A gypsum-based lightweight flame-retardant board and its preparation method

Abstract

This invention discloses a gypsum-based lightweight flame-retardant board and its preparation method, relating to the field of building materials technology. The gypsum-based lightweight flame-retardant board prepared by this invention is made by foaming a gypsum substrate with a foaming agent and a composite stabilizer, then introducing a self-made flame retardant and other raw materials, casting it between two layers of facing paper, and drying it. The composite stabilizer includes a modified acrylamide copolymer and acrylamide hydrogel. The modified acrylamide copolymer is obtained by copolymerizing N-isopropylacrylamide with silane acrylic acid and then reacting it with hyperbranched polyphosphate. The acrylamide hydrogel is obtained by polymerizing acrylic acid and acrylamide through an aqueous solution. The self-made flame retardant is obtained by reacting ammonium polyphosphate with a hydroxy heterocyclic amino alcohol. The hydroxy heterocyclic amino alcohol is obtained by reacting a heterocyclic amino alcohol with a double-terminated hydroxyl polyphenylene ether. This process gives the gypsum-based lightweight flame-retardant board excellent flame retardancy, mechanical properties, and flame-retardant stability.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a gypsum-based lightweight flame-retardant board and its preparation method. Background Technology

[0002] Gypsum board is relatively lightweight, has high strength, is thin, easy to process, and offers sound insulation, heat insulation, and fire resistance, making it one of the new lightweight building materials currently under development. At present, gypsum board is widely used in interior partitions, ceilings, sound-absorbing panels, floor baseboards, and various decorative panels in various buildings such as residences, office buildings, shops, hotels, and industrial plants.

[0003] Strength and fire resistance are two key factors that customers consider when evaluating gypsum board quality. To further improve these properties, many gypsum board manufacturers have added glass fibers, but this method is often unsatisfactory and fails to meet the requirements for lightweight practicality. Therefore, this invention researches and prepares a gypsum-based lightweight fire-retardant board to address this problem. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a gypsum-based lightweight flame-retardant board and its preparation method.

[0005] The present invention proposes a technical solution to solve the above-mentioned technical problems as follows: a gypsum-based lightweight flame-retardant board, comprising the following raw materials in parts by weight: 30-40 parts of gypsum clinker, 0.02-0.12 parts of composite stabilizer, 0.08-0.24 parts of foaming agent, 4-6 parts of self-made flame retardant, 12-18 parts of filler, 0.1-0.3 parts of retarder, and 35-45 parts of water; wherein the composite stabilizer comprises modified acrylamide copolymer and acrylamide hydrogel; and the self-made flame retardant is prepared by reacting ammonium polyphosphate with hydroxy heterocyclic amino alcohol.

[0006] Preferably, the modified acrylamide copolymer is prepared by copolymerizing N-isopropylacrylamide with silane acrylic acid and then reacting it with hyperbranched polyphosphate.

[0007] Preferably, the hyperbranched polyphosphate is prepared from bis(2-hydroxyethyl), polyethylene glycol monomethyl ether, and phosphorus oxychloride; the silane acrylic acid is prepared by reacting allyl methacrylate with 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane.

[0008] Preferably, the hydroxy heterocyclic amino alcohol is prepared by reacting a heterocyclic amino alcohol with a double-terminated hydroxyl polyphenylene ether; the filler is glass microspheres; the retarder is one or a mixture of boric acid, citric acid, sodium tartrate, and sodium acetate; and the foaming agent is one of sodium bicarbonate, ammonium bicarbonate, and azodicarbonamide.

[0009] Preferably, the preparation method of the gypsum-based lightweight flame-retardant board includes the following specific steps:

[0010] S1. Under a nitrogen atmosphere, N-isopropylacrylamide, silane acrylic acid, ethanol, and deionized water were mixed in a mass ratio of 4-5:1:20:8. After stirring until homogeneous, 0.002-0.004 times the mass of N-isopropylacrylamide initiator azobisisobutyronitrile was added. The mixture was heated to 62-65℃ and reacted for 24 hours. The pH was adjusted to 6-7 with triethylamine, and the mixture was dialyzed for 24-48 hours. The mixture was then freeze-dried at -40 to -60℃ to obtain an acrylamide copolymer. The acrylamide copolymer, dimethyl sulfoxide, and crosslinking agent 1-( 3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and catalyst N-hydroxysuccinimide were mixed in a mass ratio of 10~20:100:4.6~4.8:2.7~2.9 and stirred at 200~400 rpm for 20~30 min. Then, 3~6 times the mass of a 20~30% (w / w) solution of hyperbranched polyphosphate dimethyl sulfoxide was added. The mixture was heated to 40~42℃ and reacted for 12~14 h. The mixture was precipitated with methanol and dried under vacuum to obtain the modified acrylamide copolymer, which is the composite stabilizer.

