Polypropylene material, method for preparing the same and use thereof

Abstract

The application relates to the field of polypropylene materials, in particular to a polypropylene material and a preparation method and application thereof. The polypropylene material comprises the following components calculated according to mass parts: 60-90 parts of polypropylene resin; 25-35 parts of composite filler; 0.05-1 part of nucleating agent; 0.1-1 part of antioxidant; and 0.1-1 part of lubricant. The inorganic nanoparticles are subjected to silanization treatment through gamma-methacryloxypropyl trimethoxysilane, then the silanized inorganic nanoparticles are mixed with melamine polyphosphate and melamine cyanurate at 85-105 DEG C to obtain the composite filler, so that the inorganic nanoparticles, the melamine polyphosphate and the melamine cyanurate are uniformly dispersed in the polypropylene material and good interfacial compatibility is achieved, and the polypropylene material has excellent strength, toughness and flame retardance.

Description

Technical Field

[0001] This application relates to the field of polypropylene materials, specifically to a polypropylene material, its preparation method, and its application. Background Technology

[0002] Polypropylene resin, characterized by its low density, good processing fluidity, excellent chemical resistance, and relatively low price, has been widely used in automotive parts, home appliances, electronics, packaging materials, and building materials. However, ordinary polypropylene resin suffers from poor toughness, poor flame retardancy, and insufficient strength, which limits its application in scenarios requiring high strength, high toughness, and high flame retardancy.

[0003] In existing technologies, polypropylene is typically modified by adding additives such as inorganic fillers, elastomers, and flame retardants. Inorganic fillers can improve the strength of polypropylene materials, but traditional inorganic fillers are mostly micron-sized materials, sacrificing toughness while increasing strength. Elastomers can improve the toughness of polypropylene materials to some extent, but this also leads to a decrease in strength properties, and the toughening effect is limited. The use of halogenated flame retardants can easily cause environmental pollution, while nitrogen-based and phosphorus-based flame retardants often have poor compatibility with the polypropylene matrix, easily agglomerating, which not only worsens the flame retardant effect but also leads to a decrease in the material's mechanical properties. While compatibilizers can improve the interfacial compatibility between the additives and the polypropylene matrix, their ability to synergistically regulate the inorganic filler system, the elastomer toughening system, and the flame retardant filler system is limited, making it difficult to achieve a balance between reinforcement, toughening, and improved flame retardancy in modified polypropylene materials.

[0004] Therefore, how to achieve uniform dispersion of modifiers in polypropylene systems and good interfacial compatibility through reasonable design, while simultaneously improving the strength, toughness, and flame retardancy of polypropylene materials, is a technical problem that urgently needs to be solved in the field of polypropylene material modification. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a polypropylene material, its preparation method, and its application. Inorganic nanoparticles are silanized and modified with γ-methacryloxypropyltrimethoxysilane, and then mixed with melamine polyphosphate and melamine cyanurate at 85℃-105℃ to obtain a composite filler. This process helps to uniformly disperse the inorganic nanoparticles, melamine polyphosphate, and melamine cyanurate particles in the polypropylene material and achieve good interfacial compatibility, thereby comprehensively improving the strength, toughness, and flame retardancy of the polypropylene material.

[0006] The first aspect of this application provides a polypropylene material comprising the following components by mass: 60-90 parts polypropylene resin; 25-35 parts composite filler; 0.05-1 part nucleating agent; 0.1-1 part antioxidant; and 0.1-1 part lubricant. The method for preparing the composite filler includes the following steps: S1, dispersing inorganic nanoparticles in a mixed solvent of anhydrous ethanol and deionized water, adjusting the pH to 4-5 after uniform mixing, adding γ-methacryloyloxypropyltrimethoxysilane dropwise, and stirring the reaction at 60℃-80℃ to obtain silanized inorganic nanoparticles; S2, mixing the silanized inorganic nanoparticles obtained in step S1, melamine polyphosphate, and melamine cyanurate at 85℃-105℃, and cooling to obtain the composite filler.

