Flame-retardant polyvinyl chloride composite board and processing method thereof

Abstract

The invention discloses a flame-retardant polyvinyl chloride composite board and a processing method thereof, and relates to the technical field of polyvinyl chloride boards. The flame-retardant polyvinyl chloride board is prepared by adding a mullite whisker-metal organic framework composite material into a composite board matrix. Firstly, aluminum oxide, silicon dioxide and aluminum fluoride trihydrate are used for preparing mullite whiskers, and the mullite whiskers are single-crystal fibrous materials with many pores, large specific surface area, high temperature resistance and high strength. Preparing sol by using the mung bean polypeptide, and modifying the mullite whisker by using the sol to obtain the mullite whisker modified by the mung bean polypeptide. Zinc nitrate hexahydrate and dimethylimidazole are added to assist growth of a metal organic framework composite material on mullite whiskers, so that the strength and flame retardance of the flame-retardant polyvinyl chloride composite board are further improved.

Description

Technical Field

[0001] The invention relates to the technical field of polyvinyl chloride plates, in particular to a flame-retardant polyvinyl chloride composite plate and a processing method thereof. Background Art

[0002] PVC composite sheets are lightweight, offer excellent thermal insulation and heat preservation properties, and are easy to construct. They are widely used in architectural decoration. With the development of society, people's performance requirements for decorative materials are constantly increasing, and market demand for them is also growing. Although ordinary PVC composite sheets have a certain degree of flame retardancy, they require even higher flame retardancy in crowded places. However, some existing sheets may still burn rapidly and produce large amounts of toxic smoke when exposed to high temperatures or flames, failing to meet stringent fire safety requirements.

[0003] In order to solve the above problems and improve the flame retardancy of polyvinyl chloride composite sheets, the present invention provides a flame retardant polyvinyl chloride composite sheet and a processing method thereof. Summary of the Invention

[0004] The object of the present invention is to provide a flame retardant polyvinyl chloride composite board and a processing method thereof, so as to solve the problems raised in the prior art.

[0005] To achieve the above object, the present invention provides the following technical solutions: A method for processing a flame-retardant polyvinyl chloride composite sheet comprises the following steps: Step 1: polyvinyl chloride resin, maleic anhydride modified polyvinyl chloride, mullite whisker-metal organic framework composite material, polyethylene wax, stabilizer, epoxy soybean oil, and azodicarbonamide are mixed and stirred uniformly, melt-extruded, and pressed into a plate to obtain a flame-retardant polyvinyl chloride sheet; Step 2: Mix epoxy resin, toluene, ammonium polyphosphate, and dicyandiamide and stir to obtain a coating; Step 3: Spray the coating evenly on the surface of the flame-retardant polyvinyl chloride sheet, and heat-cure it for 20-25 minutes to obtain a flame-retardant polyvinyl chloride composite sheet.

[0006] More optimally, the raw materials of the flame-retardant polyvinyl chloride sheet include the following components: by weight, 65-70 parts by weight of polyvinyl chloride resin, 12-15 parts by weight of maleic anhydride modified polyvinyl chloride, 25-28 parts by weight of mullite whisker-metal organic framework composite material, 1-1.5 parts by weight of polyethylene wax, 2-3 parts by weight of barium zinc liquid stabilizer, 2-3 parts by weight of epoxy soybean oil, and 4-5 parts by weight of azodicarbonamide.

[0007] More optimally, the preparation method of the mullite whisker-metal organic framework composite material is: take zinc nitrate hexahydrate and methanol, stir evenly to obtain a zinc nitrate hexahydrate solution; take dimethylimidazole and methanol, stir evenly to obtain a dimethylimidazole solution; soak the mung bean polypeptide-modified mullite whiskers in the zinc nitrate hexahydrate solution for 2-3 hours, take them out, and then soak them in the dimethylimidazole solution for 2-3 hours, add the zinc nitrate hexahydrate solution and polyethyleneimine, stir evenly, let stand to react for 22-26 hours, wash and dry to obtain the mullite whisker-metal organic framework composite material.

