Environment-friendly formaldehyde-free waterproof and moistureproof stone-plastic composite wallboard and preparation method thereof

Abstract

The invention discloses an environment-friendly formaldehyde-free waterproof and moistureproof stone-plastic composite wallboard and a preparation method thereof, and belongs to the technical field of composite wallboards. The PVC resin, the polypropylene resin, the cross-linked modified nano silicon dioxide, the glass fibers, the dioctyl terephthalate, the zinc borate and other components are subjected to the processes of mixing, extruding machine granulation, mold extrusion molding, cooling shaping, traction cutting and the like to prepare the stone-plastic composite wallboard. The comprehensive advantages of environmental protection, no formaldehyde, water resistance, moisture resistance, excellent mechanical property, high durability and the like are realized. Wherein the cross-linked modified nano silicon dioxide is prepared through a multi-step reaction, firstly, an intermediate containing a cross-linked structure and active sites is constructed through nucleophilic substitution and an ultraviolet light-initiated click reaction, then, the nano silicon dioxide is subjected to alkenylation modification, and finally, organic-inorganic chemical bonding is realized through a secondary click reaction. And through the synergistic effect of the cross-linked modified nano silicon dioxide and the glass fibers, the waterproof and moisture-proof performance, the mechanical property and the durability are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of composite wall panel technology, and particularly relates to an environmentally friendly, formaldehyde-free, waterproof and moisture-proof stone-plastic composite wall panel and its preparation method. Background Technology

[0002] Stone-plastic composite wall panels (SPC) are a new type of decorative panel made from thermoplastic polymers such as polyvinyl chloride resin and polypropylene resin as the matrix, filled with a large amount of inorganic mineral fillers such as calcium carbonate and talc, and various additives, through a high-temperature extrusion molding process. Because they combine the stability of stone with the toughness of plastic, they have become an important material in the field of interior flooring and wall panels in recent years, and are widely used in the decoration of homes, commercial spaces, and public places such as medical and educational institutions. Compared with traditional wood panels, pure plastic panels, or ceramic tiles, conventional stone-plastic wall panels have advantages such as being green and recyclable, easy to install, rich in colors and patterns, and wear- and scratch-resistant. Especially in damp environments such as kitchens, bathrooms, and basements, their waterproof and moisture-proof performance is superior to most traditional materials.

[0003] As consumers' demands for health, environmental protection, and material performance continue to rise, existing stone-plastic composite wall panels are gradually revealing several significant shortcomings. To improve processing fluidity or enhance mechanical properties, some products still use formaldehyde-containing resins or aldehyde-based additives (such as urea-formaldehyde resin), which may lead to excessive formaldehyde emissions, posing a potential threat to indoor air quality and the health of residents, and failing to meet the current market's urgent demand for formaldehyde-free and environmentally friendly building materials. Furthermore, existing ordinary stone-plastic wall panels may still experience decreased dimensional stability, edge warping, and interface delamination under long-term high humidity or immersion environments, indicating room for improvement in their waterproof and moisture-proof capabilities. In addition, the poor compatibility between inorganic fillers and organic resins can easily lead to stress concentration, affecting the overall mechanical properties and durability of the panels, limiting their application in more demanding environments. Therefore, developing a truly formaldehyde-free, highly water-resistant and moisture-proof stone-plastic composite wall panel with excellent mechanical properties is of great significance. Summary of the Invention

[0004] In view of the above situation and to overcome the defects of the prior art, the present invention produces stone-plastic composite wall panels by mixing polyvinyl chloride resin, polypropylene resin, cross-linked modified nano silica, glass fiber, dioctyl terephthalate, zinc borate and other components, followed by extrusion granulation, die extrusion molding, cooling and shaping, and traction cutting. These panels have comprehensive advantages such as being environmentally friendly and formaldehyde-free, waterproof and moisture-proof, having excellent mechanical properties and high durability.

[0005] To achieve the above objectives, the following technical solution is adopted: This invention provides an environmentally friendly, formaldehyde-free, waterproof, and moisture-proof stone-plastic composite wall panel, comprising the following components in parts by weight:

[0006] The composition includes 40-60 parts polyvinyl chloride resin, 10-25 parts polypropylene resin, 3-8 parts cross-linked modified nano silica, 4-10 parts glass fiber, 3-8 parts dioctyl terephthalate, 2-6 parts zinc borate, 2-4.5 parts calcium zinc stabilizer, 0.5-2 parts lubricant, 10-30 parts calcium carbonate, 0.5-1.5 parts titanate coupling agent, and 0.2-0.6 parts antioxidant.

