Flame-retardant heat-conducting polyacrylic acid fireproof paint and preparation method thereof

Abstract

The application provides a kind of fire-retardant heat-conducting polyacrylic acid fireproof paint and its preparation method, according to mass fraction includes the following raw materials: methyl methacrylate 3-24 parts, butyl acrylate 3-30 parts, acrylic acid 0.5-9 parts, intumescent monomer 2-15 parts, modified ceramic material 0.6-10 parts, composite emulsifier 0.6-3 parts, buffer 0.8-1.8 parts and initiator 0.2-1.5 parts;Intumescent monomer is obtained by the reaction of bio-based material, methyl methacrylate phosphate and melamine;The modified ceramic material is the ceramic material modified by silane coupling agent.The fire-retardant heat-conducting polyacrylic acid fireproof paint of the application has the advantages of simple formula, no environmental pollution, low toxicity, low VOC content, no irritating odor, etc.;High efficiency of flame retardancy, can quickly generate high-quality intumescent carbon layer after fire.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable fireproof coating, in particular to a flame-retardant heat-conducting polyacrylic acid fireproof coating and a preparation method thereof. BACKGROUND

[0002] With the continuous growth of power demand and the continuous progress of power transmission technology, the transmission voltage level of power cables is also increasing. However, the heat accumulation and temperature rise problem accompanied by high-voltage power transmission poses a serious challenge to power safety, and cable fire has become a particularly urgent and non-negligible threat. Cable fire not only can cause serious damage to the power system, but also can cause casualties and heavy property losses, and its potential consequences are unpredictable.

[0003] Fireproof coating is an important part of cable fireproof measures, which is usually composed of film-forming resin, flame-retardant components and other additives. Intumescent fireproof coating has become a widely used choice in the industry because of its thin coating and flexibility to meet the stretching needs of the cable when bending. Currently, this type of coating mostly uses physical blending technology to add intumescent flame retardant and other additives to the film-forming resin. Intumescent flame retardant is a mixture of acid source, carbon source and gas source, so the ratio of the three components is extremely complex, and it is difficult to control the proportion of the three. In addition, the compounded system has the disadvantages of large total addition amount, easy precipitation, easy moisture absorption, poor thermal stability, poor compatibility with polymers, and uneven phase distribution.

[0004] In view of the above problems, researchers have developed a series of single-component intumescent flame retardants that integrate three sources into one molecule, i.e. "three-in-one" intumescent flame retardants, which can effectively reduce the addition amount and moisture absorption, and have good thermal stability. However, most of the three-in-one intumescent flame retardants are still added in a physical blending manner, which has poor compatibility with the film-forming resin and can adversely affect the mechanical properties and film-forming properties of the film-forming resin. More importantly, intumescent fireproof coating cannot improve the thermal conductivity and insulation performance of the resin material, making it difficult to effectively dissipate the heat generated by the cable during operation, and local high temperature may trigger material pyrolysis and combustion, increasing the risk of fire. In the case of cable leakage, it is more likely to cause a fire accident. SUMMARY

[0005] The technical problem to be solved by the present application is how to improve the thermal conductivity and insulation of the fireproof coating.

[0006] The present application solves the above technical problems by the following technical means:

[0007] The application provides a fire-retardant heat-conducting polyacrylic acid fireproof paint, which comprises the following raw materials in parts by mass: 3-24 parts of methyl methacrylate, 3-30 parts of butyl acrylate, 0.5-9 parts of acrylic acid, 2-15 parts of an intumescent monomer, 0.6-10 parts of modified ceramic material, 0.6-3 parts of a composite emulsifier, 0.8-1.8 parts of a buffer and 0.2-1.5 parts of an initiator; the intumescent monomer is obtained by the reaction of a bio-based material, methyl methacrylate phosphate and melamine; and the modified ceramic material is obtained by modification with a silane coupling agent.

[0008] The bio-based material is easy to obtain and green, can be directly introduced under the polymerization conditions of the acrylic acid to achieve intrinsic flame retardation, has good fire-retardant charring effect, and avoids the disadvantages of complex formula, difficult uniform dispersion and migration and precipitation of the traditional intumescent flame retardant; the functional groups in the bio-based material can improve the adhesion of the fire-retardant heat-conducting polyacrylic acid fireproof paint.

