High-performance polypropylene material and preparation process thereof

Abstract

The invention discloses a high-performance polypropylene material and a preparation process thereof. The polypropylene material comprises the following raw material components in parts by weight: 100 parts of polypropylene resin; 8 to 26 parts of montmorillonite-based multi-effect filler; 1-9 parts of a compatilizer; and 0.2-4 parts of a lubricant. According to the invention, by adding the montmorillonite-based multi-effect filler formed by multiple reinforcing components into the polypropylene, the flame retardance, thermo-oxidative aging resistance and ultraviolet aging resistance of the polypropylene can be improved, meanwhile, the mechanical properties of the polypropylene are improved to a certain extent, and the comprehensive properties of the polypropylene can be improved; therefore, the application effect is improved, and the application scene is widened.

Description

Technical Field

[0001] The present invention relates to the field of high-performance polypropylene materials, and particularly to a high-performance polypropylene material and its preparation process. Background Art

[0002] Polypropylene (PP for short) is a semi-crystalline thermoplastic polymer made from propylene monomers through a polyaddition reaction. It has the advantages of low density, good mechanical properties, high chemical stability, easy processing and molding, good heat resistance, high transparency and excellent mechanical properties, and is widely used in fiber products, household appliances, automotive parts manufacturing, medical devices, building materials and other products.

[0003] However, polypropylene has the defect of poor flame retardancy, posing a great safety hazard in case of fire, which makes the demand for flame-retardant polypropylene materials increase day by day. Adding flame retardants is an effective solution to improve the flame retardancy of polypropylene. For example, a graphene-modified flame-retardant polypropylene material and its preparation method disclosed in Patent CN115368673B, a halogen-free flame-retardant polypropylene material and its preparation method disclosed in Patent CN117700885B, a high-temperature flame-retardant modified polypropylene material and its preparation method disclosed in Patent CN118725464B, a long glass fiber-reinforced flame-retardant ceramized polypropylene material and its preparation method disclosed in Patent CN119899455A, a polypropylene material with a high flame retardant content and its preparation method disclosed in Patent CN119859346A, etc.

[0004] However, traditional flame-retardant materials have exposed many defects in the actual application process: (1) The flame retardants are not evenly dispersed in the PP system and easily deteriorate the mechanical strength of the PP matrix; (2) The flame retardants are prone to surface migration and other phenomena in the system and become ineffective, making it difficult to provide long-term flame retardant performance.

[0005] In addition, when applied to high-temperature scenarios or outdoor scenarios, traditional polypropylene materials will face the problems of thermal-oxidative aging and ultraviolet aging, greatly reducing their service life and use effect. The reason for thermal-oxidative aging is that when the polypropylene system is attacked by oxygen, the molecular chains will break, forming free radicals. These free radicals further react with oxygen to generate peroxides, and the peroxides will decompose under unstable conditions to form more free radicals, thus accelerating the degradation of the material. Polypropylene is relatively sensitive to ultraviolet light, and ultraviolet light will damage the molecular chains of polypropylene materials and accelerate the aging process. Therefore, improving the anti-aging performance of polypropylene materials can improve their service life and use effect, and can meet the needs of more application scenarios. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a high-performance polypropylene material and its preparation process in view of the deficiencies in the above-mentioned prior art.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is: a high-performance polypropylene material, comprising the following raw material components by weight:

[0008] 100 parts of polypropylene resin;

[0009] 8-26 parts of montmorillonite-based multi-functional filler;

[0010] 1-9 parts of compatibilizer;

[0011] 0.2-4 parts of lubricant;

[0012] The montmorillonite-based multi-functional filler is prepared by the following steps:

[0013] S1. Load carbon dots on montmorillonite to prepare a montmorillonite-carbon dot composite;

[0014] S2. Graft nano-mesoporous alumina onto the montmorillonite-carbon dot composite to prepare an alumina-montmorillonite-carbon dot composite particle;

[0015] S3. Perform an organic intercalation treatment on the alumina-montmorillonite-carbon dot composite particle to obtain an organic composite particle;

[0016] S4. Load a flame retardant on the organic composite particle by an impregnation method to obtain a flame retardant-modified composite particle;

[0017] S5. Graft a poly(methyl methacrylate)-acrylamide block copolymer onto the flame retardant-modified composite particle to obtain a montmorillonite-based multi-functional filler.

[0018] Preferably, the montmorillonite-based multi-functional filler is prepared by the following steps:

[0019] S1. Prepare a montmorillonite-carbon dot composite:

[0020] Soak montmorillonite in sulfuric acid and then add it to an aqueous solution of Bi(NO3)3, dropwise add ammonia water, age, filter, dry, and calcine to obtain intercalated montmorillonite; mix oxalic acid, glucose, 4-aminophenol with the intercalated montmorillonite in a mixed solution of ethanol and deionized water, and prepare a montmorillonite-carbon dot composite through a hydrothermal reaction;

[0021] S2. Mix the montmorillonite-carbon dot composite and zinc nitrate in deionized water to obtain dispersion liquid 1; disperse nano-mesoporous alumina in deionized water, add the obtained dispersion liquid 2 to dispersion liquid 1, then add a NaOH solution, and add the obtained product to a reaction kettle to prepare an alumina-montmorillonite-carbon dot composite particle through a hydrothermal reaction;

[0022] S3. Disperse the alumina-montmorillonite-carbon dot composite particles in an ethanol aqueous solution, add N-triethyl-(4-vinylbenzyl)ammonium chloride, heat and stir, filter and dry to obtain organically modified composite particles;

[0023] S4. Add phytic acid and ammonium polyphosphate to deionized water to prepare an impregnation solution; add the organically modified composite particles to the impregnation solution for impregnation treatment, and obtain flame retardant modified composite particles after impregnation;

[0024] S5. Disperse the flame retardant modified composite particles and polyvinyl alcohol in deionized water, then add methyl methacrylate and benzoyl peroxide, and heat to react to obtain a prepolymer mixture; add acrylamide, methyl methacrylate and benzoyl peroxide to the prepolymer mixture, and heat to react to obtain montmorillonite-based multi-functional filler.

[0025] Preferably, the montmorillonite-based multi-functional filler is prepared through the following steps:

[0026] S1. Prepare a montmorillonite-carbon dot composite:

[0027] S1-1. Immerse montmorillonite in a sulfuric acid solution, take it out, wash it, add it to an aqueous Bi(NO3)3 solution, dropwise add ammonia water under stirring to adjust the pH, age, filter, wash and dry the product, then calcine it in a muffle furnace and grind it to obtain supported montmorillonite;

[0028] S1-2. Load carbon dots on the supported montmorillonite;

[0029] Add the supported montmorillonite, ethanol, and oxalic acid to deionized water, ultrasonically disperse, then add glucose and 4-aminophenol, stir under nitrogen protection, add the obtained mixture to a reaction kettle, react under heating, after the reaction is completed, centrifuge and filter, wash and dry the solid product to obtain a montmorillonite-carbon dot composite;

[0030] S2. Prepare alumina-montmorillonite-carbon dot composite particles:

[0031] S2-1. Take the montmorillonite-carbon dot composite and add it to deionized water, ultrasonically disperse, then add zinc nitrate and stir to obtain dispersion liquid 1;

[0032] S2-2. Take nano-mesoporous alumina and add it to deionized water, ultrasonically disperse, add the obtained dispersion liquid 2 to dispersion liquid 1 under stirring, then add NaOH solution and stir, transfer the obtained product to a reaction kettle, react under heating, after the reaction is completed, centrifuge and filter, wash and dry the solid product to obtain alumina-montmorillonite-carbon dot composite particles;

[0033] S3. Prepare organically modified composite particles:

[0034] The alumina-montmorillonite-carbon dot composite particles are added to an ethanol aqueous solution, ultrasonically dispersed, N-triethyl-(4-vinylbenzyl)ammonium chloride is added, and the mixture is sealed and stirred under heating, cooled, filtered, washed, and dried to obtain organically modified composite particles;

[0035] S4. Preparation of flame-retardant modified composite particles:

[0036] Phytic acid and ammonium polyphosphate are added to deionized water to prepare an impregnating solution; the organically modified composite particles are added to the impregnating solution, subjected to oscillation treatment, suction filtered, the solid product is rinsed with deionized water, and dried to obtain flame-retardant modified composite particles.

[0037] S5. Grafting a poly(methyl methacrylate)-acrylamide block copolymer onto the flame-retardant modified composite particles:

[0038] S5-1. The flame-retardant modified composite particles and polyvinyl alcohol are added to deionized water, ultrasonically dispersed, then methyl methacrylate is added, nitrogen is passed through and stirred, benzoyl peroxide is added, and the reaction is carried out under heating to obtain a prepolymer mixture;

[0039] S5-2. Acrylamide, methyl methacrylate, and benzoyl peroxide are added to the prepolymer mixture, and the reaction is carried out under heating. After the reaction is completed, it is cooled, filtered, washed, and dried to obtain a montmorillonite-based multi-functional filler.

