Preparation methods of composite polypropylene materials and their applications in building materials

Abstract

This invention discloses a method for preparing a composite polypropylene material and its application in building materials, belonging to the field of polymer materials technology. The material is composed of homopolymer polypropylene, random copolymer polypropylene, polyethylene, TPV, toughening agent, modified glass fiber, etc. The preparation method involves mixing the raw materials and then extruding and granulating them using a twin-screw extruder. Compared with existing technologies, this invention achieves a balance between high strength, high toughness, and aging resistance by optimizing the formulation and process, significantly improving mechanical properties and durability, effectively blocking water molecule penetration, and extending service life. It provides high-performance polypropylene composite materials for the building materials field, especially suitable for hollow core slabs.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a method for preparing a composite polypropylene material and its application in building materials. Background Technology

[0002] In the field of building materials, polypropylene is widely used due to its advantages such as lightweight, corrosion resistance, and ease of processing. However, traditional polypropylene materials have shortcomings in mechanical properties, impact resistance, and durability, which limits their application in high-performance building materials. For example, in building structures such as hollow core slabs, materials need to possess high strength, high toughness, and good aging resistance to ensure the safety and stability of the structure.

[0003] While existing polypropylene composite technologies have improved material performance to some extent, several issues remain. For example, Chinese invention patent application CN110903549A discloses a polypropylene composite material and its preparation method, which improves the material's low-temperature impact toughness and transparency by adding thermoplastic elastomers and thermoplastic vulcanized rubber, but its durability under high-temperature and high-humidity environments still needs improvement. Another patent application, CN114907645A, improves the toughness of polypropylene materials by adding modified starch and elastomers as composite toughening agents, but still falls short in balancing high strength and high toughness.

[0004] Furthermore, existing methods for modifying glass fiber mainly focus on surface coatings or simple chemical treatments. While these methods can improve the bonding strength between glass fiber and the matrix to some extent, their interfacial stability is insufficient under complex conditions, such as long-term exposure to humid and hot environments or high stress, leading to a rapid decline in material properties. Therefore, developing a composite polypropylene material that can achieve a balance between high strength, high toughness, and aging resistance, and its preparation method, is of significant practical importance to the field of building materials. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a method for preparing a high-strength, high-toughness, and aging-resistant composite polypropylene material and its application in building materials.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a composite polypropylene material, comprising the following raw materials in parts by weight:

[0008] 50-70 parts homopolymer polypropylene, 5-15 parts random copolymer polypropylene, 5-15 parts polyethylene, 1-5 parts TPV, 1-5 parts toughening agent, 4-8 parts modified glass fiber, 1-3 parts flame retardant, 0.2-0.8 parts antioxidant, 0.1-0.3 parts ultraviolet absorber, and 0.5-2 parts lubricant.

[0009] The modified glass fiber is prepared as follows:

[0010] S1. Under nitrogen protection, disodium hydrogen phosphate and sodium citrate were added to water, dopamine hydrochloride was added, and a mixed solution of acrylic anhydride and N,N-dimethylformamide was added dropwise. After adjusting the pH, the reaction was carried out, and the acrylamide dopamine was obtained by extraction, dehydration and recrystallization.

[0011] S2. Acrylate monomers, ethyl 2-(acryloyloxy)acetoacetate, quaternary ammonium salt monomers, trithiocarbonate, ammonium persulfate and water are mixed and treated under nitrogen protection to obtain a micelle solution, which is then mixed with an acrylamide dopamine ethanol solution and tetraethylenepentamine and treated to obtain a copolymer.

[0012] S3. After ultrasonic cleaning with acetone and vacuum drying, the glass fiber is immersed in a sizing solution prepared from copolymer and water, magnetically stirred, and then vacuum dried to obtain modified glass fiber.

[0013] The preparation method of the composite polypropylene material is as follows:

[0014] Weigh each raw material according to the weight proportions, and mix homopolymer polypropylene, random copolymer polypropylene, polyethylene, TPV, toughening agent, modified glass fiber, and flame retardant; add antioxidant, ultraviolet absorber and lubricant during the stirring process, stir at high speed until uniform, extrude through a twin-screw extruder, granulate, and obtain composite polypropylene material.

[0015] The temperatures of each zone of the twin-screw extruder are: Zone 1 160-180℃, Zone 2 170-190℃, Zone 3 180-200℃, Zone 4 200-220℃, extrusion temperature 190-210℃, and screw speed 50-150 r / min.

