High-strength polypropylene composite material for filter plate and preparation method thereof

Abstract

The application relates to the technical field of high polymer materials, and particularly discloses a high-strength polypropylene composite material for filter plates and a preparation method thereof. The preparation method of the polypropylene composite material is as follows: polypropylene, polyimide, maleic anhydride grafted polypropylene, nylon 6, maleic anhydride grafted styrene butadiene styrene copolymer, aminated calcium carbonate, modified glass fiber and antioxidants and lubricants are uniformly mixed in a mass ratio of 100:12-18:2-5:1-2:3-5:3-7:6-10:0.2-0.5:0.1-0.3, melt blending, extrusion, cooling and high-strength polypropylene composite material is obtained. The synergistic effect between the nano calcium carbonate and the glass fiber improves the mechanical properties of the polypropylene, cross-linking occurs between the raw materials, a uniform network structure is formed, more energy is absorbed when the matrix is subjected to external force impact, the filter plate is not damaged when deformation occurs under high-temperature and high-pressure conditions, the obtained polypropylene composite material has high strength, good heat resistance and excellent comprehensive performance.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, in particular to a high-strength polypropylene composite material for filter plates and a preparation method thereof. Background Art

[0002] A filter press is an environmentally friendly dehydration device that uses a filter medium to apply pressure to an object, separating solids from liquids. It is widely used in the chemical, pharmaceutical, metallurgical, food, and ceramic industries. The filter plate is the core filter component of the filter press, and its performance significantly influences its performance, determining its productivity and separation accuracy. The filter plates used in traditional filter presses are mostly made of rubber, which offers good toughness but low strength and poor corrosion resistance, resulting in unstable product quality and high prices.

[0003] Polypropylene is a semi-crystalline general-purpose plastic with low price, low density, high strength and good chemical stability. It is widely used in various fields of production and life. With the rapid development of polypropylene materials, polypropylene materials have become an ideal substitute for general engineering plastics in some engineering application fields, and filter plates of filter presses have also begun to use polypropylene materials. However, the impact resistance of single polypropylene materials is poor, and the heat resistance also needs to be improved. Chinese patent application CN108752738A discloses a high-temperature and high-pressure resistant filter plate for filter presses and a preparation method thereof. The filter plate is made of polypropylene, a titanate coupling agent, calcium carbonate, a toughening agent, a modified zeolite, a wetting agent, and an antioxidant. The raw materials of the filter plate are easy to obtain and low in cost, and have good high-temperature and high-pressure resistance. However, the dispersion between the raw materials is poor, the stability is average, and the impact resistance is poor. Chinese patent application CN113637260A discloses a modified polypropylene composite filter press plate and a continuous preparation method thereof. The plate comprises high-melt-strength polypropylene, glass fiber masterbatch, composite calcium carbonate, a β-nucleating agent, a composite coupling agent, calcium stearate, a composite antioxidant, and a high-temperature resistant agent. This modified polypropylene composite filter press plate exhibits excellent tensile strength and improved heat resistance, but suffers from limited impact resistance and poor toughness. Excessive addition of glass fiber masterbatch can easily cause agglomeration, affecting the performance of the composite and the stability of the filtration system. Therefore, it is highly desirable to provide a polypropylene material that is heat-resistant, high-strength, and highly tough. Summary of the Invention

[0004] (1) Technical problems solved

[0005] In order to solve the above technical problems, the present invention provides a high-strength polypropylene composite material for filter plates and a preparation method thereof, which solves the problems of poor impact resistance and general mechanical strength of polypropylene filter plates.

[0006] (2) Technical solution

[0007] In order to achieve the above object, the application discloses a preparation method of high-strength polypropylene composite material for filter plate, which comprises the following steps:

[0008] Step one: ultrasonic dispersion of nano calcium carbonate in deionized water, after uniform dispersion, L-lysine is added, heated, mixed, reacted, after reaction, filtered, washed with anhydrous ethanol and deionized water, dried at 60℃ for 24h, to obtain aminated calcium carbonate;

[0009] Step two: mixing of ethanol solution and γ-methacryloxypropyltrimethoxysilane, adding glass fiber, stirring, adjusting pH to 4.5 with acetic acid, heating and refluxing in nitrogen atmosphere, reacting, after reaction, filtering, washing with anhydrous ethanol, vacuum drying at 60℃ for 12h, to obtain alkenylated glass fiber;

[0010] Step three: stirring and mixing of alkenylated glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, acrylamide, adding initiator in nitrogen atmosphere, heating and stirring, reacting, after reaction, washing with anhydrous ethanol, drying at 60℃ for 12h, to obtain modified glass fiber;

[0011] Step four: mixing of polypropylene, polyimide, maleic anhydride grafted polypropylene, nylon 6, maleic anhydride grafted styrene butadiene styrene copolymer (SBS-g-MAH), aminated calcium carbonate, modified glass fiber, antioxidant and lubricant, melt blending, extruding, cooling, to obtain high-strength polypropylene composite material for filter plate.