[0040] Preferably, step S1 specifically includes:

[0041] S1-1. 2.5-10 g of montmorillonite is added to a 5-30 wt% sulfuric acid solution and soaked for 5-20 h. After taking it out, it is washed with deionized water, then added to 100-400 mL of a Bi(NO3)3 aqueous solution with a concentration of 0.025-0.1 mol / L, stirred for 5-30 min, and 5-20 wt% ammonia water is added dropwise under stirring to adjust the pH to 8-9, aged for 8-24 h, filtered, the product is washed with deionized water, dried at 70-90 °C for 3-12 h, and then calcined in a muffle furnace at 400-500 °C for 1-4 h, and ground to obtain supported-layer treated montmorillonite;

[0042] S1-2. Loading carbon dots on the supported-layer treated montmorillonite;

[0043] 2.5 - 10 g of exfoliated montmorillonite, 50 - 200 mL of ethanol, and 0.81 - 3.24 g of oxalic acid are added to 150 - 600 mL of deionized water, ultrasonically dispersed for 10 - 40 min, then 0.9 - 3.6 g of glucose and 0.272 - 1.09 g of 4 - aminophenol are added, and the mixture is stirred for 15 - 60 min under nitrogen protection. The resulting mixture is added to a reaction kettle with a polytetrafluoroethylene liner and reacted at 140 - 170 °C for 6 - 24 h. After centrifugation and filtration, the solid product is washed with deionized water and vacuum - dried at 90 - 110 °C for 4 - 16 h to obtain the montmorillonite - carbon dot composite.

[0044] Preferably, step S2 specifically includes:

[0045] S2 - 1: Take 1 - 4 g of the montmorillonite - carbon dot composite and add it to 25 - 100 mL of deionized water, ultrasonically disperse for 5 - 30 min, then add 0.29 - 1.16 g of zinc nitrate, and stir for 0.5 - 2 h to obtain dispersion liquid 1;

[0046] S2 - 2: Take 0.6 - 2.4 g of nano - mesoporous alumina and add it to 25 - 100 mL of deionized water, ultrasonically disperse for 10 - 40 min. The resulting dispersion liquid 2 is added to dispersion liquid 1 under stirring, and then 7.5 - 30 mL of a NaOH solution with a concentration of 0.5 - 2 mol / L is added, and the mixture is stirred for 15 - 60 min. The resulting product is transferred to a reaction kettle with a polytetrafluoroethylene liner and reacted at 150 - 180 °C for 5 - 20 h. After cooling to room temperature, centrifugation and filtration are carried out. The solid product is washed with deionized water and vacuum - dried at 70 - 100 °C for 6 - 24 h to obtain the alumina - montmorillonite - carbon dot composite particles;

[0047] Among them, the particle size of the nano - mesoporous alumina is 100 - 400 nm.

[0048] Preferably, step S3 specifically includes:

[0049] Take 10 - 40 g of the alumina - montmorillonite - carbon dot composite particles and add them to an ethanol - aqueous solution composed of 100 - 400 mL of deionized water and ethanol in a volume ratio of 1:1, ultrasonically disperse for 15 - 60 min, add 0.25 - 1 g of N - triethyl - (4 - vinylbenzyl) ammonium chloride, heat up to 60 - 90 °C, seal and stir for 4 - 16 h, let it stand for 6 - 24 h after cooling to room temperature, filter, wash with deionized water, and vacuum - dry at 70 - 100 °C for 3 - 12 h to obtain the organic - modified composite particles.

[0050] Preferably, step S4 specifically includes:

[0051] Phytic acid and ammonium polyphosphate (ammonium tripolyphosphate is selected in the preferred embodiment) are added to deionized water to prepare an impregnation solution with the mass dispersions of phytic acid and ammonium polyphosphate being 4-16% and 5-20% respectively;

[0052] Take 2.5-10 g of organic composite particles and add them to 75-300 mL of the impregnation solution. Oscillate and treat at 60-90 °C for 15-90 min, then filter by suction. Rinse the solid product with deionized water and vacuum dry at 60-80 °C for 4-16 h to obtain flame retardant modified composite particles.

[0053] Preferably, step S5 specifically includes:

[0054] S5-1: Take 5-20 g of flame retardant modified composite particles and 0.25-1 g of polyvinyl alcohol, add them to 75-300 mL of deionized water, ultrasonically disperse for 5-30 min, then add 7.5-30 g of methyl methacrylate, stir while passing nitrogen for 15-45 min, add 0.05-0.2 g of benzoyl peroxide, and react at 60-72 °C for 1-4 h to obtain a prepolymer mixture;

[0055] S5-2: Add 1.75-7 g of acrylamide, 2.5-10 g of methyl methacrylate, and 0.05-0.2 g of benzoyl peroxide to the prepolymer mixture, react at 70-75 °C for 2-6 h, then raise the temperature to 75-80 °C and react for 2-4 h. After cooling to room temperature, filter, wash the solid product with ethanol, and vacuum dry at 60-95 °C for 6-24 h to obtain montmorillonite-based multi-functional filler.

[0056] The main preparation process of the montmorillonite-based multi-functional filler of the present invention is as follows:

[0057] (1) First, acid-leach montmorillonite with sulfuric acid, then use Bi(NO3)3 for pillar modification of the acid-leached montmorillonite. After alkali precipitation and high-temperature calcination, Bi2O3 is formed to realize the layer support treatment of montmorillonite and expand its layer spacing; then, using oxalic acid, glucose, and 4-aminophenol as carbon sources, carbon dots are in-situ deposited on the surface of montmorillonite through hydrothermal reaction to obtain montmorillonite-carbon dot composite;

[0058] (2) Then, using zinc nitrate as a linker, connect nano-mesoporous alumina to the montmorillonite-carbon dot composite through a one-pot hydrothermal reaction to form alumina-montmorillonite-carbon dot composite particles;

[0059] (3) Next, use N-triethyl-(4-vinylbenzyl)ammonium chloride as an intercalating agent to perform organic intercalation treatment on the alumina-montmorillonite-carbon dot composite particles to obtain organic composite particles;

[0060] (4) Next, the organic composite particles are impregnated with a composite flame retardant: phytic acid and ammonium polyphosphate (ammonium tripolyphosphate is selected in the preferred embodiment), to obtain flame retardant modified composite particles;

[0061] (5) Finally, by means of in-situ polymerization, using methyl methacrylate as the main active monomer, acrylamide as the doping active monomer, and benzoyl peroxide as the initiator, poly(methyl methacrylate - acrylamide) block copolymer is grafted onto the flame retardant modified composite particles, ultimately obtaining the montmorillonite-based multi-functional filler.

[0062] The montmorillonite-based multi-functional filler includes various components with enhancing or improving effects, including: montmorillonite matrix, pillar modifier, carbon dots, nano-mesoporous alumina, zinc oxide, intercalating agent, flame retardant, poly(methyl methacrylate - acrylamide) block copolymer, etc. The mechanism of action of its main components is elaborated below for better understanding of the present invention.

[0063] I. Role of Pillared Montmorillonite

[0064] 1. Role of Montmorillonite:

[0065] Montmorillonite can improve the flame retardancy: Montmorillonite can migrate to the surface of polypropylene to form an inorganic silicon-oxygen-aluminum thermal shielding layer, protecting the matrix from heat erosion and improving the high-temperature stability of polypropylene.

[0066] Montmorillonite plays a role of heterogeneous nucleation in the PP system, increasing the crystallization rate and crystallinity, making the PP spherulites finer and more closely arranged, and improving the tensile strength and impact strength of PP (Chen Xiaosui. Study on the Structure and Properties of Montmorillonite and Fiber Reinforced Flame Retardant Polypropylene Composites [D]. Beijing University of Chemical Technology, 2011. DOI: 10.7666 / d.y1878210.). Montmorillonite also has a certain ultraviolet shielding effect, which helps to improve the anti-ultraviolet aging performance of PP.

[0067] In addition, the lamellar structure of montmorillonite forms a large number of nano-pores or cavities with high adsorption capacity, which can load a large amount of flame retardant. These loaded flame retardants can be confined between the montmorillonite lamellae, thus reducing their surface migration and failure in entering the PP system and deteriorating the mechanical properties of the PP system. When combustion or thermal runaway occurs, under the action of high temperature, the montmorillonite lamellae shrink, and the flame retardant adsorbed between the layers will be extruded and overflowed rapidly, thus quickly playing its flame retardant role.

[0068] 2. Role of Pillaring Agent:

[0069] 2-1. Through ion exchange, using Bi 3+Ions pillar the montmorillonite to increase the interlayer spacing and pore volume, creating favorable conditions for subsequent organic intercalation, and also increasing the loading amount of the flame retardant in the subsequent impregnation process of the flame retardant liquid;

[0070] 2-2, Bi 3+ The formed Bi2O3 has an improving effect on the flame retardant properties: Bi2O3 and the flame retardant system (ammonium polyphosphate and phytic acid) loaded in the subsequent system can produce a synergistic effect. Bi2O3 can promote carbonization, increase the speed and strength of carbon layer formation, improve the morphology of the expanded carbon layer, improve the thermal insulation and material insulation properties of the carbon layer, and reduce the decomposition of the carbon layer at high temperatures (Wu Na, Yang Rongjie, Hao Jianwei, et al. Effect of Metal Oxides on the Flame Retardant Properties of Polypropylene Expanded Flame Retardant System [J]. Journal of Polymer Science, 2009(12):6. DOI:10.3321 / j.issn:1000-3304.2009.12.005.).