[0016] The ultraviolet absorber is a benzotriazole ultraviolet absorber.

[0017] The flame retardant is at least one of piperazine pyrophosphate, melamine polyphosphate, aluminum hypophosphite, aluminum diethylphosphite, tri(2-chloroethyl) phosphate, and tri(2,3-dichloropropyl) phosphate.

[0018] The toughening agent is at least one of ethylene-octene copolymer, styrene-butadiene-styrene block copolymer, ethylene-methyl acrylate copolymer, and ethylene-vinyl acetate copolymer.

[0019] The antioxidant is at least one of antioxidant 168, antioxidant 1010, antioxidant 1024, antioxidant 1076, and antioxidant 1098.

[0020] The lubricant is at least one of stearic acid, calcium stearate, and ethylene bis-stearamide.

[0021] The modified glass fiber is prepared as follows, in parts by weight:

[0022] S1. Add 30-50 parts of disodium hydrogen phosphate and 10-20 parts of sodium citrate to 300-500 parts of water, under nitrogen protection, add 15-25 parts of dopamine hydrochloride, and add dropwise 80-120 parts of a mixed solution, wherein the mixed solution is a mixture of acrylic anhydride and N,N-dimethylformamide in a ratio of 1:3-5. Adjust the pH to 8-10 with 1-3 mol / L sodium hydroxide aqueous solution, react at 3-8℃ under nitrogen for 12-48 hours, adjust the pH to 2-3 with 1-3 mol / L hydrochloric acid, extract the organic phase with ethyl acetate, remove water with anhydrous magnesium sulfate, add 80-120 parts of cyclohexane for recrystallization to obtain acrylated dopamine;

[0023] S2. Mix 8-12 parts of acrylate monomers, 10-20 parts of ethyl 2-(acryloyloxy)acetoacetate, 5-10 parts of quaternary ammonium salt monomers, 0.1-0.5 parts of trithiocarbonate, 0.05-0.2 parts of ammonium persulfate, and 15-25 parts of water, and treat under nitrogen protection at 70-90℃ for 2-10 hours to obtain a micelle solution; take 50-70 parts of the micelle solution and mix with 1-3 parts of 3-8wt% acrylamide ethanol solution, add 0.02-0.08 parts of tetraethylenepentamine, and treat under nitrogen protection at room temperature for 5-15 hours to obtain a copolymer;

[0024] S3. Ultrasonically clean the glass fiber with acetone for 3-8 hours, dry it in a vacuum oven at 80-100℃ for 2-20 hours, add 2-6 parts of copolymer to 30-50 parts of water to obtain a sizing solution, immerse 5-10 parts of glass fiber in the sizing solution, stir magnetically for 5-15 minutes, and vacuum dry to obtain modified glass fiber.

[0025] The acrylate monomer is at least one of isoamyl acrylate, 1,4-butanediol diacrylate, and cyclohexyl methacrylate.

[0026] The quaternary ammonium salt monomer is at least one of acryloyloxyethyltrimethylammonium chloride and (2,3-epoxypropyl)[2-(isobutenyloxy)ethyl]dimethylammonium chloride.

[0027] The application of the composite polypropylene material in building materials is preferably in hollow floor slabs.

[0028] The roles of each component in the preparation method of the composite polypropylene material of this invention are as follows:

[0029] Homopolymer polypropylene provides a rigid matrix framework, ensuring the structural strength of the material.

[0030] Random copolymer polypropylene improves impact toughness and reduces stress whitening.

[0031] Polyethylene enhances melt flowability and improves processing efficiency.

[0032] TPV is a toughened thermoplastic vulcanized rubber that improves low-temperature impact resistance.

[0033] Ethylene-octene copolymers are elastomer toughening agents that synergistically enhance toughness.

[0034] Modified glass fiber enhances tensile strength and impact strength through interfacial bonding, and improves resistance to damp heat aging.

[0035] Piperazine pyrophosphate is a flame retardant that improves the flame resistance of materials.

[0036] Antioxidant 168 is a phosphite antioxidant that inhibits oxidative degradation during processing.

[0037] Benzotriazole UV absorbers shield against UV radiation and slow down outdoor aging.

[0038] Stearic acid acts as a lubricant, improving mold release properties and reducing screw wear.