[0011] S2. A mixture of dihydroxy-terminated polyphenylene ether, toluene, tetrahydrofuran, and 4-dimethylaminopyridine in a mass ratio of 80-100:400:50:1.1-1.3 was prepared and heated to 40-42°C. The mixture was stirred at 200-400 rpm for 20-30 min. Then, a heterocyclic amino alcohol mixture with a mass ratio of 0.22-0.24 times that of the dihydroxy-terminated polyphenylene ether was added. The mass ratio of the heterocyclic amino alcohol, dicyclohexylcarbodiimide, and tetrahydrofuran in the heterocyclic amino alcohol mixture was 20-24:11-13:100. The mixture was reacted for 6-8 h. The pH was adjusted to 7-8 with triethylamine. The mixture was filtered and precipitated with methanol. The product was then dried under vacuum to obtain the hydroxy heterocyclic amino alcohol.

[0012] S3. Under a nitrogen atmosphere, ammonium polyphosphate, hydroxy heterocyclic amino alcohol and phosphoric acid with a mass fraction of 80-85% are mixed at a mass ratio of 20:4-6:1, heated to 60-62℃, stirred and preheated at 200-600 rpm for 30-50 min, heated to 220-240℃, kept at the temperature for 2-3 h, cooled to 80-90℃, and crushed to obtain the self-made flame retardant;

[0013] S4. By weight fraction, mix the foaming agent, composite stabilizer and water, foam until the foam diameter is 200~600μm, then add gypsum clinker, self-made flame retardant, filler and retarder, stir and mix at 1000~1500rpm for 3~8min to obtain slurry; pour the slurry between two layers of facing paper, press under 1~3MPa pressure for 20~40min, and dry at 170~180℃ for 15~25min to obtain gypsum-based lightweight flame retardant board.

[0014] Preferably, in step S1 above, the method for preparing silane acrylic acid is as follows: allyl methacrylate, 2,6-di-tert-butyl-p-methylphenol, and a tetrahydrofuran solution of chloroplatinic acid with a mass fraction of 3-5% are mixed at a mass ratio of 1:0.1-0.12:20-30, heated to 60-62°C, reacted for 50-70 min, and then 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane with a mass of 1.05-1.15 times that of allyl methacrylate is added dropwise at a rate of 1-3 ml / min. The reaction is carried out for 3-4 h, and then the mixture is distilled under reduced pressure to obtain silane acrylic acid.

[0015] Preferably, in step S1 above, the preparation method of hyperbranched polyphosphate is as follows: Tetrahydrofuran, bis(2-hydroxyethyl) and triethylamine are mixed in a mass ratio of 100:4.2~4.4:6~6.2, placed in an ice bath, and stirred evenly. Then, a tetrahydrofuran solution of phosphorus oxychloride with a mass fraction of 8~10% is added dropwise at a rate of 1~3 ml / min at 6.5~7.5 times the mass of bis(2-hydroxyethyl). The reaction is carried out in an ice bath for 6~8 h. Then, polyethylene glycol monomethyl ether with a mass fraction of 1.6~1.8 times the mass of bis(2-hydroxyethyl) is added dropwise at a rate of 1~3 ml / min. The reaction is continued for 6~8 h. Then, ethanol with a mass fraction of 1.2~1.6 times the mass of bis(2-hydroxyethyl) is added. The reaction is continued for 6~8 h. The mixture is filtered and concentrated, precipitated with diethyl ether 2~3 times, and dried under vacuum at room temperature to obtain hyperbranched polyphosphate.

[0016] Preferably, in step S3 above, the preparation method of heterocyclic amino alcohol is as follows: 2-thiophene methylamine and ethylene glycol diglycidyl ether are mixed at a volume ratio of 25~28:20, heated to 43~46℃, reacted for 8~10h, and then subjected to silica gel column chromatography with a volume ratio of dichloromethane and methanol of 30:1 to obtain heterocyclic amino alcohol.

[0017] Preferably, in step S3 above, the preparation method of the hydroxyl-terminated polyphenylene ether is as follows: 2,6-dimethylphenol, tetramethylbisphenol A, and toluene are mixed at a mass ratio of 8~12:1:80~100, stirred and dissolved, and then 0.002~0.004 times the mass of 2,6-dimethylphenol, cuprous chloride, and 0.001~0.003 times the mass of 2,6-dimethylphenol, 4-dimethylaminopyridine are added. During the reaction, oxygen is introduced at a flow rate of 100~200 mL / min, the temperature is raised to 38~42℃, and the reaction is carried out for 2~3 hours. The reaction is quenched with acetic acid, and saturated sodium chloride solution is added for separation. The mixture is dried with anhydrous sodium sulfate, concentrated under reduced pressure, precipitated with methanol, filtered, and washed with methanol 3~5 times. The mixture is then dried under vacuum at 80~90℃ to obtain the hydroxyl-terminated polyphenylene ether.

[0018] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0019] The gypsum-based lightweight flame-retardant board prepared by the present invention is made by foaming gypsum substrate with foaming agent and composite stabilizer, then introducing self-made flame retardant and other raw materials, and then casting it on two layers of facing paper and drying it.