[0009] The fire-retardant heat-conducting polyacrylic acid fireproof paint has the advantages of simple formula, no pollution to the environment, low toxicity, low VOC content, no irritating odor and the like; has high fire-retardant efficiency, and can rapidly generate a high-quality expanded carbon layer after being exposed to fire.

[0010] Preferably, the bio-based material is one or more of lignin, starch, cellulose, chitosan, beta-cyclodextrin and sodium alginate.

[0011] Preferably, the ceramic material is one or two of boron nitride, silicon carbide, aluminum nitride, silicon nitride and aluminum oxide.

[0012] Preferably, the silane coupling agent is one or more of KH570, A151, A171, A172 and A174.

[0013] Preferably, the composite emulsifier is nonylphenol polyoxyethylene ether and sodium dodecyl sulfonate, and the mass ratio of the nonylphenol polyoxyethylene ether to the sodium dodecyl sulfonate is 1:1-1:2.

[0014] Preferably, the initiator is one or more of potassium persulfate, sodium persulfate and ammonium persulfate.

[0015] Preferably, the buffer is one or more of sodium bicarbonate, sodium dihydrogen phosphate and sodium acetate.

[0016] Preferably, the mass ratio of the bio-based material, the methyl methacrylate phosphate and the melamine is 8-15:18-25:5-18.

[0017] The second aspect of the present application provides a preparation method of the above-mentioned flame-retardant heat-conducting polyacrylic acid fireproof coating, comprising the following steps:

[0018] S1 Pre-emulsion: 0.4-2 parts of a composite emulsifier, 0.1-0.8 parts of an initiator and 20-100 parts of water are mixed, and 2-16 parts of methyl methacrylate, 2-20 parts of butyl acrylate, 0.3-6 parts of acrylic acid, 2-15 parts of an intumescent monomer and 0.6-10 parts of a modified ceramic material are added thereto for stirring to obtain a pre-emulsion;

[0019] S2 Seed emulsion: 0.8-1.8 parts of a buffer and the remaining composite emulsifier are mixed, and the remaining methyl methacrylate, butyl acrylate and acrylic acid are added thereto for emulsification, and the remaining initiator is added for polymerization reaction until the solution begins to turn blue to obtain a seed emulsion;

[0020] S3 The pre-emulsion is slowly added to the seed emulsion for reaction, a neutralizing agent is used to adjust the pH of the solution, and then cooling and sieving are performed to obtain the flame-retardant heat-conducting polyacrylic acid fireproof coating.

[0021] Beneficial effects: The preparation method of the present application utilizes the core-shell emulsion polymerization reaction between methyl methacrylate, butyl acrylate, acrylic acid, an intumescent monomer and a modified ceramic material to prepare the flame-retardant heat-conducting polyacrylic acid fireproof coating, which can improve the flame-retardant, heat-conducting, insulating, weather-resistant and coating film performance of the cable fireproof coating.

[0022] The intumescent monomer is introduced into the acrylic acid through a copolymerization reaction to prepare the intumescent intrinsic flame-retardant heat-conducting polyacrylic acid fireproof coating. The coating has a good intumescent height and a dense foam layer after burning, and the phosphate groups and the functional groups on the bio-based material can improve the adhesion of the emulsion on the cable.

[0023] The modified ceramic material has good heat-conducting performance and excellent electrical insulating performance, wherein the silane coupling agent can act as a bridge connecting the heat-conducting insulating ceramic material and the acrylic acid emulsion, improve the interfacial bonding force, improve the dispersibility of the ceramic material and thus improve the coating film performance of the emulsion; the ceramic material can strengthen the water resistance and mechanical properties of the cable coating and play a synergistic flame-retardant effect.

[0024] The present application utilizes the seed emulsion polymerization reaction, which is different from the general copolymer or blend. Under the condition that the raw material composition is the same, the core-shell structure of the latex particle can significantly improve the wear resistance, water resistance, weather resistance, stain resistance, mechanical strength and bonding strength of the polymer emulsion, reduce the minimum film formation temperature and improve the processing performance.

[0025] Preferably, the intumescent monomer is obtained by mixing the bio-based material with the methacrylic acid phosphate, and then adding a melamine solution to react, and finally obtaining the intumescent monomer.

[0026] Preferably, the modified ceramic material is obtained by dispersing the ceramic material in a solvent, adding a silane coupling agent to it, adjusting the pH, and finally obtaining the modified ceramic material by heating the reaction.

[0027] Preferably, in S2, the emulsification temperature is 80-85℃, and the emulsification time is 0.5-2h.

