Preparation method of PVC-based flame-retardant antibacterial composite board

Abstract

This invention provides a method for preparing a flame-retardant and antibacterial composite board based on PVC material, belonging to the field of PVC board preparation technology. The preparation process includes the following steps: preparation of nano-xylan powder; preparation of modified nano-titanium dioxide; preparation of a composite antibacterial agent; preparation of a flame retardant; preparation of an antibacterial and flame-retardant coating; and preparation of the PVC board. This invention improves the antibacterial properties of xylan by nano-sizing it. Nano-xylan interferes with bacterial cell membranes, cell walls, enzymes, and metabolic processes, thereby exerting an antibacterial effect. Furthermore, the numerous hydroxyl groups and other functional groups on the surface of nano-xylan have adsorption properties, which can adsorb and immobilize bacteria, reducing their activity. The added modified nano-titanium dioxide produces a synergistic antibacterial effect with the nano-xylan, while the nano-xylan can uniformly disperse the modified nano-titanium dioxide, giving the PVC board excellent antibacterial properties.

Description

Technical Field

[0001] This invention relates to the field of PVC sheet preparation technology, and specifically to a method for preparing a flame-retardant and antibacterial composite sheet based on PVC material. Background Technology

[0002] PVC sheets are a popular new type of lightweight flooring material in the world today. Also known as "lightweight flooring," they are a popular product in Europe, America, and Asia, particularly in Japan and South Korea. They have been popular abroad and entered the Chinese market in the early 1980s. Today, they are widely recognized and used in major and medium-sized cities in China.

[0003] In public places and medical facilities, PVC sheets are frequently in contact with people as wall and floor coverings, as well as some furniture and decorative components. Therefore, PVC sheets should have excellent antibacterial properties to help inhibit the growth of bacteria and mold on their surfaces, thereby reducing the risk of cross-infection and maintaining environmental hygiene. However, the antibacterial properties of existing PVC sheets are generally poor, which affects their practicality. Furthermore, PVC sheets are prone to fire in public places and medical facilities due to their poor flame retardant properties. When exposed to fire, they will burn rapidly and release toxic fumes, which can easily cause a large number of casualties and property damage.

[0004] Therefore, we propose a method for preparing PVC composite boards that can improve the antibacterial and flame-retardant properties of PVC boards. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for preparing a flame-retardant and antibacterial composite board based on PVC material.

[0006] A method for preparing a flame-retardant and antibacterial composite board based on PVC material includes the following steps:

[0007] S1: Preparation of nano-xylan powder

[0008] Xylooligosaccharide reactants were prepared by sorbitol, citric acid and xylose. After alcohol precipitation, filtration, centrifugation and washing, nano-xylan powder was obtained from the xylooligosaccharide reactants.

[0009] S2: Preparation of Modified Nano-Titanium Dioxide

[0010] Modified nano-titanium dioxide was obtained by modifying nano-titanium dioxide with silver nitrate and sodium silicate.

[0011] S3: Preparation of compound antibacterial agents

[0012] Antibacterial hollow microsphere carriers were prepared by using dopamine hydrochloride methanol solution, and composite antibacterial agents were prepared by loading nano-xylan powder and modified nano-titanium dioxide onto the antibacterial hollow microsphere carriers.

[0013] S4: Preparation of flame retardants

[0014] Flame retardants were prepared using L-arginine, potato starch, phytic acid solution, and sodium carbonate solution as raw materials.

[0015] S5: Preparation of antibacterial and flame-retardant coatings

[0016] An antibacterial and flame-retardant coating is obtained by mixing and stirring flame retardant, composite antibacterial agent, aluminum silicate fiber, titanium dioxide, kaolin, talc, polyethylene glycol, deionized water, ethylene-vinyl acetate copolymer emulsion and vinylidene chloride emulsion.

[0017] S6: Preparation of PVC sheets

[0018] Prepare the following raw materials by weight: 80-100 parts PVC resin, 5-8 parts acrylic-maleic anhydride copolymer, 10-15 parts kaolin, 5-8 parts mica powder, 7-8 parts polyester fiber, 0.5-1 part stearic acid, 10-15 parts activated calcium carbonate, 3-5 parts boron nitride, 1-2 parts calcium-zinc stabilizer, 2-3 parts phosphorophenanthrene triazine compound, 1-2 parts lubricant, and 1-2 parts plasticizer. Prepare a PVC substrate using the above raw materials, and then coat the PVC substrate with an antibacterial and flame-retardant coating to obtain a PVC sheet.

[0019] Furthermore, the preparation of the nano-xylan powder in step S1 specifically includes the following steps:

[0020] S1.1: Weigh 3-5 parts by weight of sorbitol and 3-5 parts by weight of citric acid, and dissolve them in 5-8 parts by weight of distilled water to obtain sorbitol solution and citric acid solution. Mix 25-30 parts by weight of xylose with the above sorbitol solution and heat to 80-90℃. Stir mechanically at 20-30 r / min. Slowly add the above citric acid solution during the heating process. Continue heating for 20-30 min and then raise the temperature to 160-170℃. React for 1-2 h. Cool after the reaction to obtain xylooligosaccharide reactant.

[0021] S1.2: Weigh 2-5 parts by weight of xylooligosaccharide reactant, add 200-230 parts by weight of sodium hydroxide solution, heat to 40-50℃ to dissolve it, react for 30-40 min, then cool to room temperature, add diluted sulfuric acid to adjust pH to 5.5-5.6, then add 3-4 times the volume of 95% ethanol for alcohol precipitation, precipitate for 20-24 h to obtain alcohol precipitate;

[0022] S1.3: Filter the alcohol precipitate to obtain a precipitate. Wash the precipitate with distilled water 2-3 times. Add 2-3 times the amount of distilled water to the washed precipitate and centrifuge at 6000-7000 r / min for 2-3 min. Repeat the centrifugation 2-3 times. After centrifugation, filter to obtain filter residue.

[0023] S1.4: Pre-freeze the filter residue in a refrigerator for 1-2 hours, then dry the pre-frozen filter residue in a vacuum freeze dryer for 20-24 hours, grind and pulverize it to obtain nano xylan powder.

[0024] Furthermore, the preparation of the modified nano-titanium dioxide in step S2 specifically includes the following steps:

[0025] S2.1: Take 1-2 parts by weight of nano titanium dioxide and add 30-40 parts by weight of deionized water, sonicate for 5-8 minutes, add 0.5-1 parts by weight of silver nitrate, stir at room temperature in the dark for 2-3 hours, and then add 0.2-0.3 parts by weight of sodium silicate to obtain a mixed solution;

[0026] S2.2: Reflux the mixed solution at 60-70℃ for 1-2 hours, centrifuge the refluxed solution to obtain a precipitate, wash the precipitate with deionized water and dry it to obtain modified nano titanium dioxide.