[0020] The composite stabilizer is a modified acrylamide copolymer, which is prepared by copolymerizing N-isopropylacrylamide with silane acrylic acid and then reacting it with hyperbranched polyphosphate. The hyperbranched polyphosphate is prepared from bis(2-hydroxyethyl), polyethylene glycol monomethyl ether, and phosphorus oxychloride. The silane acrylic acid is prepared by reacting allyl methacrylate with 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane. After copolymerization, N-isopropylacrylamide and silane acrylic acid form a crosslinked network or linear copolymer. The silanol generated from the hydrolysis of siloxane further reacts with the hyperbranched polyphosphate. Branched polyphosphate condenses to form stable chemical bonds. During the preparation process, after the composite stabilizer is mixed evenly with the gypsum substrate, it not only promotes the formation and stabilization of foam, but also further enhances the stability of the foam structure through condensation reaction. In addition, the active hydroxyl groups in hyperbranched polyphosphate can also react chemically with other components in the gypsum matrix to form a tighter bond, thereby improving the overall mechanical properties of gypsum-based lightweight flame-retardant board, effectively preventing the migration and seepage of flame retardants in the gypsum matrix, and ensuring long-term stable flame-retardant performance.

[0021] The homemade flame retardant is prepared by reacting ammonium polyphosphate with hydroxy heterocyclic amino alcohols. The hydroxy heterocyclic amino alcohols are prepared by reacting heterocyclic amino alcohols with bihydroxyl-terminated polyphenylene ethers. This homemade flame retardant has excellent compatibility with the gypsum matrix. During combustion, it can promote the formation of a char layer, forming a more stable cross-linked network and a denser char layer. This effectively isolates the transfer of oxygen and heat, and prevents the volatilization of pyrolysis products and the spread of flames. At the same time, the amino groups can also react with the moisture in the gypsum matrix to generate ammonia and water vapor, further diluting the concentration of combustible gases and slowing down the combustion rate. This gives the gypsum-based lightweight flame retardant board excellent flame retardancy and flame retardant stability. Detailed Implementation

[0022] The present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those skilled in the art.

[0023] The polyester film used in this invention was purchased from Hangzhou Dahua Plastics Co., Ltd., and the polyurethane film was purchased from Zanchen New Materials Technology Co., Ltd.

[0024] To more clearly illustrate the method provided by the present invention, the following embodiments are provided for detailed explanation. The test methods for various indicators of the gypsum-based lightweight flame-retardant boards prepared in the embodiments and comparative examples are as follows:

[0025] Hardness: The fireproof gypsum boards prepared in the examples and comparative examples were tested for hardness in accordance with GB / T9775.

[0026] Weight per unit area: The fireproof gypsum boards prepared in exactly the same example and comparative examples were weighed and calculated.

[0027] Flammability: The fire-retardant plasters prepared in the examples and comparative examples were tested for limiting oxygen index in accordance with GB / T 2406.

[0028] Fire stability: The fire-resistant plasters prepared in the examples and comparative examples were tested for fire stability in accordance with GB / T9775. Example 1

[0029] In this embodiment, the components and weight proportions of the gypsum-based lightweight flame-retardant board are as follows: 30 parts of gypsum clinker, 0.02 parts of composite stabilizer, 0.08 parts of foaming agent sodium bicarbonate, 4 parts of self-made flame retardant, 12 parts of glass microspheres, 0.1 parts of retarder boric acid, and 35 parts of water.

[0030] The method for preparing the gypsum-based lightweight flame-retardant board in this embodiment is as follows:

[0031] S1. Allyl methacrylate, 2,6-di-tert-butyl-p-methylphenol, and a 3% (w / w) tetrahydrofuran solution of chloroplatinic acid were mixed at a mass ratio of 1:0.1:20. The mixture was heated to 60°C and reacted for 50 min. Then, 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane (1.05 times the mass of allyl methacrylate) was added dropwise at a rate of 1 ml / min. The reaction was allowed to proceed for 3 h, followed by vacuum distillation to obtain silane acrylic acid. Tetrahydrofuran, bis(2-hydroxyethyl), and tri... Ethylamine was mixed at a mass ratio of 100:4.2:6 and placed in an ice bath. After stirring until homogeneous, a tetrahydrofuran solution of 8% phosphorus oxychloride (6.5 times the mass of bis(2-hydroxyethyl)) was added dropwise at a rate of 1 ml / min. The mixture was reacted in an ice bath for 6 hours. Then, polyethylene glycol monomethyl ether (1.6 times the mass of bis(2-hydroxyethyl)) was added dropwise at a rate of 1 ml / min, and the reaction was continued for 6 hours. Finally, ethanol (1.2 times the mass of bis(2-hydroxyethyl)) was added, and the reaction was continued for 6 hours. The mixture was then filtered and... Concentrate the mixture, precipitate it twice with diethyl ether, and dry it under vacuum at room temperature to obtain hyperbranched polyphosphate. Under a nitrogen atmosphere, mix N-isopropylacrylamide, silane acrylic acid, ethanol, and deionized water in a mass ratio of 4:1:20:8, stir until homogeneous, add 0.002 times the mass of the initiator azobisisobutyronitrile (AIBN) to the mixture, heat to 62°C, react for 24 h, adjust the pH to 6 with triethylamine, dialyze for 24 h, and freeze-dry at -40°C to obtain an acrylamide copolymer. Then, use propylene... Acrylamide copolymer, dimethyl sulfoxide, crosslinking agent 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and catalyst N-hydroxysuccinimide were mixed in a mass ratio of 10:100:4.6:2.7 and stirred at 200 rpm for 20 min. Then, three times the mass of a 20% (w / w) solution of hyperbranched polyphosphate dimethyl sulfoxide was added. The mixture was heated to 40 °C and reacted for 12 h. The mixture was precipitated with methanol and dried under vacuum to obtain the modified acrylamide copolymer, which is the composite stabilizer.