[0012] Preferably, the mass ratio of nano calcium carbonate, deionized water and L-lysine in step one is 100:1000-1500:8-15.

[0013] Preferably, the reaction temperature in step one is 65-75℃, and the reaction time is 2-3h.

[0014] Preferably, the mass ratio of ethanol solution, γ-methacryloxypropyltrimethoxysilane and glass fiber in step two is 6800-7500:15-20:100.

[0015] Preferably, the reaction temperature in step two is 95-105℃, and the reaction time is 4-6h.

[0016] Preferably, the ethanol solution in step two is obtained by mixing anhydrous ethanol and deionized water in a volume ratio of 3:1.

[0017] Preferably, in step three, the mass ratio of olefinated glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, acrylamide, and initiator is 100:3500-4500:25-35:8-15:6-10:2-5.

[0018] Preferably, the initiator in step three is benzoyl peroxide.

[0019] Preferably, the reaction temperature in step 3 is 75-85° C., and the reaction time is 2-4 h.

[0020] Preferably, in step 4, the mass ratio of polypropylene, polyimide, maleic anhydride grafted polypropylene, nylon 6, maleic anhydride grafted styrene butadiene styrene copolymer, amino calcium carbonate, modified glass fiber, antioxidant, and lubricant is 100:12-18:2-5:1-2:3-5:3-7:6-10:0.2-0.5:0.1-0.3.

[0021] Preferably, the antioxidant in step 4 includes one or more of antioxidant 168, antioxidant 1010, and antioxidant 1098.

[0022] Preferably, the lubricant in step 4 includes one or more of polypropylene wax, stearic acid acetamide, and polyethylene wax.

[0023] Preferably, the melt blending in step 4 is carried out in a twin-screw extruder, the speed of the twin-screw extruder is 140-150 rpm, and the twin-screw extruder is provided with five temperature zones according to the forward direction of the material, and the temperatures in the temperature zones are 135-150°C, 175-190°C, 205-215°C, 225-235°C, and 240-250°C, respectively.

[0024] A high-strength polypropylene composite material for filter plates is prepared by adopting the preparation method of the high-strength polypropylene composite material for filter plates.

[0025] (3) Beneficial technical effects

[0026] In the present invention, L-lysine is used to modify nano calcium carbonate. The Ca in nano calcium carbonate is 2+Chemical bonding with the carboxyl groups in L-lysine produces amino calcium carbonate, introducing a large number of amino groups into the nano-calcium carbonate. γ-Methacryloxypropyltrimethoxysilane is used to modify glass fiber, introducing alkenyl groups onto the glass fiber surface to produce alkenyl glass fiber. In the presence of an initiator, the alkenyl glass fiber, acrylic acid, glycidyl methacrylate, and acrylamide undergo in situ polymerization to produce modified glass fiber, which incorporates a large number of active groups such as amino, carboxyl, and epoxy groups. Using polypropylene resin as the matrix, it is melt-blended in a twin-screw extruder with polyimide resin, compatibilizer maleic anhydride-grafted polypropylene, nylon 6 resin, maleic anhydride-grafted styrene-butadiene-styrene copolymer elastomer, amino calcium carbonate, modified glass fiber, antioxidant, and lubricant to produce a high-strength polypropylene composite material for filter plates.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The polypropylene in the present invention has good heat resistance, chemical stability, mechanical properties and processing properties. The comprehensive properties of the polypropylene material can be further improved by adding other fillers, resins and additives. Nano calcium carbonate has rich specific surface area and surface active sites, excellent heat resistance and mechanical properties, and can effectively enhance the mechanical properties and heat resistance of the matrix. Nano calcium carbonate can fill the defects and gaps in the matrix through diffusion and interface effects, improve the density and crystallinity of the matrix, improve the mechanical properties and heat resistance of the matrix, form an effective stress transfer network, effectively absorb deformation work, improve the toughness of the matrix, and improve the impact resistance of the material. Glass fiber has the characteristics of high tensile strength, good elasticity and good corrosion resistance. It can absorb a large amount of impact energy. When added to the polypropylene matrix, it can play the role of a skeleton in the matrix, improve the overall strength of the material, and when the material is subjected to external force, it can withstand stress, slow down the deformation of the material, prevent the material from being damaged, and at the same time improve the heat resistance of the matrix.