[0027] Furthermore, the preparation of the composite antibacterial agent in step S3 specifically includes the following steps:

[0028] S3.1: Mix 2-5 parts by weight of 0.025 mmol / L 2-methylimidazole and 2-5 parts by weight of 0.025 mmol / L zinc nitrate hexahydrate methanol solution, stir for 5-8 min, let stand for 45-50 min, and then centrifuge at 6000-7000 r / min to obtain a precipitate. Wash the precipitate with methanol and dry it to obtain powder crystals. Add 2-3 parts by weight of powder crystals to 5-8 parts by weight of methanol and disperse evenly to obtain a dispersion.

[0029] S3.2: Mix the 0.25 mol / L dopamine hydrochloride methanol solution with the dispersion evenly, heat in a water bath at 50-60℃ for 3-4 h to obtain the reactant, centrifuge the reactant at 6000-7000 r / min to obtain the reaction precipitate, wash the reaction precipitate with methanol and dry it to obtain the antibacterial hollow microsphere carrier;

[0030] S3.3: Disperse 1-2 parts by weight of nano xylan powder in 2-3 parts by weight of deionized water to obtain a nano xylan solution, add 0.5-1 parts by weight of modified nano titanium dioxide, and ultrasonically disperse for 15-20 min to obtain a composite antibacterial dispersion;

[0031] S3.4: Add 3-5 parts by weight of antibacterial hollow microsphere carrier to 8-10 parts by weight of composite antibacterial dispersion, ultrasonically disperse for 20-30 minutes, let stand for 20-24 hours, and centrifuge at high speed to obtain centrifuged precipitate, which is the composite antibacterial agent.

[0032] Furthermore, the preparation of the flame retardant in step S4 specifically includes the following steps:

[0033] S4.1: Dissolve 3-5 parts by weight of L-arginine in 4-8 parts by weight of deionized water, add acetic acid to adjust the pH to neutral, and obtain an L-arginine solution. Disperse 2-3 parts by weight of potato starch in 5-8 parts by weight of deionized water to obtain a starch dispersion.

[0034] S4.2: Add 3-5 parts by weight of phytic acid solution and 2-3 parts by weight of sodium carbonate solution to the above starch dispersion, adjust the pH to 8-9, and then heat to 75-80℃ and mechanically stir for 1-2 hours to obtain the reactant;

[0035] S4.3: Mix the reactants with the above L-arginine solution to obtain a mixture. Place the mixture in a hydrothermal reactor and hydrothermally react at 110-120℃ for 4-5 hours. After the reaction is completed, obtain the reaction product. Filter, dry and pulverize the reaction product to obtain the flame retardant.

[0036] Furthermore, the preparation of the antibacterial and flame-retardant coating in step S5 specifically includes the following steps:

[0037] S5.1: Mix 5-7 parts by weight of flame retardant, 7-10 parts by weight of composite antibacterial agent, 4-5 parts by weight of aluminum silicate fiber, 8-9 parts by weight of titanium dioxide, 3-5 parts by weight of kaolin, 5-8 parts by weight of talc, 1-2 parts by weight of polyethylene glycol, and 30-50 parts by weight of deionized water evenly to obtain a mixture.

[0038] S5.2: Place the mixture into a grinding and mixing machine and grind and disperse it at 400-500 r / min for 10-20 min, then grind and disperse it at 1000-1200 r / min for 5-8 min, and finally grind and disperse it at 500-600 r / min for 5-8 min. Add 10-15 parts by weight of ethylene-vinyl acetate copolymer emulsion and 5-10 parts by weight of vinylidene chloride emulsion, and continue stirring for 10-15 min to obtain an antibacterial and flame-retardant coating for later use.

[0039] Further, step S6, preparing the PVC sheet, specifically includes the following steps:

[0040] S6.1: Prepare raw materials by weight ratio: 80-100 parts by weight of PVC resin, 5-8 parts by weight of acrylic acid-maleic anhydride copolymer, 10-15 parts by weight of clay, 5-8 parts by weight of mica powder, 7-8 parts by weight of polyester fiber, 0.5-1 parts by weight of stearic acid, 10-15 parts by weight of activated calcium carbonate, 3-5 parts by weight of boron nitride, 1-2 parts by weight of calcium zinc stabilizer, 2-3 parts by weight of phosphorus triazine compound, 1-2 parts by weight of lubricant and 1-2 parts by weight of plasticizer;

[0041] S6.2: Mix the above-mentioned mica powder, polyester fiber, clay, stearic acid, activated calcium carbonate, boron nitride, and phosphorus triazine compound at 82-86℃ and stir evenly to obtain material I;

[0042] S6.3: Mix the above PVC resin, acrylic acid-maleic anhydride copolymer, calcium zinc stabilizer, plasticizer and lubricant, and mix them in a mixer for 8-12 minutes at a mixing temperature of 136-145℃. Add material I and stir evenly to obtain the mixture.

[0043] S6.4: The mixture is injected into an extruder, extruded through the extruder, and then shaped, drawn, and cut to obtain a PVC substrate;

[0044] S6.5: Apply antibacterial and flame-retardant coating to the surface of PVC substrate, with a coating thickness of 3-5mm, and dry at 40-60℃ to obtain PVC board.

[0045] Further, in step S6.1, the lubricant is any one of microcrystalline wax, oxidized polyethylene wax, or fatty acid complex ester.

[0046] Further, in step S6.1, the plasticizer is any one or a combination of at least two of diisononyl phthalate, dioctyl adipate, or octyl sebacate.

[0047] Furthermore, in step S6.4, the mold forming temperature is 178-183℃, the temperature of the first section of the extrusion barrel is 142-148℃, the temperature of the second section of the extrusion barrel is 144-152℃, the temperature of the third section of the extrusion barrel is 150-158℃, and the temperature of the fourth section of the extrusion barrel is 156-160℃.

[0048] Compared with the prior art, the present invention has at least the following beneficial effects:

[0049] 1. This invention enhances the antibacterial properties of xylan by nano-sizing it. Nano-xylan interferes with bacterial cell membranes, cell walls, enzymes, and metabolic processes, thus exerting an antibacterial effect. Furthermore, the numerous hydroxyl groups and other functional groups on the surface of nano-xylan have adsorption properties, adsorbing and immobilizing bacteria and reducing their activity. Simultaneously, modified nano-titanium dioxide utilizes visible light to generate electron-hole pairs. These pairs rapidly migrate to the material surface and react with water molecules and oxygen to generate highly reactive oxygen species. These reactive oxygen species can directly attack bacterial cell membranes, proteins, nucleic acids, and other biomolecules, leading to membrane structure damage, enzyme inactivation, and DNA damage, thereby killing bacteria. The added modified nano-titanium dioxide and nano-xylan produce a synergistic antibacterial effect. Simultaneously, nano-xylan ensures uniform dispersion of the modified nano-titanium dioxide, giving the PVC board excellent antibacterial properties.

