Weather-resistant plastic, preparation method thereof and application of weather-resistant plastic in electric vehicle plastic parts

Abstract

The invention discloses weather-resistant plastic, a preparation method thereof and application of the weather-resistant plastic in electric vehicle plastic parts, and relates to the field of high polymer materials. When the weather-resistant plastic is prepared, alkaline lignin reacts with 2-chloromethylphenol and formaldehyde and then reacts with 3-aminopyrrole to prepare modified lignin; the preparation method comprises the following steps: reacting graphene oxide with an ethanol solution of 3-aminopyrrole, and then reacting with chloroform solutions of anhydrous ferric trichloride and pyrrole to prepare modified graphene oxide; the preparation method comprises the following steps: carrying out gamma ray irradiation treatment on polypropylene, reacting with allyl dichlorophosphine, and reacting with N-(4-hydroxyphenyl) maleimide and triethylamine to obtain modified polypropylene; and uniformly mixing the modified lignin, the modified graphene oxide and the modified polypropylene, and carrying out extrusion granulation and hot press molding. The weather-resistant plastic prepared by the invention has good weather resistance, tensile strength, flame retardant property, self-repairing property and antistatic property.

Description

Technical Field

[0001] The present invention relates to the field of polymer materials, in particular to a weather-resistant plastic, a preparation method thereof, and application thereof in plastic parts of electric vehicles. Background Art

[0002] Polypropylene is one of the five most widely used general-purpose resins worldwide. Due to its regular crystal structure, ease of preparation and processing, and excellent mechanical properties, it is widely used in the automotive industry, packaging, and construction materials. Lignin is the only natural polymer containing aromatic rings. It has a unique aromatic and aliphatic backbone structure and a rich variety of functional groups suitable for functionalization. This makes lignin a promising alternative to petroleum-based phenolic polymers for the development of sustainable and functional materials.

[0003] Polypropylene is very susceptible to aging and degradation due to the effects of heat, oxygen, and light in actual production applications. Therefore, different types of antioxidant additives are added to commercially available polypropylene. The antioxidants currently used in polypropylene are mainly hindered phenols. However, many toxicological research reports show that hindered phenols are toxic substances, which undoubtedly adds potential risks to the sale and use of polypropylene. Lignin has a natural polyphenol structure and a natural antioxidant effect. As a biomass material, it is environmentally friendly. The weather-resistant plastic prepared by the present invention has good weather resistance, tensile strength, flame retardancy, self-repairing properties, and antistatic properties, and has broad market prospects. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing weather-resistant plastics to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: A weather-resistant plastic is disclosed. The weather-resistant plastic is prepared by reacting 2-chloromethylphenol with alkaline lignin and formaldehyde to obtain pre-modified lignin; reacting the pre-modified lignin with 3-aminopyrrole to obtain modified lignin; reacting graphene oxide with an ethanol solution of 3-aminopyrrole to obtain pyrrole-modified graphene oxide; reacting the pyrrole-modified graphene oxide with anhydrous ferric chloride and a chloroform solution of pyrrole to obtain modified graphene oxide; reacting polypropylene with allylphosphine dichloride after irradiation with gamma rays to obtain flame-retardant polypropylene; and reacting the flame-retardant polypropylene with N-(4-hydroxyphenyl)maleimide and triethylamine to obtain modified polypropylene; and the modified lignin, modified graphene oxide and modified polypropylene are uniformly mixed, and the mixture is subjected to extrusion granulation and hot-pressing molding.