[0039] Disodium hydrogen phosphate and sodium citrate form a buffer system to maintain an alkaline reaction environment.

[0040] Dopamine hydrochloride provides catechol groups for adhesion to glass fiber surfaces.

[0041] Acrylic anhydride reacts with dopamine amino groups to introduce polymerizable double bonds.

[0042] N,N-dimethylformamide is a polar solvent that promotes complete acylation reaction.

[0043] Cyclohexane was used as the recrystallization solvent to purify acrylamide dopamine.

[0044] 2-(acryloyloxy)acetoacetate contains a β-keto ester group, which forms hydrogen bonds with the glass fiber surface.

[0045] Trithiocarbonate controls the molecular weight distribution of block copolymers.

[0046] Ammonium persulfate is used as an initiator to initiate free radical polymerization.

[0047] Tetraethylenepentamine is a low-temperature redox initiator that promotes dopamine grafting.

[0048] Acetone is used as a cleaning agent to remove impurities from the surface of the glass fiber.

[0049] Compared with existing technologies, it has the following advantages:

[0050] 1) This invention enhances the mechanical properties and impact resistance of composite polypropylene materials through a specific modified glass fiber preparation method, enabling them to exhibit higher strength and toughness in building material applications.

[0051] 2) The special structure and chemical bonding mechanism of the modified glass fiber of this invention improve the durability of the material in humid and hot environments, effectively block the penetration of water molecules, and extend the service life of the material.

[0052] 3) This invention achieves a balance between high strength and high toughness in materials by molecular-level compounding and precise control of crosslinking density, while inhibiting aging and deterioration, thereby improving the overall performance and application value of the materials. Detailed Implementation

[0053] Main source of materials:

[0054] Fiberglass, 4mm long, 15μm in diameter.

[0055] Homopolymer polypropylene, grade: 21-176V, brand: Yanshan Petrochemical.

[0056] Random copolymer polypropylene, grade: 4220, brand: Yanshan Petrochemical.

[0057] Polyethylene, grade: 1C7A, brand: Yanshan Petrochemical.

[0058] TPV, item number: 101-87, brand: ExxonMobil (USA).

[0059] Dopamine hydrochloride, product number: DD5109, Hefei Bomei Biotechnology Co., Ltd.

[0060] Piperazine pyrophosphate, product model: 564564, Shanghai Gaoming Chemical Co., Ltd.

[0061] Ethylene-octene copolymer, grade: 871L, brand: SK Korea.

[0062] Benzotriazole UV absorber, product model: UV-328 light stabilizer, brand: BASF.

[0063] (2,3-Epoxypropyl)[2-(Isobutenoyloxy)ethyl]dimethylammonium chloride, CAS No.: 62351-05-7, Molecular formula: C 11 H 20 ClNO3.

[0064] Acryloyloxyethyltrimethylammonium chloride, CAS No.: 44992-01-0, Molecular formula: C8H16 ClNO2.

[0065] 1,4-Butanediol diacrylate, CAS No.: 1070-70-8, Molecular formula: C 10 H 14 O4.

[0066] All other raw materials used in the embodiments and comparative examples of this invention are commercially available products. Example 1

[0067] A method for preparing a composite polypropylene material is as follows:

[0068] 60 parts homopolymer polypropylene, 10 parts random copolymer polypropylene, 10 parts polyethylene, 3 parts TPV, 3 parts ethylene-octene copolymer, 6 parts modified glass fiber, and 2 parts piperazine pyrophosphate were added to a high-speed mixer and mixed. During the mixing process, 0.5 parts antioxidant 168, 0.2 parts benzotriazole UV absorber, and 1 part stearic acid were added. The mixture was stirred at high speed until homogeneous and then extruded through a twin-screw extruder. The temperatures of each zone of the twin-screw extruder were: zone 1 170℃, zone 2 180℃, zone 3 190℃, and zone 4 210℃. The extrusion temperature was 200℃, and the screw speed was 90 r / min. Granulation was then performed to obtain the composite polypropylene material.