[0029] (2) The polyimide resin in the present invention has excellent high temperature resistance. After being mixed with the polypropylene matrix, it can greatly improve the high temperature resistance of the polypropylene matrix. Nylon 6 has high strength and toughness, which can improve the mechanical properties of the body such as tensile strength and flexural strength. Maleic anhydride grafted styrene butadiene styrene copolymer has good elasticity, excellent toughness and strength, and can improve the toughness of the matrix and improve the impact resistance. Polyimide and nylon 6 contain a large amount of amide matrix, and maleic anhydride grafted styrene butadiene styrene copolymer contains anhydride groups.

[0030] (3) The present invention modifies nano calcium carbonate and glass fiber, effectively avoiding the agglomeration of the two, and can be evenly dispersed in the polypropylene matrix, thereby improving the compatibility between the raw materials. The synergistic effect between nano calcium carbonate and glass fiber can jointly bear external forces, improve the mechanical properties of polypropylene, and obtain high-strength polypropylene. The raw materials can be cross-linked to form a uniform network structure, which plays an effective buffering role when the matrix is ​​subjected to external force impact, disperses stress, avoids stress concentration, prevents crack extension, and has a toughening effect. The raw materials have excellent compatibility and dispersibility, can effectively destroy the regularity of the polypropylene continuous phase matrix, increase the amorphous area, and present an island-type microstructure, making the molecular chain segments easier to move and able to absorb more energy, and the induced shear bands are blocked and turned, effectively inhibiting the silver streaks from developing to a deeper level, ensuring that the filter press plate is not damaged when deformed under high temperature and high pressure conditions. The obtained polypropylene composite material has high strength, good heat resistance, and excellent comprehensive performance. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] A method for preparing a high-strength polypropylene composite material for a filter plate comprises the following steps:

[0034] (1) Ultrasonic dispersion of nano-calcium carbonate in deionized water, uniform dispersion, and then addition of L-lysine, wherein the mass ratio of nano-calcium carbonate, deionized water, and L-lysine is 100:1000:8, heating, mixing, and reacting at 65°C for 3 hours. After the reaction is completed, filtration is performed, washing with anhydrous ethanol and deionized water, and drying at 60°C for 24 hours to obtain amino calcium carbonate;

[0035] (2) The ethanol solution and γ-methacryloxypropyltrimethoxysilane were mixed evenly. The ethanol solution was obtained by mixing anhydrous ethanol and deionized water in a volume ratio of 3:1. Glass fiber was added, wherein the mass ratio of ethanol solution, γ-methacryloxypropyltrimethoxysilane and glass fiber was 6800:15:100. The mixture was stirred and the pH was adjusted to 4.5 with acetic acid. The mixture was heated under reflux in a nitrogen atmosphere and reacted at 95°C for 6 hours. After the reaction was completed, the mixture was filtered, washed with anhydrous ethanol, and vacuum dried at 60°C for 12 hours to obtain olefinic glass fiber.

[0036] (3) Alkenyl glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, and acrylamide were stirred and mixed, and in a nitrogen atmosphere, an initiator benzoyl peroxide was added, wherein the mass ratio of alkenyl glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, acrylamide, and initiator benzoyl peroxide was 100:3500:25:8:6:2, heated and stirred, and reacted at 75°C for 4h. After the reaction, the mixture was washed with anhydrous ethanol and dried at 60°C for 12h to obtain modified glass fiber;

[0037] (4) Polypropylene, polyimide, maleic anhydride grafted polypropylene, nylon 6, maleic anhydride grafted styrene butadiene styrene copolymer, amino calcium carbonate, modified glass fiber, antioxidant 1010, and lubricant polyethylene wax in a mass ratio of 100:12:2:1:3:3:6:0.2:0.1 were mixed evenly and melt blended. The melt blending was carried out in a twin-screw extruder. The speed of the twin-screw extruder was 140 rpm. The twin-screw extruder was set with five temperature zones according to the forward direction of the material. The temperatures of the temperature zones were 135°C, 175°C, 205°C, 225°C, and 240°C, respectively. The mixture was extruded and cooled to obtain a high-strength polypropylene composite material for filter plates.