[0050] 2. This invention prepares synthetic antibacterial hollow microsphere carriers. By loading nano-xylan and modified nano-titanium dioxide into the internal space and surface of the microspheres, the nano-xylan and modified nano-titanium dioxide can be slowly released, thereby achieving a long-lasting and effective antibacterial effect. By loading nano-xylan and modified nano-titanium dioxide onto the antibacterial hollow microsphere carriers, the combined antibacterial effect can be enhanced. Furthermore, the hollow microsphere carriers can increase the loading rate of nano-xylan and modified nano-titanium dioxide, thus prolonging the antibacterial effect.

[0051] 3. This invention addresses the problems of large band gap, easy recombination of electron-hole pairs, and low utilization efficiency of visible light in nano-titanium dioxide by modifying it. By introducing silver ions and sodium silicate to modify nano-titanium dioxide, the problem of low utilization efficiency of visible light in nano-titanium dioxide can be effectively solved, greatly improving its antibacterial ability, thereby enhancing the antibacterial ability of PVC boards.

[0052] 4. The ethylene-vinyl acetate copolymer emulsion and vinylidene chloride emulsion in the coating of this invention enhance the adhesion of the coating and have a certain fire resistance. They foam rapidly at high temperatures. The added flame retardant can slow down the thermal decomposition rate of PVC sheets during combustion. The char residue after combustion is continuous and dense, which can coat the surface of the PVC sheet, prevent air from entering, and effectively hinder heat conduction, thus playing a good flame retardant role and inhibiting the decomposition of PVC sheets, thereby improving the flame retardant performance of PVC sheets.

[0053] 5. In the process of preparing PVC sheets, this invention incorporates a phosphaphenanthrene triazine compound. The molecular structure of the phosphaphenanthrene triazine compound contains phosphaphenanthrene and triazine flame-retardant groups, which exert a synergistic flame-retardant effect during combustion. At the same time, the added boron nitride can have a certain synergistic effect with the phosphaphenanthrene triazine compound in the condensed phase, promoting the formation of a char layer and thus inhibiting the combustion intensity of the PVC sheet. Boron nitride can not only serve as a thermally conductive filler, but also work with the phosphaphenanthrene triazine compound to exert excellent synergistic flame-retardant properties during combustion, thereby further improving the flame-retardant performance of the PVC sheet. Attached Figure Description

[0054] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate embodiments of the present disclosure and, together with the specification, further serve to explain the principles of the present disclosure and enable those skilled in the art to implement and use the present disclosure.

[0055] Figure 1 This is a flowchart illustrating the preparation method of flame-retardant and antibacterial composite panels based on PVC material used in embodiments of the present invention. Detailed Implementation

[0056] The following describes in detail, with reference to the accompanying drawings and specific embodiments, a fungicide for controlling leaf and fruit diseases and its preparation method provided by the present invention. It should be noted that, to make the embodiments more detailed, the following embodiments are the best and preferred embodiments; those skilled in the art can also use other alternative methods to implement some known technologies; and the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0057] Example 1

[0058] A method for preparing a flame-retardant and antibacterial composite board based on PVC material, such as... Figure 1 As shown, it includes the following steps:

[0059] S1: Preparation of nano-xylan powder

[0060] S1.1: Weigh 3 parts by weight of sorbitol and 3 parts by weight of citric acid, and dissolve them in 5 parts by weight of distilled water to obtain sorbitol solution and citric acid solution respectively. Mix 25 parts by weight of xylose with the above sorbitol solution and heat to 80°C. Stir mechanically at 20 r / min. Slowly add the above citric acid solution during the heating process. Continue heating for 20 min and then raise the temperature to 160°C. React for 1 h. After the reaction, cool to obtain xylooligosaccharide reactant.

[0061] S1.2: Weigh 2 parts by weight of xylooligosaccharide reactant, add 200 parts by weight of sodium hydroxide solution, heat to 40°C to dissolve it, react for 30 min and then cool to room temperature, add diluted sulfuric acid to adjust the pH to 5.5, then add 3 times the volume of 95% ethanol for alcohol precipitation, and precipitate for 20 h to obtain alcohol precipitate.

[0062] S1.3: The alcohol precipitate was filtered to obtain a precipitate. The precipitate was washed twice with distilled water. The washed precipitate was then added to twice the amount of distilled water and centrifuged at 6000 r / min for 2 min. The centrifugation was repeated twice. After centrifugation, the precipitate was filtered to obtain a filter residue.

[0063] S1.4: Pre-freeze the filter residue in a refrigerator for 1 hour, then dry the pre-frozen filter residue in a vacuum freeze dryer for 20 hours, grind and pulverize it to obtain nano xylan powder;

[0064] S2: Preparation of Modified Nano-Titanium Dioxide

[0065] S2.1: Take 1 part by weight of nano titanium dioxide and add 30 parts by weight of deionized water, sonicate for 5 min, add 0.5 parts by weight of silver nitrate, stir at room temperature in the dark for 2 h, and then add 0.2 parts by weight of sodium silicate to obtain a mixed solution;

[0066] S2.2: The mixed solution was refluxed at 60℃ for 1 h. The refluxed solution was centrifuged to obtain a precipitate. The precipitate was washed with deionized water and then dried to obtain modified nano titanium dioxide.

[0067] S3: Preparation of compound antibacterial agents

[0068] S3.1: Mix 2 parts by weight of 0.025 mmol / L 2-methylimidazole and 2 parts by weight of 0.025 mmol / L zinc nitrate hexahydrate methanol solution and stir for 5 min. After standing for 45 min, centrifuge at 6000 r / min to obtain a precipitate. Wash the precipitate with methanol and dry it to obtain powder crystals. Add 2 parts by weight of powder crystals to 5 parts by weight of methanol and disperse evenly to obtain a dispersion.

[0069] S3.2: Mix 0.25 mol / L dopamine hydrochloride methanol solution with dispersion evenly, heat in a water bath at 50℃ for 3 h to obtain reactant, centrifuge reactant at 6000 r / min to obtain reaction precipitate, wash reaction precipitate with methanol and dry to obtain antibacterial hollow microsphere carrier;

[0070] S3.3: Disperse 1 part by weight of nano xylan powder in 2 parts by weight of deionized water to obtain a nano xylan solution, add 0.5 parts by weight of modified nano titanium dioxide, and ultrasonically disperse for 15 min to obtain a composite antibacterial dispersion;

[0071] S3.4: Add 3 parts by weight of antibacterial hollow microsphere carrier to 8 parts by weight of composite antibacterial dispersion, ultrasonically disperse for 20 min, let stand for 20 h, and centrifuge at high speed to obtain centrifuged precipitate, which is the composite antibacterial agent;

[0072] S4: Preparation of flame retardants

[0073] S4.1: Dissolve 3 parts by weight of L-arginine in 4 parts by weight of deionized water, add acetic acid to adjust the pH to neutral, and obtain an L-arginine solution. Disperse 2 parts by weight of potato starch in 5 parts by weight of deionized water to obtain a starch dispersion.