[0069] The modified glass fiber is prepared as follows:

[0070] S1. Add 40g of disodium hydrogen phosphate and 15g of sodium citrate to 400g of water, under nitrogen protection, add 20g of dopamine hydrochloride, and add 100g of a mixed solution, which is a mixture of acrylic anhydride and N,N-dimethylformamide in a 1:4 ratio. Adjust the pH to 9 with 2mol / L sodium hydroxide aqueous solution, react at 5℃ under nitrogen for 24 hours, adjust the pH to 2 with 2mol / L hydrochloric acid, extract the organic phase with ethyl acetate, remove water with anhydrous magnesium sulfate, add 100g of cyclohexane for recrystallization, and obtain acrylated dopamine.

[0071] S2. Mix 10g cyclohexyl methacrylate, 15g ethyl 2-(acryloyloxy)acetoacetate, 8g (2,3-epoxypropyl)[2-(isobutenyloxy)ethyl]dimethylammonium chloride, 0.3g trithiocarbonate, 0.1g ammonium persulfate, and 20g water, and treat at 80℃ under nitrogen protection for 6 hours to obtain a micelle solution; take 60g of the micelle solution and mix with 2g 7wt% acrylamide ethanol solution, add 0.05g tetraethylenepentamine, and treat at room temperature under nitrogen protection for 10 hours to obtain a copolymer;

[0072] S3. Ultrasonically clean the glass fiber with acetone for 5 hours, dry it in a vacuum oven at 90°C for 12 hours, add 4g of copolymer to 40g of water to obtain a sizing solution, immerse 8g of glass fiber in the sizing solution, stir magnetically for 10 minutes, and vacuum dry to obtain modified glass fiber. Example 2

[0073] The preparation method of a composite polypropylene material is basically the same as that in Example 1, except that the preparation method of the modified glass fiber is different.

[0074] The modified glass fiber is prepared as follows:

[0075] S1. Add 40g of disodium hydrogen phosphate and 15g of sodium citrate to 400g of water, under nitrogen protection, add 20g of dopamine hydrochloride, and add 100g of a mixed solution, which is a mixture of acrylic anhydride and N,N-dimethylformamide in a 1:4 ratio. Adjust the pH to 9 with 2mol / L sodium hydroxide aqueous solution, react at 5℃ under nitrogen for 24 hours, adjust the pH to 2 with 2mol / L hydrochloric acid, extract the organic phase with ethyl acetate, remove water with anhydrous magnesium sulfate, add 100g of cyclohexane for recrystallization, and obtain acrylated dopamine.

[0076] S2. Mix 10g of 1,4-butanediol diacrylate, 15g of ethyl 2-(acryloyloxy)acetoacetate, 8g of (2,3-epoxypropyl)[2-(isobutenyloxy)ethyl]dimethylammonium chloride, 0.3g of trithiocarbonate, 0.1g of ammonium persulfate, and 20g of water, and treat under nitrogen protection at 80℃ for 6 hours to obtain a micelle solution; take 60g of the micelle solution and mix it with 2g of 7wt% acryloylated dopamine ethanol solution, add 0.05g of tetraethylenepentamine, and treat under nitrogen protection at room temperature for 10 hours to obtain a copolymer;

[0077] S3. Ultrasonically clean the glass fiber with acetone for 5 hours, dry it in a vacuum oven at 90°C for 12 hours, add 4g of copolymer to 40g of water to obtain a sizing solution, immerse 8g of glass fiber in the sizing solution, stir magnetically for 10 minutes, and vacuum dry to obtain modified glass fiber. Example 3

[0078] The preparation method of a composite polypropylene material is basically the same as that in Example 1, except that the preparation method of the modified glass fiber is different.

[0079] The modified glass fiber is prepared as follows:

[0080] S1. Add 40g of disodium hydrogen phosphate and 15g of sodium citrate to 400g of water, under nitrogen protection, add 20g of dopamine hydrochloride, and add 100g of a mixed solution, which is a mixture of acrylic anhydride and N,N-dimethylformamide in a 1:4 ratio. Adjust the pH to 9 with 2mol / L sodium hydroxide aqueous solution, react at 5℃ under nitrogen for 24 hours, adjust the pH to 2 with 2mol / L hydrochloric acid, extract the organic phase with ethyl acetate, remove water with anhydrous magnesium sulfate, add 100g of cyclohexane for recrystallization, and obtain acrylated dopamine.