[0008] More optimally, the preparation method of the mung bean polypeptide-modified mullite whiskers is as follows: take tris(hydroxymethyl)aminomethane hydrochloride and deionized water, stir evenly, add sodium hydroxide solution dropwise to adjust the pH value of the solution to 8.5 to obtain a buffer solution, add the modified mung bean polypeptide sol, add mullite whiskers, stir for 22-26 hours, filter, wash, and dry to obtain mung bean polypeptide-modified mullite whiskers.

[0009] More optimally, the preparation method of the modified mung bean polypeptide sol is: take tetraethyl silicate, ethanol, and hydrochloric acid, stir at room temperature for 22-24 hours, add mung bean polypeptide, add 3-aminopropyltriethoxysilane, and stir for 30-40 minutes to obtain a modified mung bean polypeptide sol.

[0010] More optimally, the preparation method of the mullite whiskers is as follows: take alumina, silicon dioxide, and aluminum fluoride trihydrate, ball mill for 15-16 hours, heat to 1450-1455° C., and keep warm for 6-7 hours to obtain mullite whiskers.

[0011] More optimally, the raw materials of the coating include the following components: by weight, 50-60 parts by weight of epoxy resin, 80-85 parts by weight of toluene, 3-4 parts by weight of ammonium polyphosphate, and 25-30 parts by weight of dicyandiamide.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention prepares flame-retardant polyvinyl chloride sheet material by adding a mullite whisker-metal organic framework composite material to a composite sheet matrix. Mullite whiskers are first prepared using alumina, silica, and aluminum fluoride trihydrate. Mullite whiskers are a single-crystal, fibrous material with numerous pores, a large specific surface area, high temperature resistance, and high strength.

[0013] 2. The present invention uses mung bean polypeptide to prepare a sol, which is then used to modify mullite whiskers to obtain mung bean polypeptide-modified mullite whiskers. The chelating properties of the mung bean polypeptide are then utilized to assist in the growth of a metal-organic framework composite material on the mullite whiskers by adding zinc nitrate hexahydrate and dimethylimidazole, further improving the strength and flame retardancy of flame-retardant polyvinyl chloride composite sheets.

[0014] 3. The present invention also uses a coating prepared from epoxy resin, toluene, ammonium polyphosphate, and dicyandiamide. Applying this coating to the surface of a flame-retardant polyvinyl chloride sheet further improves the flame retardancy of the flame-retardant polyvinyl chloride composite sheet. The epoxy resin added to the coating reacts with the amino groups on the mullite whisker-metal organic framework composite material, thereby strengthening the bond between the coating and the flame-retardant polyvinyl chloride sheet. When the coating and the polyvinyl chloride sheet are tightly bonded, the two can better synergistically exert their flame retardant effect. The flame-retardant components produced by the thermal decomposition of the flame-retardant coating can more effectively interact with the polyvinyl chloride sheet, forming a dense char layer that prevents further decomposition and combustion of the sheet while reducing the release of combustible gases, thereby improving the flame retardancy of the flame-retardant polyvinyl chloride sheet. DETAILED DESCRIPTION

[0015] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0016] The sources and models of the substances involved in the present invention are not particularly limited, and illustratively include: polyvinyl chloride resin: can be purchased from Zhonghe, item number 1000109; epoxy resin: can be purchased from Haiyuanye Biotechnology Co., Ltd., item number S47943-25g; maleic anhydride modified polyvinyl chloride is prepared based on the existing technology Zhang Wenlong "Preparation of maleic anhydride grafted modified chlorinated polyvinyl chloride and its application in PVC" Part 1.3; alumina: γ-Al2O3, model: ZTL-AA, can be purchased from Yangzhou Zhongtianli New Materials Co., Ltd.; silicon dioxide: model: A200, can be purchased from Zhongbei Fine Chemicals; aluminum fluoride trihydrate: cas: 15098-87-0, can be purchased from Wuhan Kemik Biomedicine Technology Co., Ltd.; mung bean polypeptide: can be purchased from Fufeng Snow Biotechnology Co., Ltd.