[0006] A method for preparing a weather-resistant plastic comprises the following steps: (1) mixing graphene oxide and deionized water according to a mass ratio of 1:300, preparing graphene oxide suspension by ultrasonic dispersion, adding 3-aminopyrrole ethanol solution with a mass of 40-50 times of graphene oxide, stirring at 200-300 r / min under reflux at 85-95℃ for 20-24 h, filtering, washing the filter cake with anhydrous ethanol for 3-5 times, and drying at 65-75℃ for 4-6 h to prepare pyrrole modified graphene oxide; mixing pyrrole modified graphene oxide suspension, anhydrous ferric chloride and chloroform according to a mass ratio of 1:(1.5-2.5):(10-20), stirring at 200-300 r / min under nitrogen atmosphere at room temperature for 10-20 min, cooling to 0℃, adding pyrrole chloroform solution with a mass of 14-16 times of the pyrrole modified graphene oxide suspension, continuing to stir for 2.5-3.5 h, filtering, washing the filter cake with anhydrous ethanol for 3-5 times, and drying at 65-75℃ for 4-6 h to prepare modified graphene oxide; (2) irradiating polypropylene with γ-rays at a radiation dose of 15 kGy and a dose rate of 2.5 kGy / h, mixing the irradiated polypropylene, allyl phosphine dichloride and anhydrous ethanol according to a mass ratio of 1:(0.1-0.2):(40-60), stirring at 200-300 r / min under nitrogen atmosphere at 70-80℃ for 3-4 h, filtering, extracting the filter residue with acetone for 48 h to prepare flame-retardant polypropylene; mixing the flame-retardant polypropylene, N-(4-hydroxyphenyl)maleimide, triethylamine and tetrahydrofuran according to a mass ratio of 1:(0.2-0.3):(0.15-0.25):(30-40), stirring at 200-300 r / min under nitrogen atmosphere at room temperature for 7-9 h, filtering, washing the filter cake with anhydrous ethanol for 3-5 times, and drying at 65-75℃ for 4-6 h to prepare modified polypropylene; (3) mixing 2-chloromethylphenol, alkaline lignin and 0.1 mol / L sodium hydroxide solution according to a mass ratio of 1:(1-2):(10-20), stirring at 200-300 r / min at 75-85℃ for 1-2 h, cooling to 55-65℃, adding formaldehyde in an equal molar amount of 2-chloromethylphenol, reacting for 1-2 h, adding formaldehyde in a molar amount of 0.5 times of the modified compound, heating to 75-85℃ and continuing to react for 1-2 h, and removing water by rotary evaporation at 60-70℃ to prepare pre-modified lignin; mixing 3-aminopyrrole, pre-modified lignin, sodium carbonate and tetrahydrofuran according to a mass ratio of 1:(1.2-1.7):(1.1-1.3):(20-30), stirring at 400-600 r / min at room temperature for 3-5 h, filtering, and drying the filter residue at 40-50℃ for 5-7 h to prepare modified lignin; (4) Modified lignin, modified graphene oxide, and modified polypropylene are mixed in a mass ratio of 1: (0.8-1.2): (8-12), and granulated by extrusion using a twin-screw extruder to obtain plastic granules; the plastic granules are hot-pressed using a hot press to obtain weather-resistant plastic.

[0007] As an optimization, the graphene oxide in step (1) is graphene oxide with a diameter of 0.5 to 3 μm.

[0008] As an optimization, the preparation method of the ethanol solution of 3-aminopyrrole in step (1) is: 3-aminopyrrole and anhydrous ethanol are mixed at a mass ratio of 1: (40~50) to obtain the obtained product; the preparation method of the chloroform solution of pyrrole is: pyrrole and chloroform are mixed at a mass ratio of 1:30 to obtain the obtained product.

[0009] As an optimization, the polypropylene in step (2) is K8003 type polypropylene.

[0010] As an optimization, the alkaline lignin in step (3) is industrial grade alkaline lignin.

[0011] As an optimization, the structural formula of 2-chloromethylphenol in step (3) is: .

[0012] As an optimization, the twin-screw extrusion process parameters in step (4) are: die head temperature 165°C, zone 1 temperature 170°C, zone 2 temperature 175°C, zone 3 temperature 180°C, zone 4 temperature 175°C, and particle length 2~5mm.

[0013] As an optimization, the hot pressing process parameters of step (4) are: hot pressing temperature of 150°C, hot pressing time of 6 minutes, pressure of 4 MPa, cold pressing temperature of room temperature, cold pressing time of 6 minutes, cold pressing pressure of 4 MPa.

[0014] Compared with the prior art, the present invention has the following beneficial effects: In the preparation of the weather-resistant plastic, the present invention comprises the following steps: reacting 2-chloromethylphenol with alkaline lignin and formaldehyde to obtain pre-modified lignin; reacting the pre-modified lignin with 3-aminopyrrole to obtain modified lignin; reacting graphene oxide with an ethanol solution of 3-aminopyrrole to obtain pyrrole-modified graphene oxide; reacting the pyrrole-modified graphene oxide with anhydrous ferric chloride and a chloroform solution of pyrrole to obtain modified graphene oxide; treating polypropylene with gamma ray irradiation and reacting it with allylphosphine dichloride to obtain flame-retardant polypropylene; and then reacting the flame-retardant polypropylene with N-(4-hydroxyphenyl)maleimide and triethylamine to obtain modified polypropylene; and uniformly mixing the modified lignin, modified graphene oxide and modified polypropylene, followed by extrusion granulation and hot pressing to obtain the weather-resistant plastic.