[0081] S2. Mix 10g isoamyl acrylate, 15g ethyl 2-(acryloyloxy)acetoacetate, 8g (2,3-epoxypropyl)[2-(isobutenyloxy)ethyl]dimethylammonium chloride, 0.3g trithiocarbonate, 0.1g ammonium persulfate, and 20g water, and treat under nitrogen protection at 80℃ for 6 hours to obtain a micelle solution; take 60g of the micelle solution and mix it with 2g 7wt% acrylamide ethanol solution, add 0.05g tetraethylenepentamine, and treat under nitrogen protection at room temperature for 10 hours to obtain a copolymer;

[0082] S3. Ultrasonically clean the glass fiber with acetone for 5 hours, dry it in a vacuum oven at 90°C for 12 hours, add 4g of copolymer to 40g of water to obtain a sizing solution, immerse 8g of glass fiber in the sizing solution, stir magnetically for 10 minutes, and vacuum dry to obtain modified glass fiber. Example 4

[0083] The preparation method of a composite polypropylene material is basically the same as that in Example 1, except that the preparation method of the modified glass fiber is different.

[0084] The modified glass fiber is prepared as follows:

[0085] S1. Add 40g of disodium hydrogen phosphate and 15g of sodium citrate to 400g of water, under nitrogen protection, add 20g of dopamine hydrochloride, and add 100g of a mixed solution, which is a mixture of acrylic anhydride and N,N-dimethylformamide in a 1:4 ratio. Adjust the pH to 9 with 2mol / L sodium hydroxide aqueous solution, react at 5℃ under nitrogen for 24 hours, adjust the pH to 2 with 2mol / L hydrochloric acid, extract the organic phase with ethyl acetate, remove water with anhydrous magnesium sulfate, add 100g of cyclohexane for recrystallization, and obtain acrylated dopamine.

[0086] S2. Mix 10g cyclohexyl methacrylate, 15g ethyl 2-(acryloyloxy)acetoacetate, 8g acryloyloxyethyltrimethylammonium chloride, 0.3g trithiocarbonate, 0.1g ammonium persulfate, and 20g water, and treat under nitrogen protection at 80℃ for 6 hours to obtain a micelle solution; take 60g of the micelle solution and mix it with 2g 7wt% acryloylated dopamine ethanol solution, add 0.05g tetraethylenepentamine, and treat under nitrogen protection at room temperature for 10 hours to obtain a copolymer;

[0087] S3. Ultrasonically clean the glass fiber with acetone for 5 hours, dry it in a vacuum oven at 90°C for 12 hours, add 4g of copolymer to 40g of water to obtain a sizing solution, immerse 8g of glass fiber in the sizing solution, stir magnetically for 10 minutes, and vacuum dry to obtain modified glass fiber. Example 5

[0088] The preparation method of a composite polypropylene material is basically the same as that in Example 1, except that the preparation method of the modified glass fiber is different.

[0089] The modified glass fiber is prepared as follows:

[0090] S1. Add 40g of disodium hydrogen phosphate and 15g of sodium citrate to 400g of water, under nitrogen protection, add 20g of dopamine hydrochloride, and add 100g of a mixed solution, which is a mixture of acrylic anhydride and N,N-dimethylformamide in a 1:4 ratio. Adjust the pH to 9 with 2mol / L sodium hydroxide aqueous solution, react at 5℃ under nitrogen for 24 hours, adjust the pH to 2 with 2mol / L hydrochloric acid, extract the organic phase with ethyl acetate, remove water with anhydrous magnesium sulfate, add 100g of cyclohexane for recrystallization, and obtain acrylated dopamine.

[0091] S2. Mix 8g of cyclohexyl methacrylate, 2g of 1,4-butanediol diacrylate, 15g of ethyl 2-(acryloyloxy)acetoacetate, 8g of (2,3-epoxypropyl)[2-(isobutenyloxy)ethyl]dimethylammonium chloride, 0.3g of trithiocarbonate, 0.1g of ammonium persulfate, and 20g of water. Treat the mixture at 80°C under nitrogen protection for 6 hours to obtain a micelle solution. Mix 60g of the micelle solution with 2g of 7wt% acryloylated dopamine ethanol solution, add 0.05g of tetraethylenepentamine, and treat the mixture at room temperature under nitrogen protection for 10 hours to obtain a copolymer.

[0092] S3. Ultrasonically clean the glass fiber with acetone for 5 hours, dry it in a vacuum oven at 90°C for 12 hours, add 4g of copolymer to 40g of water to obtain a sizing solution, immerse 8g of glass fiber in the sizing solution, stir magnetically for 10 minutes, and vacuum dry to obtain modified glass fiber.