[0007] Furthermore, the cross-linked modified nano-silica is prepared through the following steps:

[0008] S1. Add 4,6-dichloro-N,N-dihexyl-1,3,5-triazine-2-amine, anhydrous potassium carbonate, hydroquinone (polymerization inhibitor), and N,N-dimethylformamide to the reaction vessel, start stirring and heat to 60-70℃, then slowly add N,N-diallylethanolamine, heat to 80-85℃ and react for 4-6 hours. After filtration, vacuum distillation, washing, and vacuum drying, intermediate one is obtained.

[0009] S2. Add intermediate pentaerythritol tetrakis(3-mercaptopropionic acid) ester, toluene, polymerization inhibitor p-hydroxyanisole, and photoinitiator 2,2-dimethoxy-2-phenylacetophenone to the reaction vessel, heat to 40-50℃, and perform photoinitiation at a wavelength of 365nm and an intensity of 15mW / cm. 2 The reaction was carried out under ultraviolet light for 2-3 hours, followed by vacuum distillation, washing with n-hexane, and vacuum drying to obtain intermediate II;

[0010] S3. Add nano-silica, anhydrous ethanol and dispersant polyethylene glycol 400 to the reactor, stir at room temperature for 30-60 min to form a stable suspension, then add 1% hydrochloric acid to adjust the pH of the system to 3-4, then slowly add alkenyl silane coupling agent, react at 60-65℃ for 4-5 h, and obtain alkenylated nano-silica by centrifugation, washing with anhydrous ethanol and vacuum drying.

[0011] S4. Add alkenylated nano-silica, sodium dodecylbenzenesulfonate, and dichloromethane to the reaction vessel. Stir at room temperature for 40-60 minutes to form a stable suspension. Add intermediate di and the photoinitiator 1-hydroxycyclohexylphenyl ketone. After stirring evenly, raise the temperature to 30-40℃, with a wavelength of 365nm and an intensity of 15mW / cm. 2 The reaction was carried out under ultraviolet light for 2-3 hours, followed by filtration, washing, and vacuum drying to obtain cross-linked modified nano-silica.

[0012] Further, in step S1, the feeding ratio of 4,6-dichloro-N,N-dihexyl-1,3,5-triazine-2-amine, N,N-diallylethanolamine, anhydrous potassium carbonate, hydroquinone, and N,N-dimethylformamide is 150g:120-180mL:100-150g:1.2-2.8g:800-1200mL.

[0013] Further, in step S2, the feeding ratio of intermediate I, pentaerythritol tetrakis(3-mercaptopropionic acid), toluene, p-hydroxyanisole, and 2,2-dimethoxy-2-phenylacetophenone is 100g: 200-300mL: 1200-1800mL: 0.6-0.9g: 3.0-4.5g.

[0014] Furthermore, in step S3, the feeding ratio of nano-silica, anhydrous ethanol, polyethylene glycol 400, and alkenyl silane coupling agent is 50g: 400-500mL: 0.5-2mL: 40-60mL.

[0015] Further, in step S4, the feeding ratio of intermediate di, alkenylated nano-silica, sodium dodecylbenzenesulfonate, dichloromethane, and 1-hydroxycyclohexylphenyl ketone is 80g:100g:5.6-8.5g:900-1260mL:2.16-3.24g.

[0016] Furthermore, the alkenylsilane coupling agent is selected from at least one of A-171, A-172, and KH-570.

[0017] Furthermore, the lubricant is selected from at least one of polyethylene wax, butyl stearate, calcium stearate, and zinc stearate.

[0018] Furthermore, the titanate coupling agent is selected from at least one of isopropyl tris(dioctyl pyrophosphate) titanate, isopropyl tris(dioctyl pyrophosphate) titanate, and bis(dioctyl pyrophosphate) ethylene titanate.

[0019] Furthermore, the antioxidant is selected from at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl)phosphite, and octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0020] On the other hand, the present invention also provides a method for preparing an environmentally friendly, formaldehyde-free, waterproof and moisture-proof stone-plastic composite wall panel, comprising the following steps:

[0021] (1) Dry polyvinyl chloride resin and polypropylene resin in an oven at 60-75℃ for 2-3 hours to remove moisture; pass calcium carbonate through a 300-400 mesh sieve and mix it with titanate coupling agent in a high-speed mixer at a speed of 800-1000 r / min at room temperature for 15-20 minutes.

[0022] (2) Add the pretreated resin, calcium carbonate, cross-linked modified nano silica, glass fiber, dioctyl terephthalate, zinc borate, calcium zinc stabilizer, lubricant and antioxidant to a high-speed mixer in sequence. Stir at 1200-1500 r / min for 8-12 min at 100-110℃, then transfer to a twin-screw extruder for granulation. The extrusion temperature is 160-180℃ and the screw speed is 300-400 r / min to obtain composite particles.