[0015] Firstly, polypyrrole is coated on the surface of graphene oxide, polypyrrole has a large number of conjugated structures, and conductive electrons can jump on the pyrrole ring of the conjugated structure, thereby improving the antistatic performance of the weather-resistant plastic; and the polypyrrole structure on the graphene oxide can form stable chemical crosslinking with the maleimide structure on the modified polypropylene through a thermal reversible reaction, thereby improving the mechanical properties and self-repairing performance of the weather-resistant plastic; allyl phosphine dichloride is grafted on polypropylene, so that the weather-resistant plastic contains rich phosphorus elements, and the phosphorus elements have good flame retardant performance, thereby effectively improving the flame retardant performance of the weather-resistant plastic, and the chlorine introduced by the allyl phosphine dichloride can react with N-(4-hydroxyphenyl) maleimide to introduce the maleimide structure on the polypropylene.

[0016] Secondly, lignin contains rich phenolic hydroxyl structures, and the phenolic hydroxyl structures can react with free radicals to capture the electrons of the free radicals, thereby interrupting the chain reaction of the free radicals and effectively improving the weather resistance of the weather-resistant plastic; a modified compound is prepared by reacting 3-aminopyrrole with o-chlorophenol, and the pyrrole structure is introduced on the phenol structure, and the pyrrole group is introduced on the lignin by the reaction of the phenol structure with alkaline lignin and formaldehyde through the reaction of phenol and aldehyde, and the pyrrole ring conjugated structure on the pyrrole can undergo a 2+4 cycloaddition reaction with the double bond of the maleimide on the modified polypropylene, the 2+4 cycloaddition reaction is a thermal reversible reaction, which is disconnected at high temperature and combined at low temperature, so that the weather-resistant plastic can realize self-repairing effect under heating condition, and the thermal reversible reaction can form stable chemical crosslinking, thereby improving the self-repairing performance and mechanical properties of the weather-resistant plastic. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0018] Embodiment 1: A preparation method of a weather-resistant plastic, comprising the following preparation steps: (1) 3-aminopyrrole and anhydrous ethanol were mixed at a mass ratio of 1:40 to obtain an ethanol solution of 3-aminopyrrole; graphene oxide and deionized water were mixed at a mass ratio of 1:300, and graphene oxide suspension was obtained by ultrasonic dispersion. 3-aminopyrrole ethanol solution with a mass of 40 times that of graphene oxide was added, and the mixture was stirred and refluxed at 200 r / min at 85°C for 20 h, filtered, and the filter cake was washed with anhydrous ethanol for 3 times and dried at 65°C for 4 h to obtain pyrrole-modified graphene oxide; pyrrole-modified graphene oxide and chloroform were prepared into a suspension with a concentration of 2.5 mg / ml and Ultrasonic treatment for 4 hours to obtain a pyrrole-modified graphene oxide suspension; pyrrole and chloroform were mixed at a mass ratio of 1:30 to obtain a chloroform solution of pyrrole; the pyrrole-modified graphene oxide suspension, anhydrous ferric chloride, and chloroform were mixed at a mass ratio of 1:1.5:10, stirred at room temperature at 200 r / min for 10 minutes under a nitrogen atmosphere, cooled to 0°C, and 14 times the mass of the pyrrole-modified graphene oxide suspension of chloroform solution of pyrrole was added, and the reaction was continued with stirring for 2.5 hours, filtered, and the filter cake was washed with anhydrous ethanol three times and dried at 65°C for 4 hours to obtain modified graphene oxide; (2) Polypropylene was irradiated with gamma rays at a radiation dose of 15 kGy and a dose rate of 2.5 kGy / h. The irradiated polypropylene, allylphosphine dichloride, and anhydrous ethanol were mixed in a mass ratio of 1:0.1:40, stirred at 200 r / min at 70 ° C for 3 h under a nitrogen atmosphere, filtered, and the filter residue was extracted with acetone for 48 h to obtain flame-retardant polypropylene; flame-retardant polypropylene, N-(4-hydroxyphenyl)maleimide, triethylamine, and tetrahydrofuran were mixed in a mass ratio of 1:0.2:0.15:30, stirred at 200 r / min at room temperature under a nitrogen atmosphere for 7 h, filtered, and the filter cake was washed with anhydrous ethanol three times and dried at 65 ° C for 4 h to obtain modified polypropylene; (3) 2-chloromethylphenol, alkaline lignin, and 0.1 mol / L sodium hydroxide solution were mixed in a mass ratio of 1:1:10, stirred at 200 r / min at 75 °C for 1 h, cooled to 55 °C, and formaldehyde in an amount equal to the molar number of 2-chloromethylphenol was added, reacted for 1 h, and then formaldehyde in an amount 0.5 times the molar number of the modified compound was added, heated to 75 °C and continued to react for 1 h, and water was removed by rotary evaporation at 60 °C to obtain pre-modified lignin; 3-aminopyrrole, pre-modified lignin, sodium carbonate, and tetrahydrofuran were mixed in a mass ratio of 1:1.2:1.1:20, stirred at 400 r / min at room temperature for 3 h, filtered, and the filter residue was dried at 40 °C for 5 h to obtain modified lignin; (4) Modified lignin, modified graphene oxide, and modified polypropylene were mixed in a mass ratio of 1:0.8:8, and extruded into granules using a twin-screw extruder. The positions of each section were set as follows: head temperature 165°C, zone 1 temperature 170°C, zone 2 temperature 175°C, zone 3 temperature 180°C, zone 4 temperature 175°C, and granule length 2 mm to obtain plastic granules; the plastic granules were hot-pressed using a hot press at a temperature of 150°C, a hot-pressing time of 6 min, and a pressure of 4 MPa, and then cold-pressed at room temperature for 6 min, with the pressure kept constant, to obtain weather-resistant plastic.