[0074] S4.2: Add 3 parts by weight of phytic acid solution and 2 parts by weight of sodium carbonate solution to the above starch dispersion, adjust the pH to 8, and then heat to 75°C and mechanically stir for 1 hour to obtain the reactant;

[0075] S4.3: Mix the reactants with the above L-arginine solution to obtain a mixture. Place the mixture in a hydrothermal reactor and hydrothermally react at 110°C for 4 hours. After the reaction is completed, obtain the reaction product. Filter, dry and pulverize the reaction product to obtain the flame retardant.

[0076] S5: Preparation of antibacterial and flame-retardant coatings

[0077] S5.1: Mix 5 parts by weight of flame retardant, 7 parts by weight of composite antibacterial agent, 4 parts by weight of aluminum silicate fiber, 8 parts by weight of titanium dioxide, 3 parts by weight of kaolin, 5 parts by weight of talc, 1 part by weight of polyethylene glycol, and 30 parts by weight of deionized water evenly to obtain a mixture.

[0078] S5.2: Place the mixture into a grinding and mixing machine and grind and disperse it at 400 r / min for 10 min, then grind and disperse it at 1000 r / min for 5 min, and finally grind and disperse it at 500 r / min for 5 min. Add 10 parts by weight of ethylene-vinyl acetate copolymer emulsion and 5 parts by weight of vinylidene chloride emulsion, and continue stirring for 10 min to obtain an antibacterial and flame-retardant coating for later use.

[0079] S6: Preparation of PVC sheets

[0080] S6.1: Prepare raw materials by weight ratio: 80 parts PVC resin, 5 parts acrylic acid-maleic anhydride copolymer, 10 parts kaolin, 5 parts mica powder, 7 parts polyester fiber, 0.5 parts stearic acid, 10 parts activated calcium carbonate, 3 parts boron nitride, 1 part calcium zinc stabilizer, 2 parts phosphaphenanthrene triazine compound, 1 part oxidized polyethylene wax and 1 part diisononyl phthalate;

[0081] S6.2: Mix the above-mentioned mica powder, polyester fiber, clay, stearic acid, activated calcium carbonate, boron nitride, and phosphorus triazine compound at 82°C and stir evenly to obtain material I;

[0082] S6.3: Mix the above PVC resin, acrylic-maleic anhydride copolymer, calcium-zinc stabilizer, plasticizer and lubricant, and mix them in a mixer for 8 minutes at a mixing temperature of 136°C. Add material I and stir evenly to obtain a mixture.

[0083] S6.4: The mixture is injected into the extruder, extruded through the extruder, and then PVC substrate is obtained through die forming, traction and cutting processes. The die forming temperature is 178℃, the temperature of the first section of the extrusion barrel is 142℃, the temperature of the second section of the extrusion barrel is 144℃, the temperature of the third section of the extrusion barrel is 150℃, and the temperature of the fourth section of the extrusion barrel is 156℃.

[0084] S6.5: Apply antibacterial and flame-retardant coating to the surface of PVC substrate with a coating thickness of 3mm, and dry at 40℃ to obtain PVC board.

[0085] Example 2

[0086] A method for preparing a flame-retardant and antibacterial composite board based on PVC material, such as... Figure 1 As shown, it includes the following steps:

[0087] S1: Preparation of nano-xylan powder

[0088] S1.1: Weigh 5 parts by weight of sorbitol and 5 parts by weight of citric acid, and dissolve them in 8 parts by weight of distilled water to obtain sorbitol solution and citric acid solution respectively. Mix 30 parts by weight of xylose with the above sorbitol solution and heat to 80°C. Stir mechanically at 20 r / min. Slowly add the above citric acid solution during the heating process. Continue heating for 20 min and then raise the temperature to 160°C. React for 1 h. After the reaction, cool to obtain xylooligosaccharide reactant.

[0089] S1.2: Weigh 5 parts by weight of xylooligosaccharide reactant, add 230 parts by weight of sodium hydroxide solution, heat to 40°C to dissolve it, react for 30 min and then cool to room temperature, add diluted sulfuric acid to adjust the pH to 5.5, then add 4 times the volume of 95% ethanol for alcohol precipitation, and precipitate for 20 h to obtain alcohol precipitate.

[0090] S1.3: The alcohol precipitate was filtered to obtain a precipitate. The precipitate was washed twice with distilled water. The washed precipitate was then added to 3 times the amount of distilled water and centrifuged at 6000 r / min for 2 min. The centrifugation was repeated twice. After centrifugation, the precipitate was filtered to obtain a filter residue.

[0091] S1.4: Pre-freeze the filter residue in a refrigerator for 1 hour, then dry the pre-frozen filter residue in a vacuum freeze dryer for 20 hours, grind and pulverize it to obtain nano xylan powder;

[0092] S2: Preparation of Modified Nano-Titanium Dioxide

[0093] S2.1: Take 2 parts by weight of nano titanium dioxide and add 40 parts by weight of deionized water, sonicate for 5 min, add 1 part by weight of silver nitrate, stir at room temperature in the dark for 2 h, and then add 0.3 parts by weight of sodium silicate to obtain a mixed solution;

[0094] S2.2: The mixed solution was refluxed at 60℃ for 1 h. The refluxed solution was centrifuged to obtain a precipitate. The precipitate was washed with deionized water and then dried to obtain modified nano titanium dioxide.

[0095] S3: Preparation of compound antibacterial agents

[0096] S3.1: Mix 5 parts by weight of 0.025 mmol / L 2-methylimidazole and 5 parts by weight of 0.025 mmol / L zinc nitrate hexahydrate methanol solution, stir for 5 min, let stand for 45 min, and centrifuge at 6000 r / min to obtain precipitate. Wash the precipitate with methanol and dry to obtain powder crystals. Add 3 parts by weight of powder crystals to 8 parts by weight of methanol and disperse evenly to obtain dispersion.

[0097] S3.2: Mix 0.25 mol / L dopamine hydrochloride methanol solution with dispersion evenly, heat in a water bath at 50℃ for 3 h to obtain reactant, centrifuge reactant at 6000 r / min to obtain reaction precipitate, wash reaction precipitate with methanol and dry to obtain antibacterial hollow microsphere carrier;

[0098] S3.3: Disperse 2 parts by weight of nano xylan powder in 3 parts by weight of deionized water to obtain nano xylan solution, add 1 part by weight of modified nano titanium dioxide, and ultrasonically disperse for 15 min to obtain composite antibacterial dispersion;

[0099] S3.4: Add 5 parts by weight of antibacterial hollow microsphere carrier to 10 parts by weight of composite antibacterial dispersion, sonicate for 20 min, let stand for 20 h, and centrifuge at high speed to obtain centrifuged precipitate, which is the composite antibacterial agent;

[0100] S4: Preparation of flame retardants

[0101] S4.1: Dissolve 5 parts by weight of L-arginine in 8 parts by weight of deionized water, add acetic acid to adjust the pH to neutral, and obtain an L-arginine solution. Disperse 3 parts by weight of potato starch in 8 parts by weight of deionized water to obtain a starch dispersion.