[0028] Preferably, the polymerization temperature is 80-90℃.

[0029] Preferably, in S3, the reaction temperature is 85-90℃, and the reaction time is 1-3h.

[0030] Preferably, the neutralizing agent is one or more of triethylamine, dimethyl ethanolamine, triethanolamine, and ammonia. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is the structural formula of the intumescent monomer PCSM of Example 1;

[0032] Figure 2 is the infrared spectrum of melamine, chitosan, methacrylate phosphate, and intumescent monomer PCSM in Example 1;

[0033] Figure 3 is the performance test table of the flame-retardant heat-conducting polypropylene acid fireproof coating of Examples 1-4 and Comparative Examples 1-3. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0035] The test materials and reagents used in the following examples, etc., can be obtained from commercial channels if not otherwise specified.

[0036] If the specific techniques or conditions are not specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0037] Example 1

[0038] The embodiment provides a fire-retardant heat-conducting polyacrylic acid fireproof coating and a preparation method thereof, and specifically as follows.

[0039] The fire-retardant heat-conducting polyacrylic acid fireproof coating comprises the following raw materials in parts by mass: 8.2 parts of methyl methacrylate, 10 parts of butyl acrylate, 1 part of acrylic acid, 4.8 parts of an intumescent monomer, 2.8 parts of modified boron nitride, 0.6 part of a composite emulsifier, 0.8 part of sodium bicarbonate and 0.2 part of potassium persulfate; the composite emulsifier is obtained by mixing nonylphenol polyoxyethylene ether and sodium dodecyl sulfonate at a mass ratio of 1:1.5; the intumescent monomer is obtained by reacting chitosan, methyl methacrylate phosphate and melamine; and the modified boron nitride is obtained by modifying boron nitride with silane coupling agent KH570.

[0040] The fire-retardant heat-conducting polyacrylic acid fireproof coating is prepared, and the preparation specifically comprises the following steps.

[0041] S1 Preparation of the intumescent monomer

[0042] 9.6 parts of chitosan and 21 parts of methyl methacrylate phosphate are subjected to esterification reaction at 120℃ to generate a bio-based phosphate ester. Then, the temperature is adjusted to 100℃, and a melamine solution obtained by dissolving 12.6 parts of melamine in 30 parts of ethanol is added dropwise, and the reaction is continued for 1h to ensure that the melamine and the bio-based phosphate ester are fully reacted to form the expected salification product. After the reaction is completed, the solution is gradually cooled to room temperature, and the solid product is separated by centrifugation, and then the product is washed several times with ethanol and deionized water, and finally dried to obtain the intumescent monomer PCSM, and the structural formula is as shown in Figure 1 .

[0043] The infrared spectra of the melamine, chitosan, methyl methacrylate phosphate and the intumescent monomer PCSM are as shown in Figure 2 . As can be seen from the figure, due to the esterification reaction between chitosan and methyl methacrylate phosphate and the salification reaction between melamine and methyl methacrylate phosphate, the P–OH stretching vibration peak of the intumescent monomer PCSM at 1058 cm -1 disappears, the C–O stretching vibration signal in the C–OH structure at 1085 cm -1 is obviously weakened, the –NH2 stretching vibration signal at 3470 cm -1 and 3420 cm -1 is obviously weakened, and the stretching vibration peaks of P=O at 1330 cm -1 and NH3 + at 3140 cm -1 appear, which fully proves the successful synthesis of the intumescent monomer PCSM.

[0044] S2 Preparation of modified boron nitride

[0045] 3 parts of boron nitride were added to 200 parts of anhydrous ethanol aqueous solution, wherein the volume ratio of anhydrous ethanol to water was 3:1, and ultrasonic dispersion was performed for 1 h. Then, 20 parts of silane coupling agent KH570 were added, acetic acid was added to adjust the pH to about 4, and then the mixture was placed in an oil bath at 100℃ and heated and stirred for 4 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged, washed with ethanol and deionized water alternately, and dried to obtain modified boron nitride.

[0046] S3 Preparation of fire-retardant and heat-conducting polyacrylic acid fireproof coating

[0047] (1) Pre-emulsion: 0.4 parts of a composite emulsifier, 0.1 parts of potassium persulfate, and 50 parts of deionized water were mixed and stirred uniformly, 5.6 parts of methyl methacrylate, 6.7 parts of butyl acrylate, 0.7 parts of acrylic acid, 4.8 parts of intumescent monomer PCSM, and 2.8 parts of modified boron nitride were slowly added thereto while stirring, and after the dropwise addition was completed, rapid stirring was continued at room temperature for 1.5 h to prepare a pre-emulsion.