[0019] Example 2: A method for preparing a weather-resistant plastic comprises the following steps: (1) 3-aminopyrrole and anhydrous ethanol were mixed at a mass ratio of 1:45 to obtain an ethanol solution of 3-aminopyrrole; graphene oxide and deionized water were mixed at a mass ratio of 1:300, and graphene oxide suspension was obtained by ultrasonic dispersion. 3-aminopyrrole ethanol solution with a mass of 45 times that of graphene oxide was added, and the mixture was stirred and refluxed at 250 r / min at 90°C for 22 h, filtered, and the filter cake was washed with anhydrous ethanol for 4 times and dried at 70°C for 5 h to obtain pyrrole-modified graphene oxide; pyrrole-modified graphene oxide and chloroform were prepared into a suspension with a concentration of 2.5 mg / ml. The suspension was ultrasonically treated for 5 hours to obtain a pyrrole-modified graphene oxide suspension; pyrrole and chloroform were mixed at a mass ratio of 1:30 to obtain a chloroform solution of pyrrole; the pyrrole-modified graphene oxide suspension, anhydrous ferric chloride, and chloroform were mixed at a mass ratio of 1:2:15, stirred at room temperature at 250 r / min for 15 minutes under a nitrogen atmosphere, cooled to 0°C, and 15 times the mass of the pyrrole-modified graphene oxide suspension of chloroform solution of pyrrole was added, and the reaction was continued by stirring for 3 minutes, filtered, and the filter cake was washed with anhydrous ethanol 4 times, and dried at 70°C for 5 hours to obtain modified graphene oxide; (2) Polypropylene was irradiated with gamma rays at a radiation dose of 15 kGy and a dose rate of 2.5 kGy / h. The irradiated polypropylene, allylphosphine dichloride, and anhydrous ethanol were mixed in a mass ratio of 1:0.15:50, stirred at 250 r / min at 75 ° C for 3.5 h under a nitrogen atmosphere, filtered, and the filter residue was extracted with acetone for 48 h to obtain flame-retardant polypropylene; flame-retardant polypropylene, N-(4-hydroxyphenyl)maleimide, triethylamine, and tetrahydrofuran were mixed in a mass ratio of 1:0.25:0.2:35, stirred at 250 r / min at room temperature for 8 h under a nitrogen atmosphere, filtered, and the filter cake was washed with anhydrous ethanol 4 times and dried at 70 ° C for 5 h to obtain modified polypropylene; (3) 2-chloromethylphenol, alkaline lignin, and 0.1 mol / L sodium hydroxide solution were mixed in a mass ratio of 1:1.5:15, stirred at 250 r / min at 80 °C for 1.5 h, cooled to 60 °C, and formaldehyde in an amount equal to the molar number of 2-chloromethylphenol was added, and the reaction was continued for 1.5 h. Then, formaldehyde in an amount 0.5 times the molar number of the modified compound was added, and the temperature was raised to 80 °C and the reaction was continued for 1.5 h. Water was removed by rotary evaporation at 65 °C to obtain pre-modified lignin; 3-aminopyrrole, pre-modified lignin, sodium carbonate, and tetrahydrofuran were mixed in a mass ratio of 1:1.4:1.2:25, stirred at 500 r / min at room temperature for 4 h, filtered, and the filter residue was dried at 45 °C for 6 h to obtain modified lignin; (4) Modified lignin, modified graphene oxide, and modified polypropylene were mixed in a mass ratio of 1:1:10, and extruded into granules using a twin-screw extruder. The positions of each section were set as follows: head temperature 165°C, zone 1 temperature 170°C, zone 2 temperature 175°C, zone 3 temperature 180°C, zone 4 temperature 175°C, and granule length 3.5 mm to obtain plastic granules; the plastic granules were hot-pressed using a hot press at a temperature of 150°C, a hot-pressing time of 6 min, and a pressure of 4 MPa, and then cold-pressed at room temperature for 6 min, with the pressure kept constant, to obtain weather-resistant plastic.