[0032] S2. 2-Thiophene methylamine and ethylene glycol diglycidyl ether were mixed at a volume ratio of 25:20, heated to 43°C, and reacted for 8 hours. The mixture was then subjected to silica gel column chromatography with dichloromethane and methanol at a volume ratio of 30:1 to obtain a heterocyclic amino alcohol. 2,6-Dimethylphenol, tetramethylbisphenol A, and toluene were mixed at a mass ratio of 8:1:80, stirred until dissolved, and then 0.002 times the mass of cuprous chloride and 0.001 times the mass of 2,6-dimethylphenol were added. Oxygen was introduced during the reaction at a flow rate of 100 mL / min, the temperature was raised to 38°C, and the reaction was carried out for 2 hours. The reaction was quenched with acetic acid, and the mixture was separated by adding saturated sodium chloride solution. Sodium sulfate solution was dried, concentrated under reduced pressure, precipitated with methanol, filtered, and washed three times with methanol. The mixture was then dried under vacuum at 80°C to obtain dihydroxylated polyphenylene ether. Dihydroxylated polyphenylene ether, toluene, tetrahydrofuran, and 4-dimethylaminopyridine were mixed in a mass ratio of 80:400:50:1.1, heated to 40°C, and stirred at 200 rpm for 20 min. A heterocyclic amino alcohol mixture with a mass ratio of 0.22 times the mass of the dihydroxylated polyphenylene ether was added. The heterocyclic amino alcohol, dicyclohexylcarbodiimide, and tetrahydrofuran had a mass ratio of 20:11:100. The reaction was carried out for 6 h. The pH was adjusted to 7 with triethylamine, filtered, precipitated with methanol, and dried under vacuum to obtain hydroxylated heterocyclic amino alcohol.

[0033] S3. Under a nitrogen atmosphere, ammonium polyphosphate, hydroxy heterocyclic amino alcohol and 80% phosphoric acid were mixed in a mass ratio of 20:4:1, heated to 60°C, preheated by stirring at 200 rpm for 30 min, heated to 220°C, kept at the temperature for 2 h, cooled to 80°C, and crushed to obtain the self-made flame retardant.

[0034] S4. By weight fraction, the foaming agent, composite stabilizer and water are mixed and foamed until the foam diameter is 200μm. By weight fraction, gypsum clinker, self-made flame retardant, filler and retarder are added and stirred at 1000rpm for 3min to obtain slurry. The slurry is poured between two layers of facing paper, pressed at 1MPa for 20min, and dried at 170℃ for 25min to obtain gypsum-based lightweight flame retardant board. Example 2

[0035] In this embodiment, the components and weight proportions of the gypsum-based lightweight flame-retardant board are as follows: 35 parts of gypsum clinker, 0.08 parts of composite stabilizer, 0.16 parts of foaming agent ammonium bicarbonate, 5 parts of self-made flame retardant, 16 parts of glass microspheres, 0.2 parts of retarder citric acid, and 40 parts of water.

[0036] The method for preparing the gypsum-based lightweight flame-retardant board in this embodiment is as follows:

[0037] S1. Allyl methacrylate, 2,6-di-tert-butyl-p-methylphenol, and a 4% (w / w) tetrahydrofuran solution of chloroplatinic acid were mixed at a mass ratio of 1:0.11:25. The mixture was heated to 61°C and reacted for 60 min. Then, 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane (1.10 times the mass of allyl methacrylate) was added dropwise at a rate of 2 ml / min. The reaction was continued for 3.5 h, followed by vacuum distillation to obtain silane acrylic acid. Tetrahydrofuran, bis(2-hydroxyethyl), and tri... Ethylamine was mixed in a mass ratio of 100:4.3:6.1 and placed in an ice bath. After stirring until homogeneous, a 9% tetrahydrofuran solution of phosphorus oxychloride (7.0 times the mass of bis(2-hydroxyethyl)) was added dropwise at a rate of 2 ml / min. The mixture was reacted in an ice bath for 7 h. Then, polyethylene glycol monomethyl ether (1.7 times the mass of bis(2-hydroxyethyl)) was added dropwise at a rate of 2 ml / min, and the reaction was continued for 7 h. Finally, ethanol (1.4 times the mass of bis(2-hydroxyethyl)) was added, and the reaction was continued for 7 h. The mixture was then filtered and concentrated. The mixture was condensed, precipitated 2.5 times with diethyl ether, and dried under vacuum at room temperature to obtain hyperbranched polyphosphate. Under a nitrogen atmosphere, N-isopropylacrylamide, silane acrylic acid, ethanol, and deionized water were mixed in a mass ratio of 4.5:1:20:8. After stirring until homogeneous, 0.003 times the mass of the initiator azobisisobutyronitrile (AIBN) was added. The mixture was heated to 64°C and reacted for 24 hours. The pH was adjusted to 6.5 with triethylamine, dialyzed for 36 hours, and then freeze-dried at -50°C to obtain an acrylamide copolymer. Acrylamide copolymer, dimethyl sulfoxide, crosslinking agent 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and catalyst N-hydroxysuccinimide were mixed in a mass ratio of 15:100:4.7:2.8 and stirred at 300 rpm for 25 min. Then, 4.5 times the mass of a 25% (w / w) solution of hyperbranched polyphosphate dimethyl sulfoxide was added. The mixture was heated to 41 °C and reacted for 13 h. The mixture was precipitated with methanol and dried under vacuum to obtain the modified acrylamide copolymer, which is the composite stabilizer.