[0048] (2) Seed emulsion: 0.8 parts of sodium bicarbonate, 0.2 parts of a composite emulsifier, and 25 parts of deionized water were mixed and heated to 80℃, 2.6 parts of methyl methacrylate, 3.3 parts of butyl acrylate, and 0.3 parts of acrylic acid were slowly added thereto while stirring, emulsification was performed for 0.5 h after the dropwise addition was completed, 0.1 parts of potassium persulfate was slowly added, and the temperature was increased to 88℃ for polymerization reaction, and a seed emulsion was obtained when the emulsion began to turn blue.

[0049] (3) The pre-emulsion was added dropwise to the blue seed emulsion at 85℃, and the dropwise addition was completed in 1.5 h, and after the reaction was continued for 1.5 h, the temperature was decreased to 50℃, triethylamine was used to adjust the pH to 7.0, and then cooling and sieving were performed to obtain a fire-retardant and heat-conducting polyacrylic acid fireproof coating.

[0050] Example 2

[0051] The present embodiment provides a fire-retardant and heat-conducting polyacrylic acid fireproof coating and a preparation method thereof, which are as follows:

[0052] A fire-retardant and heat-conducting polyacrylic acid fireproof coating comprises the following raw materials in parts by mass: methyl methacrylate 7 parts, butyl acrylate 12 parts, acrylic acid 5 parts, intumescent monomer 8 parts, modified boron nitride / aluminum nitride 6.1 parts, composite emulsifier 1 part, sodium bicarbonate 1.4 parts, and potassium persulfate 0.6 parts; the composite emulsifier is obtained by mixing nonylphenol polyoxyethylene ether and sodium dodecyl sulfonate at a mass ratio of 1:1.2; the intumescent monomer is obtained by reacting starch, methyl methacrylate phosphate, and melamine; and the modified boron nitride / aluminum nitride is modified by silane coupling agent A171.

[0053] The preparation of the fire-retardant and heat-conducting polyacrylic acid fireproof coating specifically comprises the following steps:

[0054] S1 Preparation of intumescent monomer

[0055] 9.0 parts of starch was esterified with 21 parts of methacrylate phosphate at 110°C to form a bio-based phosphate. Then, the temperature was adjusted to 100°C, and a melamine solution obtained by dissolving 12.6 parts of melamine in 35 parts of ethanol was added dropwise, and the reaction was carried out for 2h to ensure that the melamine and the bio-based phosphate were fully reacted to form the expected salification product. After the reaction was completed, the solution was gradually cooled to room temperature, and the solid product was separated by centrifugation, and then washed with ethanol and deionized water several times, and finally dried to obtain the intumescent monomer PSTM, whose structural formula is shown below.

[0056]

[0057] Intumescent monomer PSTM

[0058] S2 Preparation of modified boron nitride / aluminum nitride

[0059] 7 parts of boron nitride and aluminum nitride (a mixture with a mass ratio of 1:1) were added to 350 parts of anhydrous ethanol aqueous solution, and the volume ratio of anhydrous ethanol to water was 3:1, and ultrasonic dispersion was carried out for 3h. Then, 20 parts of silane coupling agent A171 was added, and acetic acid was added to adjust the pH value to about 4, and then it was placed in an oil bath at 110°C for heating and stirring for 6h. After the reaction was completed, it was cooled to room temperature, and then washed with ethanol and deionized water alternately, and dried to obtain the modified boron nitride / aluminum nitride.

[0060] S3 Preparation of fire-retardant and heat-conducting polyacrylic acid fireproof coating

[0061] (1) Pre-emulsion: 0.5 parts of composite emulsifier, 0.3 parts of sodium persulfate and 43.7 parts of deionized water were mixed and stirred uniformly, and 4.7 parts of methyl methacrylate, 8 parts of butyl acrylate, 3.3 parts of acrylic acid, 8 parts of intumescent monomer PSTM and 6.1 parts of modified boron nitride / aluminum nitride were slowly added thereto while stirring, and after the dropwise addition was completed, the pre-emulsion was prepared by continuously stirring at room temperature for 2h.