[0020] Example 3: A method for preparing a weather-resistant plastic comprises the following steps: (1) 3-aminopyrrole and anhydrous ethanol were mixed at a mass ratio of 1:50 to obtain an ethanol solution of 3-aminopyrrole; graphene oxide and deionized water were mixed at a mass ratio of 1:300, and graphene oxide suspension was obtained by ultrasonic dispersion. 3-aminopyrrole ethanol solution with a mass of 50 times that of graphene oxide was added, and the mixture was stirred and refluxed at 300 r / min at 95°C for 24 h, filtered, and the filter cake was washed with anhydrous ethanol for 5 times, and dried at 75°C for 6 h to obtain pyrrole-modified graphene oxide; pyrrole-modified graphene oxide and chloroform were prepared into a suspension with a concentration of 2.5 mg / ml and Ultrasonic treatment for 6 hours to obtain a pyrrole-modified graphene oxide suspension; pyrrole and chloroform were mixed at a mass ratio of 1:30 to obtain a chloroform solution of pyrrole; the pyrrole-modified graphene oxide suspension, anhydrous ferric chloride, and chloroform were mixed at a mass ratio of 1:2.5:20, stirred at 300 r / min at room temperature for 20 minutes under a nitrogen atmosphere, cooled to 0°C, and 16 times the mass of the pyrrole-modified graphene oxide suspension in chloroform solution was added, and the reaction was continued with stirring for 3.5 hours, filtered, and the filter cake was washed with anhydrous ethanol 5 times and dried at 75°C for 6 hours to obtain modified graphene oxide; (2) Polypropylene was irradiated with gamma rays at a radiation dose of 15 kGy and a dose rate of 2.5 kGy / h. The irradiated polypropylene, allylphosphine dichloride, and anhydrous ethanol were mixed in a mass ratio of 1:0.2:60, stirred at 300 r / min at 80 °C for 4 h under a nitrogen atmosphere, filtered, and the filter residue was extracted with acetone for 48 h to obtain flame-retardant polypropylene; flame-retardant polypropylene, N-(4-hydroxyphenyl)maleimide, triethylamine, and tetrahydrofuran were mixed in a mass ratio of 1:0.3:0.25:40, stirred at 300 r / min at room temperature for 9 h under a nitrogen atmosphere, filtered, and the filter cake was washed with anhydrous ethanol 5 times and dried at 75 °C for 6 h to obtain modified polypropylene; (3) 2-chloromethylphenol, alkaline lignin, and 0.1 mol / L sodium hydroxide solution were mixed in a mass ratio of 1:2:20, stirred at 85°C and 300 r / min for 2 h, cooled to 65°C, and formaldehyde in an amount equal to the molar number of 2-chloromethylphenol was added, and the reaction was continued for 2 h. Then, formaldehyde in an amount 0.5 times the molar number of the modified compound was added, and the temperature was raised to 85°C and the reaction was continued for 1-2 h. Water was removed by rotary evaporation at 70°C to obtain pre-modified lignin; 3-aminopyrrole, pre-modified lignin, sodium carbonate, and tetrahydrofuran were mixed in a mass ratio of 1:1.7:1.3:30, stirred at room temperature and 600 r / min for 5 h, filtered, and the filter residue was dried at 50°C for 7 h to obtain modified lignin; (4) Modified lignin, modified graphene oxide, and modified polypropylene were mixed in a mass ratio of 1:1.2:12, and extruded into granules using a twin-screw extruder. The positions of each section were set as follows: head temperature 165°C, zone 1 temperature 170°C, zone 2 temperature 175°C, zone 3 temperature 180°C, zone 4 temperature 175°C, and granule length 5 mm to obtain plastic granules; the plastic granules were hot-pressed using a hot press at a temperature of 150°C, a hot-pressing time of 6 min, and a pressure of 4 MPa, and then cold-pressed at room temperature for 6 min, with the pressure kept constant, to obtain weather-resistant plastic.