[0023] (3) Add the composite particles to a single screw extruder, with an extrusion temperature of 170-190℃ and a screw speed of 250-350r / min. Extrude the material through a die, and then cool and shape it before traction cutting to obtain an environmentally friendly, formaldehyde-free, waterproof and moisture-proof stone-plastic composite wall panel.

[0024] The beneficial effects of this invention are:

[0025] The stone-plastic composite wall panel disclosed in this invention is made from polyvinyl chloride resin, polypropylene resin, cross-linked modified nano silica, glass fiber, dioctyl terephthalate, zinc borate and other components through mixing, extrusion granulation, die extrusion molding, cooling and shaping, traction cutting and other processes. It has comprehensive advantages such as being environmentally friendly and formaldehyde-free, waterproof and moisture-proof, having excellent mechanical properties and high durability.

[0026] This invention significantly improves the compatibility and interfacial bonding of nano-silica with resin matrices through multi-step crosslinking modification. First, a nucleophilic substitution reaction is carried out between the chlorine atom in 4,6-dichloro-N,N-dihexyl-1,3,5-triazine-2-amine and the hydroxyl group in N,N-diallylethanolamine, introducing an allyl double bond into the triazine backbone to form an intermediate that can be further functionalized. Then, a click chemistry reaction is initiated by ultraviolet light between multiple thiol groups in pentaerythritol tetrakis(3-mercaptopropionic acid) and the allyl double bond to construct a reactive polymer with a crosslinked structure and residual thiol groups. This structure not only enhances the rigidity and thermal stability of the molecular chain, but also provides active sites for subsequent reactions with nanoparticles.

[0027] This invention employs an alkenylsilane coupling agent to modify the surface of the nanoparticles with alkenylation, which significantly improves the dispersibility and interfacial compatibility of the nanoparticles in the resin system. Finally, through a secondary click reaction between the remaining mercapto groups in intermediate II and the alkenyl bonds on the surface of the alkenylated nano silica, chemical bonding between the nanoparticles and the organic crosslinking network is achieved, thereby forming a stable organic-inorganic hybrid structure in the composite material. This structure can effectively inhibit the penetration and diffusion of water molecules, while improving the mechanical strength of the material.

[0028] In addition, the triazine ring structure has high chemical stability and hydrophobicity. Triazine compounds are also highly efficient char-forming agents and carbonization catalysts. The triazine structure can promote cross-linking, cyclization and aromatization reactions of the polymer matrix, accelerating the formation of a dense and stable expanded carbon layer. The introduction of hexyl segments further enhances the hydrophobic properties of the system, thereby significantly improving the waterproof and moisture-proof performance of the wall panel. The addition of glass fiber forms a synergistic reinforcing effect with cross-linked modified nano-silica, jointly improving the mechanical properties of the wall panel. Attached Figure Description

[0029] Figure 1 The mass change rate of the composite wall panel samples of the various embodiments and comparative examples of the present invention after immersion in water for 24 hours;

[0030] Figure 2 The values ​​represent the change rates of the length and width of the composite wall panel samples before and after immersion in the various embodiments and comparative examples of this invention.

[0031] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0034] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the experimental materials used in the following examples are all purchased from commercial channels.

[0035] Example 1: An environmentally friendly, formaldehyde-free, waterproof, and moisture-proof stone-plastic composite wall panel, comprising the following components in parts by weight:

[0036] The composition includes 40 parts polyvinyl chloride resin, 10 parts polypropylene resin, 3 parts cross-linked modified nano silica, 4 parts glass fiber, 3 parts dioctyl terephthalate, 2 parts zinc borate, 2 parts calcium zinc stabilizer, 0.5 parts lubricant, 10 parts calcium carbonate, 0.5 parts titanate coupling agent, and 0.2 parts antioxidant.

[0037] The cross-linked modified nano-silica is prepared through the following steps:

[0038] S1. Add 4,6-dichloro-N,N-dihexyl-1,3,5-triazine-2-amine, anhydrous potassium carbonate, hydroquinone (polymerization inhibitor), and N,N-dimethylformamide to the reaction vessel, start stirring and heat to 60°C, then slowly add N,N-diallylethanolamine, heat to 80°C and react for 4 hours. After filtration, vacuum distillation, washing, and vacuum drying, intermediate one is obtained.