[0062] (2) Seed emulsion: 1.4 parts of sodium bicarbonate, 0.5 parts of composite emulsifier and 21.8 parts of deionized water are mixed and heated to 80℃, 2.3 parts of methyl methacrylate, 4 parts of butyl acrylate and 1.7 parts of acrylic acid are slowly added dropwise and stirred constantly, after the dropwise addition is completed, emulsification is performed for 0.5h, 0.3 parts of sodium persulfate is slowly added dropwise, heating to 85℃ for polymerization reaction, until the emulsion starts to turn blue to obtain the seed emulsion.

[0063] (3) At 85℃, the pre-emulsion is added dropwise into the seed emulsion which has turned blue, the dropwise addition is completed in 1.5 hours, after 1.5h of continuous reaction, the temperature is lowered to 50℃, ammonia is used to adjust the pH of the system to 8.0, and then cooling, sieving are performed to obtain the flame-retardant and heat-conducting polyacrylic acid fireproof coating.

[0064] Example 3

[0065] The present embodiment provides a flame-retardant and heat-conducting polyacrylic acid fireproof coating and a preparation method thereof, which are as follows:

[0066] A flame-retardant and heat-conducting polyacrylic acid fireproof coating, according to mass fraction, comprises the following raw materials: 5.4 parts of methyl methacrylate, 20 parts of butyl acrylate, 1 part of acrylic acid, 4.8 parts of intumescent monomer, 4.7 parts of modified silicon carbide, 1.5 parts of composite emulsifier, 1.8 parts of sodium acetate and 0.5 parts of ammonium persulfate; the composite emulsifier is obtained by mixing nonylphenol polyoxyethylene ether and sodium dodecyl sulfonate at a mass ratio of 1:1.5; the intumescent monomer is obtained by the reaction of β-cyclodextrin, methyl methacrylate phosphate and melamine; and the modified silicon carbide is obtained by modification with silane coupling agent A151.

[0067] The preparation of the flame-retardant and heat-conducting polyacrylic acid fireproof coating specifically comprises the following steps:

[0068] S1 Preparation of intumescent monomer

[0069] 5.6 parts of β-cyclodextrin and 21 parts of methyl methacrylate phosphate are subjected to esterification reaction at 150℃ to generate bio-based phosphate ester. Subsequently, the temperature is adjusted to 90℃, and a melamine solution is added dropwise, the melamine solution is obtained by dissolving 12.6 parts of melamine in 30 parts of ethanol, and the reaction is continued for 2h to ensure that the melamine and bio-based phosphate ester are fully reacted to form the expected salt product. After the reaction is completed, the solution is gradually cooled to room temperature, and the solid product is separated by centrifugation, then the product is washed several times with ethanol and deionized water respectively, and finally dried to obtain the intumescent monomer PCDM, the structural formula of which is shown below.

[0070]

[0071] Intumescent monomer PCDM

[0072] S2 Preparation of modified silicon carbide

[0073] 5 parts of silicon carbide nanomaterials were added to 250 parts of an aqueous solution of anhydrous ethanol, wherein the volume ratio of anhydrous ethanol to water was 3:1, and ultrasonic dispersion was performed for 1 h. Then, 20 parts of silane coupling agent A151 were added, and acetic acid was added to adjust the pH to about 4, and then it was placed in an oil bath at 100℃ and heated and stirred for 4 h. After the reaction was completed, it was cooled to room temperature, and centrifugation, alternating washing with ethanol and deionized water, and drying were performed to obtain modified silicon carbide.

[0074] S3 Preparation of flame-retardant and heat-conducting polyacrylic acid fireproof coating

[0075] (1) Pre-emulsion: 0.9 parts of a composite emulsifier, 0.3 parts of ammonium persulfate, and 45.5 parts of deionized water were mixed and stirred uniformly, 3.6 parts of methyl methacrylate, 16.7 parts of butyl acrylate, 0.7 parts of acrylic acid, 4.8 parts of intumescent monomer PCDM, and 4.7 parts of modified silicon carbide were slowly added thereto while continuously stirring, and after the dropwise addition was completed, rapid stirring was continued at room temperature for 1.5 h to prepare a pre-emulsion.