[0021] Comparative Example 1: A method for preparing a weather-resistant plastic comprises the following steps: (1) 3-aminopyrrole and anhydrous ethanol were mixed at a mass ratio of 1:45 to obtain an ethanol solution of 3-aminopyrrole; graphene oxide and deionized water were mixed at a mass ratio of 1:300, and graphene oxide suspension was obtained by ultrasonic dispersion. 3-aminopyrrole ethanol solution with a mass of 45 times that of graphene oxide was added, and the mixture was stirred and refluxed at 250 r / min at 90°C for 22 h, filtered, and the filter cake was washed with anhydrous ethanol for 4 times and dried at 70°C for 5 h to obtain pyrrole-modified graphene oxide; pyrrole-modified graphene oxide and chloroform were prepared into a suspension with a concentration of 2.5 mg / ml. The suspension was ultrasonically treated for 5 hours to obtain a pyrrole-modified graphene oxide suspension; pyrrole and chloroform were mixed at a mass ratio of 1:30 to obtain a chloroform solution of pyrrole; the pyrrole-modified graphene oxide suspension, anhydrous ferric chloride, and chloroform were mixed at a mass ratio of 1:2:15, stirred at room temperature at 250 r / min for 15 minutes under a nitrogen atmosphere, cooled to 0°C, and 15 times the mass of the pyrrole-modified graphene oxide suspension of chloroform solution of pyrrole was added, and the reaction was continued by stirring for 3 minutes, filtered, and the filter cake was washed with anhydrous ethanol 4 times, and dried at 70°C for 5 hours to obtain modified graphene oxide; (2) Polypropylene was irradiated with gamma rays at a radiation dose of 15 kGy and a dose rate of 2.5 kGy / h. The irradiated polypropylene, N-allylmaleimide, and anhydrous ethanol were mixed in a mass ratio of 1:0.15:50. The mixture was stirred at 250 r / min at 75°C for 3.5 h under a nitrogen atmosphere. The mixture was filtered and the residue was extracted with acetone for 48 h to obtain modified polypropylene. (3) 2-chloromethylphenol, alkaline lignin, and 0.1 mol / L sodium hydroxide solution were mixed in a mass ratio of 1:1.5:15, stirred at 250 r / min at 80 °C for 1.5 h, cooled to 60 °C, and formaldehyde in an amount equal to the molar number of 2-chloromethylphenol was added, and the reaction was continued for 1.5 h. Then, formaldehyde in an amount 0.5 times the molar number of the modified compound was added, and the temperature was raised to 80 °C and the reaction was continued for 1.5 h. Water was removed by rotary evaporation at 65 °C to obtain pre-modified lignin; 3-aminopyrrole, pre-modified lignin, sodium carbonate, and tetrahydrofuran were mixed in a mass ratio of 1:1.4:1.2:25, stirred at 500 r / min at room temperature for 4 h, filtered, and the filter residue was dried at 45 °C for 6 h to obtain modified lignin; (4) Modified lignin, modified graphene oxide, and modified polypropylene were mixed in a mass ratio of 1:1:10, and extruded into granules using a twin-screw extruder. The positions of each section were set as follows: head temperature 165°C, zone 1 temperature 170°C, zone 2 temperature 175°C, zone 3 temperature 180°C, zone 4 temperature 175°C, and granule length 3.5 mm to obtain plastic granules; the plastic granules were hot-pressed using a hot press at a temperature of 150°C, a hot-pressing time of 6 min, and a pressure of 4 MPa, and then cold-pressed at room temperature for 6 min, with the pressure kept constant, to obtain weather-resistant plastic.