[0007] Inorganic nanoparticles, due to their nanosize effect and interfacial interaction, can simultaneously strengthen and toughen polypropylene resin when used to modify it. However, due to the poor compatibility between inorganic nanoparticles and polypropylene resin, they are prone to agglomeration, making it difficult to obtain high-performance polypropylene materials when used directly. The applicant's research found that silanizing inorganic nanoparticles to introduce organic segments on the surface can reduce the polarity difference between inorganic nanoparticles and polypropylene resin, improve their wettability and dispersion stability in the resin matrix, reduce agglomeration, and form a good interfacial bond with polypropylene resin. When the material is subjected to external impact, stress can be efficiently transferred from polypropylene resin to the nanoparticle network, avoiding excessive local stress, thereby effectively improving the strength and toughness of polypropylene materials. Melamine polyphosphate and melamine cyanurate, as flame retardants, can form a highly efficient intumescent flame retardant system through synergistic effects during combustion. However, melamine polyphosphate and melamine cyanurate also have poor compatibility and are prone to agglomeration with polypropylene resin, which not only reduces the flame retardant effect but also leads to a decrease in the mechanical properties of the material. The applicant further discovered through research that pre-heat mixing silanized inorganic nanoparticles, melamine polyphosphate, and melamine cyanurate at 85℃-105℃ helps to improve the flame retardant properties, strength, and toughness of polypropylene materials. This may be because after using γ-methacryloxypropyltrimethoxysilane as a silane coupling agent to modify inorganic nanoparticles, the surface of the silanized inorganic nanoparticles has ester groups (-COO-). During the pre-heat mixing process, the organic segments on the surface of the silanized inorganic nanoparticles acquire sufficient mobility, which is conducive to the formation of hydrogen bonds between the ester groups and the polar groups (e.g., -NH2) on the surface of melamine polyphosphate and melamine cyanurate particles. This enables the inorganic nanoparticles to adsorb melamine polyphosphate and melamine cyanurate particles, and the melamine polyphosphate and melamine cyanurate particles are distributed in the inorganic nanoparticles. The formation of inorganic nanoparticle-flame retardant particle composite fillers in the gaps between nanoparticles is beneficial for the uniform dispersion of melamine polyphosphate and melamine cyanurate in polypropylene materials, reducing the adverse effects of local enrichment of flame retardants on the strength, toughness, and flame retardant properties of the material. However, directly mixing silanized inorganic nanoparticles, melamine polyphosphate, and melamine cyanurate with polypropylene resin for melt extrusion makes it difficult to form a structure in which flame retardant particles are distributed in the gaps between inorganic nanoparticles. Melamine polyphosphate and melamine cyanurate are prone to agglomeration in polypropylene materials, which deteriorates the strength, toughness, and flame retardancy of polypropylene materials.

[0008] In any embodiment, the inorganic nanoparticles in step S1 include nano-calcium carbonate and nano-silica; wherein the particle size of nano-calcium carbonate is 50nm-100nm, the particle size of nano-silica is 30nm-50nm, and the particle size of nano-calcium carbonate is larger than the particle size of nano-silica.

[0009] The applicant further discovered through research that using inorganic nanoparticles of two different sizes can further improve the flame retardancy, strength, and toughness of polypropylene materials. This may be because the small-sized silica can fill the gaps between the large-sized calcium carbonate particles, which is more conducive to the formation of good interfacial compatibility between the silanized inorganic nanoparticles and the polypropylene matrix, as well as the adsorption of melamine polyphosphate and melamine cyanurate particles. This further reduces the agglomeration probability of inorganic nanoparticles, melamine polyphosphate, and melamine cyanurate, thus further improving the strength, toughness, and flame retardancy of polypropylene materials. Moreover, nano-silica and nano-calcium carbonate can have a synergistic effect with melamine polyphosphate during combustion, improving the density of the expanded flame-retardant carbon layer, which is beneficial to further improving the flame retardancy of polypropylene materials.

[0010] In any embodiment, the mass ratio of nano-calcium carbonate to nano-silica in step S1 is 4:1-6:1.

[0011] Further experimental research in this application has revealed that when the mass ratio of nano-calcium carbonate to nano-silica is 4:1-6:1, it is more conducive to the formation of small-diameter silica particles filling the gaps between large-diameter calcium carbonate particles. This further enhances the compatibility between inorganic nanoparticles and polypropylene resin, as well as the adsorption of melamine polyphosphate and melamine cyanurate. It also further reduces the probability of agglomeration of inorganic nanoparticles, melamine polyphosphate, and melamine cyanurate, thereby further improving the strength, toughness, and flame retardancy of polypropylene materials.