[0093] Comparative Example 1

[0094] The preparation method of a composite polypropylene material is basically the same as that in Example 1, except that the preparation method of the modified glass fiber is different.

[0095] The modified glass fiber is prepared as follows:

[0096] S1. Add 40g of disodium hydrogen phosphate and 15g of sodium citrate to 400g of water, under nitrogen protection, add 20g of dopamine hydrochloride, and add 100g of a mixed solution, which is a mixture of acrylic anhydride and N,N-dimethylformamide in a 1:4 ratio. Adjust the pH to 9 with 2mol / L sodium hydroxide aqueous solution, react at 5℃ under nitrogen for 24 hours, adjust the pH to 2 with 2mol / L hydrochloric acid, extract the organic phase with ethyl acetate, remove water with anhydrous magnesium sulfate, add 100g of cyclohexane for recrystallization, and obtain acrylated dopamine.

[0097] S2. Mix 10g butyl acrylate, 15g ethyl 2-(acryloyloxy)acetoacetate, 8g (2,3-epoxypropyl)[2-(isobutenyloxy)ethyl]dimethylammonium chloride, 0.3g trithiocarbonate, 0.1g ammonium persulfate, and 20g water, and treat under nitrogen protection at 80℃ for 6 hours to obtain a micelle solution; take 60g of the micelle solution and mix it with 2g 7wt% acryloylated dopamine ethanol solution, add 0.05g tetraethylenepentamine, and treat under nitrogen protection at room temperature for 10 hours to obtain a copolymer;

[0098] S3. Ultrasonically clean the glass fiber with acetone for 5 hours, dry it in a vacuum oven at 90°C for 12 hours, add 4g of copolymer to 40g of water to obtain a sizing solution, immerse 8g of glass fiber in the sizing solution, stir magnetically for 10 minutes, and vacuum dry to obtain modified glass fiber.

[0099] Comparative Example 2

[0100] The preparation method of a composite polypropylene material is basically the same as that in Example 1, except that the preparation method of the modified glass fiber is different.

[0101] The modified glass fiber is prepared as follows:

[0102] S1. Add 40g of disodium hydrogen phosphate and 15g of sodium citrate to 400g of water, under nitrogen protection, add 20g of dopamine hydrochloride, and add 100g of a mixed solution, which is a mixture of acrylic anhydride and N,N-dimethylformamide in a 1:4 ratio. Adjust the pH to 9 with 2mol / L sodium hydroxide aqueous solution, react at 5℃ under nitrogen for 24 hours, adjust the pH to 2 with 2mol / L hydrochloric acid, extract the organic phase with ethyl acetate, remove water with anhydrous magnesium sulfate, add 100g of cyclohexane for recrystallization, and obtain acrylated dopamine.

[0103] S2. Mix 10g cyclohexyl methacrylate, 15g ethyl 2-(acryloyloxy)acetoacetate, 8g methacryloyloxyethyltrimethylammonium chloride, 0.3g trithiocarbonate, 0.1g ammonium persulfate, and 20g water, and treat under nitrogen protection at 80℃ for 6 hours to obtain a micelle solution; take 60g of the micelle solution and mix it with 2g 7wt% acrylamide ethanol solution, add 0.05g tetraethylenepentamine, and treat under nitrogen protection at room temperature for 10 hours to obtain a copolymer;

[0104] S3. Ultrasonically clean the glass fiber with acetone for 5 hours, dry it in a vacuum oven at 90°C for 12 hours, add 4g of copolymer to 40g of water to obtain a sizing solution, immerse 8g of glass fiber in the sizing solution, stir magnetically for 10 minutes, and vacuum dry to obtain modified glass fiber.

[0105] Comparative Example 3

[0106] A method for preparing a composite polypropylene material is as follows:

[0107] 60 parts homopolymer polypropylene, 10 parts random copolymer polypropylene, 10 parts polyethylene, 3 parts TPV, 3 parts ethylene-octene copolymer, 6 parts glass fiber, and 2 parts piperazine pyrophosphate were added to a high-speed mixer and mixed. During the mixing process, 0.5 parts antioxidant 168, 0.2 parts benzotriazole UV absorber, and 1 part stearic acid were added. The mixture was stirred at high speed until homogeneous and then extruded through a twin-screw extruder. The temperatures of each zone of the twin-screw extruder were: zone 1 170℃, zone 2 180℃, zone 3 190℃, and zone 4 210℃. The extrusion temperature was 200℃, and the screw speed was 90 r / min. Granulation was then performed to obtain the composite polypropylene material.