[0022] Comparative Example 2: A method for preparing a weather-resistant plastic comprises the following steps: (1) 3-aminopyrrole and anhydrous ethanol were mixed at a mass ratio of 1:45 to obtain an ethanol solution of 3-aminopyrrole; graphene oxide and deionized water were mixed at a mass ratio of 1:300, and graphene oxide suspension was obtained by ultrasonic dispersion. 3-aminopyrrole ethanol solution with a mass of 45 times that of graphene oxide was added, and the mixture was stirred and refluxed at 250 r / min at 90°C for 22 h, filtered, and the filter cake was washed with anhydrous ethanol for 4 times and dried at 70°C for 5 h to obtain pyrrole-modified graphene oxide; pyrrole-modified graphene oxide and chloroform were prepared into a suspension with a concentration of 2.5 mg / ml. The suspension was ultrasonically treated for 5 hours to obtain a pyrrole-modified graphene oxide suspension; pyrrole and chloroform were mixed at a mass ratio of 1:30 to obtain a chloroform solution of pyrrole; the pyrrole-modified graphene oxide suspension, anhydrous ferric chloride, and chloroform were mixed at a mass ratio of 1:2:15, stirred at room temperature at 250 r / min for 15 minutes under a nitrogen atmosphere, cooled to 0°C, and 15 times the mass of the pyrrole-modified graphene oxide suspension of chloroform solution of pyrrole was added, and the reaction was continued by stirring for 3 minutes, filtered, and the filter cake was washed with anhydrous ethanol 4 times, and dried at 70°C for 5 hours to obtain modified graphene oxide; (2) Polypropylene was irradiated with gamma rays at a radiation dose of 15 kGy and a dose rate of 2.5 kGy / h. The irradiated polypropylene, allylphosphine dichloride, and anhydrous ethanol were mixed in a mass ratio of 1:0.15:50. The mixture was stirred at 250 r / min at 75°C for 3.5 h under a nitrogen atmosphere. The mixture was filtered and the residue was extracted with acetone for 48 h to obtain modified polypropylene. (3) 2-chloromethylphenol, alkaline lignin, and 0.1 mol / L sodium hydroxide solution were mixed in a mass ratio of 1:1.5:15, stirred at 250 r / min at 80 °C for 1.5 h, cooled to 60 °C, and formaldehyde in an amount equal to the molar number of 2-chloromethylphenol was added, and the reaction was continued for 1.5 h. Then, formaldehyde in an amount 0.5 times the molar number of the modified compound was added, and the temperature was raised to 80 °C and the reaction was continued for 1.5 h. Water was removed by rotary evaporation at 65 °C to obtain pre-modified lignin; 3-aminopyrrole, pre-modified lignin, sodium carbonate, and tetrahydrofuran were mixed in a mass ratio of 1:1.4:1.2:25, stirred at 500 r / min at room temperature for 4 h, filtered, and the filter residue was dried at 45 °C for 6 h to obtain modified lignin; (4) Modified lignin, modified graphene oxide, and modified polypropylene were mixed in a mass ratio of 1:1:10, and extruded into granules using a twin-screw extruder. The positions of each section were set as follows: head temperature 165°C, zone 1 temperature 170°C, zone 2 temperature 175°C, zone 3 temperature 180°C, zone 4 temperature 175°C, and granule length 3.5 mm to obtain plastic granules; the plastic granules were hot-pressed using a hot press at a temperature of 150°C, a hot-pressing time of 6 min, and a pressure of 4 MPa, and then cold-pressed at room temperature for 6 min, with the pressure kept constant, to obtain weather-resistant plastic.