[0102] S4.2: Add 5 parts by weight of phytic acid solution and 3 parts by weight of sodium carbonate solution to the above starch dispersion, adjust the pH to 8, and then heat to 75°C and mechanically stir for 1 hour to obtain the reactant;

[0103] S4.3: Mix the reactants with the above L-arginine solution to obtain a mixture. Place the mixture in a hydrothermal reactor and hydrothermally react at 110°C for 4 hours. After the reaction is completed, obtain the reaction product. Filter, dry and pulverize the reaction product to obtain the flame retardant.

[0104] S5: Preparation of antibacterial and flame-retardant coatings

[0105] S5.1: Mix 7 parts by weight of flame retardant, 10 parts by weight of composite antibacterial agent, 5 parts by weight of aluminum silicate fiber, 9 parts by weight of titanium dioxide, 5 parts by weight of kaolin, 8 parts by weight of talc, 2 parts by weight of polyethylene glycol, and 50 parts by weight of deionized water evenly to obtain a mixture.

[0106] S5.2: Place the mixture into a grinding and mixing machine and grind and disperse it at 400 r / min for 10 min, then grind and disperse it at 1000 r / min for 5 min, and finally grind and disperse it at 500 r / min for 5 min. Add 15 parts by weight of ethylene-vinyl acetate copolymer emulsion and 10 parts by weight of vinylidene chloride emulsion, and continue stirring for 10 min to obtain an antibacterial and flame-retardant coating for later use.

[0107] S6: Preparation of PVC sheets

[0108] S6.1: Prepare raw materials by weight ratio: 100 parts PVC resin, 8 parts acrylic acid-maleic anhydride copolymer, 15 parts kaolin, 8 parts mica powder, 8 parts polyester fiber, 1 part stearic acid, 15 parts activated calcium carbonate, 5 parts boron nitride, 2 parts calcium zinc stabilizer, 3 parts phosphaphenanthrene triazine compound, 2 parts oxidized polyethylene wax and 2 parts diisononyl phthalate;

[0109] S6.2: Mix the above-mentioned mica powder, polyester fiber, clay, stearic acid, activated calcium carbonate, boron nitride, and phosphorus triazine compound at 82°C and stir evenly to obtain material I;

[0110] S6.3: Mix the above PVC resin, acrylic-maleic anhydride copolymer, calcium-zinc stabilizer, plasticizer and lubricant, and mix them in a mixer for 8 minutes at a mixing temperature of 136°C. Add material I and stir evenly to obtain a mixture.

[0111] S6.4: The mixture is injected into the extruder, extruded through the extruder, and then PVC substrate is obtained through die forming, traction and cutting processes. The die forming temperature is 178℃, the temperature of the first section of the extrusion barrel is 142℃, the temperature of the second section of the extrusion barrel is 144℃, the temperature of the third section of the extrusion barrel is 150℃, and the temperature of the fourth section of the extrusion barrel is 156℃.

[0112] S6.5: Apply antibacterial and flame-retardant coating to the surface of PVC substrate with a coating thickness of 3mm, and dry at 40℃ to obtain PVC board.

[0113] Example 3

[0114] A method for preparing a flame-retardant and antibacterial composite board based on PVC material, such as... Figure 1 As shown, it includes the following steps:

[0115] S1: Preparation of nano-xylan powder

[0116] S1.1: Weigh 3 parts by weight of sorbitol and 3 parts by weight of citric acid, and dissolve them in 5 parts by weight of distilled water to obtain sorbitol solution and citric acid solution respectively. Mix 25 parts by weight of xylose with the above sorbitol solution and heat to 90°C. Stir mechanically at 30 r / min. Slowly add the above citric acid solution during the heating process. Continue heating for 30 min and then raise the temperature to 170°C. React for 2 h. After the reaction, cool to obtain xylooligosaccharide reactant.

[0117] S1.2: Weigh 2 parts by weight of xylooligosaccharide reactant, add 200 parts by weight of sodium hydroxide solution, heat to 50°C to dissolve it, react for 40 min and then cool to room temperature, add diluted sulfuric acid to adjust the pH to 5.6, then add 3 times the volume of 95% ethanol for alcohol precipitation, and precipitate for 24 h to obtain alcohol precipitate.

[0118] S1.3: The alcohol precipitate was filtered to obtain a precipitate. The precipitate was washed three times with distilled water. The washed precipitate was then added to twice the amount of distilled water and centrifuged at 7000 r / min for 3 min. The centrifugation was repeated three times. After centrifugation, the precipitate was filtered to obtain a filter residue.

[0119] S1.4: Pre-freeze the filter residue in a refrigerator for 2 hours, then dry the pre-frozen filter residue in a vacuum freeze dryer for 24 hours, grind and pulverize it to obtain nano xylan powder;

[0120] S2: Preparation of Modified Nano-Titanium Dioxide

[0121] S2.1: Take 1 part by weight of nano titanium dioxide and add it to 30 parts by weight of deionized water. Disperse it by ultrasonication for 8 min, add 0.5 parts by weight of silver nitrate, stir it in the dark at room temperature for 3 h, and then add 0.2 parts by weight of sodium silicate to obtain a mixed solution.

[0122] S2.2: The mixed solution was refluxed at 70℃ for 2 hours. The refluxed solution was centrifuged to obtain a precipitate. The precipitate was washed with deionized water and then dried to obtain modified nano titanium dioxide.

[0123] S3: Preparation of compound antibacterial agents

[0124] S3.1: Mix 2 parts by weight of 0.025 mmol / L 2-methylimidazole and 2 parts by weight of 0.025 mmol / L zinc nitrate hexahydrate methanol solution and stir for 8 min. After standing for 50 min, centrifuge at 7000 r / min to obtain a precipitate. Wash the precipitate with methanol and dry it to obtain powder crystals. Add 2 parts by weight of powder crystals to 5 parts by weight of methanol and disperse evenly to obtain a dispersion.

[0125] S3.2: Mix 0.25 mol / L dopamine hydrochloride methanol solution with dispersion evenly, heat in a water bath at 60℃ for 4 h to obtain reactant, centrifuge reactant at 7000 r / min to obtain reaction precipitate, wash reaction precipitate with methanol and dry to obtain antibacterial hollow microsphere carrier;

[0126] S3.3: Disperse 1 part by weight of nano xylan powder in 2 parts by weight of deionized water to obtain a nano xylan solution, add 0.5 parts by weight of modified nano titanium dioxide, and ultrasonically disperse for 20 min to obtain a composite antibacterial dispersion;

[0127] S3.4: Add 3 parts by weight of antibacterial hollow microsphere carrier to 8 parts by weight of composite antibacterial dispersion, sonicate for 30 min, let stand for 24 h, and centrifuge at high speed to obtain centrifuged precipitate, which is the composite antibacterial agent;

[0128] S4: Preparation of flame retardants

[0129] S4.1: Dissolve 3 parts by weight of L-arginine in 4 parts by weight of deionized water, add acetic acid to adjust the pH to neutral, and obtain an L-arginine solution. Disperse 2 parts by weight of potato starch in 5 parts by weight of deionized water to obtain a starch dispersion.