[0012] In any embodiment, the mass percentage of γ-methacryloyloxypropyltrimethoxysilane in step S1 is 3%-7% of the mass of the inorganic nanoparticles.

[0013] Further experiments in this application have revealed that when the mass percentage of γ-methacryloxypropyltrimethoxysilane in the inorganic nanoparticles is 3%-7%, it not only ensures sufficient silanization of the inorganic nanoparticle surface but also reduces the probability of agglomeration caused by excessive silane coupling agent. This further enhances the strength, toughness, and flame retardancy of the polypropylene material while reducing production costs.

[0014] In any embodiment, the ratio of the mass of inorganic nanoparticles in step S1 to the total mass of melamine polyphosphate and melamine cyanurate in step S2 is 1:1 to 4:1.

[0015] When the mass ratio of inorganic nanoparticles to melamine polyphosphate and melamine cyanurate is within the above range, melamine polyphosphate and melamine cyanurate can achieve good dispersion in polypropylene materials, while also exhibiting excellent flame retardant effects and having a moderate impact on the mechanical properties of the materials. As a result, polypropylene materials possess excellent flame retardancy, strength, and toughness.

[0016] In any embodiment, the preparation method of the composite filler includes the following steps: S1, by mass, 18 parts of nano-calcium carbonate and 4 parts of nano-silica are dispersed in a mixed solvent of anhydrous ethanol and deionized water, mixed evenly, and the pH is adjusted to 4-5. 1.1 parts of γ-methacryloyloxypropyltrimethoxysilane are added dropwise, and the mixture is stirred at 60℃-80℃ for 2h-4h to obtain silanized inorganic nanoparticles; S2, by mass, the silanized inorganic nanoparticles obtained in step S1, 6 parts of melamine polyphosphate and 3 parts of melamine cyanurate are mixed at 85℃-105℃ and 1100r / min-1300r / min for 10min-30min, and the mixture is cooled to obtain the composite filler.

[0017] When the process parameters for preparing the composite filler are within the above range, the polypropylene material exhibits excellent flame retardancy, strength, and toughness.

[0018] In any embodiment, the nucleating agent includes one or more of sodium benzoate, dibenzyl sorbitol, 1,3:2,4-bis(3,4-dimethylbenzyl)sorbitol, sodium 2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate, bis[2,2'-methylenebis(4,6-di-tert-butylphenoxy)]hydroxyaluminum, and N,N'-dicyclohexyl-2,6-naphthalenediamide.

[0019] Nucleating agents can improve the crystallinity and crystallization rate of polypropylene resin, reduce the size of spherulites, shorten the molding cycle of polypropylene materials, and improve the transparency and mechanical properties of polypropylene materials.

[0020] In any embodiment, the lubricant includes one or more of calcium stearate, zinc stearate, ethylene bis-stearamide, polyethylene wax, oxidized polyethylene wax, pentaerythritol stearate, and silicone masterbatch.

[0021] Lubricants help reduce internal friction between polypropylene molecular chains, increase melt flow rate, and also help reduce the coefficient of friction between the melt and the mold, making injection molding, extrusion and other processes smoother.

[0022] In any embodiment, the antioxidant includes antioxidant 1010 and antioxidant 168.

[0023] The combined use of antioxidants 1010 and 168 is beneficial to improving the thermal stability and antioxidant properties of polypropylene materials.

[0024] A second aspect of this application provides a method for preparing a polypropylene material, the method comprising the following steps: By weight, 60-90 parts of polypropylene resin, 0.05-1 part of nucleating agent, 0.1-1 part of antioxidant, and 0.1-1 part of lubricant are added to the main feed port of the twin-screw extruder, and 25-35 parts of composite filler are added through the side feed port. The temperature of each zone of the twin-screw extruder is 160℃-210℃. After extrusion and drying, polypropylene material is obtained.

[0025] The applicant further discovered through research that adding the inorganic nanoparticle-flame retardant particle composite filler through the side filler port helps protect the structure of the inorganic nanoparticle-flame retardant particle composite filler, further reduces the agglomeration probability of melamine polyphosphate and melamine cyanurate, and further improves the strength, toughness and flame retardancy of polypropylene materials.