[0039] S2. Add intermediate pentaerythritol tetrakis(3-mercaptopropionic acid), toluene, polymerization inhibitor p-hydroxyanisole, and photoinitiator 2,2-dimethoxy-2-phenylacetophenone to the reaction vessel, heat to 40°C, and perform photoinitiation at a wavelength of 365 nm and an intensity of 15 mW / cm². 2 The reaction was carried out under ultraviolet light for 2 hours, followed by vacuum distillation, washing with n-hexane, and vacuum drying to obtain intermediate II;

[0040] S3. Add nano-silica, anhydrous ethanol and dispersant polyethylene glycol 400 to the reactor, stir at room temperature for 30 min to form a stable suspension, then add 1% hydrochloric acid to adjust the pH of the system to 3, then slowly add alkenyl silane coupling agent, react at 60℃ for 4 h, and obtain alkenylated nano-silica by centrifugation, washing with anhydrous ethanol and vacuum drying.

[0041] S4. Add alkenylated nano-silica, sodium dodecylbenzenesulfonate, and dichloromethane to the reaction vessel, stir at room temperature for 40 min to form a stable suspension, add intermediate II and photoinitiator 1-hydroxycyclohexylphenyl ketone, stir evenly, and then heat to 30℃ with a wavelength of 365 nm and an intensity of 15 mW / cm. 2 The reaction was carried out under ultraviolet light for 2 hours, and then filtered, washed and vacuum dried to obtain cross-linked modified nano-silica.

[0042] In step S1, the feeding ratio of 4,6-dichloro-N,N-dihexyl-1,3,5-triazine-2-amine, N,N-diallylethanolamine, anhydrous potassium carbonate, hydroquinone, and N,N-dimethylformamide is 150g:120mL:100g:1.2g:800mL.

[0043] In step S2, the feed ratio of intermediate I, pentaerythritol tetrakis(3-mercaptopropionic acid) ester, toluene, p-hydroxyanisole, and 2,2-dimethoxy-2-phenylacetophenone is 100g:200mL:1200mL:0.6g:3.0g.

[0044] In step S3, the feeding ratio of nano-silica, anhydrous ethanol, polyethylene glycol 400, and alkenyl silane coupling agent is 50g:400mL:0.5mL:40mL.

[0045] In step S4, the feeding ratio of intermediate di, alkenylated nano-silica, sodium dodecylbenzenesulfonate, dichloromethane, and 1-hydroxycyclohexylphenyl ketone is 80g:100g:5.6g:900mL:2.16g.

[0046] The alkenylsilane coupling agent is obtained by combining A-171 and A-172 in a mass ratio of 1:1; the lubricant is obtained by combining polyethylene wax, butyl stearate, and calcium stearate in a mass ratio of 2:1:1; the titanate coupling agent is obtained by combining isopropyl tris(dioctyl pyrophosphoryloxy) titanate and isopropyl tris(dioctyl phosphoryloxy) titanate in a mass ratio of 1:1; the antioxidant is obtained by combining pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl) phosphite in a mass ratio of 2:1.

[0047] The preparation method of the environmentally friendly, formaldehyde-free, waterproof, and moisture-proof stone-plastic composite wall panel includes the following steps:

[0048] (1) Dry polyvinyl chloride resin and polypropylene resin in an oven at 60°C for 2 hours to remove moisture; pass calcium carbonate through a 300-mesh sieve and mix it with titanate coupling agent in a high-speed mixer at 800 r / min at room temperature for 15 min.

[0049] (2) Add the pretreated resin, calcium carbonate, cross-linked modified nano silica, glass fiber, dioctyl terephthalate, zinc borate, calcium zinc stabilizer, lubricant and antioxidant to the high-speed mixer in sequence. First, stir at 1200 r / min for 8 min at 100℃, then transfer to a twin-screw extruder for granulation. The extrusion temperature is 160℃ and the screw speed is 300 r / min to obtain composite particles.

[0050] (3) The composite particles are added to a single screw extruder, the extrusion temperature is 170℃, the screw speed is 250r / min, and the extrusion is formed through a die. After cooling and shaping, and traction cutting, environmentally friendly formaldehyde-free waterproof and moisture-proof stone-plastic composite wall panels are obtained.

[0051] Example 2: An environmentally friendly, formaldehyde-free, waterproof, and moisture-proof stone-plastic composite wall panel, comprising the following components in parts by weight:

[0052] The composition includes 60 parts polyvinyl chloride resin, 25 parts polypropylene resin, 8 parts cross-linked modified nano silica, 10 parts glass fiber, 8 parts dioctyl terephthalate, 6 parts zinc borate, 4.5 parts calcium zinc stabilizer, 2 parts lubricant, 30 parts calcium carbonate, 1.5 parts titanate coupling agent, and 0.6 parts antioxidant.