[0130] S4.2: Add 3 parts by weight of phytic acid solution and 2 parts by weight of sodium carbonate solution to the above starch dispersion, adjust the pH to 9, and then heat to 80°C and mechanically stir for 2 hours to obtain the reactant;

[0131] S4.3: Mix the reactants with the above L-arginine solution to obtain a mixture. Place the mixture in a hydrothermal reactor and hydrothermally react at 120°C for 5 hours. After the reaction is completed, obtain the reaction product. Filter, dry and pulverize the reaction product to obtain the flame retardant.

[0132] S5: Preparation of antibacterial and flame-retardant coatings

[0133] S5.1: Mix 5 parts by weight of flame retardant, 7 parts by weight of composite antibacterial agent, 4 parts by weight of aluminum silicate fiber, 8 parts by weight of titanium dioxide, 3 parts by weight of kaolin, 5 parts by weight of talc, 1 part by weight of polyethylene glycol, and 30 parts by weight of deionized water evenly to obtain a mixture.

[0134] S5.2: Place the mixture into a grinding and mixing machine and grind and disperse it at 500 r / min for 20 min, then grind and disperse it at 1200 r / min for 8 min, and finally grind and disperse it at 600 r / min for 8 min. Add 10 parts by weight of ethylene-vinyl acetate copolymer emulsion and 5 parts by weight of vinylidene chloride emulsion, and continue stirring for 15 min to obtain an antibacterial and flame-retardant coating for later use.

[0135] S6: Preparation of PVC sheets

[0136] S6.1: Prepare raw materials by weight ratio: 80 parts PVC resin, 5 parts acrylic acid-maleic anhydride copolymer, 10 parts kaolin, 5 parts mica powder, 7 parts polyester fiber, 0.5 parts stearic acid, 10 parts activated calcium carbonate, 3 parts boron nitride, 1 part calcium zinc stabilizer, 2 parts phosphaphenanthrene triazine compound, 1 part oxidized polyethylene wax and 1 part diisononyl phthalate;

[0137] S6.2: Mix the above-mentioned mica powder, polyester fiber, clay, stearic acid, activated calcium carbonate, boron nitride, and phosphorus triazine compound at 86°C and stir evenly to obtain material I;

[0138] S6.3: Mix the above PVC resin, acrylic-maleic anhydride copolymer, calcium-zinc stabilizer, plasticizer and lubricant, and mix them in a mixer for 12 minutes at a mixing temperature of 145°C. Add material I and stir evenly to obtain a mixture.

[0139] S6.4: The mixture is injected into the extruder, extruded through the extruder, and then PVC substrate is obtained through die forming, traction and cutting processes. The die forming temperature is 183℃, the temperature of the first section of the extrusion barrel is 148℃, the temperature of the second section of the extrusion barrel is 152℃, the temperature of the third section of the extrusion barrel is 158℃, and the temperature of the fourth section of the extrusion barrel is 160℃.

[0140] S6.5: Apply antibacterial and flame-retardant coating to the surface of PVC substrate with a coating thickness of 5mm, and dry at 60℃ to obtain PVC board.

[0141] Comparative Example 1

[0142] Compared with Example 1, the difference of Comparative Example 1 is that step S2 is removed, and the modified nano titanium dioxide in step S3.3 is replaced with an equal mass of nano titanium dioxide, while the remaining steps remain unchanged to prepare PVC sheets. This is referred to as Comparative Example 1.

[0143] Comparative Example 2

[0144] Compared with Example 1, Comparative Example 2 differs in that the modified nano-titanium dioxide in steps S2 and S3.3 is removed, while the remaining steps remain unchanged to prepare PVC sheets, and this is referred to as Comparative Example 2.

[0145] Comparative Example 3

[0146] Compared with Example 1, Comparative Example 3 differs in that the nano-xylan solution in steps S1 and S3.3 is removed, while the remaining steps remain unchanged to prepare PVC boards, and this is referred to as Comparative Example 3.

[0147] Comparative Example 4

[0148] Compared with Example 1, Comparative Example 4 differs in that steps S1, S2 and S3.3-S3.4 are removed in Comparative Example 4, the composite antibacterial agent in step S5.1 is replaced with an equal mass of the antibacterial hollow microsphere carrier in step S3.2, and the remaining steps are unchanged in the preparation of PVC board, which is referred to as Comparative Example 4.

[0149] 24-hour antibacterial rate determination:

[0150] The PVC sheets prepared in Examples 1-3 and Comparative Examples 1-4 were tested for 24-hour antibacterial rate according to GB / T21510-2008 "Test Method for Antibacterial Properties of Nano-Inorganic Materials". The test results are shown in Table 1.

[0151] Table 1. Antibacterial performance test results of Examples 1-3 and Comparative Examples 1-4

[0152] Example 1 99.69 Example 2 99.78 Example 3 99.72 Comparative Example 1 95.45 Comparative Example 2 94.14 Comparative Example 3 93.94 Comparative Example 4 82.48

[0153] As can be seen from the data in Table 1, the antibacterial rate of Comparative Example 1 is lower than that of Example 1, indicating that the modified nano-titanium dioxide has increased its antibacterial ability. The data of Comparative Examples 2-4 show that the added modified nano-titanium dioxide and nano-xylan can produce a synergistic antibacterial effect. Compared with the addition of a single component, the antibacterial performance of the two used at the same time is better, thereby effectively improving the antibacterial performance of PVC sheets.

[0154] Comparative Example 5

[0155] Compared with Example 1, Comparative Example 5 differs in that steps S3.1, S3.2 and S3.4 are removed, the composite antibacterial agent in step S5.1 is replaced with an equal mass of the antibacterial dispersion in step S3.3, and the remaining steps are unchanged in the preparation of PVC boards, which is referred to as Comparative Example 5.

[0156] Comparative Example 6

[0157] Compared with Example 1, Comparative Example 6 differs in that steps S3.1-S3.2 are removed, and the antibacterial hollow microsphere carrier in step S3.4 is replaced with an equal mass of antibacterial solid microsphere carrier synthesized by prior art. The remaining steps are unchanged in the preparation of PVC sheets, and this is referred to as Comparative Example 6.

[0158] The antibacterial rates of the PVC sheets prepared in Examples 1-3 and Comparative Examples 5-6 were determined according to GB / T21510-2008 "Test Method for Antibacterial Properties of Nano-Inorganic Materials" at 24h and 7d. The test results are shown in Table 2.