[0071] 2-3. In the process of loading carbon dots, the montmorillonite treated with the support layer is first mixed with oxalic acid as a carbon source. Under the action of the acid, a certain amount of Bi2O3 on the surface of the montmorillonite treated with the support layer will be generated. 3+ Ions, the metal ions can combine with functional groups such as hydroxyl and amino groups in glucose and 4-aminophenol through electrostatic adsorption and / or coordination, thereby playing a role of cross-linking, making the carbon source evenly attached to the surface of the supporting layer-treated montmorillonite, which is beneficial to the in-situ deposition of carbon dots on its surface and achieving uniform and large-scale loading.

[0072] 2. The role of carbon dots

[0073] The main causes of aging of polypropylene materials (PP) include thermal oxidation aging and ultraviolet aging. When the polypropylene system is attacked by oxygen, the molecular chain will break and form free radicals. These free radicals further react with oxygen to form peroxides, and peroxides will decompose under unstable conditions to form more free radicals, thereby accelerating the degradation of the material. Polypropylene is sensitive to ultraviolet rays, which will destroy the molecular chains of polypropylene materials and accelerate the aging process.

[0074] Oxalic acid and 4-aminophenol as carbon sources have strong reducing ability, and glucose also has certain reducing property. The prepared carbon dots inherit the reducing property of the precursor well, and can efficiently remove the free radicals with oxidizing ability in the PP system, which can give the montmorillonite-based multi-effect filler excellent antioxidant properties. At the same time, the carbon dots also have excellent ultraviolet absorption ability, thereby improving the light aging resistance of PP. Therefore, the loading of the carbon dots can simultaneously improve the thermal oxidation aging resistance and ultraviolet aging resistance of polypropylene.

[0075] 3. Alumina-montmorillonite-carbon dot composite particles:

[0076] 1. Role of porous nano-aluminum oxide: When polypropylene materials are at high temperatures, due to softening and deformation and structural collapse, the position of the flame ablation point will expand, exacerbating the fire situation. Alumina can improve thermal stability and reduce structural collapse, thereby inhibiting the expansion of the position of the flame ablation point. At the same time, alumina can improve the crystallization temperature and mechanical properties of PP. Its high hardness can enhance the scratch resistance of the material. On the other hand, the alumina in the present invention has a nanoporous structure. Through its internal pores, a large amount of flame retardant can be loaded, providing a slow-release effect, which can avoid the failure of the flame retardant due to surface migration and other reasons after entering the PP system in excess, and having a negative impact on the mechanical properties of the PP system, and improving the long-term flame retardant effect for the PP system.

[0077] By connecting montmorillonite and nano-mesoporous alumina to form a dual-loading system, on the one hand, it can significantly reduce the adverse effects of the flame retardant on the PP system, and on the other hand, it can achieve the self-adaptive release and slow-release of the flame retardant: at high temperatures, the flame retardant silver between the montmorillonite layers shrinks and extrudes to accelerate the release, and during normal use, the slow release of the flame retardant is realized by means of the nanoporous structure of nano-mesoporous alumina, thereby significantly improving the flame retardant effect of PP.

[0078] 2. Role of zinc oxide:

[0079] During the preparation process, zinc ions play a bridging role and at the same time combine with functional groups such as carboxyl and hydroxyl groups on the surface of carbon dots in the montmorillonite-carbon dot composite and the hydroxyl groups on the surface of nano-mesoporous alumina, and then form ZnO at high temperatures, achieving a firm connection between the montmorillonite-carbon dot composite and porous nano-aluminum oxide through chemical bonds.

[0080] At the same time, in the PP system, zinc oxide can capture HCl generated by the degradation of polypropylene as an acidic acceptor, improving thermal stability; zinc oxide can absorb ultraviolet light, thereby improving the anti-ultraviolet performance (Liu Jie, Wu Fengqin, Yao Chao, etc. Research on the preparation, characterization and ultraviolet shielding performance of TiO2 / ZnO / attapulgite composites [J]. New Chemical Materials, 2016, 44(4): 3. DOI: CNKI:SUN:HGXC.0.2016-04-046.).

[0081] IV. Role of the intercalating agent

[0082] N-triethyl-(4-vinylbenzyl)ammonium chloride, also known as triethyl(4-vinylbenzyl)ammonium chloride, CAS No.: 14350-43-7, molecular formula: C 15 H 24 ClN, and its chemical structural formula is shown in Formula I below:

[0083]

[0084] N-triethyl-(4-vinylbenzyl)ammonium chloride as an intercalating agent can be intercalated between the montmorillonite layers by ion exchange with the cations (such as Na + ) between the montmorillonite layers, increasing the layer spacing and changing the montmorillonite from hydrophilic to lipophilic. This can reduce the surface energy of the inorganic montmorillonite sheets, increase the wettability with other polymers, and improve the compatibility between the montmorillonite and the organic system. At the same time, since N-triethyl-(4-vinylbenzyl)ammonium chloride contains double bonds, it can participate in the polymer reaction when grafting poly(methyl methacrylate)-acrylamide block copolymer subsequently, creating favorable conditions for the grafting of the block copolymer on the inorganic montmorillonite sheets and improving the grafting amount and grafting strength.

[0085] V. Function of Flame Retardants

[0086] Both ammonium polyphosphate and phytic acid (cyclohexanehexol hexaphosphate) have excellent flame retardant properties. The phytic acid-based flame retardant decomposes at high temperatures to produce incombustible gases (such as water vapor, carbon dioxide, etc.). These gases can dilute the oxygen concentration in the combustion area, reduce the mixing of combustible gases and oxygen, and thus inhibit or interrupt the combustion process (Wang Dong. Preparation and Flame Retardant Mechanism Research of Phytic Acid-based Flame Retardants [D]. Jiangnan University, 2022.). Ammonium polyphosphate (APP) is a commonly used flame retardant. It decomposes upon heating to release the incombustible gases NH3 and H2O and produces phosphoric acid with a dehydrating and carbonizing effect. The combined use of ammonium polyphosphate and phytic acid can provide a better flame retardant effect.

[0087] VI. Function of Grafted Poly(methyl methacrylate)-acrylamide Block Copolymer

[0088] Grafting and coating poly(methyl methacrylate)-acrylamide block copolymer on the flame retardant modified composite particles can simultaneously improve the compatibility of inorganic montmorillonite and nano-mesoporous alumina with the polypropylene system, promote their uniform dispersion in the polypropylene system, and thus give full play to their enhancement performance; among them, the incorporation of poly(methyl methacrylate) in the polypropylene system can also reduce the viscosity of polypropylene, improve the processing performance, and is beneficial to improving the toughness and impact resistance of the polypropylene material; acrylamide has excellent high temperature resistance, and through the polar groups (such as amide groups) in the PAM molecular chain, it forms physical cross-linking or hydrogen bond interactions with PMMA, which can improve the tensile strength, toughness and impact resistance. Thus, on the one hand, it can improve the thermal stability and strength of the poly(methyl methacrylate)-acrylamide block copolymer coating film and avoid the rupture or decomposition of the coating film during the melt extrusion processing of polypropylene. On the other hand, it can also improve the high temperature resistance, tensile strength, toughness and impact resistance of the PP system.

[0089] In addition, the coating of the block copolymer can form a certain coating barrier effect on the nano-porous alumina and montmorillonite, playing a role in plugging the pores, so as to further reduce the entry of the flame retardant loaded in the nano-porous alumina and montmorillonite into the polypropylene system under normal use conditions. In the case of high temperature during a fire, the coating layer can melt or break and lose the barrier effect, enabling the internal flame retardant to be smoothly released without affecting the exertion of its flame retardant performance.

[0090] Preferably, the polypropylene resin is a homopolypropylene resin.

[0091] Preferably, the compatibilizer is one or a combination of maleic anhydride grafted polypropylene, acrylic acid grafted polypropylene, acrylonitrile grafted polypropylene, ethylene-acrylic acid copolymer, ethylene-acrylate-maleic anhydride copolymer; more preferably maleic anhydride grafted polypropylene.

[0092] The lubricant is polypropylene wax, ethylene bisstearamide, stearamide, fatty amide, polyethylene wax, zinc stearate, calcium stearate. More preferably calcium stearate.

[0093] The present invention also provides a preparation process of the high-performance polypropylene material as described above, including the following steps:

[0094] 1) According to the weight ratio, mix the polypropylene resin, montmorillonite-based multi-functional filler, compatibilizer, and lubricant evenly to obtain a mixed material;

[0095] 2) Melt-extrude the mixed material in a twin-screw extruder, cool and pelletize to obtain the high-performance polypropylene material.

[0096] The beneficial effects of the present invention are:

[0097] In the present invention, by adding a montmorillonite-based multi-functional filler formed by using multiple reinforcing components in polypropylene, the flame retardant performance, thermal oxygen aging resistance, and ultraviolet aging resistance of polypropylene can be improved, overcoming the defects of traditional flame retardant polypropylene materials. At the same time, the mechanical properties of polypropylene can be improved to a certain extent, so as to realize the improvement of the comprehensive performance of polypropylene, improve its application effect, and broaden its application scenarios.