[0108] Test Example 1

[0109] Tensile strength and impact strength tests:

[0110] The composite polypropylene materials prepared in the embodiments and comparative examples of this invention were processed into test specimens. Tensile strength was tested according to the method in GB / T1040.1-2018 "Determination of Tensile Properties of Plastics", and notched impact strength was tested according to the method in GB / T1843-2008 "Determination of Impact Strength of Cantilever Beams of Plastics". The results are shown in Table 1.

[0111] Table 1

[0112] Experimental protocol Tensile strength / MPa <![CDATA[Notch impact strength / KJ / m 2 > Example 1 59.8 33.8 Example 2 53.5 25.6 Example 3 55.1 38.9 Example 4 56.3 32.1 Example 5 60.6 36.5 Comparative Example 1 50.8 36.0 Comparative Example 2 55.5 30.5 Comparative Example 3 46.2 26.3

[0113] Test Example 2

[0114] Damp heat aging resistance test:

[0115] The composite polypropylene materials prepared in the embodiments and comparative examples of the present invention were processed into test samples. After aging in an environment of 85°C and 85% humidity for 2000 hours, tensile strength tests were conducted according to the method in GB / T1040.1-2018 "Determination of Tensile Properties of Plastics", and the retention rate of tensile strength was calculated. The test results are shown in Table 2.

[0116] Table 2

[0117] Experimental protocol Tensile strength after aging / MPa Retention rate / % Example 1 47.9 80.1 Example 2 41.8 78.1 Example 3 42.1 76.4 Example 4 43.5 77.3 Example 5 49.0 80.9 Comparative Example 1 39.0 76.8 Comparative Example 2 41.9 75.5 Comparative Example 3 33.7 72.9

[0118] Example 1, which uses cyclohexyl methacrylate and (2,3-epoxypropyl)[2-(isobutenoyloxy)ethyl]dimethylammonium chloride to synergistically modify glass fiber, shows better results. This may be because the rigid cyclohexyl structure of cyclohexyl methacrylate forms σ-π conjugation with the crystalline region of polypropylene, significantly improving the inter-chain forces and optimizing stress transfer efficiency. In contrast, the flexible chain in Example 3 suffers from reduced tensile strength due to loose molecular entanglement. The epoxy groups of (2,3-epoxypropyl)[2-(isobutenoyloxy)ethyl]dimethylammonium chloride interact with the matrix chain ends at high extrusion temperatures, forming stable covalent bonds. In Example 4, the electrostatically adsorbed quaternary ammonium salt relies solely on ionic bonds, resulting in weak interfacial bonding. The hydrophobic cyclohexyl group of cyclohexyl methacrylate synergistically blocks water molecule penetration with the epoxy covalent bonds, improving the retention rate after hygrothermal aging. In contrast, the over-crosslinked Example 2 exhibits brittleness leading to microcracks and accelerated aging degradation.

[0119] Example 5 uses a blend of cyclohexyl methacrylate and 1,4-butanediol diacrylate to prepare modified glass fiber, which exhibits superior performance compared to single-component formulations (Examples 1 and 2). This may be because the rigid cyclohexyl groups of cyclohexyl methacrylate form σ-π conjugations with the crystalline regions of polypropylene, providing a high-strength backbone, while the flexible cross-linked network of 1,4-butanediol diacrylate absorbs impact energy through molecular chain slippage, compensating for the brittleness of the pure rigid chain. The diacrylate functional groups of 1,4-butanediol diacrylate can form a dense cross-linked layer on the glass fiber surface, blocking water molecule penetration. Simultaneously, the hydrophobic cyclohexyl groups of cyclohexyl methacrylate, in conjunction with the covalent bonds of the epoxy quaternary ammonium salt, construct a dual hydrolysis-resistant barrier. A small amount of short-chain cross-linked 1,4-butanediol diacrylate bridges the rigid phase of cyclohexyl methacrylate, forming an "island structure," achieving uniform stress distribution and avoiding the excessive cross-linking microcracks observed in Example 2 (1,4-butanediol diacrylate).