[0026] In any embodiment, the preparation method includes the following steps: by weight, 80 parts of polypropylene resin, 0.3 parts of nucleating agent, 0.5 parts of antioxidant, and 0.5 parts of lubricant are added to the main feed port of a twin-screw extruder, and 31 parts of composite filler and 0.16 parts of dicumyl peroxide are added through the side feed port. The temperature of each zone of the twin-screw extruder is 160℃-210℃. After extrusion and drying, polypropylene material is obtained.

[0027] The applicant further discovered through research that adding dicumyl peroxide through a side feed port further enhances the strength, toughness, and flame retardancy of polypropylene materials. This is likely because the surface of the inorganic nanoparticles modified with γ-methacryloxypropyltrimethoxysilane contains carbon-carbon double bonds, which, under the action of the catalyst dicumyl peroxide, can undergo free radical reactions with the polypropylene matrix. This helps to further enhance the interfacial bonding between the polypropylene resin and the inorganic nanoparticle-flame retardant composite filler, further reducing the agglomeration probability of inorganic nanoparticles, melamine polyphosphate, and melamine cyanurate, thus further improving the strength, toughness, and flame retardancy of the polypropylene material.

[0028] The third aspect of this application provides the application of polypropylene materials prepared by the method described in the first aspect or the second aspect in automobiles or home appliances.

[0029] In summary, this application has the following beneficial effects: The compatibility between inorganic nanoparticles treated with γ-methacryloxypropyltrimethoxysilane and polypropylene resin is improved, which helps to reduce the agglomeration probability of inorganic nanoparticles and effectively improve the strength and toughness of polypropylene materials. Silanized inorganic nanoparticles, melamine polyphosphate, and melamine cyanurate are premixed at 85℃-105℃. The ester groups on the surface of the silanized inorganic nanoparticles are adsorbed onto the surface of the melamine polyphosphate and melamine cyanurate particles through hydrogen bonding. The melamine polyphosphate and melamine cyanurate particles are distributed in the gaps between the inorganic nanoparticles to form an inorganic nanoparticle-flame retardant particle composite filler, which is beneficial to the uniform dispersion of melamine polyphosphate and melamine cyanurate in polypropylene materials, resulting in a comprehensive improvement in the strength, toughness, and flame retardant properties of polypropylene materials. By combining nano-calcium carbonate and nano-silica with two different particle sizes, the compatibility between silanized inorganic nanoparticles and polypropylene resin is further improved, as well as the adsorption and dispersion of melamine polyphosphate and melamine cyanurate particles. Furthermore, nano-calcium carbonate, nano-silica, and melamine polyphosphate can produce a synergistic effect during combustion, further enhancing the strength, toughness, and flame retardancy of polypropylene materials.

[0030] By controlling the mass ratio of nano-calcium carbonate to nano-silica, the percentage of γ-methacryloyloxypropyltrimethoxysilane in the mass of inorganic nanoparticles, and the mass ratio of inorganic nanoparticles to flame retardants, the strength, toughness, and flame retardancy of polypropylene materials are further improved. Adding the composite filler through the side feed port helps protect the structure of the inorganic nanoparticle-flame retardant particle composite filler, and further improves the strength, toughness and flame retardancy of the polypropylene material.

[0031] (5) Adding dicumyl peroxide through the side feed port is beneficial to further enhance the interfacial bonding between polypropylene resin and inorganic nanoparticles, and to form a uniformly dispersed anchoring structure between inorganic nanoparticle-flame retardant particle composite filler and polypropylene resin, thereby further improving the strength, toughness and flame retardancy of polypropylene materials. Attached Figure Description

[0032] Figure 1 These are scanning electron microscope images of the composite filler prepared in Example 1 of this application; Detailed Implementation

[0033] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents. The present application will be further described in detail below with reference to embodiments and comparative examples.