[0053] The cross-linked modified nano-silica is prepared through the following steps:

[0054] S1. Add 4,6-dichloro-N,N-dihexyl-1,3,5-triazine-2-amine, anhydrous potassium carbonate, hydroquinone (polymerization inhibitor), and N,N-dimethylformamide to the reaction vessel, start stirring and heat to 70°C, then slowly add N,N-diallylethanolamine, heat to 85°C and react for 6 hours. After filtration, vacuum distillation, washing, and vacuum drying, intermediate one is obtained.

[0055] S2. Add intermediate pentaerythritol tetrakis(3-mercaptopropionic acid) ester, toluene, polymerization inhibitor p-hydroxyanisole, and photoinitiator 2,2-dimethoxy-2-phenylacetophenone to the reaction vessel, heat to 50°C, and perform photoinitiation at a wavelength of 365 nm and an intensity of 15 mW / cm². 2 The reaction was carried out under ultraviolet light for 3 hours, and intermediate II was obtained by vacuum distillation, washing with n-hexane, and vacuum drying.

[0056] S3. Add nano-silica, anhydrous ethanol and dispersant polyethylene glycol 400 to the reactor, stir at room temperature for 60 min to form a stable suspension, then add 1% hydrochloric acid to adjust the pH of the system to 4, then slowly add alkenyl silane coupling agent, react at 65℃ for 5 h, and obtain alkenylated nano-silica by centrifugation, washing with anhydrous ethanol and vacuum drying.

[0057] S4. Add alkenylated nano-silica, sodium dodecylbenzenesulfonate, and dichloromethane to the reaction vessel, stir at room temperature for 60 min to form a stable suspension, add intermediate II and photoinitiator 1-hydroxycyclohexylphenyl ketone, stir evenly, and then heat to 40℃ with a wavelength of 365 nm and an intensity of 15 mW / cm. 2 The reaction was carried out under ultraviolet light for 3 hours, and then filtered, washed and vacuum dried to obtain cross-linked modified nano-silica.

[0058] In step S1, the feeding ratio of 4,6-dichloro-N,N-dihexyl-1,3,5-triazine-2-amine, N,N-diallylethanolamine, anhydrous potassium carbonate, hydroquinone, and N,N-dimethylformamide is 150g:180mL:150g:2.8g:1200mL.

[0059] In step S2, the feed ratio of intermediate I, pentaerythritol tetrakis(3-mercaptopropionic acid) ester, toluene, p-hydroxyanisole, and 2,2-dimethoxy-2-phenylacetophenone is 100g:300mL:1800mL:0.9g:4.5g.

[0060] In step S3, the feeding ratio of nano-silica, anhydrous ethanol, polyethylene glycol 400, and alkenyl silane coupling agent is 50g:500mL:2mL:60mL.

[0061] In step S4, the feeding ratio of intermediate di, alkenylated nano-silica, sodium dodecylbenzenesulfonate, dichloromethane, and 1-hydroxycyclohexylphenyl ketone is 80g:100g:8.5g:1260mL:3.24g.

[0062] The alkenylsilane coupling agent is A-171; the lubricant is obtained by combining butyl stearate, calcium stearate and zinc stearate in a mass ratio of 1:2:1; the titanate coupling agent is bis(dioctyloxypyrophosphate) ethylene titanate; the antioxidant is obtained by combining tris(2,4-di-tert-butylphenyl) phosphite and β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate in a mass ratio of 2:1.

[0063] The preparation method of the environmentally friendly, formaldehyde-free, waterproof, and moisture-proof stone-plastic composite wall panel includes the following steps:

[0064] (1) Dry polyvinyl chloride resin and polypropylene resin in an oven at 75°C for 3 hours to remove moisture; pass calcium carbonate through a 400-mesh sieve and mix it with titanate coupling agent in a high-speed mixer at 1000 r / min at room temperature for 20 minutes.

[0065] (2) Add the pretreated resin, calcium carbonate, cross-linked modified nano silica, glass fiber, dioctyl terephthalate, zinc borate, calcium zinc stabilizer, lubricant and antioxidant to a high-speed mixer in sequence. First, stir at 1500 r / min for 12 min at 110℃, then transfer to a twin-screw extruder for granulation. The extrusion temperature is 180℃ and the screw speed is 400 r / min to obtain composite particles.

[0066] (3) The composite particles are added to a single screw extruder, the extrusion temperature is 190℃, the screw speed is 350r / min, and the extrusion is formed through a die. After cooling and shaping, and traction cutting, environmentally friendly formaldehyde-free waterproof and moisture-proof stone-plastic composite wall panels are obtained.

[0067] Example 3: An environmentally friendly, formaldehyde-free, waterproof, and moisture-proof stone-plastic composite wall panel, comprising the following components in parts by weight:

[0068] The composition includes 50 parts polyvinyl chloride resin, 17.5 parts polypropylene resin, 5.5 parts cross-linked modified nano silica, 7 parts glass fiber, 5.5 parts dioctyl terephthalate, 4 parts zinc borate, 3.25 parts calcium zinc stabilizer, 1.25 parts lubricant, 20 parts calcium carbonate, 1 part titanate coupling agent, and 0.4 parts antioxidant.