[0017] Example 1: A method for processing a flame-retardant polyvinyl chloride composite sheet, comprising the following steps: Step 1: Preparation of mullite whisker-metal organic framework composite material: Take 40g of aluminum oxide, 17g of silicon dioxide, and 10g of aluminum fluoride trihydrate, ball mill for 15.5h, heat to 1452℃, and keep warm for 6.5h to obtain mullite whiskers; Take 15 mL of tetraethyl silicate, 80 mL of ethanol, and 4 mL of 0.01 mol / L hydrochloric acid, stir at room temperature for 23 h, add 2 g of mung bean polypeptide, add 0.3 g of 3-aminopropyltriethoxysilane, and stir for 30 minutes to obtain a modified mung bean polypeptide sol; Take 0.4g of tris(hydroxymethyl)aminomethane hydrochloride and 200mL of deionized water, stir evenly, add sodium hydroxide solution dropwise to adjust the solution pH to 8.5 to obtain a buffer solution, add 2g of modified mung bean polypeptide sol, add 8g of mullite whiskers, stir for 23h, filter, wash, and dry to obtain mung bean polypeptide-modified mullite whiskers; Take 6g of zinc nitrate hexahydrate and 400mL of methanol, stir evenly to obtain a zinc nitrate hexahydrate solution; take 8g of dimethylimidazole and 120mL of methanol, stir evenly to obtain a dimethylimidazole solution; soak the mung bean polypeptide-modified mullite whiskers in 200mL of zinc nitrate hexahydrate solution for 2.5h, take them out, and then soak them in 120mL of dimethylimidazole solution for 2.5h, add 200mL of zinc nitrate hexahydrate solution and 2g of polyethyleneimine, stir evenly, let them stand for 24h, wash and dry them to obtain a mullite whisker-metal organic framework composite material; Step 2: Preparation of coating: Mixing epoxy resin, toluene, ammonium polyphosphate and dicyandiamide to obtain a coating; The raw materials of the coating include the following components: 55 parts by weight of epoxy resin, 82 parts by weight of toluene, 3.5 parts by weight of ammonium polyphosphate, and 27 parts by weight of dicyandiamide; Step 3: Preparation of flame retardant polyvinyl chloride composite sheet: Polyvinyl chloride resin, maleic anhydride modified polyvinyl chloride, mullite whisker-metal organic framework composite material, polyethylene wax, stabilizer, epoxy soybean oil, and azodicarbonamide are mixed and stirred uniformly, melt-extruded, and pressed into a plate to obtain a flame-retardant polyvinyl chloride plate; The raw materials of the flame-retardant polyvinyl chloride sheet include the following components: 67 parts by weight of polyvinyl chloride resin, 13 parts by weight of maleic anhydride-modified polyvinyl chloride, 26 parts by weight of mullite whisker-metal organic framework composite material, 1.2 parts by weight of polyethylene wax, 2.5 parts by weight of barium zinc liquid stabilizer, 2.5 parts by weight of epoxy soybean oil, and 4.5 parts by weight of azodicarbonamide; The coating was evenly sprayed on the surface of the flame-retardant polyvinyl chloride sheet by a spray gun, with a coating thickness of 0.3 mm, and then placed in an oven for thermal curing for 22 minutes to obtain a flame-retardant polyvinyl chloride composite sheet.