[0098] In the montmorillonite-based multi-functional filler of the present invention, montmorillonite is treated by using Bi ions as pillar modification to obtain pillared montmorillonite, and then carbon dots are deposited by hydrothermal reaction to obtain a montmorillonite-carbon dot composite; then Zn ions are used as a bridging agent to connect nano-mesoporous alumina to the montmorillonite-carbon dot composite to obtain alumina-montmorillonite-carbon dot composite particles; then the alumina-montmorillonite-carbon dot composite particles are successively subjected to organic intercalation treatment and impregnation with a flame retardant to obtain flame retardant modified composite particles; and finally, a poly(methyl methacrylate)-acrylamide block copolymer is grafted to obtain the montmorillonite-based multi-functional filler. The montmorillonite-based multi-functional filler utilizes a dual-carrier structure: pillared montmorillonite and nano-mesoporous alumina load the flame retardant, the carbon dots loaded on the montmorillonite serve as antioxidant active components, and the poly(methyl methacrylate)-acrylamide block copolymer grafted on the dual-carrier structure serves as an organic coating agent to improve the compatibility between the dual-carrier and polypropylene. Through the synergistic cooperation among the structural components, the comprehensive improvement of the properties of polypropylene can be achieved. Description of the Drawings

[0099] Figure 1 For the tensile strength test results in the test examples;

[0100] Figure 2 For the impact strength test results in the test examples;

[0101] Figure 3 For the limiting oxygen index test results in the test examples;

[0102] Figure 4 For the anti-thermal oxygen aging performance test results in the test examples;

[0103] Figure 5 For the anti-ultraviolet aging performance test results in the test examples;

[0104] Figure 6 For the flame retardant slow release performance test results of the montmorillonite-based multi-functional filler in the test examples;

[0105] Figure 7 For the antioxidant performance test results in the test examples;

[0106] Figure 8 For the infrared absorption spectrum of the alumina-montmorillonite-carbon dot composite particles prepared in Example 1. Detailed Description of the Embodiments

[0107] The present invention will be further described in detail below with reference to the embodiments, so that those skilled in the art can implement it according to the description in the specification.

[0108] It should be understood that the terms such as "having", "comprising" and "including" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0109] The test methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples are all commercially available unless otherwise specified. In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0110] Polypropylene resin, homopolymer polypropylene resin, Korea Petrochemical HJ4012, purchased from Shanghai Qiaowei Chemical Technology Co., Ltd.;

[0111] Montmorillonite, sodium montmorillonite, average particle size 16-22μm, interlayer spacing 1.2-1.4nm; Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.;

[0112] N-triethyl-(4-vinylbenzyl)ammonium chloride, CAS number: 14350-43-7, purchased from Xi'an Qiyue Biotechnology Co., Ltd.;

[0113] P123, triblock copolymer (PEO-PPO-PEO, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer), Ma=5800, Shanghai Jinjinle Industrial Co., Ltd.;

[0114] Maleic anhydride grafted polypropylene, grade PO-1015, brand: Exxon, purchased from Suzhou Dijie Plastic Chemical Co., Ltd.;

[0115] Calcium stearate, model QDHG, Changzhou Qidi Chemical Co., Ltd.;

[0116] Phytic acid, Jiangsu Rayen Environmental Protection Technology Co., Ltd.

[0117] Ammonium polyphosphate, specifically ammonium tripolyphosphate, with the chemical formula (NH4)5P3O10, Guangdong Wengjiang Chemical Reagent Co., Ltd.;

[0118] Polyvinyl alcohol, brand Kuraray Japan, grade PVA48-80, purchased from Suzhou Deyi Polyplastics Co., Ltd.;

[0119] Methyl methacrylate, benzoyl peroxide, Nanjing Chemical Reagent Co., Ltd.

[0120] Acrylamide, Shanghai MacLean Biochemical Technology Co., Ltd.

[0121] Example 1

[0122] A high-performance polypropylene material comprises the following raw material components in parts by weight:

[0123] 100 parts of polypropylene resin;

[0124] 17 parts of montmorillonite-based multi-functional filler;

[0125] 4 parts of maleic anhydride grafted polypropylene;

[0126] 1.5 parts of calcium stearate;

[0127] The preparation method of the high-performance polypropylene material includes the following steps:

[0128] 1) According to the weight ratio, mix polypropylene resin, montmorillonite-based multi-functional filler, compatibilizer maleic anhydride grafted polypropylene, and lubricant calcium stearate, and stir at 100 °C for 45 min to obtain a mixture;

[0129] 2) Melt-extrude the mixture in a twin-screw extruder at 230 °C (screw speed is 300 rpm), cool and pelletize to obtain the high-performance polypropylene material.

[0130] The montmorillonite-based multi-functional filler is prepared through the following steps:

[0131] S1. Load carbon dots on montmorillonite to prepare a montmorillonite-carbon dot composite;

[0132] S1-1. Prepare intercalated montmorillonite:

[0133] Add 5 g of montmorillonite to 10 wt% sulfuric acid solution and soak for 10 h. After taking it out, wash it with deionized water, then add it to 200 mL of 0.05 mol / L Bi(NO3)3 aqueous solution, stir for 15 min, dropwise add 10 wt% ammonia water under stirring to adjust the pH to 8, age for 12 h, filter, wash the product with deionized water, dry at 80 °C for 6 h, then calcine in a muffle furnace at 450 °C for 2 h, and grind to obtain intercalated montmorillonite;

[0134] S1-2. Load carbon dots on the intercalated montmorillonite;

[0135] Add 5 g of intercalated montmorillonite, 100 mL of ethanol, and 1.62 g of oxalic acid to 300 mL of deionized water, ultrasonically disperse for 20 min, then add 1.8 g of glucose and 0.545 g of 4-aminophenol, stir for 30 min under nitrogen protection, add the obtained mixture to a reaction kettle with a polytetrafluoroethylene liner, react at 160 °C for 12 h, centrifuge and filter, wash the solid product with deionized water, and vacuum dry at 100 °C for 8 h to obtain a montmorillonite-carbon dot composite.

[0136] S2. Graft nano-porous alumina onto the montmorillonite-carbon dot composite to prepare alumina-montmorillonite-carbon dot composite particles:

[0137] S2-1. Take 2 g of montmorillonite-carbon dot composite and add it to 50 mL of deionized water. Ultrasonically disperse for 15 min, then add 0.58 g of zinc nitrate and stir for 1 h to obtain dispersion liquid 1.

[0138] S2-2. Take 1.2 g of nano-porous alumina and add it to 50 mL of deionized water. Ultrasonically disperse for 20 min. Add the obtained dispersion liquid 2 to dispersion liquid 1 under stirring, then add 15 mL of 1 mol / L NaOH solution and stir for 30 min. Transfer the obtained product to a reaction kettle with a polytetrafluoroethylene liner, react at 160 °C for 10 h, cool to room temperature, centrifuge and filter. Wash the solid product with deionized water and vacuum dry at 90 °C for 12 h to obtain alumina-montmorillonite-carbon dot composite particles.

[0139] Among them, the preparation method of the nano-porous alumina is as follows:

[0140] Weigh 8.5 g of Al2(SO4)3 and add it to 50 mL of deionized water. Stir until completely dissolved, then add 50 mL of P123 triblock copolymer (PEO-PPO-PEO, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) and stir for 30 min. Dropwise add 5 wt% ammonia water solution to adjust the pH of the solution to 9. After continuing to stir for 2 h, filter by suction, wash with deionized water, dry at 90 °C for 8 h, then calcine at 500 °C for 4 h, and grind into powder to obtain nano-porous alumina. After testing, the average particle size of this nano-porous alumina is 220 nm, the specific surface area is 255 m 2 / g, the average pore diameter is 7.5 nm, and the pore volume is 0.44 cm 3 / g.

[0141] S3. Carry out organic intercalation treatment on the alumina-montmorillonite-carbon dot composite particles:

[0142] Take 20 g of alumina-montmorillonite-carbon dot composite particles and add them to an ethanol aqueous solution composed of 200 mL of deionized water and ethanol in a volume ratio of 1:1. Ultrasonically disperse for 30 min, add 0.5 g of N-triethyl-(4-vinylbenzyl) ammonium chloride, heat up to 80 °C, seal and stir for 8 h. After cooling to room temperature, let it stand for 12 h, filter, wash with deionized water, and vacuum dry at 90 °C for 6 h to obtain organic composite particles.

[0143] S4. Impregnate with a flame retardant:

[0144] Add phytic acid and ammonium polyphosphate to deionized water to prepare an impregnation solution with the mass dispersions of phytic acid and ammonium polyphosphate being 8% and 10% respectively.

[0145] Take 5 g of the organic composite particles and add them to 150 mL of the impregnation solution. Treat them by shaking at 80 °C for 45 min, then perform suction filtration. Rinse the solid product with deionized water and vacuum dry it at 70 °C for 8 h to obtain the flame-retardant modified composite particles.