[0159] Table 2. Antibacterial rate determination results of Examples 1-3 and Comparative Examples 5-6 at 24h and 7d

[0160] Example 1 99.69 98.84 Example 2 99.78 98.75 Example 3 99.72 98.45 Comparative Example 5 98.24 90.87 Comparative Example 6 99.68 93.34

[0161] As can be seen from the data in Table 2, the antibacterial effect can be prolonged by loading modified nano-titanium dioxide and nano-xylan onto antibacterial hollow microspheres, achieving a long-lasting antibacterial effect. Furthermore, by preparing hollow microspheres, the loading of modified nano-titanium dioxide and nano-xylan can be increased. The higher the loading of modified nano-titanium dioxide and nano-xylan, the better the long-lasting antibacterial effect is achieved, thereby further improving the long-lasting antibacterial effect.

[0162] Comparative Example 7

[0163] Compared with Example 1, Comparative Example 7 differs in that the flame retardant in steps S4 and S5.1 is removed in Comparative Example 7, while the remaining steps remain unchanged in preparing PVC sheets. This is referred to as Comparative Example 7.

[0164] Comparative Example 8

[0165] Compared with Example 1, Comparative Example 8 differs in that boron nitride in step S6.1 is removed in Comparative Example 8, while the remaining steps remain unchanged in preparing PVC sheets, and is referred to as Comparative Example 8.

[0166] Comparative Example 9

[0167] Compared with Example 1, Comparative Example 9 differs in that Comparative Example 9 involves removing the phosphenanthrene triazine compound in step S6.1 while keeping the other steps unchanged in preparing PVC sheets, and is referred to as Comparative Example 9.

[0168] Comparative Example 10

[0169] Compared with Example 1, Comparative Example 10 differs in that Comparative Example 10 involves removing the phosphenanthrene triazine compound and boron nitride in step S6.1, while the remaining steps remain unchanged to prepare PVC sheets, and is referred to as Comparative Example 10.

[0170] The PVC sheets prepared in Examples 1-3 and Comparative Examples 7-10 were tested for their limiting oxygen index according to GB / T2406-1993 "Test Method for Burning Performance of Plastics - Oxygen Index Method". The test results are shown in Table 3.

[0171] Table 3. Limiting oxygen index determination results of Examples 1-3 and Comparative Examples 7-10

[0172] Example 1 39 Example 2 38 Example 3 38 Comparative Example 7 29 Comparative Example 8 35 Comparative Example 9 32 Comparative Example 10 30

[0173] The data in Table 3 show that the addition of flame retardants effectively improves the flame retardant properties of PVC sheets. Furthermore, the phosphaphenanthrene triazine compound and boron nitride exhibit excellent synergistic flame retardant properties during combustion, further enhancing the flame retardant performance of PVC sheets. Data from Comparative Examples 7 and 10 indicate that the flame retardant performance of adding a single flame retardant or phosphaphenanthrene triazine compound and boron nitride is not as good as that of adding the flame retardant along with these compounds simultaneously. The phosphaphenanthrene triazine compound and boron nitride promote the formation of a char layer during the combustion process of the flame retardant. Moreover, the char layer produced by the phosphaphenanthrene triazine compound and boron nitride complements the char layer produced during the combustion process of the flame retardant, resulting in a more continuous and dense char layer. The synergistic effect between the flame retardant and the phosphaphenanthrene triazine compound and boron nitride further improves the flame retardant performance of PVC sheets.

[0174] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing a flame-retardant and antibacterial composite board based on PVC material, characterized in that, Includes the following steps: S1: Preparation of nano-xylan powder Xylooligosaccharide reactants were prepared by sorbitol, citric acid and xylose. After alcohol precipitation, filtration, centrifugation and washing, nano-xylan powder was obtained from the xylooligosaccharide reactants. S2: Preparation of Modified Nano-Titanium Dioxide Modified nano-titanium dioxide was obtained by modifying nano-titanium dioxide with silver nitrate and sodium silicate. S3: Preparation of compound antibacterial agents Antibacterial hollow microsphere carriers were prepared by using dopamine hydrochloride methanol solution, and composite antibacterial agents were prepared by loading nano-xylan powder and modified nano-titanium dioxide onto the antibacterial hollow microsphere carriers. S4: Preparation of flame retardants Flame retardants were prepared using L-arginine, potato starch, phytic acid solution, and sodium carbonate solution as raw materials. S5: Preparation of antibacterial and flame-retardant coatings An antibacterial and flame-retardant coating is obtained by mixing and stirring flame retardant, composite antibacterial agent, aluminum silicate fiber, titanium dioxide, kaolin, talc, polyethylene glycol, deionized water, ethylene-vinyl acetate copolymer emulsion and vinylidene chloride emulsion. S6: Preparation of PVC sheets Prepare the following raw materials by weight: 80-100 parts PVC resin, 5-8 parts acrylic-maleic anhydride copolymer, 10-15 parts kaolin, 5-8 parts mica powder, 7-8 parts polyester fiber, 0.5-1 part stearic acid, 10-15 parts activated calcium carbonate, 3-5 parts boron nitride, 1-2 parts calcium-zinc stabilizer, 2-3 parts phosphorophenanthrene triazine compound, 1-2 parts lubricant, and 1-2 parts plasticizer. Prepare a PVC substrate using the above raw materials, and then coat the PVC substrate with an antibacterial and flame-retardant coating to obtain a PVC sheet.

2. The method for preparing a flame-retardant and antibacterial composite board based on PVC material according to claim 1, Its features are, Step S1, the preparation of nano-xylan powder, specifically includes the following steps: S1.1: Weigh 3-5 parts by weight of sorbitol and 3-5 parts by weight of citric acid, and dissolve them in 5-8 parts by weight of distilled water to obtain sorbitol solution and citric acid solution. Mix 25-30 parts by weight of xylose with the above sorbitol solution and heat to 80-90℃. Stir mechanically at 20-30 r / min. Slowly add the above citric acid solution during the heating process. Continue heating for 20-30 min and then raise the temperature to 160-170℃. React for 1-2 h. Cool after the reaction to obtain xylooligosaccharide reactant. S1.2: Weigh 2-5 parts by weight of xylooligosaccharide reactant, add 200-230 parts by weight of sodium hydroxide solution, heat to 40-50℃ to dissolve it, react for 30-40 min, then cool to room temperature, add diluted sulfuric acid to adjust pH to 5.5-5.6, then add 3-4 times the volume of 95% ethanol for alcohol precipitation, precipitate for 20-24 h to obtain alcohol precipitate; S1.3: Filter the alcohol precipitate to obtain a precipitate. Wash the precipitate with distilled water 2-3 times. Add 2-3 times the amount of distilled water to the washed precipitate and centrifuge at 6000-7000 r / min for 2-3 min. Repeat the centrifugation 2-3 times. After centrifugation, filter to obtain filter residue. S1.4: Pre-freeze the filter residue in a refrigerator for 1-2 hours, then dry the pre-frozen filter residue in a vacuum freeze dryer for 20-24 hours, grind and pulverize it to obtain nano xylan powder.