[0018] Example 2: A method for processing a flame-retardant polyvinyl chloride composite sheet, comprising the following steps: Step 1: Preparation of mullite whisker-metal organic framework composite material: Take 40g of aluminum oxide, 17g of silicon dioxide, and 10g of aluminum fluoride trihydrate, ball mill for 15h, heat to 1450℃, and keep warm for 6h to obtain mullite whiskers; Take 15 mL of tetraethyl silicate, 80 mL of ethanol, and 4 mL of 0.01 mol / L hydrochloric acid, stir at room temperature for 22 h, add 2 g of mung bean polypeptide, add 0.3 g of 3-aminopropyltriethoxysilane, and stir for 30 minutes to obtain a modified mung bean polypeptide sol; Take 0.4g of tris(hydroxymethyl)aminomethane hydrochloride and 200mL of deionized water, stir evenly, add sodium hydroxide solution dropwise to adjust the solution pH to 8.5 to obtain a buffer solution, add 2g of modified mung bean polypeptide sol, add 8g of mullite whiskers, stir for 22h, filter, wash, and dry to obtain mung bean polypeptide-modified mullite whiskers; 6 g of zinc nitrate hexahydrate and 400 mL of methanol were mixed and stirred to obtain a zinc nitrate hexahydrate solution; 8 g of dimethylimidazole and 120 mL of methanol were mixed and stirred to obtain a dimethylimidazole solution; mung bean polypeptide-modified mullite whiskers were immersed in 200 mL of zinc nitrate hexahydrate solution for 2 h, taken out, and then immersed in 120 mL of dimethylimidazole solution for 2 h, 200 mL of zinc nitrate hexahydrate solution and 2 g of polyethyleneimine were added, stirred and stirred, and the mixture was allowed to react for 22 h, washed, and dried to obtain a mullite whisker-metal organic framework composite material; Step 2: Preparation of coating: Mixing epoxy resin, toluene, ammonium polyphosphate and dicyandiamide to obtain a coating; The raw materials of the coating include the following components: 50 parts by weight of epoxy resin, 80 parts by weight of toluene, 3 parts by weight of ammonium polyphosphate, and 25 parts by weight of dicyandiamide; Step 3: Preparation of flame retardant polyvinyl chloride composite sheet: Polyvinyl chloride resin, maleic anhydride modified polyvinyl chloride, mullite whisker-metal organic framework composite material, polyethylene wax, stabilizer, epoxy soybean oil, and azodicarbonamide are mixed and stirred uniformly, melt-extruded, and pressed into a plate to obtain a flame-retardant polyvinyl chloride plate; The raw materials of the flame-retardant polyvinyl chloride sheet include the following components: 65 parts by weight of polyvinyl chloride resin, 12 parts by weight of maleic anhydride modified polyvinyl chloride, 25 parts by weight of mullite whisker-metal organic framework composite material, 1 part by weight of polyethylene wax, 2 parts by weight of barium zinc liquid stabilizer, 2 parts by weight of epoxy soybean oil, and 4 parts by weight of azodicarbonamide; The coating was evenly sprayed onto the surface of the flame-retardant polyvinyl chloride sheet using a spray gun, with a coating thickness of 0.3 mm. The sheet was then placed in an oven for thermal curing for 20 minutes to obtain a flame-retardant polyvinyl chloride composite sheet.

[0019] Example 3: A method for processing a flame-retardant polyvinyl chloride composite sheet, comprising the following steps: Step 1: Preparation of mullite whisker-metal organic framework composite material: Take 40g of aluminum oxide, 17g of silicon dioxide, and 10g of aluminum fluoride trihydrate, ball mill for 16h, heat to 1455℃, and keep warm for 7h to obtain mullite whiskers; Take 15 mL of tetraethyl silicate, 80 mL of ethanol, and 4 mL of 0.01 mol / L hydrochloric acid, stir at room temperature for 24 h, add 2 g of mung bean polypeptide, add 0.3 g of 3-aminopropyltriethoxysilane, and stir for 30 min to obtain a modified mung bean polypeptide sol; Take 0.4g of tris(hydroxymethyl)aminomethane hydrochloride and 200mL of deionized water, stir evenly, add sodium hydroxide solution dropwise to adjust the solution pH to 8.5 to obtain a buffer solution, add 2g of modified mung bean polypeptide sol, add 8g of mullite whiskers, stir for 26h, filter, wash, and dry to obtain mung bean polypeptide-modified mullite whiskers; 6 g of zinc nitrate hexahydrate and 400 mL of methanol were mixed and stirred to obtain a zinc nitrate hexahydrate solution; 8 g of dimethylimidazole and 120 mL of methanol were mixed and stirred to obtain a dimethylimidazole solution; mung bean polypeptide-modified mullite whiskers were immersed in 200 mL of zinc nitrate hexahydrate solution for 3 h, taken out, and then immersed in 120 mL of dimethylimidazole solution for 3 h, 200 mL of zinc nitrate hexahydrate solution and 2 g of polyethyleneimine were added, stirred and stirred, and the mixture was allowed to react for 26 h, washed and dried to obtain a mullite whisker-metal organic framework composite material; Step 2: Preparation of coating: Mixing epoxy resin, toluene, ammonium polyphosphate and dicyandiamide to obtain a coating; The raw materials of the coating include the following components: 60 parts by weight of epoxy resin, 85 parts by weight of toluene, 4 parts by weight of ammonium polyphosphate, and 30 parts by weight of dicyandiamide; Step 3: Preparation of flame retardant polyvinyl chloride composite sheet: Polyvinyl chloride resin, maleic anhydride modified polyvinyl chloride, mullite whisker-metal organic framework composite material, polyethylene wax, stabilizer, epoxy soybean oil, and azodicarbonamide are mixed and stirred uniformly, melt-extruded, and pressed into a plate to obtain a flame-retardant polyvinyl chloride plate; The raw materials of the flame-retardant polyvinyl chloride sheet include the following components: 70 parts by weight of polyvinyl chloride resin, 15 parts by weight of maleic anhydride modified polyvinyl chloride, 28 parts by weight of mullite whisker-metal organic framework composite material, 1.5 parts by weight of polyethylene wax, 3 parts by weight of barium zinc liquid stabilizer, 3 parts by weight of epoxy soybean oil, and 5 parts by weight of azodicarbonamide; The coating was evenly sprayed onto the surface of the flame-retardant polyvinyl chloride sheet using a spray gun, with a coating thickness of 0.3 mm. The sheet was then placed in an oven for thermal curing for 25 minutes to obtain a flame-retardant polyvinyl chloride composite sheet.