[0038] Example 2

[0039] A method for preparing a high-strength polypropylene composite material for a filter plate comprises the following steps:

[0040] (1) Ultrasonic dispersion of nano-calcium carbonate in deionized water, uniform dispersion, and then adding L-lysine, wherein the mass ratio of nano-calcium carbonate, deionized water, and L-lysine is 100:1200:10, heating, mixing, and reacting at 70°C for 2.5 hours. After the reaction is completed, filtering, washing with anhydrous ethanol and deionized water, and drying at 60°C for 24 hours to obtain amino calcium carbonate;

[0041] (2) The ethanol solution and γ-methacryloxypropyltrimethoxysilane were mixed evenly. The ethanol solution was obtained by mixing anhydrous ethanol and deionized water in a volume ratio of 3:1. Glass fiber was added, wherein the mass ratio of ethanol solution, γ-methacryloxypropyltrimethoxysilane and glass fiber was 7000:16:100. The mixture was stirred and the pH was adjusted to 4.5 with acetic acid. The mixture was heated under reflux in a nitrogen atmosphere and reacted at 100°C for 4.5 hours. After the reaction was completed, the mixture was filtered, washed with anhydrous ethanol, and vacuum dried at 60°C for 12 hours to obtain olefinic glass fiber.

[0042] (3) Alkenyl glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, and acrylamide were stirred and mixed, and in a nitrogen atmosphere, an initiator benzoyl peroxide was added, wherein the mass ratio of alkenyl glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, acrylamide, and initiator benzoyl peroxide was 100:3800:28:10:7:3, heated and stirred, reacted at 80°C for 2.5h, and after the reaction, washed with anhydrous ethanol and dried at 60°C for 12h to obtain modified glass fiber;

[0043] (4) Polypropylene, polyimide, maleic anhydride grafted polypropylene, nylon 6, maleic anhydride grafted styrene butadiene styrene copolymer, amino calcium carbonate, modified glass fiber, antioxidant 1010, and lubricant polyethylene wax in a mass ratio of 100:14:3:1.5:3.5:4:7:0.3:0.2 were mixed evenly and melt blended. The melt blending was carried out in a twin-screw extruder with a speed of 145 rpm. The twin-screw extruder was provided with five temperature zones according to the forward direction of the material. The temperatures of the temperature zones were 140°C, 180°C, 210°C, 228°C, and 245°C, respectively. The mixture was extruded and cooled to obtain a high-strength polypropylene composite material for filter plates.

[0044] Example 3

[0045] A method for preparing a high-strength polypropylene composite material for a filter plate comprises the following steps:

[0046] (1) Ultrasonic dispersion of nano-calcium carbonate in deionized water, uniform dispersion, and then addition of L-lysine, wherein the mass ratio of nano-calcium carbonate, deionized water, and L-lysine is 100:1400:14, heating, mixing, and reacting at 70°C for 2.5 hours. After the reaction is completed, filtration is performed, washing with anhydrous ethanol and deionized water, and drying at 60°C for 24 hours to obtain amino calcium carbonate;

[0047] (2) The ethanol solution and γ-methacryloxypropyltrimethoxysilane were mixed evenly. The ethanol solution was obtained by mixing anhydrous ethanol and deionized water in a volume ratio of 3:1. Glass fiber was added, wherein the mass ratio of ethanol solution, γ-methacryloxypropyltrimethoxysilane and glass fiber was 7400:18:100. The mixture was stirred and the pH was adjusted to 4.5 with acetic acid. The mixture was heated under reflux in a nitrogen atmosphere and reacted at 100°C for 5.5 hours. After the reaction was completed, the mixture was filtered, washed with anhydrous ethanol, and vacuum dried at 60°C for 12 hours to obtain olefinic glass fiber.

[0048] (3) Alkenyl glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, and acrylamide were stirred and mixed, and in a nitrogen atmosphere, an initiator benzoyl peroxide was added, wherein the mass ratio of alkenyl glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, acrylamide, and initiator benzoyl peroxide was 100:4200:32:12:9:4, heated and stirred, and reacted at 80°C for 3.5h. After the reaction, the mixture was washed with anhydrous ethanol and dried at 60°C for 12h to obtain modified glass fiber;

[0049] (4) Polypropylene, polyimide, maleic anhydride grafted polypropylene, nylon 6, maleic anhydride grafted styrene butadiene styrene copolymer, amino calcium carbonate, modified glass fiber, antioxidant 1010, and lubricant polyethylene wax in a mass ratio of 100:14:3:1.5:3.5:4:7:0.3:0.2 were mixed evenly and melt blended. The melt blending was carried out in a twin-screw extruder with a speed of 145 rpm. The twin-screw extruder was provided with five temperature zones according to the forward direction of the material. The temperatures of the temperature zones were 140°C, 180°C, 210°C, 228°C, and 245°C, respectively. The mixture was extruded and cooled to obtain a high-strength polypropylene composite material for filter plates.

