame retardant resin: Take the modified multilayer UiO-66 nanomaterial, modified boron nitride and base material, mix them, heat and stir to disperse evenly to obtain fire retardant coating.

7. The preparation method according to claim 6, characterized in that, In step S2, the concentration of boron nitride in the mixture is 1-5 wt%; the pH is adjusted to 7-12; the mass ratio of 3-aminopropyltriethoxysilane to boron nitride is 1-5:1; the reaction temperature is 55-70℃, and the reaction time is 3-6 h.

8. The preparation method according to claim 6, characterized in that, In step S3, the concentration of chitosan in the chitosan-acetic acid aqueous solution is 0.5-5 wt%; the concentration of acetic acid in the chitosan-acetic acid aqueous solution is 0.5-2 wt%; the concentration of phytic acid in the phytic acid aqueous solution is 2-7 wt%; and the impregnation time is 1-10 min.

9. The preparation method according to claim 6, characterized in that, In step S4, the heating and stirring is carried out at 60~105℃ for 1.5~12 h.

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