[0146] S5. Graft a poly(methyl methacrylate)-acrylamide block copolymer onto the flame-retardant modified composite particles to obtain the montmorillonite-based multi-functional filler:

[0147] S5-1. Take 10 g of the flame-retardant modified composite particles and 0.5 g of polyvinyl alcohol, add them to 150 mL of deionized water, disperse them ultrasonically for 15 min, then add 15 g of methyl methacrylate, stir while passing nitrogen for 30 min, add 0.1 g of benzoyl peroxide, and react at 70 °C for 2 h to obtain a prepolymer mixture;

[0148] S5-2. Add 3.5 g of acrylamide, 5 g of methyl methacrylate, and 0.1 g of benzoyl peroxide to the prepolymer mixture, react at 72 °C for 4 h, then raise the temperature to 78 °C and react for 3 h. After cooling to room temperature, filter. Wash the solid product with ethanol and vacuum dry it at 80 °C for 12 h to obtain the montmorillonite-based multi-functional filler.

[0149] Example 2

[0150] A high-performance polypropylene material, comprising the following raw material components by weight parts:

[0151] 100 parts of polypropylene resin;

[0152] 15 parts of montmorillonite-based multi-functional filler;

[0153] 4.5 parts of maleic anhydride-grafted polypropylene;

[0154] 1.5 parts of calcium stearate;

[0155] The preparation method of the high-performance polypropylene material comprises the following steps:

[0156] 1) According to the weight part ratio, mix the polypropylene resin, the montmorillonite-based multi-functional filler, the compatibilizer, and the lubricant, and stir at 100 °C for 45 min to obtain a mixed material;

[0157] 2) Melt-extrude the mixed material in a twin-screw extruder at 240 °C (the screw speed is 300 rpm), cool and pelletize to obtain the high-performance polypropylene material.

[0158] The montmorillonite-based multi-functional filler is prepared through the following steps:

[0159] S1. Load carbon dots on montmorillonite to prepare a montmorillonite-carbon dot composite;

[0160] S1-1. Prepare the intercalated montmorillonite;

[0161] 5 g of montmorillonite was added to a 10 wt% sulfuric acid solution and soaked for 10 h. After taking it out, it was washed with deionized water, and then added to 200 mL of an aqueous Bi(NO3)3 solution with a concentration of 0.05 mol / L. It was stirred for 15 min, and 10 wt% ammonia water was added dropwise under stirring to adjust the pH to 8. It was aged for 12 h, filtered, and the product was washed with deionized water, dried at 80 °C for 6 h, then calcined in a muffle furnace at 450 °C for 2 h, and ground to obtain the intercalated montmorillonite;

[0162] S1-2. Load carbon dots on the intercalated montmorillonite;

[0163] 5 g of the intercalated montmorillonite, 100 mL of ethanol, and 1.62 g of oxalic acid were added to 300 mL of deionized water, ultrasonically dispersed for 20 min, then 1.8 g of glucose and 0.545 g of 4-aminophenol were added, and it was stirred for 30 min under nitrogen protection. The obtained mixture was added to a reaction kettle with a polytetrafluoroethylene inner liner and reacted at 160 °C for 12 h. It was centrifuged and filtered, and the solid product was washed with deionized water and vacuum dried at 100 °C for 8 h to obtain the montmorillonite-carbon dot composite.

[0164] S2. Graft nano-mesoporous alumina onto the montmorillonite-carbon dot composite to prepare alumina-montmorillonite-carbon dot composite particles:

[0165] S2-1. Take 2.5 g of the montmorillonite-carbon dot composite and add it to 50 mL of deionized water, ultrasonically disperse it for 15 min, then add 0.58 g of zinc nitrate and stir for 1 h to obtain dispersion liquid 1;

[0166] S2-2. Take 1.2 g of nano-mesoporous alumina and add it to 50 mL of deionized water, ultrasonically disperse it for 20 min. The obtained dispersion liquid 2 was added to dispersion liquid 1 under stirring, and then 15 mL of a NaOH solution with a concentration of 1 mol / L was added, and it was stirred for 30 min. The obtained product was transferred to a reaction kettle with a polytetrafluoroethylene inner liner and reacted at 160 °C for 10 h. It was cooled to room temperature, centrifuged and filtered, and the solid product was washed with deionized water and vacuum dried at 90 °C for 12 h to obtain the alumina-montmorillonite-carbon dot composite particles;

[0167] Among them, the preparation method of the nano-mesoporous alumina is as follows:

[0168] Weigh 8.5 g of Al2(SO4)3 and add it to 50 mL of deionized water. Stir until it is completely dissolved, then add 50 mL of P123 triblock copolymer (PEO-PPO-PEO, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer). Stir for 30 min, add 5 wt% ammonia water solution dropwise, adjust the pH of the solution to 9, continue stirring for 2 hours, then perform suction filtration, wash with deionized water, dry at 90 °C for 8 h, then calcine at 500 °C for 4 h, and grind into powder to obtain nano-porous alumina. After testing, the average particle size of this nano-porous alumina is 220 nm, the specific surface area is 255 m 2 / g, the average pore diameter is 7.5 nm, and the pore volume is 0.44 cm 3 / g.

[0169] S3. Perform an organic intercalation treatment on the alumina-montmorillonite-carbon dot composite particles:

[0170] Take 20 g of alumina-montmorillonite-carbon dot composite particles and add them to an ethanol aqueous solution composed of 200 mL of deionized water and ethanol in a volume ratio of 1:1. Ultrasonically disperse for 30 min, add 0.5 g of N-triethyl-(4-vinylbenzyl)ammonium chloride, heat up to 80 °C, seal and stir for 8 h, cool to room temperature and then let it stand for 12 h, filter, wash with deionized water, and vacuum dry at 90 °C for 6 h to obtain organic composite particles.

[0171] S4. Impregnate with a flame retardant;

[0172] Add phytic acid and ammonium polyphosphate to deionized water to prepare an impregnation solution with the mass dispersions of phytic acid and ammonium polyphosphate being 8% and 10% respectively;

[0173] Take 5 g of organic composite particles and add them to 150 mL of the impregnation solution. Oscillate at 80 °C for 45 min, perform suction filtration, rinse the solid product with deionized water, and vacuum dry at 70 °C for 8 h to obtain flame retardant modified composite particles.

[0174] S5. Graft a polymethyl methacrylate-acrylamide block copolymer onto the flame retardant modified composite particles to obtain a montmorillonite-based multi-functional filler:

[0175] S5-1. Take 10 g of flame retardant modified composite particles and 0.5 g of polyvinyl alcohol and add them to 150 mL of deionized water. Ultrasonically disperse for 15 min, then add 15 g of methyl methacrylate, stir while passing nitrogen for 30 min, add 0.1 g of benzoyl peroxide, and react at 70 °C for 2 h to obtain a prepolymer mixture;

[0176] S5-2. Add 3.5 g of acrylamide, 5 g of methyl methacrylate, and 0.1 g of benzoyl peroxide to the prepolymer mixture, react at 72 °C for 4 h, then raise the temperature to 78 °C and react for 3 h. After cooling to room temperature, filter. Wash the solid product with ethanol and dry it under vacuum at 80 °C for 12 h to obtain the montmorillonite-based multi-functional filler.

[0177] Example 3

[0178] A high-performance polypropylene material, comprising the following raw material components by weight:

[0179] 100 parts of polypropylene resin;

[0180] 17 parts of montmorillonite-based multi-functional filler;

[0181] 4 parts of maleic anhydride grafted polypropylene;

[0182] 1.5 parts of calcium stearate;

[0183] The preparation method of the high-performance polypropylene material comprises the following steps:

[0184] 1) According to the weight ratio, mix polypropylene resin, montmorillonite-based multi-functional filler, compatibilizer, and lubricant, and stir at 100 °C for 60 min to obtain a mixed material;

[0185] 2) Melt-extrude the mixed material in a twin-screw extruder at 225 °C (screw speed is 300 rpm), cool and pelletize to obtain the high-performance polypropylene material.

[0186] The montmorillonite-based multi-functional filler is prepared through the following steps:

[0187] S1. Load carbon dots on montmorillonite to prepare a montmorillonite-carbon dot composite;

[0188] S1-1. Prepare intercalated montmorillonite;

[0189] Add 5 g of montmorillonite to a 10 wt% sulfuric acid solution and soak for 8 h. Take it out, wash with deionized water, then add it to 200 mL of an aqueous Bi(NO3)3 solution with a concentration of 0.05 mol / L, stir for 15 min, dropwise add 10 wt% ammonia water under stirring to adjust the pH to 8, age for 12 h, filter, wash the product with deionized water, dry at 80 °C for 6 h, then calcine in a muffle furnace at 450 °C for 2.5 h, and grind to obtain intercalated montmorillonite;

[0190] S1-2. Load carbon dots on the intercalated montmorillonite;

[0191] 5.5 g of exfoliated montmorillonite, 100 mL of ethanol, and 1.62 g of oxalic acid were added to 300 mL of deionized water, and ultrasonically dispersed for 20 min. Then, 1.8 g of glucose and 0.545 g of 4-aminophenol were added, and the mixture was stirred for 30 min under nitrogen protection. The obtained mixture was added to a reaction kettle with a polytetrafluoroethylene liner and reacted at 160 °C for 12 h. After centrifugation and filtration, the solid product was washed with deionized water and vacuum dried at 100 °C for 8 h to obtain a montmorillonite-carbon dot composite.