[0050] Example 4

[0051] A method for preparing a high-strength polypropylene composite material for a filter plate comprises the following steps:

[0052] (1) Ultrasonic dispersion of nano-calcium carbonate in deionized water, uniform dispersion, and then addition of L-lysine, wherein the mass ratio of nano-calcium carbonate, deionized water, and L-lysine is 100:1400:14, heating, mixing, and reacting at 70°C for 2.5 hours. After the reaction is completed, filtration is performed, washing with anhydrous ethanol and deionized water, and drying at 60°C for 24 hours to obtain amino calcium carbonate;

[0053] (2) The ethanol solution and γ-methacryloxypropyltrimethoxysilane were mixed evenly. The ethanol solution was obtained by mixing anhydrous ethanol and deionized water in a volume ratio of 3:1. Glass fiber was added, wherein the mass ratio of ethanol solution, γ-methacryloxypropyltrimethoxysilane and glass fiber was 7400:18:100. The mixture was stirred and the pH was adjusted to 4.5 with acetic acid. The mixture was heated under reflux in a nitrogen atmosphere and reacted at 100°C for 5.5 hours. After the reaction was completed, the mixture was filtered, washed with anhydrous ethanol, and vacuum dried at 60°C for 12 hours to obtain olefinic glass fiber.

[0054] (3) Alkenyl glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, and acrylamide were stirred and mixed, and in a nitrogen atmosphere, an initiator benzoyl peroxide was added, wherein the mass ratio of alkenyl glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, acrylamide, and initiator benzoyl peroxide was 100:4200:32:12:9:4, heated and stirred, and reacted at 80°C for 3.5h. After the reaction, the mixture was washed with anhydrous ethanol and dried at 60°C for 12h to obtain modified glass fiber;

[0055] (4) Polypropylene, polyimide, maleic anhydride grafted polypropylene, nylon 6, maleic anhydride grafted styrene butadiene styrene copolymer, amino calcium carbonate, modified glass fiber, antioxidant 1010, and lubricant polyethylene wax in a mass ratio of 100:16:4:1.8:4.5:6:9:0.4:0.2 were mixed evenly and melt blended. The melt blending was carried out in a twin-screw extruder. The speed of the twin-screw extruder was 148 rpm. The twin-screw extruder was set with five temperature zones according to the forward direction of the material. The temperatures of the temperature zones were 145°C, 185°C, 210°C, 232°C, and 248°C, respectively. The mixture was extruded and cooled to obtain a high-strength polypropylene composite material for filter plates.

[0056] Example 5

[0057] A method for preparing a high-strength polypropylene composite material for a filter plate comprises the following steps:

[0058] (1) Ultrasonic dispersion of nano-calcium carbonate in deionized water, uniform dispersion, and then addition of L-lysine, wherein the mass ratio of nano-calcium carbonate, deionized water, and L-lysine is 100:1500:15, heating, mixing, and reacting at 75°C for 2 h. After the reaction is completed, filtration is performed, washing with anhydrous ethanol and deionized water, and drying at 60°C for 24 h to obtain amino calcium carbonate;

[0059] (2) The ethanol solution and γ-methacryloxypropyltrimethoxysilane were mixed evenly. The ethanol solution was obtained by mixing anhydrous ethanol and deionized water in a volume ratio of 3:1. Glass fiber was added, wherein the mass ratio of ethanol solution, γ-methacryloxypropyltrimethoxysilane and glass fiber was 7500:20:100. The mixture was stirred and the pH was adjusted to 4.5 with acetic acid. The mixture was heated under reflux in a nitrogen atmosphere and reacted at 105°C for 4 hours. After the reaction was completed, the mixture was filtered, washed with anhydrous ethanol, and vacuum dried at 60°C for 12 hours to obtain olefinic glass fiber.