[0020] Comparative Example 1: No metal organic framework composite material was added, and the rest was the same as Example 1: Step 1: Preparation of mullite whiskers modified with mung bean peptide: Take 40g of aluminum oxide, 17g of silicon dioxide, and 10g of aluminum fluoride trihydrate, ball mill for 15.5h, heat to 1452℃, and keep warm for 6.5h to obtain mullite whiskers; Take 15 mL of tetraethyl silicate, 80 mL of ethanol, and 4 mL of 0.01 mol / L hydrochloric acid, stir at room temperature for 23 h, add 2 g of mung bean polypeptide, add 0.3 g of 3-aminopropyltriethoxysilane, and stir for 30 minutes to obtain a modified mung bean polypeptide sol; Take 0.4g of tris(hydroxymethyl)aminomethane hydrochloride and 200mL of deionized water, stir evenly, add sodium hydroxide solution dropwise to adjust the solution pH to 8.5 to obtain a buffer solution, add 2g of modified mung bean polypeptide sol, add 8g of mullite whiskers, stir for 23h, filter, wash, and dry to obtain mung bean polypeptide-modified mullite whiskers; Step 2: Preparation of coating: Mixing epoxy resin, toluene, ammonium polyphosphate and dicyandiamide to obtain a coating; The raw materials of the coating include the following components: 55 parts by weight of epoxy resin, 82 parts by weight of toluene, 3.5 parts by weight of ammonium polyphosphate, and 27 parts by weight of dicyandiamide; Step 3: Preparation of flame retardant polyvinyl chloride composite sheet: Polyvinyl chloride resin, maleic anhydride modified polyvinyl chloride, mung bean polypeptide modified mullite whiskers, polyethylene wax, stabilizer, epoxy soybean oil, and azodicarbonamide are mixed and stirred evenly, melt-extruded, and pressed into a plate to obtain a flame-retardant polyvinyl chloride sheet; The raw materials of the flame-retardant polyvinyl chloride sheet include the following components: 67 parts by weight of polyvinyl chloride resin, 13 parts by weight of maleic anhydride-modified polyvinyl chloride, 26 parts by weight of mung bean polypeptide-modified mullite whiskers, 1.2 parts by weight of polyethylene wax, 2.5 parts by weight of barium zinc liquid stabilizer, 2.5 parts by weight of epoxy soybean oil, and 4.5 parts by weight of azodicarbonamide; The coating was evenly sprayed on the surface of the flame-retardant polyvinyl chloride sheet by a spray gun, with a coating thickness of 0.3 mm, and then placed in an oven for thermal curing for 22 minutes to obtain a flame-retardant polyvinyl chloride composite sheet.