3. The method for preparing a flame-retardant and antibacterial composite board based on PVC material according to claim 2, characterized in that, The preparation of modified nano-titanium dioxide in step S2 specifically includes the following steps: S2.1: Take 1-2 parts by weight of nano titanium dioxide and add 30-40 parts by weight of deionized water, sonicate for 5-8 minutes, add 0.5-1 parts by weight of silver nitrate, stir at room temperature in the dark for 2-3 hours, and then add 0.2-0.3 parts by weight of sodium silicate to obtain a mixed solution; S2.2: Reflux the mixed solution at 60-70℃ for 1-2 hours, centrifuge the refluxed solution to obtain a precipitate, wash the precipitate with deionized water and dry it to obtain modified nano titanium dioxide.

4. The method for preparing a flame-retardant and antibacterial composite board based on PVC material according to claim 3, characterized in that, The preparation of the composite antibacterial agent in step S3 specifically includes the following steps: S3.1: Mix 2-5 parts by weight of 0.025 mmol / L 2-methylimidazole and 2-5 parts by weight of 0.025 mmol / L zinc nitrate hexahydrate methanol solution, stir for 5-8 min, let stand for 45-50 min, and then centrifuge at 6000-7000 r / min to obtain a precipitate. Wash the precipitate with methanol and dry it to obtain powder crystals. Add 2-3 parts by weight of powder crystals to 5-8 parts by weight of methanol and disperse evenly to obtain a dispersion. S3.2: Mix the 0.25 mol / L dopamine hydrochloride methanol solution with the dispersion evenly, heat in a water bath at 50-60℃ for 3-4 h to obtain the reactant, centrifuge the reactant at 6000-7000 r / min to obtain the reaction precipitate, wash the reaction precipitate with methanol and dry it to obtain the antibacterial hollow microsphere carrier; S3.3: Disperse 1-2 parts by weight of nano xylan powder in 2-3 parts by weight of deionized water to obtain a nano xylan solution, add 0.5-1 parts by weight of modified nano titanium dioxide, and ultrasonically disperse for 15-20 min to obtain a composite antibacterial dispersion; S3.4: Add 3-5 parts by weight of antibacterial hollow microsphere carrier to 8-10 parts by weight of composite antibacterial dispersion, ultrasonically disperse for 20-30 minutes, let stand for 20-24 hours, and centrifuge at high speed to obtain centrifuged precipitate, which is the composite antibacterial agent.

5. The method for preparing a flame-retardant and antibacterial composite board based on PVC material according to claim 4, characterized in that, The preparation of the flame retardant in step S4 specifically includes the following steps: S4.1: Dissolve 3-5 parts by weight of L-arginine in 4-8 parts by weight of deionized water, add acetic acid to adjust the pH to neutral, and obtain an L-arginine solution. Disperse 2-3 parts by weight of potato starch in 5-8 parts by weight of deionized water to obtain a starch dispersion. S4.2: Add 3-5 parts by weight of phytic acid solution and 2-3 parts by weight of sodium carbonate solution to the above starch dispersion, adjust the pH to 8-9, and then heat to 75-80℃ and mechanically stir for 1-2 hours to obtain the reactant; S4.3: Mix the reactants with the above L-arginine solution to obtain a mixture. Place the mixture in a hydrothermal reactor and hydrothermally react at 110-120℃ for 4-5 hours. After the reaction is completed, obtain the reaction product. Filter, dry and pulverize the reaction product to obtain the flame retardant.

6. The method for preparing a flame-retardant and antibacterial composite board based on PVC material according to claim 5, characterized in that, Step S5, the preparation of the antibacterial and flame-retardant coating, specifically includes the following steps: S5.1: Mix 5-7 parts by weight of flame retardant, 7-10 parts by weight of composite antibacterial agent, 4-5 parts by weight of aluminum silicate fiber, 8-9 parts by weight of titanium dioxide, 3-5 parts by weight of kaolin, 5-8 parts by weight of talc, 1-2 parts by weight of polyethylene glycol, and 30-50 parts by weight of deionized water evenly to obtain a mixture. S5.2: Place the mixture into a grinding and mixing machine and grind and disperse it at 400-500 r / min for 10-20 min, then grind and disperse it at 1000-1200 r / min for 5-8 min, and finally grind and disperse it at 500-600 r / min for 5-8 min. Add 10-15 parts by weight of ethylene-vinyl acetate copolymer emulsion and 5-10 parts by weight of vinylidene chloride emulsion, and continue stirring for 10-15 min to obtain an antibacterial and flame-retardant coating for later use.

7. The method for preparing a flame-retardant and antibacterial composite board based on PVC material according to claim 6, characterized in that, Step S6 involves preparing PVC sheets, specifically including the following steps: S6.1: Prepare raw materials by weight ratio: 80-100 parts by weight of PVC resin, 5-8 parts by weight of acrylic acid-maleic anhydride copolymer, 10-15 parts by weight of clay, 5-8 parts by weight of mica powder, 7-8 parts by weight of polyester fiber, 0.5-1 parts by weight of stearic acid, 10-15 parts by weight of activated calcium carbonate, 3-5 parts by weight of boron nitride, 1-2 parts by weight of calcium zinc stabilizer, 2-3 parts by weight of phosphorus triazine compound, 1-2 parts by weight of lubricant and 1-2 parts by weight of plasticizer; S6.2: Mix the above-mentioned mica powder, polyester fiber, clay, stearic acid, activated calcium carbonate, boron nitride, and phosphorus triazine compound at 82-86℃ and stir evenly to obtain material I; S6.3: Mix the above PVC resin, acrylic acid-maleic anhydride copolymer, calcium zinc stabilizer, plasticizer and lubricant, and mix them in a mixer for 8-12 minutes at a mixing temperature of 136-145℃. Add material I and stir evenly to obtain the mixture. S6.4: The mixture is injected into an extruder, extruded through the extruder, and then shaped, drawn, and cut to obtain a PVC substrate; S6.5: Apply antibacterial and flame-retardant coating to the surface of PVC substrate, with a coating thickness of 3-5mm, and dry at 40-60℃ to obtain PVC board.

8. The method for preparing a flame-retardant and antibacterial composite board based on PVC material according to claim 7, characterized in that, In step S6.1, the lubricant is any one of microcrystalline wax, oxidized polyethylene wax, or fatty acid complex ester.

9. The method for preparing a flame-retardant and antibacterial composite board based on PVC material according to claim 7, characterized in that, In step S6.1, the plasticizer is any one or a combination of at least two of diisononyl phthalate, dioctyl adipate, or octyl sebacate.

10. The method for preparing a flame-retardant and antibacterial composite board based on PVC material according to claim 7, characterized in that, In step S6.4, the mold forming temperature is 178-183℃, the temperature of the first section of the extrusion barrel is 142-148℃, the temperature of the second section of the extrusion barrel is 144-152℃, the temperature of the third section of the extrusion barrel is 150-158℃, and the temperature of the fourth section of the extrusion barrel is 156-160℃.

Images