[0060] (3) the alkenyl glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, acrylamide are stirred and mixed, and the initiator benzoyl peroxide is added in a nitrogen atmosphere, wherein the mass ratio of the alkenyl glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, acrylamide, initiator benzoyl peroxide is 100:4500:35:15:10:5, and the mixture is stirred and heated, and reacted at 85℃ for 2h, after the reaction is completed, washed with anhydrous ethanol, and dried at 60℃ for 12h to obtain the modified glass fiber;

[0061] (4) polypropylene, polyimide, maleic anhydride grafted polypropylene, nylon 6, maleic anhydride grafted styrene butadiene styrene copolymer, amino calcium carbonate, modified glass fiber, antioxidant 1010, lubricant polyethylene wax with a mass ratio of 100:18:5:2:5:7:10:0.5:0.3 are uniformly mixed, and melt blending is performed, the melt blending is performed in a twin-screw extruder, the rotating speed of the twin-screw extruder is 150rpm, five temperature zones are arranged in the twin-screw extruder according to the material advancing direction, and the temperature of the temperature zones is 150℃, 190℃, 215℃, 235℃ and 250℃ respectively, extrusion, cooling, and a high-strength polypropylene composite material for filter plates is obtained.

[0062] Comparative Example 1

[0063] A preparation method of a polypropylene composite material, comprising the following steps:

[0064] (1) nano calcium carbonate is ultrasonically dispersed into deionized water, after uniform dispersion, L-lysine is added, wherein the mass ratio of nano calcium carbonate, deionized water, L-lysine is 100:1400:14, heating, mixing, and reacting at 70℃ for 2.5h, after the reaction is completed, suction filtration, washing with anhydrous ethanol and deionized water, and drying at 60℃ for 24h to obtain amino calcium carbonate;

[0065] (2) polypropylene, polyimide, maleic anhydride grafted polypropylene, nylon 6, maleic anhydride grafted styrene butadiene styrene copolymer, amino calcium carbonate, glass fiber, antioxidant 1010, lubricant polyethylene wax with a mass ratio of 100:16:4:1.8:4.5:6:9:0.4:0.2 are uniformly mixed, and melt blending is performed, the melt blending is performed in a twin-screw extruder, the rotating speed of the twin-screw extruder is 148rpm, five temperature zones are arranged in the twin-screw extruder according to the material advancing direction, and the temperature of the temperature zones is 145℃, 185℃, 210℃, 232℃ and 248℃ respectively, extrusion, cooling, and a polypropylene composite material is obtained.

[0066] Comparative Example 2

[0067] A preparation method of a polypropylene composite material, comprising the following steps:

[0068] (1) mixing uniformly an ethanol solution and γ-methacryloyloxypropyltrimethoxysilane, the ethanol solution being obtained by mixing anhydrous ethanol and deionized water in a volume ratio of 3:1, and adding glass fibers, wherein the mass ratio of the ethanol solution, the γ-methacryloyloxypropyltrimethoxysilane and the glass fibers is 7400:18:100, stirring, adjusting pH to 4.5 using acetic acid, heating to reflux in a nitrogen atmosphere, reacting at 100℃ for 5.5h, after the reaction is completed, suction filtration, washing with anhydrous ethanol, and drying at 60℃ under vacuum for 12h to obtain alkenylated glass fibers;

[0069] (2) stirring and mixing the alkenylated glass fibers, anhydrous ethanol, acrylic acid, glycidyl methacrylate, acrylamide, and adding an initiator benzoyl peroxide in a nitrogen atmosphere, wherein the mass ratio of the alkenylated glass fibers, the anhydrous ethanol, the acrylic acid, the glycidyl methacrylate, the acrylamide and the initiator benzoyl peroxide is 100:4200:32:12:9:4, heating and stirring, reacting at 80℃ for 3.5h, after the reaction is completed, washing with anhydrous ethanol, and drying at 60℃ for 12h to obtain modified glass fibers;

[0070] (3) mixing uniformly polypropylene, polyimide, maleic anhydride grafted polypropylene, nylon 6, maleic anhydride grafted styrene butadiene styrene copolymer, nano calcium carbonate, modified glass fibers, antioxidant 1010, lubricant polyethylene wax in a mass ratio of 100:16:4:1.8:4.5:6:9:0.4:0.2, melt blending, melt blending is carried out in a twin-screw extruder, the rotating speed of the twin-screw extruder is 148rpm, five temperature zones are set in the twin-screw extruder according to the direction of material advancement, the temperatures of the temperature zones are 145℃, 185℃, 210℃, 232℃ and 248℃ respectively, extruding, cooling to obtain a polypropylene composite material.