[0038] S2. 2-Thiophene methylamine and ethylene glycol diglycidyl ether were mixed at a volume ratio of 27:20, heated to 45°C, and reacted for 9 h. The mixture was then subjected to silica gel column chromatography with dichloromethane and methanol at a volume ratio of 30:1 to obtain a heterocyclic amino alcohol. 2,6-Dimethylphenol, tetramethylbisphenol A, and toluene were mixed at a mass ratio of 10:1:90, stirred until dissolved, and then 0.003 times the mass of cuprous chloride and 0.002 times the mass of 4-dimethylaminopyridine were added. Oxygen was bubbled through the mixture at a flow rate of 150 mL / min during the reaction. The temperature was raised to 40°C, and the reaction was carried out for 2.5 h. The reaction was quenched with acetic acid, and then separated by adding a saturated sodium chloride solution. Anhydrous sodium sulfate was dried, concentrated under reduced pressure, precipitated with methanol, filtered, and washed four times with methanol. The mixture was then dried under vacuum at 85°C to obtain dihydroxylated polyphenylene ether. Dihydroxylated polyphenylene ether, toluene, tetrahydrofuran, and 4-dimethylaminopyridine were mixed in a mass ratio of 90:400:50:1.2, heated to 41°C, and stirred at 300 rpm for 25 min. A heterocyclic amino alcohol mixture with a mass ratio of 0.23 times the mass of the dihydroxylated polyphenylene ether was added. The heterocyclic amino alcohol, dicyclohexylcarbodiimide, and tetrahydrofuran had a mass ratio of 22:12:100. The reaction was carried out for 7 h. The pH was adjusted to 7.5 with triethylamine, filtered, precipitated with methanol, and dried under vacuum to obtain hydroxylated heterocyclic amino alcohol.

[0039] S3. Under a nitrogen atmosphere, ammonium polyphosphate, hydroxy heterocyclic amino alcohol and phosphoric acid with a mass fraction of 83% were mixed in a mass ratio of 20:5:1, heated to 61°C, preheated by stirring at 400 rpm for 40 min, heated to 230°C, kept at the temperature for 2.5 h, cooled to 85°C, and crushed to obtain the self-made flame retardant.

[0040] S4. By weight fraction, the foaming agent, composite stabilizer and water are mixed and foamed until the foam diameter is 400μm. By weight fraction, gypsum clinker, self-made flame retardant, filler and retarder are added and stirred at 1400rpm for 5min to obtain slurry. The slurry is poured between two layers of facing paper, pressed at 2MPa for 30min, and dried at 175℃ for 20min to obtain gypsum-based lightweight flame retardant board. Example 3

[0041] In this embodiment, the components and weight proportions of the gypsum-based lightweight flame-retardant board are as follows: 40 parts of gypsum clinker, 0.12 parts of composite stabilizer, 0.24 parts of foaming agent azodicarbonamide, 6 parts of self-made flame retardant, 18 parts of glass microspheres, 0.3 parts of retarder sodium acetate, and 45 parts of water.

[0042] The method for preparing the gypsum-based lightweight flame-retardant board in this embodiment is as follows:

[0043] S1. Allyl methacrylate, 2,6-di-tert-butyl-p-methylphenol, and a 5% (w / w) tetrahydrofuran solution of chloroplatinic acid were mixed at a mass ratio of 1:0.12:30. The mixture was heated to 62°C and reacted for 70 min. Then, 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane (1.15 times the mass of allyl methacrylate) was added dropwise at a rate of 3 ml / min. The reaction was allowed to proceed for 4 h, followed by vacuum distillation to obtain silane acrylic acid. Tetrahydrofuran, bis(2-hydroxyethyl), and triethyl... Amines were mixed at a mass ratio of 100:4.4:6.2 and placed in an ice bath. After stirring until homogeneous, a 10% tetrahydrofuran solution of phosphorus oxychloride (7.5 times the mass of bis(2-hydroxyethyl)) was added dropwise at a rate of 3 ml / min. The reaction was carried out in an ice bath for 6–8 h. Then, polyethylene glycol monomethyl ether (1.8 times the mass of bis(2-hydroxyethyl)) was added dropwise at a rate of 3 ml / min, and the reaction was continued for 8 h. Finally, ethanol (1.6 times the mass of bis(2-hydroxyethyl)) was added, and the reaction was continued for 8 h. The mixture was filtered and concentrated, then precipitated three times with diethyl ether, and dried under vacuum at room temperature to obtain hyperbranched polyphosphate. Under a nitrogen atmosphere, N-isopropylacrylamide, silane acrylic acid, ethanol, and deionized water were mixed in a mass ratio of 5:1:20:8. After thorough stirring, 0.004 times the mass of the initiator azobisisobutyronitrile (AIBN) was added, the mixture was heated to 65°C, reacted for 24 hours, the pH was adjusted to 7 with triethylamine, dialyzed for 48 hours, and then freeze-dried at -60°C to obtain an acrylamide copolymer. Acrylamide copolymer, dimethyl sulfoxide, crosslinking agent 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and catalyst N-hydroxysuccinimide were mixed in a mass ratio of 20:100:4.8:2.9 and stirred at 400 rpm for 30 min. Six times the mass of a 30% (w / w) solution of hyperbranched polyphosphate dimethyl sulfoxide was added, the mixture was heated to 42 °C and reacted for 14 h. The mixture was then precipitated with methanol and dried under vacuum to obtain the modified acrylamide copolymer, which is the composite stabilizer.