[0076] (2) Seed emulsion preparation: 1.8 parts of sodium acetate, 0.6 parts of a composite emulsifier, and 22.8 parts of deionized water were mixed and heated to 80℃, 1.8 parts of methyl methacrylate, 3.3 parts of butyl acrylate, and 0.3 parts of acrylic acid were slowly added thereto while continuously stirring, and after the dropwise addition was completed, emulsification was performed for 0.5 h, and then 0.2 parts of ammonium persulfate was slowly added and heated to 88℃ for polymerization reaction, and the seed emulsion was obtained when the emulsion began to turn blue.

[0077] (3) The pre-emulsion was added to the blue seed emulsion at 85℃, and the dropwise addition was completed in 1.5 h, and then the reaction was continued for 1.5 h, and then the temperature was lowered to 50℃, dimethyl ethanolamine was used to adjust the pH to 7.0, and then cooling and sieving were performed to obtain the flame-retardant and heat-conducting polyacrylic acid fireproof coating.

[0078] Example 4

[0079] The present embodiment provides a flame-retardant and heat-conducting polyacrylic acid fireproof coating and a preparation method thereof, which are as follows:

[0080] The application discloses a fireproof coating of flame-retardant and heat-conducting polyacrylic acid, which comprises the following raw materials in parts by mass: 4.4 parts of methyl methacrylate, 15 parts of butyl acrylate, 3 parts of acrylic acid, 5.6 parts of an intumescent monomer, 1.6 parts of modified silicon nitride / alumina, 0.7 parts of a composite emulsifier, 0.9 parts of triethanolamine and 0.3 parts of potassium persulfate; the composite emulsifier is obtained by mixing nonylphenol polyoxyethylene ether and sodium dodecyl sulfonate at a mass ratio of 1:1.8; the intumescent monomer is obtained by reacting lignin, methyl methacrylate phosphate and melamine; and the modified silicon nitride / alumina is obtained by modification of a silane coupling agent A174.

[0081] The preparation of the fireproof coating of flame-retardant and heat-conducting polyacrylic acid specifically comprises the following steps:

[0082] S1 Preparation of the intumescent monomer

[0083] 9.8 parts of lignin and 21 parts of methyl methacrylate phosphate are subjected to esterification reaction at 160 DEG C to generate a bio-based phosphate ester. Then, the temperature is adjusted to 90 DEG C, a melamine solution obtained by dissolving 12.6 parts of melamine in 50 parts of ethanol is added dropwise, and the reaction is continued for 4 hours to ensure that the melamine and the bio-based phosphate ester are fully reacted to form a desired salification product. After the reaction is completed, the temperature is gradually cooled to room temperature, the solid product is separated by centrifugation, and then the product is washed several times with ethanol and deionized water, respectively, and finally dried to obtain the intumescent monomer PLiM, which has the following structural formula.

[0084]

[0085] The intumescent monomer PLiM

[0086] S2 Preparation of the modified silicon nitride / alumina

[0087] 5 parts of silicon nitride and alumina (a mixture at a mass ratio of 1:1) are added into 550 parts of anhydrous ethanol aqueous solution (the volume ratio of anhydrous ethanol to water is 3:1) and ultrasonically dispersed for 2 hours. Then, 20 parts of silane coupling agent A174 is added, acetic acid is added to adjust the pH value to about 4, and the mixture is placed in an oil bath at 100 DEG C and heated and stirred for 4 hours. After the reaction is completed, the temperature is cooled to room temperature, and the modified silicon nitride / alumina is obtained by centrifugation, alternating centrifugal washing with ethanol and deionized water and drying.

[0088] S3 Preparation of the fireproof coating of flame-retardant and heat-conducting polyacrylic acid

[0089] (1) Pre-emulsion preparation: 0.5 parts of composite emulsifier, 0.2 parts of potassium persulfate and 46.9 parts of deionized water are mixed and stirred uniformly, 2.9 parts of methyl methacrylate, 10 parts of butyl acrylate, 2 parts of acrylic acid, 5.6 parts of intumescent monomer PLiM and 1.6 parts of modified silicon nitride / alumina are slowly added thereto with continuous stirring, after the dropwise addition is completed, rapid stirring is continued at room temperature for 1.5 h to prepare a pre-emulsion.

[0090] (2) Seed emulsion preparation: 0.2 parts of triethanolamine, 0.2 parts of composite emulsifier and 23.4 parts of deionized water are mixed and heated to 80°C, 1.5 parts of methyl methacrylate, 5 parts of butyl acrylate and 1 part of acrylic acid are slowly added thereto with continuous stirring, after the dropwise addition is completed, emulsification is performed for 0.5 h, 0.1 parts of potassium persulfate is then slowly added dropwise, after the dropwise addition is completed, the temperature is increased to 85°C for polymerization reaction, and the seed emulsion is obtained when the emulsion begins to turn blue.