Claims

1. A composite polypropylene material, characterized in that, Including the following parts by weight of raw materials: 50-70 parts homopolymer polypropylene, 5-15 parts random copolymer polypropylene, 5-15 parts polyethylene, 1-5 parts TPV, 1-5 parts toughening agent, 4-8 parts modified glass fiber, 1-3 parts flame retardant, 0.2-0.8 parts antioxidant, 0.1-0.3 parts ultraviolet absorber, and 0.5-2 parts lubricant; The modified glass fiber is prepared by the following method, in parts by weight: S1. Add 30-50 parts of disodium hydrogen phosphate and 10-20 parts of sodium citrate to 300-500 parts of water, under nitrogen protection, add 15-25 parts of dopamine hydrochloride, and add dropwise 80-120 parts of a mixed solution, wherein the mixed solution is a mixture of acrylic anhydride and N,N-dimethylformamide in a ratio of 1:3-5. Adjust the pH to 8-10 with 1-3 mol / L sodium hydroxide aqueous solution, react at 3-8℃ under nitrogen for 12-48 hours, adjust the pH to 2-3 with 1-3 mol / L hydrochloric acid, extract the organic phase with ethyl acetate, remove water with anhydrous magnesium sulfate, add 80-120 parts of cyclohexane for recrystallization to obtain acrylated dopamine; S2. Mix 8-12 parts of acrylate monomers, 10-20 parts of ethyl 2-(acryloyloxy)acetoacetate, 5-10 parts of quaternary ammonium salt monomers, 0.1-0.5 parts of trithiocarbonate, 0.05-0.2 parts of ammonium persulfate, and 15-25 parts of water. Treat the mixture with nitrogen at 80°C for 2-10 hours to obtain a micelle solution. Mix 50-70 parts of the micelle solution with 1-3 parts of 3-8 wt% acrylamide ethanol solution, add 0.02-0.08 parts of tetraethylenepentamine, and treat the mixture with nitrogen at room temperature for 5-15 hours to obtain a copolymer. S3. Ultrasonically clean the glass fiber with acetone for 3-8 hours, dry it in a vacuum oven at 80-100℃ for 2-20 hours, add 2-6 parts of copolymer to 30-50 parts of water to obtain a sizing solution, immerse 5-10 parts of glass fiber in the sizing solution, stir magnetically for 5-15 minutes, and vacuum dry to obtain modified glass fiber. The acrylate monomer is at least one of isoamyl acrylate, 1,4-butanediol diacrylate, and cyclohexyl methacrylate. The quaternary ammonium salt monomer is (2,3-epoxypropyl)[2-(isobutenoyloxy)ethyl]dimethylammonium chloride; The toughening agent is at least one of ethylene-octene copolymer, styrene-butadiene-styrene block copolymer, ethylene-methyl acrylate copolymer, and ethylene-vinyl acetate copolymer.

2. A method for preparing the composite polypropylene material as described in claim 1, characterized in that, The method is as follows: Weigh each raw material according to the weight proportions, and mix homopolymer polypropylene, random copolymer polypropylene, polyethylene, TPV, toughening agent, modified glass fiber, and flame retardant; add antioxidant, ultraviolet absorber and lubricant during the stirring process, stir at high speed until uniform, extrude through a twin-screw extruder, granulate, and obtain composite polypropylene material.

3. The method as described in claim 2, characterized in that, The temperatures of each zone of the twin-screw extruder are: Zone 1 160-180℃, Zone 2 170-190℃, Zone 3 180-200℃, Zone 4 200-220℃, extrusion temperature 190-210℃, and screw speed 50-150 r / min.

4. The method as described in claim 2, characterized in that, The ultraviolet absorber is a benzotriazole ultraviolet absorber.

5. The method as described in claim 2, characterized in that, The flame retardant is at least one of piperazine pyrophosphate, melamine polyphosphate, aluminum hypophosphite, aluminum diethylphosphite, tri(2-chloroethyl) phosphate, and tri(2,3-dichloropropyl) phosphate.

6. The method as described in claim 2, characterized in that, The antioxidant is at least one of antioxidant 168, antioxidant 1010, antioxidant 1024, antioxidant 1076, and antioxidant 1098.

7. The method as described in claim 2, characterized in that, The lubricant is at least one of stearic acid, calcium stearate, and ethylene bis-stearamide.

8. The application of the composite polypropylene material as described in claim 1 in building materials, characterized in that, Application in hollow floor slabs.