[0021] Comparative Example 2: No mung bean polypeptide was added, and the rest was the same as Example 1: Step 1: Preparation of mullite whisker-metal organic framework composite material: Take 40g of aluminum oxide, 17g of silicon dioxide, and 10g of aluminum fluoride trihydrate, ball mill for 15.5h, heat to 1452℃, and keep warm for 6.5h to obtain mullite whiskers; Take 15 mL of tetraethyl silicate, 80 mL of ethanol, and 4 mL of 0.01 mol / L hydrochloric acid, stir at room temperature for 23 h, add 0.3 g of 3-aminopropyltriethoxysilane, and stir for 30 minutes to obtain a modified sol; 0.4 g of tris(hydroxymethyl)aminomethane hydrochloride and 200 mL of deionized water were mixed and stirred evenly. Sodium hydroxide solution was added dropwise to adjust the pH value of the solution to 8.5 to obtain a buffer solution. 2 g of the modified sol was added, and 8 g of mullite whiskers were added. The mixture was stirred for 23 h, filtered, washed, and dried to obtain sol-modified mullite whiskers. 6 g of zinc nitrate hexahydrate and 400 mL of methanol were mixed and stirred to obtain a zinc nitrate hexahydrate solution; 8 g of dimethylimidazole and 120 mL of methanol were mixed and stirred to obtain a dimethylimidazole solution; the sol-modified mullite whiskers were immersed in 200 mL of zinc nitrate hexahydrate solution for 2.5 hours, taken out, and then immersed in 120 mL of dimethylimidazole solution for 2.5 hours, 200 mL of zinc nitrate hexahydrate solution and 2 g of polyethyleneimine were added, stirred and stirred, and the mixture was allowed to react for 24 hours, washed and dried to obtain a mullite whisker-metal organic framework composite material; Step 2: Preparation of coating: Mixing epoxy resin, toluene, ammonium polyphosphate and dicyandiamide to obtain a coating; The raw materials of the coating include the following components: 55 parts by weight of epoxy resin, 82 parts by weight of toluene, 3.5 parts by weight of ammonium polyphosphate, and 27 parts by weight of dicyandiamide; Step 3: Preparation of flame retardant polyvinyl chloride composite sheet: Polyvinyl chloride resin, maleic anhydride modified polyvinyl chloride, mullite whisker-metal organic framework composite material, polyethylene wax, stabilizer, epoxy soybean oil, and azodicarbonamide are mixed and stirred uniformly, melt-extruded, and pressed into a plate to obtain a flame-retardant polyvinyl chloride plate; The raw materials of the flame-retardant polyvinyl chloride sheet include the following components: 67 parts by weight of polyvinyl chloride resin, 13 parts by weight of maleic anhydride-modified polyvinyl chloride, 26 parts by weight of mullite whisker-metal organic framework composite material, 1.2 parts by weight of polyethylene wax, 2.5 parts by weight of barium zinc liquid stabilizer, 2.5 parts by weight of epoxy soybean oil, and 4.5 parts by weight of azodicarbonamide; The coating was evenly sprayed on the surface of the flame-retardant polyvinyl chloride sheet by a spray gun, with a coating thickness of 0.3 mm, and then placed in an oven for thermal curing for 22 minutes to obtain a flame-retardant polyvinyl chloride composite sheet.