[0091] (3) At 85°C, the pre-emulsion is added dropwise to the blue seed emulsion, the dropwise addition is completed in 1.5 h, the reaction is continued for 1.5 h, then the temperature is decreased to 50°C, triethanolamine is used to adjust the pH to 8.0, and then cooling and sieving are performed to obtain the flame-retardant and heat-conducting polyacrylic acid fireproof coating.

[0092] Comparative Example 1

[0093] The difference between this comparative example and Example 1 is that the intumescent monomer PCSM is not added in this comparative example, and the others are the same as in Example 1.

[0094] Comparative Example 2

[0095] The difference between this comparative example and Example 1 is that the modified boron nitride is not added in this comparative example, and the others are the same as in Example 1.

[0096] Comparative Example 3

[0097] The difference between this comparative example and Example 1 is that the intumescent monomer in this comparative example is obtained by physically mixing chitosan, methacrylate phosphate and melamine in the same mass parts as in Example 1, and the boron nitride is not modified by a silane coupling agent, and the others are the same as in Example 1.

[0098] Experimental Example

[0099] The flame retardant and thermal conductive polyacrylic acid fire retardant coatings of Examples 1-4 and Comparative Examples 1-3 were subjected to performance tests. Clean steel plates were selected as substrates. The flame retardant and thermal conductive polyacrylic acid fire retardant coatings of Examples 1-4 and Comparative Examples 1-3 were brushed on the substrates respectively, left at room temperature for 12 hours, and then placed in a blast drying oven and baked at 80°C for 1 hour. The thickness was controlled according to different test items. The thickness standard was referenced to GB / T 1727-2021. Three substrates were brushed on each group of samples as samples. According to relevant standards, test standards and performance indicators are as follows: Figure 3 shown.

[0100] from Figure 3 It can be seen from the data that the flame retardant and thermally conductive polyacrylic acid fire retardant coatings of Examples 1-4 have excellent comprehensive performance, which is significantly better than that of Comparative Examples 1-3, fully verifying the synergistic effect of the "three-source-in-one" intumescent monomer and modified ceramic material.

[0101] The adhesion and hardness of Examples 1-4 are both higher than those of Comparative Examples 1-3, indicating that the dense network formed by chemical cross-linking of the "three-source-in-one" expandable monomer works synergistically with the strong interfacial bonding force of the ceramic material modified by the silane coupling agent to jointly construct a highly stable coating skeleton structure, thereby effectively inhibiting crack propagation and improving mechanical strength.

[0102] The flame-retardant and thermally conductive polyacrylic fire-retardant coatings of Examples 1-4 remained intact in the corrosion and boiling water tests, while the comparative examples 1-3 showed wrinkling and blistering, which was attributed to the density of the fire-retardant coatings and the uniform dispersion of the modified ceramic material, which effectively blocked the penetration of the medium.

[0103] The limiting oxygen index of the flame retardant and thermally conductive polyacrylic acid fire retardant coatings of Examples 1-4 is much higher than that of Comparative Examples 1-3, among which the flame retardant and thermally conductive polyacrylic acid fire retardant coating of Comparative Example 1 has the lowest oxygen index, proving that the intumescent monomer PCSM is an effective component that exerts a flame retardant effect.

[0104] The oxygen index of the flame-retardant thermally conductive polyacrylic fire-retardant coating of Comparative Example 3 is lower than that of all the examples but higher than that of Comparative Examples 1-2, indicating that the physically mixed methacrylate phosphate / melamine / chitosan still has a certain flame retardant effect, but the efficiency is lower than that of the "three-in-one" expandable monomer PCSM.

[0105] The flame-retardant, thermally conductive polyacrylic acid fire-retardant coatings of Examples 1-4 exhibit significantly longer flame retardancy than Comparative Examples 1-3, with smaller carbonized volumes, demonstrating the effective thermal insulation and flame retardancy of the intumescent PCSM carbon layer. Comparative Example 2 exhibits the lowest thermal conductivity, demonstrating the dominant role of modified boron nitride in thermal conductivity. However, Comparative Example 3 exhibits limited thermal conductivity due to the poor dispersibility of unmodified boron nitride. Due to the insulating properties of modified boron nitride, the volume resistivity of Example 1 is significantly higher than that of Comparative Example 2. Comparative Example 3 exhibits reduced insulation due to leakage caused by interface defects in the unmodified filler.