[0192] S2. Graft nano-mesoporous alumina onto the montmorillonite-carbon dot composite to prepare alumina-montmorillonite-carbon dot composite particles:

[0193] S2-1. Take 2 g of the montmorillonite-carbon dot composite and add it to 50 mL of deionized water, ultrasonically disperse for 15 min, then add 0.58 g of zinc nitrate, and stir for 1 h to obtain dispersion liquid 1;

[0194] S2-2. Take 1.1 g of nano-mesoporous alumina and add it to 50 mL of deionized water, ultrasonically disperse for 20 min. The obtained dispersion liquid 2 was added to dispersion liquid 1 under stirring, and then 15 mL of a 1 mol / L NaOH solution was added, and the mixture was stirred for 30 min. The obtained product was transferred to a reaction kettle with a polytetrafluoroethylene liner and reacted at 160 °C for 10 h. After cooling to room temperature, centrifugation and filtration were carried out. The solid product was washed with deionized water and vacuum dried at 90 °C for 12 h to obtain alumina-montmorillonite-carbon dot composite particles;

[0195] Among them, the preparation method of nano-mesoporous alumina is as follows:

[0196] Weigh 8.5 g of Al2(SO4)3 and add it to 50 mL of deionized water, stir until completely dissolved, then add 50 mL of P123 triblock copolymer (PEO-PPO-PEO, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer), stir for 30 min, dropwise add 5 wt% ammonia water solution to adjust the pH of the solution to 9, continue to stir for 2 hours, then carry out suction filtration, wash with deionized water, dry at 90 °C for 8 h, and then calcine at 500 °C for 4 h, and grind into powder to obtain nano-mesoporous alumina. After testing, the average particle size of this nano-mesoporous alumina is 220 nm, the specific surface area is 255 m 2 / g, the average pore diameter is 7.5 nm, and the pore volume is 0.44 cm 3 / g.

[0197] S3. Carry out organic intercalation treatment on the alumina-montmorillonite-carbon dot composite particles:

[0198] Take 20 g of alumina-montmorillonite-carbon dot composite particles and add them to an ethanol aqueous solution composed of 200 mL of deionized water and ethanol in a volume ratio of 1:1. Ultrasonically disperse for 30 min, add 0.5 g of N-triethyl-(4-vinylbenzyl)ammonium chloride, heat to 80 °C, seal and stir for 8 h, cool to room temperature, then let stand for 12 h, filter, wash with deionized water, and vacuum dry at 90 °C for 6 h to obtain organically modified composite particles.

[0199] S4. Impregnate with a flame retardant;

[0200] Add phytic acid and ammonium polyphosphate to deionized water to prepare an impregnating solution with mass dispersions of phytic acid and ammonium polyphosphate of 8% and 10% respectively;

[0201] Take 5 g of organically modified composite particles and add them to 150 mL of the impregnating solution. Treat by shaking at 80 °C for 45 min, filter with suction, rinse the solid product with deionized water, and vacuum dry at 70 °C for 8 h to obtain flame retardant modified composite particles.

[0202] S5. Graft a poly(methyl methacrylate)-acrylamide block copolymer onto the flame retardant modified composite particles to obtain a montmorillonite-based multi-functional filler:

[0203] S5-1. Take 10 g of flame retardant modified composite particles and 0.5 g of polyvinyl alcohol, add them to 150 mL of deionized water, ultrasonically disperse for 15 min, then add 15 g of methyl methacrylate, stir while passing nitrogen for 30 min, add 0.1 g of benzoyl peroxide, and react at 70 °C for 2 h to obtain a prepolymer mixture;

[0204] S5-2. Add 4.0 g of acrylamide, 5 g of methyl methacrylate, and 0.1 g of benzoyl peroxide to the prepolymer mixture, react at 72 °C for 4 h, then heat to 78 °C and react for 3 h. After cooling to room temperature, filter, wash the solid product with ethanol, and vacuum dry at 80 °C for 12 h to obtain a montmorillonite-based multi-functional filler.

[0205] Comparative Example 1

[0206] The difference between this example and Example 1 is:

[0207] Step S1-1 is specifically:

[0208] Add 5 g of montmorillonite to a 10 wt% sulfuric acid solution, soak for 10 h, take out, wash with deionized water, filter, wash the product with deionized water, dry at 80 °C for 6 h, then calcine in a muffle furnace at 450 °C for 2 h, and grind to obtain intercalated montmorillonite.

[0209] The rest is the same as in Example 1.

[0210] Comparative Example 2

[0211] The difference between this example and Example 1 is as follows:

[0212] The montmorillonite-based multi-functional filler is prepared through the following steps:

[0213] S1. Prepare the pillared montmorillonite, and the steps are the same as those of Step S1-1 in Example 1;

[0214] S2. Graft nano-mesoporous alumina onto the pillared montmorillonite to prepare alumina-montmorillonite composite particles:

[0215] S2-1. Take 2 g of the pillared montmorillonite, add it to 50 mL of deionized water, ultrasonically disperse for 15 min, then add 0.58 g of zinc nitrate, and stir for 1 h to obtain Dispersion Liquid 1;

[0216] S2-2. Take 1.2 g of nano-mesoporous alumina, add it to 50 mL of deionized water, ultrasonically disperse for 20 min, add the obtained Dispersion Liquid 2 to Dispersion Liquid 1 under stirring, then add 15 mL of a NaOH solution with a concentration of 1 mol / L, stir for 30 min, transfer the obtained product to a reaction kettle with a polytetrafluoroethylene inner lining, react at 160 °C for 10 h, cool to room temperature, centrifuge and filter, wash the solid product with deionized water, and vacuum dry at 90 °C for 12 h to obtain alumina-montmorillonite composite particles;

[0217] Among them, the preparation method of the nano-mesoporous alumina is the same as that in Example 1;

[0218] S3. Conduct an organic intercalation treatment on the alumina-montmorillonite composite particles:

[0219] Take 20 g of the alumina-montmorillonite composite particles, add them to an ethanol aqueous solution composed of 200 mL of deionized water and ethanol in a volume ratio of 1:1, ultrasonically disperse for 30 min, add 0.5 g of N-triethyl-(4-vinylbenzyl)ammonium chloride, heat up to 80 °C, seal and stir for 8 h, let it stand for 12 h after cooling to room temperature, filter, wash with deionized water, and vacuum dry at 90 °C for 6 h to obtain the organic composite particles.

[0220] The rest is the same as in Example 1.

[0221] Comparative Example 3

[0222] The difference between this example and Example 1 is as follows:

[0223] The montmorillonite-based multi-functional filler is prepared through the following steps:

[0224] S1. Load carbon dots onto the montmorillonite to prepare a montmorillonite-carbon dot composite, and the steps are the same as those in Example 1;

[0225] S2. Conduct an organic intercalation treatment on the montmorillonite-carbon dot composite particles:

[0226] Take 20 g of montmorillonite-carbon dot composite particles and add them to an ethanol aqueous solution composed of 200 mL of deionized water and ethanol in a volume ratio of 1:1. Ultrasonically disperse for 30 min, add 0.5 g of N-triethyl-(4-vinylbenzyl)ammonium chloride, heat up to 80 °C, seal and stir for 8 h, cool to room temperature and then stand for 12 h, filter, wash with deionized water, and vacuum dry at 90 °C for 6 h to obtain organically modified composite particles.

[0227] S3. Impregnate with a flame retardant, and the steps are the same as those of step S4 in Example 1;

[0228] S4. Graft a poly(methyl methacrylate)-acrylamide block copolymer onto the flame retardant modified composite particles to obtain a montmorillonite-based multi-functional filler, and the steps are the same as those of step S5 in Example 1.

[0229] Comparative Example 4

[0230] The difference between this example and Example 1 is:

[0231] The montmorillonite-based multi-functional filler is prepared through the following steps:

[0232] S1. Load carbon dots on montmorillonite to prepare a montmorillonite-carbon dot composite, and the steps are the same as those in Example 1;

[0233] S2. Graft nano-mesoporous alumina onto the montmorillonite-carbon dot composite to prepare alumina-montmorillonite-carbon dot composite particles, and the steps are the same as those in Example 1;

[0234] S3. Impregnate with a flame retardant:

[0235] Add phytic acid and ammonium polyphosphate to deionized water to prepare an impregnating solution with the mass dispersions of phytic acid and ammonium polyphosphate being 8% and 10% respectively;

[0236] Take 5 g of alumina-montmorillonite-carbon dot composite particles and add them to 150 mL of the impregnating solution. Oscillate at 80 °C for 45 min, filter by suction, rinse the solid product with deionized water, and vacuum dry at 70 °C for 8 h to obtain flame retardant modified composite particles.

[0237] S4. Graft a poly(methyl methacrylate)-acrylamide block copolymer onto the flame retardant modified composite particles to obtain a montmorillonite-based multi-functional filler, and the steps are the same as those of step S5 in Example 1.

[0238] Comparative Example 5

[0239] The difference between this example and Example 1 is:

[0240] Use the flame retardant modified composite particles prepared by step S4 of Example 1 as the montmorillonite-based multi-functional filler.

[0241] Comparative Example 6

[0242] The difference between this example and Example 1 is as follows:

[0243] During the preparation of the montmorillonite-based multi-functional filler, acrylamide is not added in step S5-2.