[0022] Comparative Example 3: No polyethyleneimine was added, and the rest was the same as in Example 1: Step 1: Preparation of mullite whisker-metal organic framework composite material: Take 40g of aluminum oxide, 17g of silicon dioxide, and 10g of aluminum fluoride trihydrate, ball mill for 15.5h, heat to 1452℃, and keep warm for 6.5h to obtain mullite whiskers; Take 15 mL of tetraethyl silicate, 80 mL of ethanol, and 4 mL of 0.01 mol / L hydrochloric acid, stir at room temperature for 23 h, add 2 g of mung bean polypeptide, add 0.3 g of 3-aminopropyltriethoxysilane, and stir for 30 minutes to obtain a modified mung bean polypeptide sol; Take 0.4g of tris(hydroxymethyl)aminomethane hydrochloride and 200mL of deionized water, stir evenly, add sodium hydroxide solution dropwise to adjust the solution pH to 8.5 to obtain a buffer solution, add 2g of modified mung bean polypeptide sol, add 8g of mullite whiskers, stir for 23h, filter, wash, and dry to obtain mung bean polypeptide-modified mullite whiskers; 6 g of zinc nitrate hexahydrate and 400 mL of methanol were mixed and stirred to obtain a zinc nitrate hexahydrate solution; 8 g of dimethylimidazole and 120 mL of methanol were mixed and stirred to obtain a dimethylimidazole solution; the mung bean polypeptide-modified mullite whiskers were immersed in 200 mL of zinc nitrate hexahydrate solution for 2.5 hours, taken out, and then immersed in 120 mL of dimethylimidazole solution for 2.5 hours, 200 mL of zinc nitrate hexahydrate solution was added, stirred, and allowed to react for 24 hours, washed, and dried to obtain a mullite whisker-metal organic framework composite material; Step 2: Preparation of coating: Mixing epoxy resin, toluene, ammonium polyphosphate and dicyandiamide to obtain a coating; The raw materials of the coating include the following components: 55 parts by weight of epoxy resin, 82 parts by weight of toluene, 3.5 parts by weight of ammonium polyphosphate, and 27 parts by weight of dicyandiamide; Step 3: Preparation of flame retardant polyvinyl chloride composite sheet: Polyvinyl chloride resin, maleic anhydride modified polyvinyl chloride, mullite whisker-metal organic framework composite material, polyethylene wax, stabilizer, epoxy soybean oil, and azodicarbonamide are mixed and stirred uniformly, melt-extruded, and pressed into a plate to obtain a flame-retardant polyvinyl chloride plate; The raw materials of the flame-retardant polyvinyl chloride sheet include the following components: 67 parts by weight of polyvinyl chloride resin, 13 parts by weight of maleic anhydride-modified polyvinyl chloride, 26 parts by weight of mullite whisker-metal organic framework composite material, 1.2 parts by weight of polyethylene wax, 2.5 parts by weight of barium zinc liquid stabilizer, 2.5 parts by weight of epoxy soybean oil, and 4.5 parts by weight of azodicarbonamide; The coating was evenly sprayed on the surface of the flame-retardant polyvinyl chloride sheet by a spray gun, with a coating thickness of 0.3 mm, and then placed in an oven for thermal curing for 22 minutes to obtain a flame-retardant polyvinyl chloride composite sheet.

[0023] experiment: The flame-retardant polyvinyl chloride composite sheets prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to performance tests. The notched impact strength was tested according to GB / T 1043.1. The limiting oxygen index was tested using a JF-5 oxygen index tester. The obtained data are shown in Table 1 below: Table 1

[0024] Conclusion: From the comparison of the data in the table, it can be seen that in Comparative Example 1, no metal-organic framework composite material is added, and the strength and flame retardancy of the flame-retardant polyvinyl chloride composite board are reduced. In Comparative Example 2, no mung bean polypeptide is added, and the metal-organic framework composite material loaded on the mullite whiskers becomes less, and the strength and flame retardancy of the polyvinyl chloride composite board are reduced. In Comparative Example 3, no polyethyleneimine is added, the coating is not tightly bonded to the polyvinyl chloride board, and the flame retardant performance is reduced. Examples 1-3 of the present invention prepare flame-retardant polyvinyl chloride boards by adding mullite whiskers-metal-organic framework composite materials to the composite board matrix. A sol is prepared using mung bean polypeptide, and then the sol is used to modify mullite whiskers to obtain mullite whiskers modified with mung bean polypeptide. Then, the chelating property of mung bean polypeptide is utilized, and zinc nitrate hexahydrate and dimethylimidazole are added to assist the growth of metal-organic framework composite materials on the mullite whiskers, thereby further improving the strength and flame retardant performance of the flame-retardant polyvinyl chloride composite board. The amino groups on the mullite whisker-metal organic framework composite material can react with the epoxy resin in the coating to strengthen the bonding strength between the coating and the flame retardant polyvinyl chloride sheet, thereby improving the flame retardant properties of the flame retardant polyvinyl chloride sheet.