[0034] Example 1

[0035] S1. By mass, 22 parts of nano-calcium carbonate (purchased from Xianfeng Nano, particle size: 50nm-100nm) were dried at 105℃ for 2h, cooled to 25℃, and then added to a reaction vessel along with 88 parts of anhydrous ethanol and 12 parts of deionized water. The mixture was dispersed at 600r / min for 30min to obtain an inorganic nanoparticle dispersion. Glacial acetic acid was added to the inorganic nanoparticle dispersion to adjust the pH of the system to 4.5. Under stirring at 600r / min, 1.1 parts of γ-methacryloyloxypropyltrimethoxysilane (purity ≥99%) were added dropwise at a rate of 0.2 parts / min. After the addition was completed, the temperature was raised to 65℃ and reacted at 900r / min for 3h. After the reaction was completed, the mixture was filtered, and the filter cake was washed twice with anhydrous ethanol. The washed filter cake was then vacuum dried at 80℃ and -0.090MPa for 6h to obtain silanized inorganic nanoparticles. S2. The silanized inorganic nanoparticles obtained in step S1, 6 parts of melamine polyphosphate (purchased from Shandong Shouguang Weidong Chemical Co., Ltd., brand name FR-NP) and 3 parts of melamine cyanurate (purchased from Shandong Shouguang Weidong Chemical Co., Ltd., brand name MC15) are added to a high-speed mixing device and mixed at 95℃ and 1200r / min for 20min. After mixing is completed, heating is stopped and stirring is continued at 300r / min to cool to 40℃ to obtain the composite filler. S3. Weigh 80 parts by weight of polypropylene resin (purchased from Yanshan Petrochemical, grade K7100, melt flow rate 105 g / 10 min, tensile yield strength 23.5 MPa, notched impact strength at 23℃ and simple support beam 6.5 KJ / m). 20.3 parts of 2,2'-methylene bis(4,6-di-tert-butylphenyl) phosphate, 0.3 parts of antioxidant 1010 (Tianjin Lialong RIANOX), 0.2 parts of antioxidant 168 (Tianjin Lialong RIANOX), and 0.5 parts of ethylene bis-stearamide; 80 parts of dried polypropylene resin were dried at 80℃ for 3 hours. The dried polypropylene resin, 0.3 parts of 2,2'-methylene bis(4,6-di-tert-butylphenyl) phosphate, 0.3 parts of antioxidant 1010, 0.2 parts of antioxidant 168, and 0.5 parts of ethylene bis-stearamide were then mixed evenly in a high-speed mixer to obtain a premix. The premixed material was added to the main feed port of the twin-screw extruder, and 31 parts of the composite filler obtained in step S2 were added through the side feed port, which was set in the fourth temperature zone of the twin-screw extruder. The temperatures of zones one to eight of the twin-screw extruder were set to 165℃, 175℃, 185℃, 195℃, 205℃, 205℃, 200℃ and 195℃ respectively, the die head temperature was set to 195℃, the screw speed was 240 r / min, the vacuum degree of the vacuum exhaust section was -0.080 MPa, and the residence time of the material in the screw was 90s. After melt grafting, dispersion anchoring and extrusion stranding, the extrudate was stranded and cooled in a 25℃ water bath, and then air-dried for 30 minutes before being pelletized to obtain polypropylene material.

[0036] Example 2

[0037] The preparation methods of Example 2 and Example 1 are basically the same, except that in step S1, 22 parts of nano calcium carbonate are replaced with 18 parts of nano calcium carbonate (purchased from Xianfeng Nano, particle size: 50nm-100nm) and 4 parts of nano silica (purchased from Hangzhou Jikang New Materials, particle size: 30nm-50nm), and the rest is the same as in Example 1.

[0038] Example 3

[0039] The preparation methods of Example 3 and Example 1 are basically the same, except that in step S1, 22 parts of nano calcium carbonate are replaced with 17.6 parts of nano calcium carbonate (purchased from Xianfeng Nano, particle size: 50nm-100nm) and 4.4 parts of nano silica (purchased from Hangzhou Jikang New Materials, particle size: 30nm-50nm), and the rest is the same as in Example 1.

[0040] Example 4

[0041] The preparation method of Example 4 is basically the same as that of Example 1, except that in step S1, 22 parts of nano calcium carbonate are replaced with 18.8 parts of nano calcium carbonate (purchased from Xianfeng Nano, particle size: 50nm-100nm) and 3.2 parts of nano silica (purchased from Hangzhou Jikang New Materials, particle size: 30nm-50nm), and the rest is the same as in Example 1.

[0042] Example 5

[0043] The preparation methods of Example 5 and Example 2 are basically the same, except that in step S2, 6 parts of melamine polyphosphate and 3 parts of melamine cyanurate are replaced with 3.7 parts of melamine polyphosphate and 1.8 parts of melamine cyanurate, and in step S3, the number of parts of composite filler is 27.5 parts, and the rest is the same as in Example 2.