[0244] Test Example

[0245] The high-performance polypropylene material particles prepared in the examples and comparative examples were injection molded at a temperature of 250 °C to prepare samples for performance tests 1-5 as follows;

[0246] 1. Tensile strength was tested with reference to standard ASTM-D638, and the test results are shown in Table 1 below:

[0247] Table 1

[0248]

[0249] 2. Impact strength was tested with reference to standard GB / T 1043.2-2018, and the test results are shown in Table 2 below:

[0250] Table 2

[0251]

[0252] It can be seen from the test results in Tables 1-2 that Examples 1-3 and Comparative Examples 1-2 have relatively high tensile strength and impact strength, while the tensile strength and impact strength of Comparative Examples 3-6 have decreased significantly. The decrease in mechanical properties in Comparative Example 4 is due to the lack of organic intercalation treatment, which affects the subsequent block copolymer grafting and reduces the dispersion of the montmorillonite-based multi-functional filler in the polypropylene system; while the results of Comparative Example 5 intuitively show that when block copolymer grafting is not carried out, the montmorillonite-based multi-functional filler is difficult to disperse uniformly in the polypropylene system, resulting in the deterioration of the mechanical strength of polypropylene.

[0253] 3. Limiting oxygen index (LOI): It was tested with reference to standard GB / T 2406—80, and the test results are shown in Table 3 below:

[0254] Table 3

[0255]

[0256] As can be seen from the test results, the polypropylene in Examples 1-3 has excellent flame retardancy and long-term flame retardant performance; the flame retardancy of the comparative examples decreased to varying degrees. Among them, in Comparative Example 3, nano-mesoporous alumina was not connected to the montmorillonite, resulting in a decrease in the slow-release ability of the flame retardant and a significant reduction in the long-term flame retardant performance; in Comparative Example 5, the poly(methyl methacrylate)-acrylamide block copolymer film was not grafted and coated, which affected its dispersion and the slow-release ability of the flame retardant, and the long-term flame retardant performance also decreased significantly.

[0257] 4. Thermal-oxidative aging resistance

[0258] The samples were placed in a hot air aging oven and aged at 150 °C for 168 h, with a wind speed of 1 m / s and an air replacement rate of once every 5 min. After thermal-oxidative aging treatment, the tensile strength was tested according to the standard ASTM-D638, and the tensile strength retention rate was calculated: (tensile strength after aging / tensile strength before aging) × 100%. The test results are shown in Table 4 below:

[0259] Table 4

[0260]

[0261] As can be seen from the test results, the polypropylene in Examples 1-3 has excellent thermal-oxidative aging resistance, and the comparative examples 1-6 decreased to varying degrees.

[0262] 5. Ultraviolet aging resistance

[0263] The test was carried out with reference to the standard GB / T 16422.1, using a UV-A (340 nm) ultraviolet lamp, an irradiation intensity of 0.85 W / m 2 , a temperature of 50 °C, a humidity of 50%, and a treatment time of 100 h. After ultraviolet aging treatment, the tensile strength was tested according to the standard ASTM-D638, and the tensile strength retention rate was calculated: (tensile strength after aging / tensile strength before aging) × 100%. The test results are shown in Table 5 below:

[0264] Table 5

[0265]

[0266] As can be seen from the test results, the polypropylene in Examples 1-3 has excellent ultraviolet aging resistance, and the comparative examples 1-5 decreased to varying degrees.

[0267] 6. Test the slow-release performance of the flame retardant of the montmorillonite-based multi-functional filler:

[0268] Put 10 g of the montmorillonite-based multi-functional filler prepared in Example 1 into a filter bag, and then place it in a beaker. The following operations were carried out every 20 h:

[0269] (1) It was added to 50 mL of ethanol, sonicated for 5 min, then soaked for 250 min, taken out and rinsed 3 times with ethanol. The rinsing and soaking solutions (ethanol obtained after soaking) were collected, combined, the total volume of the liquid was measured, and the phytic acid concentration therein was detected (detected by spectrophotometry, referring to the standard GB5009.153 2016), and the phytic acid release amount was calculated.

[0270] (2) It was continuously tested for 200 h, and a release curve was plotted with the cumulative value of the release percentage as the ordinate and the release time as the abscissa.

[0271] Among them, Q t represents the cumulative release amount within time t, Q0 represents the total loading amount of phytic acid in the montmorillonite-based multi-functional filler, and the total loading amount = the amount of phytic acid in the impregnating solution before impregnation - the amount of phytic acid in the impregnating solution after impregnation.

[0272] The test results are as Figure 6 shown, and it can be seen that the montmorillonite-based multi-functional filler prepared in Example 1 can achieve the slow release of phytic acid.

[0273] 7. Characterize and test the properties of the intermediate products prepared in Example 1: pillared montmorillonite, montmorillonite-carbon dot composite, and alumina-montmorillonite-carbon dot composite particles

[0274] (1) Test the antioxidant properties of pillared montmorillonite, montmorillonite-carbon dot composite, and alumina-montmorillonite-carbon dot composite particles

[0275] The pillared montmorillonite (denoted as 1#), montmorillonite-carbon dot composite (denoted as 2#), and alumina-montmorillonite-carbon dot composite particles (denoted as 3#) prepared in Example 1 were respectively added to ethanol, sonicated and dispersed for 45 min, and a dispersion with a concentration of 1 mg / mL was prepared. Then, the antioxidant properties of the dispersion at different times were measured using a nitrogen radical (DPPH) scavenging ability test kit (A001-96T spectrophotometry method, Shanghai Huicheng Biotechnology Co., Ltd.). The test principle is as follows:

[0276] The DPPH radical has a single electron and has a strong absorption at 517 nm. When there is an antioxidant, the absorbance at 517 nm will decrease, and the degree of decrease in absorbance is proportional to the antioxidant property. That is to say, the more the absorbance decreases, the stronger the antioxidant property.

[0277] The test results are as Figure 7As shown, both the montmorillonite-carbon dot composite and the alumina-montmorillonite-carbon dot composite particles exhibit excellent antioxidant properties, indicating that the antioxidant properties of the montmorillonite-carbon dot composite are not affected after grafting with nano-mesoporous alumina; the difference in antioxidant properties between the montmorillonite-carbon dot composite and the intercalated montmorillonite indicates that the antioxidant properties are mainly provided by the loaded carbon dots.

[0278] (2) Figure 8 Figure (2) is the infrared absorption spectrum of the alumina-montmorillonite-carbon dot composite particles prepared in Example 1. The characteristic peaks of amino groups, carboxyl groups, benzene rings, etc. originate from the carbon dots, indicating the successful synthesis of the carbon dots. The appearance of characteristic peaks such as Zn-O, Bi-O, and Al-O indicates the successful grafting of nano-mesoporous alumina onto the montmorillonite-carbon dot composite, thus indicating the successful synthesis of the alumina-montmorillonite-carbon dot composite particles.

[0279] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to specific details.

Claims

1. A high-performance polypropylene material, characterized in that, Comprising the following raw material components by weight parts: 100 parts of polypropylene resin; 8 - 26 parts of montmorillonite-based multi-functional filler; 1 - 9 parts of compatibilizer; 0.2 - 4 parts of lubricant; The montmorillonite-based multi-functional filler is prepared through the following steps: S1. Load carbon dots onto montmorillonite to prepare a montmorillonite-carbon dot composite; S2. Graft nano-mesoporous alumina onto the montmorillonite-carbon dot composite to prepare alumina-montmorillonite-carbon dot composite particles; S3. Conduct an organic intercalation treatment on the alumina-montmorillonite-carbon dot composite particles to obtain organic composite particles; S4. Load a flame retardant onto the organic composite particles by an impregnation method to obtain flame retardant modified composite particles; S5. Graft a poly(methyl methacrylate)-acrylamide block copolymer onto the flame retardant modified composite particles to obtain the montmorillonite-based multi-functional filler.

2. The high-performance polypropylene material according to claim 1, characterized in that, The montmorillonite-based multi-functional filler is prepared through the following steps: S1. Prepare the montmorillonite-carbon dot composite: Soak montmorillonite with sulfuric acid and then add it to an aqueous Bi(NO3)3 solution. Dropwise add ammonia water, age, filter, dry, and calcine to obtain intercalated montmorillonite. Blend oxalic acid, glucose, 4-aminophenol with the intercalated montmorillonite in a mixed solution of ethanol and deionized water, and prepare the montmorillonite-carbon dot composite through a hydrothermal reaction; S2. Mix the montmorillonite-carbon dot composite and zinc nitrate in deionized water to obtain dispersion liquid 1. Disperse nano-mesoporous alumina in deionized water, add the obtained dispersion liquid 2 to dispersion liquid 1, then add a NaOH solution, and add the obtained product to a reaction kettle to prepare alumina-montmorillonite-carbon dot composite particles through a hydrothermal reaction; S3. Disperse the alumina-montmorillonite-carbon dot composite particles in an ethanol aqueous solution, add N-triethyl-(4-vinylbenzyl)ammonium chloride, heat and stir, filter and dry to obtain organic composite particles; S4. Add phytic acid and ammonium polyphosphate to deionized water to prepare an impregnation solution. Add the organic composite particles to the impregnation solution for impregnation treatment, and obtain flame retardant modified composite particles after impregnation; S5. Disperse the flame retardant modified composite particles and polyvinyl alcohol in deionized water, then add methyl methacrylate and benzoyl peroxide, and heat to react to obtain a prepolymer mixture. Add acrylamide, methyl methacrylate, and benzoyl peroxide to the prepolymer mixture and heat to react to obtain the montmorillonite-based multi-functional filler.