[0106] The above examples are only used to illustrate the technical solutions of the present application, but not to limit the present application; although the present application has been described in detail with reference to the foregoing examples, those ordinarily skilled in the art should understand: the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A flame retardant and thermally conductive polyacrylic acid fire retardant coating, characterized in that: The following raw materials are included in parts by mass: 3-24 parts of methyl methacrylate, 3-30 parts of butyl acrylate, 0.5-9 parts of acrylic acid, 2-15 parts of expandable monomer, 0.6-10 parts of modified ceramic material, 0.6-3 parts of composite emulsifier, 0.8-1.8 parts of buffer and 0.2-1.5 parts of initiator; The expandable monomer is obtained by reacting a bio-based material, methacrylate phosphate and melamine; the bio-based material is one of lignin, starch, chitosan and β-cyclodextrin; the expandable monomer is obtained by the following method: the bio-based material and methacrylate phosphate are mixed and reacted, and then a melamine solution is added thereto to react, thereby finally obtaining the expandable monomer; the modified ceramic material is obtained by modifying with a silane coupling agent.

2. The flame retardant and thermally conductive polyacrylic acid fire retardant coating according to claim 1, characterized in that: The ceramic material is one or two of boron nitride, silicon carbide, aluminum nitride, silicon nitride and aluminum oxide; the silane coupling agent is one or more of KH570, A151, A171, A172 and A174.

3. The flame retardant and thermally conductive polyacrylic acid fire retardant coating according to claim 1, characterized in that: The composite emulsifier is obtained by mixing nonylphenol polyoxyethylene ether and sodium lauryl sulfonate, and the mass ratio of the nonylphenol polyoxyethylene ether to the sodium lauryl sulfonate is 1:1-1:

2.

4. The flame retardant and thermally conductive polyacrylic acid fire retardant coating according to claim 1, characterized in that: The initiator is one or more of potassium persulfate, sodium persulfate or ammonium persulfate; the buffer is one or more of sodium bicarbonate, sodium dihydrogen phosphate or sodium acetate.

5. The flame retardant and thermally conductive polyacrylic acid fire retardant coating according to claim 1, characterized in that: The mass ratio of the bio-based material, methacrylate phosphate and melamine is 8-15:18-25:5-18.

6. The method for preparing the flame retardant and heat conductive polyacrylic acid fire retardant coating according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1 Pre-emulsion: 0.4-2 parts of a composite emulsifier, 0.1-0.8 parts of an initiator, and 20-100 parts of water are mixed, and 2-16 parts of methyl methacrylate, 2-20 parts of butyl acrylate, 0.3-6 parts of acrylic acid, 2-15 parts of an expandable monomer, and 0.6-10 parts of a modified ceramic material are added thereto and stirred to obtain a pre-emulsion; S2 Seed emulsion: 0.8-1.8 parts of the buffer and the remaining composite emulsifier are mixed, and the remaining methyl methacrylate, butyl acrylate, and acrylic acid are added thereto for emulsification, and the remaining initiator is added thereto for polymerization reaction. The reaction is carried out until the emulsion begins to turn blue to obtain a seed emulsion; S3: slowly dropwise adding the pre-emulsion into the seed emulsion to react, adjusting the pH of the solution with a neutralizer, and then cooling and sieving to obtain a flame-retardant and thermally conductive polyacrylic acid fire retardant coating.

7. The method for preparing the flame retardant and heat conductive polyacrylic acid fire retardant coating according to claim 6, characterized in that: The modified ceramic material is obtained by the following method: dispersing the ceramic material in a solvent, adding a silane coupling agent thereto, adjusting the pH, and heating the reaction to finally obtain the modified ceramic material.

8. The method for preparing the flame retardant and heat conductive polyacrylic acid fire retardant coating according to claim 6, wherein: In S2, the emulsification temperature is 80-85°C, the emulsification time is 0.5-2h; the polymerization temperature is 80-90°C.

9. The method for preparing the flame retardant and heat conductive polyacrylic acid fire retardant coating according to claim 6, wherein: In S3, the reaction temperature is 85-90° C., and the reaction time is 1-3 hours; the neutralizing agent is one or more of triethylamine, dimethylethanolamine, triethanolamine, and ammonia water.

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