[0044] S2. 2-Thiophene methylamine and ethylene glycol diglycidyl ether were mixed at a volume ratio of 28:20, heated to 46°C, and reacted for 10 h. The mixture was then subjected to silica gel column chromatography with dichloromethane and methanol at a volume ratio of 30:1 to obtain a heterocyclic amino alcohol. 2,6-Dimethylphenol, tetramethylbisphenol A, and toluene were mixed at a mass ratio of 12:1:100, stirred until dissolved, and then 0.004 times the mass of cuprous chloride and 0.003 times the mass of 4-dimethylaminopyridine were added. Oxygen was bubbled through the mixture at a flow rate of 200 mL / min during the reaction. The temperature was raised to 42°C, and the reaction was carried out for 3 h. The reaction was quenched with acetic acid, and the mixture was separated by adding a saturated sodium chloride solution. Anhydrous sodium sulfate was dried, concentrated under reduced pressure, precipitated with methanol, filtered, and washed five times with methanol. The mixture was then dried under vacuum at 90°C to obtain dihydroxylated polyphenylene ether. Dihydroxylated polyphenylene ether, toluene, tetrahydrofuran, and 4-dimethylaminopyridine were mixed in a mass ratio of 100:400:50:1.3, heated to 42°C, and stirred at 400 rpm for 30 min. A heterocyclic amino alcohol mixture with a mass ratio of 0.24 times the mass of the dihydroxylated polyphenylene ether was added. The mass ratio of heterocyclic amino alcohol, dicyclohexylcarbodiimide, and tetrahydrofuran in the heterocyclic amino alcohol mixture was 24:13:100. The reaction was carried out for 8 h. The pH was adjusted to 8 with triethylamine, filtered, precipitated with methanol, and dried under vacuum to obtain hydroxylated heterocyclic amino alcohol.

[0045] S3. Under a nitrogen atmosphere, ammonium polyphosphate, hydroxy heterocyclic amino alcohol and phosphoric acid with a mass fraction of 85% were mixed in a mass ratio of 20:6:1, heated to 62°C, stirred at 600 rpm for 50 min for preheating, heated to 240°C, kept at the temperature for 2-3 h, cooled to 90°C, and crushed to obtain the self-made flame retardant.

[0046] S4. By weight fraction, the foaming agent, composite stabilizer and water are mixed and foamed until the foam diameter is 600μm. By weight fraction, gypsum clinker, self-made flame retardant, filler and retarder are added and stirred at 1500rpm for 8min to obtain slurry. The slurry is poured between two layers of facing paper, pressed at 3MPa for 40min, and dried at 180℃ for 25min to obtain gypsum-based lightweight flame retardant board.

[0047] Comparative Example 1

[0048] The preparation method of Comparative Example 1 is the same as that of Example 2. The difference between this gypsum-based lightweight flame-retardant board and Example 2 is that the composite stabilizer is only prepared by reacting N-isopropylacrylamide with hyperbranched polyphosphate.

[0049] Comparative Example 2

[0050] The preparation method of Comparative Example 2 is the same as that of Example 2. The difference between the hot air furnace and Example 2 is that the composite stabilizer is a modified acrylamide copolymer, which is prepared by copolymerizing N-isopropylacrylamide and allyl methacrylate, and then reacting it with hyperbranched polyphosphate.

[0051] Comparative Example 3

[0052] The preparation method of Comparative Example 3 is the same as that of Example 2. The difference between this gypsum-based lightweight flame-retardant board and Example 2 is that the modified acrylamide copolymer is obtained only by copolymerizing N-isopropylacrylamide and silane acrylic acid.

[0053] Comparative Example 4

[0054] The preparation method of Comparative Example 4 is the same as that of Example 2. The difference between this gypsum-based lightweight flame-retardant board and Example 2 is that the self-made flame retardant is only ammonium polyphosphate.

[0055] Comparative Example 5

[0056] The preparation method of Comparative Example 5 is the same as that of Example 2. The difference between this gypsum-based lightweight flame-retardant board and Example 2 is that the self-made flame retardant is prepared by reacting ammonium polyphosphate with dihydroxyl-terminated polyphenylene ether.

[0057] Comparative Example 6

[0058] The preparation method of Comparative Example 6 is the same as that of Example 2. The difference between this gypsum-based lightweight flame-retardant board and Example 2 is that the self-made flame retardant is prepared by reacting ammonium polyphosphate with heterocyclic amino alcohol.