3. The high-performance polypropylene material according to claim 2, wherein The montmorillonite-based multi-functional filler is prepared through the following steps: S1. Prepare the montmorillonite-carbon dot composite: S1-1. Add montmorillonite to a sulfuric acid solution for soaking, take it out, wash it, and then add it to an aqueous Bi(NO3)3 solution. Dropwise add ammonia water under stirring to adjust the pH, age, filter, wash and dry the product, then calcine it in a muffle furnace and grind it into powder to obtain intercalated montmorillonite; S1-2. Load carbon dots onto the intercalated montmorillonite; Montmorillonite treated with a support layer, ethanol, and oxalic acid were added to deionized water, ultrasonically dispersed, then glucose and 4-aminophenol were added, and stirred under nitrogen protection. The resulting mixture was added to a reaction kettle and reacted under heating. After the reaction, it was centrifuged and filtered, and the solid product was washed and dried to obtain a montmorillonite-carbon dot composite; S2. Preparation of alumina-montmorillonite-carbon dot composite particles: S2-1. Take the montmorillonite-carbon dot composite and add it to deionized water, ultrasonically disperse it, then add zinc nitrate and stir to obtain dispersion liquid 1; S2-2. Take nano-mesoporous alumina and add it to deionized water, ultrasonically disperse it. The resulting dispersion liquid 2 was added to dispersion liquid 1 under stirring, then NaOH solution was added and stirred. The resulting product was transferred to a reaction kettle and reacted under heating. After the reaction, it was centrifuged and filtered, and the solid product was washed and dried to obtain alumina-montmorillonite-carbon dot composite particles; S3. Preparation of organic composite particles: Take the alumina-montmorillonite-carbon dot composite particles and add them to an ethanol aqueous solution, ultrasonically disperse them, add N-triethyl-(4-vinylbenzyl)ammonium chloride, and seal and stir under heating. After cooling, filtering, washing, and drying, organic composite particles were obtained; S4. Preparation of flame-retardant modified composite particles: Phytic acid and ammonium polyphosphate were added to deionized water to prepare an impregnation solution; take the organic composite particles and add them to the impregnation solution, oscillate, filter, wash the solid product with deionized water, and dry to obtain flame-retardant modified composite particles. S5. Grafting poly(methyl methacrylate)-acrylamide block copolymer onto the flame-retardant modified composite particles: S5-1. Take the flame-retardant modified composite particles and polyvinyl alcohol and add them to deionized water, ultrasonically disperse them, then add methyl methacrylate, stir while passing nitrogen, add benzoyl peroxide, and react under heating to obtain a prepolymer mixture; S5-2. Add acrylamide, methyl methacrylate, and benzoyl peroxide to the prepolymer mixture and react under heating. After the reaction, cool, filter, wash, and dry to obtain montmorillonite-based multi-functional fillers.

4. The high-performance polypropylene material according to claim 3, wherein Step S1 specifically includes: S1-1. Add 2.5 - 10 g of montmorillonite to a 5 - 30 wt% sulfuric acid solution and soak for 5 - 20 h. After taking it out, wash it with deionized water, then add it to 100 - 400 mL of an aqueous Bi(NO3)3 solution with a concentration of 0.025 - 0.1 mol / L, stir for 5 - 30 min, and dropwise add 5 - 20 wt% ammonia water while stirring to adjust the pH to 8 - 9. Age for 8 - 24 h, filter, wash the product with deionized water, dry it at 70 - 90 °C for 3 - 12 h, then calcine it in a muffle furnace at 400 - 500 °C for 1 - 4 h, and grind it into powder to obtain montmorillonite treated with a support layer; S1-2. Load carbon dots on the montmorillonite treated with a support layer; 2.5 - 10 g of exfoliated montmorillonite, 50 - 200 mL of ethanol, and 0.81 - 3.24 g of oxalic acid are added to 150 - 600 mL of deionized water, and ultrasonically dispersed for 10 - 40 min. Then, 0.9 - 3.6 g of glucose and 0.272 - 1.09 g of 4 - aminophenol are added, and stirred for 15 - 60 min under nitrogen protection. The resulting mixture is added to a reaction kettle with a polytetrafluoroethylene inner liner, and reacted at 140 - 170 °C for 6 - 24 h. After centrifugal filtration, the solid product is washed with deionized water and vacuum - dried at 90 - 110 °C for 4 - 16 h to obtain the montmorillonite - carbon dot composite.

5. The high-performance polypropylene material according to claim 3, wherein Step S2 specifically includes: S2 - 1. Take 1 - 4 g of the montmorillonite - carbon dot composite and add it to 25 - 100 mL of deionized water, ultrasonically disperse for 5 - 30 min, then add 0.29 - 1.16 g of zinc nitrate, and stir for 0.5 - 2 h to obtain dispersion liquid 1; S2 - 2. Take 0.6 - 2.4 g of nano - mesoporous alumina and add it to 25 - 100 mL of deionized water, ultrasonically disperse for 10 - 40 min. The resulting dispersion liquid 2 is added to dispersion liquid 1 under stirring, and then 7.5 - 30 mL of a NaOH solution with a concentration of 0.5 - 2 mol / L is added, and stirred for 15 - 60 min. The resulting product is transferred to a reaction kettle with a polytetrafluoroethylene inner liner, and reacted at 150 - 180 °C for 5 - 20 h. After cooling to room temperature, centrifugal filtration is carried out, the solid product is washed with deionized water, and vacuum - dried at 70 - 100 °C for 6 - 24 h to obtain the alumina - montmorillonite - carbon dot composite particles; Among them, the particle size of the nano - mesoporous alumina is 100 - 400 nm.

6. The high-performance polypropylene material according to claim 3, wherein, Step S3 specifically includes: Take 10 - 40 g of the alumina - montmorillonite - carbon dot composite particles and add them to an ethanol - aqueous solution composed of 100 - 400 mL of deionized water and ethanol in a volume ratio of 1:1, ultrasonically disperse for 15 - 60 min, add 0.25 - 1 g of N - triethyl - (4 - vinylbenzyl)ammonium chloride, heat up to 60 - 90 °C, seal and stir for 4 - 16 h. After cooling to room temperature, let it stand for 6 - 24 h, filter, wash with deionized water, and vacuum - dry at 70 - 100 °C for 3 - 12 h to obtain the organic - modified composite particles.

7. The high-performance polypropylene material according to claim 3, wherein Step S4 specifically includes: Phytic acid and ammonium polyphosphate are added to deionized water to prepare an impregnation solution with mass fractions of phytic acid and ammonium polyphosphate being 4 - 16% and 5 - 20% respectively; Take 2.5 - 10 g of the organic - modified composite particles and add them to 75 - 300 mL of the impregnation solution, oscillate at 60 - 90 °C for 15 - 90 min, carry out suction filtration, rinse the solid product with deionized water, and vacuum - dry at 60 - 80 °C for 4 - 16 h to obtain the flame - retardant modified composite particles.

8. The high-performance polypropylene material according to claim 3, wherein Step S5 specifically includes: S5 - 1. Take 5 - 20 g of the flame - retardant modified composite particles and 0.25 - 1 g of polyvinyl alcohol, add them to 75 - 300 mL of deionized water, ultrasonically disperse for 5 - 30 min, then add 7.5 - 30 g of methyl methacrylate, stir while passing nitrogen for 15 - 45 min, add 0.05 - 0.2 g of benzoyl peroxide, and react at 60 - 72 °C for 1 - 4 h to obtain a prepolymer mixture; S5-2. Add 1.75 - 7 g of acrylamide, 2.5 - 10 g of methyl methacrylate, and 0.05 - 0.2 g of benzoyl peroxide to the prepolymer mixture, react at 70 - 75 °C for 2 - 6 h, then raise the temperature to 75 - 80 °C and react for 2 - 4 h. After cooling to room temperature, filter, wash the solid product with ethanol, and vacuum dry at 60 - 95 °C for 6 - 24 h to obtain the montmorillonite-based multi-functional filler.

9. The high-performance polypropylene material according to claim 1, wherein The compatibilizer is one or a combination of maleic anhydride grafted polypropylene, acrylic acid grafted polypropylene, acrylonitrile grafted polypropylene, ethylene-acrylic acid copolymer, and ethylene-acrylate-maleic anhydride copolymer; The lubricant is polypropylene wax, ethylene bisstearamide, stearamide, fatty amide, polyethylene wax, zinc stearate, or calcium stearate.

10. A preparation process of a high-performance polypropylene material as described in any one of claims 1-9, characterized in that, It includes the following steps: 1) Mix polypropylene resin, montmorillonite-based multi-functional filler, compatibilizer, and lubricant evenly according to the weight ratio to obtain a mixed material; 2) Melt-extrude the mixed material in a twin-screw extruder, cool and pelletize to obtain the high-performance polypropylene material.

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