[0025] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for processing a flame-retardant polyvinyl chloride composite sheet, characterized in that: The following steps are involved: Step 1: polyvinyl chloride resin, maleic anhydride modified polyvinyl chloride, mullite whisker-metal organic framework composite material, polyethylene wax, stabilizer, epoxy soybean oil, and azodicarbonamide are mixed and stirred uniformly, melt-extruded, and pressed into a plate to obtain a flame-retardant polyvinyl chloride sheet; Step 2: Mix epoxy resin, toluene, ammonium polyphosphate, and dicyandiamide and stir to obtain a coating; Step 3: Spray the coating evenly on the surface of the flame-retardant polyvinyl chloride sheet, and heat-cure it for 20-25 minutes to obtain a flame-retardant polyvinyl chloride composite sheet.

2. The method for processing a flame-retardant polyvinyl chloride composite sheet according to claim 1, characterized in that: The raw materials of the flame-retardant polyvinyl chloride sheet include the following components: 65-70 parts by weight of polyvinyl chloride resin, 12-15 parts by weight of maleic anhydride modified polyvinyl chloride, 25-28 parts by weight of mullite whisker-metal organic framework composite material, 1-1.5 parts by weight of polyethylene wax, 2-3 parts by weight of barium zinc liquid stabilizer, 2-3 parts by weight of epoxy soybean oil, and 4-5 parts by weight of azodicarbonamide.

3. The method for processing a flame-retardant polyvinyl chloride composite sheet according to claim 2, characterized in that: The preparation method of the mullite whisker-metal organic framework composite material comprises the following steps: taking zinc nitrate hexahydrate and methanol, stirring evenly to obtain a zinc nitrate hexahydrate solution; taking dimethylimidazole and methanol, stirring evenly to obtain a dimethylimidazole solution; soaking mung bean polypeptide-modified mullite whiskers in the zinc nitrate hexahydrate solution for 2-3 hours, taking out, and then soaking in the dimethylimidazole solution for 2-3 hours, adding the zinc nitrate hexahydrate solution and polyethyleneimine, stirring evenly, standing to react for 22-26 hours, washing, and drying to obtain the mullite whisker-metal organic framework composite material.

4. The method for processing a flame-retardant polyvinyl chloride composite sheet according to claim 3, characterized in that: The preparation method of the mung bean polypeptide-modified mullite whiskers comprises: taking tris(hydroxymethyl)aminomethane hydrochloride and deionized water, stirring evenly, adding sodium hydroxide solution dropwise to adjust the pH value of the solution to 8.5 to obtain a buffer solution, adding the modified mung bean polypeptide sol, adding the mullite whiskers, stirring for 22-26 hours, filtering, washing, and drying to obtain the mung bean polypeptide-modified mullite whiskers.

5. The method for processing a flame-retardant polyvinyl chloride composite sheet according to claim 4, characterized in that: The preparation method of the modified mung bean polypeptide sol is as follows: tetraethyl silicate, ethanol, and hydrochloric acid are taken, stirred at room temperature for 22-24 hours, mung bean polypeptide is added, 3-aminopropyltriethoxysilane is added, and stirred for 30-40 minutes to obtain the modified mung bean polypeptide sol.

6. The method for processing a flame-retardant polyvinyl chloride composite sheet according to claim 4, characterized in that: The preparation method of the mullite whisker is as follows: taking aluminum oxide, silicon dioxide and aluminum fluoride trihydrate, ball milling for 15-16 hours, heating to 1450-1455° C., and keeping the temperature for 6-7 hours to obtain the mullite whisker.

7. The method for processing a flame-retardant polyvinyl chloride composite sheet according to claim 1, characterized in that: The raw materials of the coating include the following components: 50-60 parts by weight of epoxy resin, 80-85 parts by weight of toluene, 3-4 parts by weight of ammonium polyphosphate, and 25-30 parts by weight of dicyandiamide.

8. A flame-retardant polyvinyl chloride composite board obtained by processing the flame-retardant polyvinyl chloride composite board according to claims 1-7.

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