[0044] Example 6

[0045] The preparation methods of Example 6 and Example 2 are basically the same, except that in step S2, 6 parts of melamine polyphosphate and 3 parts of melamine cyanurate are replaced with 7.3 parts of melamine polyphosphate and 3.7 parts of melamine cyanurate, and in step S3, the number of parts of composite filler is 33 parts, and the rest is the same as in Example 2.

[0046] Example 7

[0047] The preparation methods of Example 7 and Example 2 are basically the same, except that in step S3, "add the premix to the main feed port of the twin-screw extruder and add 31 parts of the composite filler obtained in step S2 through the side feed port" is replaced with "add the premix and 31 parts of the composite filler obtained in step S2 together through the main feed port of the twin-screw extruder". Everything else is the same as in Example 2.

[0048] Example 8

[0049] The preparation methods of Example 8 and Example 2 are basically the same, except that: in step S3, "add 31 parts of the composite filler obtained in step S2 through the side feed port" is changed to "add 31 parts of the composite filler obtained in step S2 and 0.16 parts of dicumyl peroxide through the side feed port", and the rest is the same as in Example 2.

[0050] Comparative Example 1 The preparation methods of Comparative Example 1 and Example 1 are basically the same, except that in step S1, 22 parts of nano calcium carbonate are replaced with 22 parts of calcium carbonate with a particle size of 5 μm. Otherwise, they are the same as in Example 1.

[0051] Comparative Example 2 The preparation method of Comparative Example 2 is basically the same as that of Example 1, except that in step S1, 1.1 parts of γ-methacryloyloxypropyltrimethoxysilane are replaced with 1.1 parts of methyltrimethoxysilane, and the rest is the same as that of Example 1.

[0052] Comparative Example 3 The preparation method of Comparative Example 3 is basically the same as that of Example 1, except that in step S2 "mixing at 95°C and 1200r / min for 20min", the temperature is adjusted to 25°C, and the rest is the same as that of Example 1.

[0053] Performance testing To evaluate the comprehensive performance of the polypropylene materials obtained in this invention, performance tests were conducted on the polypropylene materials obtained in Examples 1-8 and Comparative Examples 1-3. Before testing, the polypropylene granules of each group were dried in an 80℃ forced-air drying oven for 3 hours. After drying, standard samples were injection molded using an injection molding machine. The temperatures of zones one to four of the injection molding machine barrel were set to 190℃, 200℃, 210℃, and 205℃ respectively; the nozzle temperature was set to 205℃; the mold temperature was set to 40℃; the injection pressure was set to 80MPa; the holding pressure was set to 50MPa; the holding time was set to 12s; and the cooling time was set to 25s. The injection-molded samples were placed in an environment of 23℃ and 50% relative humidity for 24 hours before testing.

[0054] Tensile strength was tested according to the method specified in GB / T 1040.2. A type 1A dumbbell-shaped specimen was used, with a total length of 170 mm, a narrow parallel section width of 10 mm, and a thickness of 4 mm. During testing, the specimen was fixed in the fixture of an electronic universal testing machine, with the initial distance between the fixtures set to 75 mm and the tensile speed set to 50 mm / min. The maximum tensile stress and elongation at break were recorded.

[0055] The limiting oxygen index (OI) was tested according to the method specified in GB / T 2406.2. The sample size was 80 mm × 10 mm × 4 mm. During the test, the sample was vertically fixed inside the combustion chamber of the oxygen index tester. The top of the sample was ignited, and the flow rates of oxygen and nitrogen were repeatedly adjusted using the "lifting method." Based on the specified combustion criteria (flaming combustion time exceeding 180 s or flame burning past the 50 mm mark), the minimum oxygen concentration (expressed as a volume fraction) required to maintain combustion of the sample was statistically calculated, which is the limiting oxygen index (OI) of the sample. The higher the limiting oxygen index value of the material, the better its flame retardant performance.