[0069] The cross-linked modified nano-silica is prepared through the following steps:

[0070] S1. Add 4,6-dichloro-N,N-dihexyl-1,3,5-triazine-2-amine, anhydrous potassium carbonate, hydroquinone (polymerization inhibitor), and N,N-dimethylformamide to a reaction vessel, start stirring and heat to 65°C, then slowly add N,N-diallylethanolamine, heat to 82.5°C and react for 5 hours. After filtration, vacuum distillation, washing, and vacuum drying, intermediate one is obtained.

[0071] S2. Add intermediate pentaerythritol tetrakis(3-mercaptopropionic acid), toluene, polymerization inhibitor p-hydroxyanisole, and photoinitiator 2,2-dimethoxy-2-phenylacetophenone to the reaction vessel, heat to 45°C, and perform photoinitiation at a wavelength of 365 nm and an intensity of 15 mW / cm². 2 The reaction was carried out under ultraviolet light for 2.5 h, and intermediate II was obtained by vacuum distillation, washing with n-hexane, and vacuum drying.

[0072] S3. Add nano-silica, anhydrous ethanol and dispersant polyethylene glycol 400 to the reactor, stir at room temperature for 45 min to form a stable suspension, then add 1% hydrochloric acid to adjust the pH of the system to 3.5, then slowly add alkenyl silane coupling agent, react at 62.5℃ for 4.5 h, and obtain alkenylated nano-silica by centrifugation, washing with anhydrous ethanol and vacuum drying.

[0073] S4. Add alkenylated nano-silica, sodium dodecylbenzenesulfonate, and dichloromethane to the reaction vessel, stir at room temperature for 50 min to form a stable suspension, add intermediate II and photoinitiator 1-hydroxycyclohexylphenyl ketone, stir evenly, and then heat to 35℃ with a wavelength of 365 nm and an intensity of 15 mW / cm. 2 The reaction was carried out under ultraviolet light for 2.5 h, and the cross-linked modified nano-silica was obtained by filtration, washing and vacuum drying.

[0074] In step S1, the feed ratio of 4,6-dichloro-N,N-dihexyl-1,3,5-triazine-2-amine, N,N-diallylethanolamine, anhydrous potassium carbonate, hydroquinone, and N,N-dimethylformamide is 150g:150mL:125g:2g:1000mL.

[0075] In step S2, the feed ratio of intermediate I, pentaerythritol tetrakis(3-mercaptopropionic acid) ester, toluene, p-hydroxyanisole, and 2,2-dimethoxy-2-phenylacetophenone is 100g:250mL:1500mL:0.75g:3.75g.

[0076] In step S3, the feeding ratio of nano-silica, anhydrous ethanol, polyethylene glycol 400, and alkenyl silane coupling agent is 50g:450mL:1.25mL:50mL.

[0077] In step S4, the feeding ratio of intermediate di, alkenylated nano-silica, sodium dodecylbenzenesulfonate, dichloromethane, and 1-hydroxycyclohexylphenyl ketone is 80g:100g:7.05g:1080mL:2.7g.

[0078] The alkenylsilane coupling agent is KH-570; the lubricant is obtained by combining polyethylene wax, butyl stearate, calcium stearate and zinc stearate in a mass ratio of 2:2:2:1; the titanate coupling agent is obtained by combining isopropyl tris(dioctyl pyrophosphate) titanate, isopropyl tris(dioctyl pyrophosphate) titanate and bis(dioctyl pyrophosphate) ethylene titanate in a mass ratio of 2:2:1; the antioxidant is obtained by combining pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite and octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate in a mass ratio of 1:2:1.

[0079] The preparation method of the environmentally friendly, formaldehyde-free, waterproof, and moisture-proof stone-plastic composite wall panel includes the following steps:

[0080] (1) Dry polyvinyl chloride resin and polypropylene resin in an oven at 67.5℃ for 2.5h to remove moisture; pass calcium carbonate through a 350-mesh sieve and mix it with titanate coupling agent in a high-speed mixer at 900r / min at room temperature for 17.5min.

[0081] (2) Add the pretreated resin, calcium carbonate, cross-linked modified nano silica, glass fiber, dioctyl terephthalate, zinc borate, calcium zinc stabilizer, lubricant and antioxidant to a high-speed mixer in sequence. First, stir at 1350 r / min for 10 min at 105℃, then transfer to a twin-screw extruder for granulation. The extrusion temperature is 170℃ and the screw speed is 350 r / min to obtain composite particles.