[0059] Example of effect

[0060] Table 1 below shows the performance test results of the gypsum-based lightweight flame-retardant boards prepared in the examples and comparative examples;

[0061] Table 1

[0062] Hardness (N) <![CDATA[Weight per unit area (kg / m 2 )]]> Limiting Oxygen Index (LOI) Fire stability (min) Example 1 498 10.4 33 169 Example 2 503 10.2 33 173 Example 3 496 10.5 33 171 Comparative Example 1 464 11.1 31 159 Comparative Example 2 453 11.5 31 157 Comparative Example 3 451 11.9 30 152 Comparative Example 4 497 10.5 28 134 Comparative Example 5 496 10.6 29 142 Comparative Example 6 495 10.6 29 144

[0063] As can be seen from the performance data comparison in Table 1, the gypsum-based lightweight flame-retardant board prepared by the present invention is not only lightweight, but also has excellent hardness, flame retardancy and stability.

[0064] A comparison of the experimental data from Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3 reveals that N-isopropylacrylamide copolymerizes with silane acrylic acid to form a cross-linked network or linear copolymer. The silanol generated from the hydrolysis of siloxane further condenses with hyperbranched polyphosphate to form stable chemical bonds. During the preparation process, the composite stabilizer, after being uniformly mixed with the gypsum substrate, not only promotes the formation and stabilization of foam, but also further enhances the stability of the foam structure through a condensation reaction. In addition, the active hydroxyl groups in the hyperbranched polyphosphate can also react chemically with other components in the gypsum matrix to form a tighter bond, thereby improving the overall mechanical properties of the gypsum-based lightweight flame-retardant board, effectively preventing the migration and seepage of flame retardants in the gypsum matrix, and ensuring long-term stable flame-retardant performance.

[0065] A comparison of the experimental data from Examples 1, 2, and 3 and Comparative Examples 4, 5, and 6 reveals that the self-made flame retardant exhibits excellent compatibility with the gypsum matrix. During combustion, it promotes the formation of a char layer, creating a more stable cross-linked network and a denser char layer. This effectively isolates oxygen and heat transfer, prevents the volatilization of pyrolysis products and the spread of flames. Furthermore, the amino group reacts with moisture in the gypsum matrix to generate ammonia and water vapor, further diluting the concentration of combustible gases and slowing down the combustion rate. Consequently, the gypsum-based lightweight flame-retardant board possesses excellent flame retardancy and flame-retardant stability.

[0066] Obviously, the above embodiments are merely examples to clearly illustrate the embodiments of the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all embodiments here. However, these obvious variations or modifications derived from the spirit of the present invention are still within the protection scope of the present invention.

Claims

1. A gypsum-based lightweight flame-retardant board, characterized in that, The raw materials include the following parts by weight: 30-40 parts of gypsum clinker, 0.02-0.12 parts of composite stabilizer, 0.08-0.24 parts of foaming agent, 4-6 parts of self-made flame retardant, 12-18 parts of filler, 0.1-0.3 parts of retarder, and 35-45 parts of water; the composite stabilizer is a modified acrylamide copolymer; the self-made flame retardant is prepared by reacting ammonium polyphosphate with hydroxy heterocyclic amino alcohol; the modified acrylamide copolymer is prepared by copolymerizing N-isopropylacrylamide with silane acrylic acid and then reacting it with hyperbranched polyphosphate; the silane acrylic acid is prepared by reacting allyl methacrylate with 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane.

2. The gypsum-based lightweight flame-retardant board according to claim 1, characterized in that, The hyperbranched polyphosphate ester is prepared from bis(2-hydroxyethyl) disulfide, polyethylene glycol monomethyl ether, and phosphorus oxychloride.

3. The gypsum-based lightweight flame-retardant board according to claim 1, characterized in that, The hydroxy heterocyclic amino alcohol is prepared by reacting heterocyclic amino alcohol with bihydroxyl-terminated polyphenylene ether; the filler is glass microspheres; the retarder is one or a mixture of boric acid, citric acid, sodium tartrate, and sodium acetate; and the foaming agent is one of sodium bicarbonate, ammonium bicarbonate, and azodicarbonamide.

4. The method for preparing a gypsum-based lightweight flame-retardant board according to claim 1, characterized in that, The specific steps include the following: S1. Under a nitrogen atmosphere, N-isopropylacrylamide, silane acrylic acid, ethanol, and deionized water were mixed in a mass ratio of 4-5:1:20:

8. After stirring until homogeneous, 0.002-0.004 times the mass of N-isopropylacrylamide initiator azobisisobutyronitrile was added. The mixture was heated to 62-65℃ and reacted for 24 hours. The pH was adjusted to 6-7 with triethylamine, and the mixture was dialyzed for 24-48 hours. The mixture was then freeze-dried at -40 to -60℃ to obtain an acrylamide copolymer. The acrylamide copolymer, dimethyl sulfoxide, and crosslinking agent 1-( 3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and catalyst N-hydroxysuccinimide were mixed in a mass ratio of 10~20:100:4.6~4.8:2.7~2.9 and stirred at 200~400 rpm for 20~30 min. Then, 3~6 times the mass of a 20~30% (w / w) solution of hyperbranched polyphosphate dimethyl sulfoxide was added. The mixture was heated to 40~42℃ and reacted for 12~14 h. The mixture was precipitated with methanol and dried under vacuum to obtain the modified acrylamide copolymer, which is the composite stabilizer. S2. A mixture of dihydroxy-terminated polyphenylene ether, toluene, tetrahydrofuran, and 4-dimethylaminopyridine in a mass ratio of 80-100:400:50:1.1-1.3 was heated to 40-42°C and stirred at 200-400 rpm for 20-30 min. 0.22-0.24 times the mass of the dihydroxy-terminated polyphenylene ether was added to a mixture of heterocyclic amino alcohols. The mixture was reacted for 6-8 h. The pH was adjusted to 7-8 with triethylamine. The mixture was filtered and precipitated with methanol. The product was then dried under vacuum to obtain hydroxy heterocyclic amino alcohols. In the heterocyclic amino alcohol mixture, the mass ratio of heterocyclic amino alcohol, dicyclohexylcarbodiimide and tetrahydrofuran is 20~24:11~13:100; S3. Under a nitrogen atmosphere, ammonium polyphosphate, hydroxy heterocyclic amino alcohol and phosphoric acid with a mass fraction of 80-85% are mixed at a mass ratio of 20:4-6:1, heated to 60-62℃, stirred and preheated at 200-600 rpm for 30-50 min, heated to 220-240℃, kept at the temperature for 2-3 h, cooled to 80-90℃, and crushed to obtain the self-made flame retardant; S4. By weight fraction, mix the foaming agent, composite stabilizer and water, foam until the foam diameter is 200~600μm, then add gypsum clinker, self-made flame retardant, filler and retarder, stir and mix at 1000~1500rpm for 3~8min to obtain slurry; pour the slurry between two layers of facing paper, press under 1~3MPa pressure for 20~40min, and dry at 170~180℃ for 15~25min to obtain gypsum-based lightweight flame retardant board.

5. The method for preparing a gypsum-based lightweight flame-retardant board according to claim 4, characterized in that, In step S1 above, the preparation method of silane acrylic acid is as follows: allyl methacrylate, 2,6-di-tert-butyl-p-methylphenol and a tetrahydrofuran solution of chloroplatinic acid with a mass fraction of 3-5% are mixed at a mass ratio of 1:0.1-0.12:20-30, heated to 60-62℃, reacted for 50-70 min, and then 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxane with a mass of 1.05-1.15 times that of allyl methacrylate is added dropwise at a rate of 1-3 ml / min. The reaction is carried out for 3-4 h, and then the mixture is distilled under reduced pressure to obtain silane acrylic acid.

6. The method for preparing a gypsum-based lightweight flame-retardant board according to claim 4, characterized in that, In step S1 above, the preparation method of hyperbranched polyphosphate is as follows: Tetrahydrofuran, bis(2-hydroxyethyl) disulfide and triethylamine are mixed in a mass ratio of 100:4.2~4.4:6~6.2, placed in an ice bath, and stirred evenly. Then, a tetrahydrofuran solution of phosphorus oxychloride with a mass fraction of 8~10% is added dropwise at a rate of 1~3 ml / min, which is 6.5~7.5 times the mass of bis(2-hydroxyethyl) disulfide. The reaction is carried out in an ice bath for 6~8 h. Then, polyethylene glycol monomethyl ether with a mass fraction of 1.6~1.8 times the mass of bis(2-hydroxyethyl) disulfide is added dropwise at a rate of 1~3 ml / min. The reaction is continued for 6~8 h. Then, ethanol with a mass fraction of 1.2~1.6 times the mass of bis(2-hydroxyethyl) disulfide is added. The reaction is continued for 6~8 h. The mixture is filtered and concentrated, precipitated with diethyl ether 2~3 times, and dried under vacuum at room temperature to obtain hyperbranched polyphosphate.

7. The method for preparing a gypsum-based lightweight flame-retardant board according to claim 4, characterized in that, In step S2 above, the preparation method of heterocyclic amino alcohol is as follows: 2-thiophene methylamine and ethylene glycol diglycidyl ether are mixed at a volume ratio of 25~28:20, heated to 43~46℃, reacted for 8~10h, and then subjected to silica gel column chromatography with a volume ratio of dichloromethane and methanol of 30:1 to obtain heterocyclic amino alcohol.

8. The method for preparing a gypsum-based lightweight flame-retardant board according to claim 4, characterized in that, In step S2 above, the preparation method of the hydroxyl-terminated polyphenylene ether is as follows: 2,6-dimethylphenol, tetramethylbisphenol A and toluene are mixed in a mass ratio of 8~12:1:80~100, stirred and dissolved, and then 0.002~0.004 times the mass of 2,6-dimethylphenol cuprous chloride and 0.001~0.003 times the mass of 2,6-dimethylphenol 4-dimethylaminopyridine are added. Oxygen is introduced during the reaction at a flow rate of 100~200mL / min, the temperature is raised to 38~42℃, and the reaction is carried out for 2~3h. The reaction is quenched with acetic acid, and saturated sodium chloride solution is added for separation. The mixture is dried with anhydrous sodium sulfate, concentrated under reduced pressure, precipitated with methanol, filtered and washed with methanol 3~5 times, and dried under vacuum at 80~90℃ to obtain the hydroxyl-terminated polyphenylene ether.