[0056] The notched impact strength of a simply supported beam was tested according to the method specified in GB / T 1043.1. The specimen dimensions were 80mm × 10mm × 4mm, using a type A notch with a depth of 2.0mm and a bottom radius of 0.25mm. Before testing, the specimen was conditioned for at least 24 hours at a temperature of (23±2)℃ and a relative humidity of (50±10)%. During testing, the specimen was placed horizontally on the two supports of the simply supported beam impact testing machine, with the notch facing away from the impact hammer. The pendulum was released to impact the specimen, and the energy absorbed when the specimen fractured was recorded. The formula for calculating the notched impact strength of a simply supported beam is the absorbed energy divided by the remaining cross-sectional area at the notch of the specimen, expressed in kJ / m². 2 .

[0057] The test results of the polypropylene materials obtained in Examples 1-8 and Comparative Examples 1-3 are shown in Table 1.

[0058] Table 1 Performance test results of polypropylene materials in Examples 1-8 and Comparative Examples 1-3

[0059] from Figure 1 It can be seen that the inorganic nanoparticles in the prepared composite filler are adsorbed on the surface of the flame retardant particles, which is beneficial to the uniform dispersion of the flame retardant particles in the polypropylene material.

[0060] Referring to Table 1, comparing the test results of Examples 1-8 of this application with those of Comparative Examples 1-3, it can be seen that, compared to Comparative Example 1 which uses micron-sized calcium carbonate, Comparative Example 2 which uses methyltrimethoxysilane as a silane coupling agent, and Comparative Example 3 which mixes silanized inorganic nanoparticles, melamine polyphosphate, and melamine cyanurate at room temperature, the examples of this application use γ-methacryloyloxypropyltrimethoxysilane to silanize inorganic nanoparticles, and then premix the silanized inorganic nanoparticles with melamine polyphosphate and melamine cyanurate at 85℃-105℃ to obtain a silanized inorganic nanoparticle-flame retardant particle composite filler. The tensile strength, toughness, and flame retardancy of the polypropylene material are improved.

[0061] In Comparative Example 1, the addition of micron-sized calcium carbonate helps improve the tensile strength of polypropylene materials, but it deteriorates their toughness. Furthermore, due to the large particle size of micron-sized calcium carbonate, its adsorption effect on flame retardant particles is poor during preheating and mixing with melamine polyphosphate and melamine cyanurate. The flame retardant particles struggle to achieve excellent dispersion and are prone to agglomeration in the polypropylene material, negatively impacting its toughness and tensile strength, while offering limited improvement in flame retardancy. In Comparative Example 2, methyltrimethoxysilane was used as a silane coupling agent. During the premixing of silanized inorganic nanoparticles with melamine polyphosphate and melamine cyanurate, the lack of ester groups on the surface of the inorganic nanoparticles resulted in weak hydrogen bonding with the flame retardant particles. This led to poor adsorption and dispersion of the flame retardant, making it prone to agglomeration and hindering improvements in the tensile strength, toughness, and flame retardancy of the polypropylene material. Comparative Example 3, which mixes silanized inorganic nanoparticles, melamine polyphosphate, and melamine cyanurate at room temperature, is not conducive to the formation of hydrogen bonds between the silanized inorganic nanoparticles and the melamine polyphosphate and melamine cyanurate particles. This increases the probability of flame retardant agglomeration and is not conducive to improving the tensile strength, toughness, and flame retardancy of polypropylene materials.

[0062] As can be seen from the comparison between Examples 2-4 and Example 1, the inorganic nanoparticles, including nano-calcium carbonate and nano-silica, further improve the tensile strength, toughness and flame retardancy of polypropylene materials.

[0063] As can be seen from Examples 2-4, when the mass ratio of nano-calcium carbonate to nano-silica is 4:1-6:1, the polypropylene material exhibits excellent tensile strength, toughness, and flame retardancy.

[0064] As can be seen from Examples 2, 5, and 6, the mass ratio of inorganic nanoparticles to the total mass of melamine polyphosphate and melamine cyanurate is 1:1 to 4:1, and the polypropylene material has excellent tensile strength, toughness, and flame retardancy.

[0065] As can be seen from the comparison between Example 2 and Example 7, feeding the composite filler through the side feed port helps to maintain the integrity of the silanized inorganic nanoparticle-flame retardant particle composite filler structure, and further improves the tensile strength, toughness and flame retardancy of polypropylene material.

[0066] As can be seen from the comparison between Example 8 and Example 2, the tensile strength, toughness and flame retardancy of polypropylene material are further improved by adding dicumyl peroxide through the side feed port during the preparation process of polypropylene material.