[0082] (3) The composite particles are added to a single screw extruder, the extrusion temperature is 180℃, the screw speed is 300r / min, and the extrusion is formed through a die. After cooling and shaping, and traction cutting, environmentally friendly formaldehyde-free waterproof and moisture-proof stone-plastic composite wall panels are obtained.

[0083] Comparative Example 1: The difference between this comparative example and Example 3 is that the cross-linked modified nano-silica is replaced with an equal amount of unmodified nano-silica, and all other aspects are the same as in Example 3.

[0084] Comparative Example 2: The difference between this comparative example and Example 3 is that no alkenylsilane coupling agent is added, and nano-silica is directly used to react with intermediate 2. All other aspects are the same as in Example 3.

[0085] Results Analysis

[0086] The formaldehyde concentration in the absorbent liquid of the composite wall panels prepared in each example and comparative example was tested 24 hours in accordance with GB18583-2008. The results are shown in Table 1.

[0087] Table 1 Comparison of formaldehyde release levels between the examples and comparative examples

[0088] Group <![CDATA[Formaldehyde emission (mg / m 3 )]]> Environmental assessment Example 1 Not detected (<0.01) Formaldehyde-free qualified Example 2 Not detected (<0.01) Formaldehyde-free qualified Example 3 Not detected (<0.01) Formaldehyde-free qualified Comparative Example 1 Not detected (<0.01) Formaldehyde-free qualified Comparative Example 2 Not detected (<0.01) Formaldehyde-free qualified

[0089] The mass change rate of composite wall panel samples from each example and comparative example group after immersion in water for 24 hours was tested according to GB / T4897-2015. The results are shown in […]. Figure 1 .

[0090] According to GB / T11718-2021, the change rates of length and width of composite wall panel samples before and after immersion in each group of examples and comparative examples were tested, and the results are shown in […]. Figure 2 .

[0091] As can be seen from Table 1, no formaldehyde was detected in Examples 1-3 and Comparative Examples 1-2, indicating that the formaldehyde-free component system of the present invention can achieve environmental protection and formaldehyde-free status. Figure 1 and Figure 2 As can be seen from the examples, the water absorption rate and the size change rate of Examples 1-3 are low. This is mainly due to the organic-inorganic hybrid structure formed by the cross-linked modified nano-silica, as well as the hydrophobicity of the triazine ring and the interfacial bonding force of the alkenylation modification, which effectively block the penetration of water molecules. In contrast, Comparative Example 1 has a much higher water absorption rate and size change rate than the examples because the nanoparticles are easy to aggregate, have poor compatibility with the resin, and have gaps at the interface. This proves that the cross-linking modification effectively improves the waterproofness.

[0092] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0093] The present invention and its embodiments have been described above. This description is not restrictive, and the embodiments shown are only one of the embodiments of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. An environmentally friendly, formaldehyde-free, waterproof and moisture-proof stone plastic composite wallboard, characterized in that: The composition comprises the following components by mass parts: Polyvinyl chloride resin 40-60 parts, polypropylene resin 10-25 parts, crosslinking modified nano-silica 3-8 parts, glass fiber 4-10 parts, dioctyl terephthalate 3-8 parts, zinc borate 2-6 parts, calcium zinc stabilizer 2-4.5 parts, lubricant 0.5-2 parts, calcium carbonate 10-30 parts, titanate coupling agent 0.5-1.5 parts, antioxidant 0.2-0.6 parts; The crosslinking modified nano-silica is prepared by the following steps: S1. Add 4,6-dichloro-N,N-dihexyl-1,3,5-triazine-2-amine, anhydrous potassium carbonate, polymerization inhibitor hydroquinone and N,N-dimethylformamide to the reaction container, start stirring and warm up to 60-70℃, then slowly add N,N-diallyl ethanolamine, warm up to 80-85℃ and react for 4-6h, then filter, distill under reduced pressure, wash and vacuum dry to obtain intermediate one; S2. Into the reaction vessel, intermediate one, pentaerythritol tetra(3-mercaptopropionate), toluene, polymerization inhibitor p-hydroxyanisole and photoinitiator 2,2-dimethoxy-2-phenylacetophenone were added, and the temperature was raised to 40-50°C. The reaction was carried out under a UV lamp with a wavelength of 365 nm and an intensity of 15 mW / cm 2 for 2-3 h. After vacuum distillation, n-hexane washing and vacuum drying, intermediate two was obtained. S3. Add nano-silica, anhydrous ethanol and dispersant polyethylene glycol 400 to the reactor, stir at room temperature for 30-60min to form a stable suspension, then add 1% hydrochloric acid to adjust the pH value of the system to 3-4, then slowly add the alkenyl silane coupling agent, react at 60-65℃ for 4-5h, then centrifuge, wash with anhydrous ethanol and vacuum dry to obtain alkenylated nano-silica; S4. To the reaction vessel, add the alkenylized nanosilica, sodium dodecyl benzene sulfonate and dichloromethane, stir at room temperature for 40-60 min to form a stable suspension, add intermediate II and photoinitiator 1-hydroxycyclohexyl phenyl ketone, after stirring uniformly, warm to 30-40°C, react under a UV lamp with wavelength of 365 nm and intensity of 15 mW / cm 2 for 2-3 h, and obtain the crosslinked modified nanosilica by suction filtration, washing and vacuum drying.