[0071] Comparative Example 3

[0072] A method for preparing a polypropylene composite material, comprising the following steps:

[0073] (1) mixing uniformly polypropylene, polyimide, maleic anhydride grafted polypropylene, nylon 6, maleic anhydride grafted styrene butadiene styrene copolymer, nano calcium carbonate, glass fibers, antioxidant 1010, lubricant polyethylene wax in a mass ratio of 100:16:4:1.8:4.5:6:9:0.4:0.2, melt blending, melt blending is carried out in a twin-screw extruder, the rotating speed of the twin-screw extruder is 148rpm, five temperature zones are set in the twin-screw extruder according to the direction of material advancement, the temperatures of the temperature zones are 145℃, 185℃, 210℃, 232℃ and 248℃ respectively, extruding, cooling to obtain a polypropylene composite material.

[0074] Comparative Example 4

[0075] A method for preparing a polypropylene composite material comprises the following steps:

[0076] (1) Ultrasonic dispersion of nano-calcium carbonate in deionized water, uniform dispersion, and then addition of L-lysine, wherein the mass ratio of nano-calcium carbonate, deionized water, and L-lysine is 100:1400:14, heating, mixing, and reacting at 70°C for 2.5 hours. After the reaction is completed, filtration is performed, washing with anhydrous ethanol and deionized water, and drying at 60°C for 24 hours to obtain amino calcium carbonate;

[0077] (2) The ethanol solution and γ-methacryloxypropyltrimethoxysilane were mixed evenly. The ethanol solution was obtained by mixing anhydrous ethanol and deionized water in a volume ratio of 3:1. Glass fiber was added, wherein the mass ratio of ethanol solution, γ-methacryloxypropyltrimethoxysilane and glass fiber was 7400:18:100. The mixture was stirred and the pH was adjusted to 4.5 with acetic acid. The mixture was heated under reflux in a nitrogen atmosphere and reacted at 100°C for 5.5 hours. After the reaction was completed, the mixture was filtered, washed with anhydrous ethanol, and vacuum dried at 60°C for 12 hours to obtain olefinic glass fiber.

[0078] (3) Alkenyl glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, and acrylamide were stirred and mixed, and in a nitrogen atmosphere, an initiator benzoyl peroxide was added, wherein the mass ratio of alkenyl glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, acrylamide, and initiator benzoyl peroxide was 100:4200:32:12:9:4, heated and stirred, and reacted at 80°C for 3.5h. After the reaction, the mixture was washed with anhydrous ethanol and dried at 60°C for 12h to obtain modified glass fiber;

[0079] (4) Polypropylene, maleic anhydride grafted polypropylene, amino calcium carbonate, modified glass fiber, antioxidant 1010, and lubricant polyethylene wax in a mass ratio of 122.3:4:6:9:0.4:0.2 were mixed evenly and melt-blended. The melt-blending was carried out in a twin-screw extruder. The speed of the twin-screw extruder was 148 rpm. The twin-screw extruder was set with five temperature zones according to the forward direction of the material. The temperatures of the temperature zones were 145°C, 185°C, 210°C, 232°C, and 248°C, respectively. The materials were extruded and cooled to obtain a polypropylene composite material.

[0080] The nano calcium carbonate in the application is purchased from Guangxi Huana Technology Co., Ltd., with an average particle size of 20 nm and a purity of ≥99.99 %; the glass fiber is purchased from Taishan Glass Fiber Co., Ltd., with a model of T439; the polypropylene is purchased from Daqing Petrochemical Company of China Petroleum, with a model of T30S; the polyimide is purchased from Japan Mitsui Chemical, with a model of PIPL6200; the maleic anhydride grafted polypropylene is purchased from Shanghai Risheng New Technology Development Co., Ltd., with a model of CMG9801; the maleic anhydride grafted styrene butadiene styrene copolymer (SBS-g-MAH) is an industrial grade, purchased from the United States Cortext Company; the nylon 6 resin is purchased from Xinhui Meida-DSM Nylon Slice Co., Ltd., with a brand of M25001; and other undisclosed raw materials and reagents are commercially available.

[0081] The polypropylene composite materials in Examples 1-5 and Comparative Examples 1-4 are taken as samples to perform relevant performance tests, and the tests are as follows:

[0082] (1) Mechanical property test: impact strength test is performed on an XCJD model pendulum impact testing machine, with a test standard of GB / T 1843-2008, and each sample is tested for 3 times to take an average value; tensile property test is performed on a WDW-1000G universal testing machine, with a test standard of GB / T 1040.2-2022, and each sample is tested for 3 times to take an average value;

[0083] (2) Heat resistance test: the polypropylene composite material is made into a sample bar with a size of 80 mm×10 mm×4 mm, with a test standard of GB / T 1674.1-2004, and a load of 1.80 MPa;

[0084] The above test results are shown in Table 1:

[0085] Table 1

[0086]

[0087] According to the test results in Table 1, it can be seen that the samples corresponding to Examples 1-5 in the application have excellent mechanical properties, excellent tensile properties and impact resistance, good toughness, and excellent heat resistance. In Comparative Example 1, the glass fiber is not modified, and the dispersibility and compatibility of the glass fiber are poor; in Comparative Example 2, the nano calcium carbonate is not modified, and the dispersibility and compatibility of the nano calcium carbonate are poor, and the comprehensive performance of the polypropylene composite material is reduced. In Comparative Example 3, the glass fiber and the nano calcium carbonate are directly added to the matrix, and the comprehensive performance of the obtained polypropylene composite material is greatly reduced. In Comparative Example 4, polyimide, nylon 6 and maleic anhydride grafted styrene butadiene styrene copolymer are not added, and the mechanical properties of the polypropylene composite material are reduced, and the heat resistance is less affected.

[0088] While the embodiments of the application have been illustrated and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and alterations can be made therein without departing from the spirit and scope of the application.

Claims

1. A method for preparing a high-strength polypropylene composite material for a filter plate, characterized in that: The steps include: Step 1: Ultrasonic dispersion of nano-calcium carbonate in deionized water, uniform dispersion, adding L-lysine, heating, mixing, reacting, filtering, washing, and drying at 60°C for 24 hours to obtain amino calcium carbonate; Step 2: Evenly mix the ethanol solution and γ-methacryloxypropyltrimethoxysilane, add the glass fiber, stir, adjust the pH to 4.5, heat under reflux in a nitrogen atmosphere to react, and after the reaction is completed, filter, wash, and vacuum dry at 60° C. for 12 hours to obtain olefinated glass fiber; Step 3: Mix the olefinized glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, and acrylamide, add an initiator in a nitrogen atmosphere, heat and stir to react, wash, and dry at 60° C. for 12 hours to obtain a modified glass fiber; Step 4: uniformly mix polypropylene, polyimide, maleic anhydride grafted polypropylene, nylon 6, maleic anhydride grafted styrene butadiene styrene copolymer, amino calcium carbonate, modified glass fiber, antioxidant, and lubricant, melt blend, extrude, and cool to obtain a high-strength polypropylene composite material for filter plates; In the step 1, the mass ratio of nano-calcium carbonate, deionized water, and L-lysine is 100:1000-1500:8-15, the reaction temperature is 65-75° C., and the reaction time is 2-3 h; In the step 3, the mass ratio of olefinated glass fiber, anhydrous ethanol, acrylic acid, glycidyl methacrylate, acrylamide, and initiator is 100:3500-4500:25-35:8-15:6-10:2-5; in the step 4, the mass ratio of polypropylene, polyimide, maleic anhydride grafted polypropylene, nylon 6, maleic anhydride grafted styrene butadiene styrene copolymer, amino calcium carbonate, modified glass fiber, antioxidant, and lubricant is 100:12-18:2-5:1-2:3-5:3-7:6-10:0.2-0.5:0.1-0.3; The melt blending in the step 4 is carried out in a twin-screw extruder, the speed of the twin-screw extruder is 140-150 rpm, and the twin-screw extruder is provided with five temperature zones according to the forward direction of the material, and the temperatures in the temperature zones are 135-150°C, 175-190°C, 205-215°C, 225-235°C, and 240-250°C, respectively.

2. The method for preparing a high-strength polypropylene composite material for filter plates according to claim 1, characterized in that: In the step 2, the mass ratio of the ethanol solution, γ-methacryloxypropyltrimethoxysilane and the glass fiber is 6800-7500:15-20:100, the reaction temperature is 95-105° C., and the reaction time is 4-6 hours.

3. The method for preparing a high-strength polypropylene composite material for filter plates according to claim 1, characterized in that: The initiator in step 3 is benzoyl peroxide.

4. The method for preparing a high-strength polypropylene composite material for filter plates according to claim 1, characterized in that: The reaction temperature in step 3 is 75-85° C., and the reaction time is 2-4 h.

5. The method for preparing a high-strength polypropylene composite material for filter plates according to claim 1, characterized in that: In step 4, the antioxidant includes one or more of antioxidant 168, antioxidant 1010, and antioxidant 1098, and the lubricant includes one or more of polypropylene wax, stearic acid acetamide, and polyethylene wax.

6. A high-strength polypropylene composite material for filter plates prepared by the method for preparing a high-strength polypropylene composite material for filter plates according to any one of claims 1 to 5.

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