[0067] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A polypropylene material, characterized in that, The polypropylene material comprises the following components in parts by weight: 60-90 parts of polypropylene resin; 25-35 parts of composite filler; Nucleating agent 0.05-1 part; Antioxidant 0.1 to 1 part; Lubricant 0.1-1 part; The method for preparing the composite filler includes the following steps: S1. Inorganic nanoparticles are dispersed in a mixed solvent of anhydrous ethanol and deionized water. After mixing evenly, the pH is adjusted to 4-5, and γ-methacryloyloxypropyltrimethoxysilane is added dropwise. The mixture is stirred at 60℃-80℃ to obtain silanized inorganic nanoparticles. The inorganic nanoparticles include nano-calcium carbonate and nano-silica. The particle size of the nano-calcium carbonate is 50nm-100nm, and the particle size of the nano-silica is 30nm-50nm. The particle size of the nano-calcium carbonate is larger than that of the nano-silica. The mass ratio of the nano-calcium carbonate to the nano-silica is 4:1-6:

1. S2. The silanized inorganic nanoparticles, melamine polyphosphate, and melamine cyanurate obtained in step S1 are mixed at 85℃-105℃ and cooled to obtain a composite filler; wherein, the mass ratio of the inorganic nanoparticles in step S1 to the total mass of melamine polyphosphate and melamine cyanurate in step S2 is 1:1-4:

1.

2. The polypropylene material according to claim 1, characterized in that, In step S1, the mass percentage of γ-methacryloyloxypropyltrimethoxysilane to the mass of the inorganic nanoparticles is 3%-7%.

3. The polypropylene material according to claim 1, characterized in that, The method for preparing the composite filler includes the following steps: S1. By mass, 18 parts of nano-calcium carbonate and 4 parts of nano-silica are dispersed in a mixed solvent of anhydrous ethanol and deionized water. After mixing evenly, the pH is adjusted to 4-5, and 1.1 parts of γ-methacryloyloxypropyltrimethoxysilane are added dropwise. The mixture is stirred at 60℃-80℃ for 2-4 hours to obtain silanized inorganic nanoparticles. S2. By mass, the silanized inorganic nanoparticles obtained in step S1, 6 parts of melamine polyphosphate and 3 parts of melamine cyanurate are mixed at 85℃-105℃ and 1100r / min-1300r / min for 10min-30min, and then cooled to obtain the composite filler.

4. The polypropylene material according to claim 1, characterized in that, The nucleating agent includes one or more of sodium benzoate, dibenzyl sorbitol, 1,3:2,4-bis(3,4-dimethylbenzyl)sorbitol, sodium 2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate, bis[2,2'-methylenebis(4,6-di-tert-butylphenoxy)]hydroxyaluminum, and N,N'-dicyclohexyl-2,6-naphthalenedicarboxamide; the lubricant includes one or more of calcium stearate, zinc stearate, ethylene bis-stearamide, polyethylene wax, oxidized polyethylene wax, pentaerythritol stearate, and silicone masterbatch; the antioxidant includes antioxidant 1010 and antioxidant 168.

5. The method for preparing polypropylene material according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: By weight, 60-90 parts of polypropylene resin, 0.05-1 part of nucleating agent, 0.1-1 part of antioxidant, and 0.1-1 part of lubricant are added to the main feed port of a twin-screw extruder, and 25-35 parts of the composite filler are added through the side feed port. The temperature of each zone of the twin-screw extruder is 160℃-210℃. After extrusion and drying, the polypropylene material is obtained.

6. The method for preparing polypropylene material according to claim 5, characterized in that, The preparation method includes the following steps: By weight, 80 parts of polypropylene resin, 0.3 parts of nucleating agent, 0.5 parts of antioxidant, and 0.5 parts of lubricant are added to the main feed port of a twin-screw extruder, and 31 parts of composite filler and 0.16 parts of dicumyl peroxide are added through the side feed port. The temperature of each zone of the twin-screw extruder is 160℃-210℃. After extrusion and drying, the polypropylene material is obtained.

7. The application of a polypropylene material as described in any one of claims 1-4 or a polypropylene material prepared by the preparation method as described in any one of claims 5 or 6 in automobiles or home appliances.

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