2. The environment-friendly formaldehyde-free waterproof and moisture-proof stone plastic composite wallboard according to claim 1, characterized in that: In the step S1, the feeding ratio of 4,6-dichloro-N,N-dihexyl-1,3,5-triazine-2-amine, N,N-diallyl ethanolamine, anhydrous potassium carbonate, hydroquinone and N,N-dimethylformamide is 150g:120-180mL:100-150g:1.2-2.8g:800-1200mL.

3. The environment-friendly formaldehyde-free waterproof and moisture-proof stone plastic composite wallboard according to claim 2, characterized in that: In the step S2, the feeding ratio of intermediate one, tetra(3-mercaptopropionic acid) pentaerythritol ester, toluene, p-hydroxyanisole, 2,2-dimethoxy-2-phenylacetophenone is 100g:200-300mL:1200-1800mL:0.6-0.9g:3.0-4.5g.

4. The environment-friendly formaldehyde-free waterproof and moisture-proof stone plastic composite wallboard according to claim 3, characterized in that: In the step S3, the feeding ratio of nano-silica, anhydrous ethanol, polyethylene glycol 400 and alkenyl silane coupling agent is 50g:400-500mL:0.5-2mL:40-60mL.

5. The environment-friendly formaldehyde-free waterproof and moisture-proof stone plastic composite wallboard according to claim 4, characterized in that: In the step S4, the feeding ratio of intermediate two, alkenylated nano-silica, sodium dodecylbenzenesulfonate, dichloromethane and 1-hydroxycyclohexyl phenyl ketone is 80g:100g:5.6-8.5g:900-1260mL:2.16-3.24g.

6. The environment-friendly formaldehyde-free waterproof and moisture-proof stone plastic composite wallboard according to claim 5, characterized in that: The alkenyl silane coupling agent is selected from at least one of A-171, A-172 and KH-570.

7. The environment-friendly formaldehyde-free waterproof and moisture-proof stone plastic composite wallboard according to claim 6, characterized in that: The lubricant is selected from at least one of polyethylene wax, butyl stearate, calcium stearate and zinc stearate.

8. The environment-friendly formaldehyde-free waterproof and moisture-proof stone plastic composite wallboard according to claim 7, characterized in that: The titanate coupling agent is selected from at least one of isopropyl tri(dioctyl pyrophosphato) titanate, isopropyl tri(dioctyl phosphato) titanate and bis(dioctyloxy pyrophosphato) ethylene titanate.

9. The environment-friendly formaldehyde-free waterproof and moisture-proof stone plastic composite wallboard according to claim 8, characterized in that: The antioxidant is selected from at least one of the following: tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester, tris(2,4-di-tert-butylphenyl)phosphite, and n-octadecanol β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

10. A method for preparing the environment-friendly formaldehyde-free waterproof and moisture-proof stone plastic composite wallboard according to any one of claims 1-9, characterized in that: The method comprises the following steps: (1) drying polyvinyl chloride resin, polypropylene resin in 60-75℃ oven for 2-3h to remove moisture; calcium carbonate is sieved through 300-400 mesh, and mixed with titanate coupling agent in a high-speed mixer at 800-1000r / min for 15-20min at room temperature; (2) adding pretreated resin, calcium carbonate, crosslinking modified nano-silica, glass fiber, dioctyl terephthalate, zinc borate, calcium-zinc stabilizer, lubricant, antioxidant into the high-speed mixer in sequence, stirring at 100-110℃ and 1200-1500r / min for 8-12min, and then transferring into a double-screw extruder for granulation, with extrusion temperature of 160-180℃ and screw rotation speed of 300-400r / min, to obtain composite particles; (3) adding the composite particles into a single-screw extruder, with extrusion temperature of 170-190℃ and screw rotation speed of 250-350r / min, extruding through a mold, and then cooling, setting, pulling and cutting to obtain environment-friendly formaldehyde-free waterproof and moisture-proof stone plastic composite wallboard.

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