[0023] Comparative Example 3: A method for preparing a weather-resistant plastic comprises the following steps: (1) Polypropylene was irradiated with gamma rays at a radiation dose of 15 kGy and a dose rate of 2.5 kGy / h. The irradiated polypropylene, allylphosphine dichloride, and anhydrous ethanol were mixed in a mass ratio of 1:0.15:50, stirred at 250 r / min at 75 ° C for 3.5 h under a nitrogen atmosphere, filtered, and the filter residue was extracted with acetone for 48 h to obtain flame-retardant polypropylene; flame-retardant polypropylene, N-(4-hydroxyphenyl)maleimide, triethylamine, and tetrahydrofuran were mixed in a mass ratio of 1:0.25:0.2:35, stirred at 250 r / min at room temperature for 8 h under a nitrogen atmosphere, filtered, and the filter cake was washed with anhydrous ethanol 4 times and dried at 70 ° C for 5 h to obtain modified polypropylene; (2) 2-chloromethylphenol, alkaline lignin, and 0.1 mol / L sodium hydroxide solution were mixed in a mass ratio of 1:1.5:15, stirred at 250 r / min at 80 °C for 1.5 h, cooled to 60 °C, and formaldehyde in an amount equal to the molar number of 2-chloromethylphenol was added, reacted for 1.5 h, and then formaldehyde in an amount 0.5 times the molar number of the modified compound was added, heated to 80 °C, and continued to react for 1.5 h. Water was removed by rotary evaporation at 65 °C to obtain pre-modified lignin; 3-aminopyrrole, pre-modified lignin, sodium carbonate, and tetrahydrofuran were mixed in a mass ratio of 1:1.4:1.2:25, stirred at 500 r / min at room temperature for 4 h, filtered, and the filter residue was dried at 45 °C for 6 h to obtain modified lignin; (3) Modified lignin, graphene oxide, and modified polypropylene were mixed in a mass ratio of 1:1:10, and extruded into granules using a twin-screw extruder. The positions of each section were set as follows: head temperature 165°C, zone 1 temperature 170°C, zone 2 temperature 175°C, zone 3 temperature 180°C, zone 4 temperature 175°C, and granule length 3.5 mm to obtain plastic granules. The plastic granules were hot-pressed using a hot press at a temperature of 150°C, a hot-pressing time of 6 min, and a pressure of 4 MPa, and then cold-pressed at room temperature for 6 min, with the pressure kept constant, to obtain weather-resistant plastic.

[0024] Comparative Example 4: A method for preparing a weather-resistant plastic comprises the following steps: (1) 3-aminopyrrole and anhydrous ethanol were mixed at a mass ratio of 1:45 to obtain an ethanol solution of 3-aminopyrrole; graphene oxide and deionized water were mixed at a mass ratio of 1:300, and graphene oxide suspension was obtained by ultrasonic dispersion. 3-aminopyrrole ethanol solution with a mass of 45 times that of graphene oxide was added, and the mixture was stirred and refluxed at 250 r / min at 90°C for 22 h, filtered, and the filter cake was washed with anhydrous ethanol for 4 times and dried at 70°C for 5 h to obtain pyrrole-modified graphene oxide; pyrrole-modified graphene oxide and chloroform were prepared into a suspension with a concentration of 2.5 mg / ml. The suspension was ultrasonically treated for 5 hours to obtain a pyrrole-modified graphene oxide suspension; pyrrole and chloroform were mixed at a mass ratio of 1:30 to obtain a chloroform solution of pyrrole; the pyrrole-modified graphene oxide suspension, anhydrous ferric chloride, and chloroform were mixed at a mass ratio of 1:2:15, stirred at room temperature at 250 r / min for 15 minutes under a nitrogen atmosphere, cooled to 0°C, and 15 times the mass of the pyrrole-modified graphene oxide suspension of chloroform solution of pyrrole was added, and the reaction was continued by stirring for 3 minutes, filtered, and the filter cake was washed with anhydrous ethanol 4 times, and dried at 70°C for 5 hours to obtain modified graphene oxide; (2) Polypropylene was irradiated with gamma rays at a radiation dose of 15 kGy and a dose rate of 2.5 kGy / h. The irradiated polypropylene, allylphosphine dichloride, and anhydrous ethanol were mixed in a mass ratio of 1:0.15:50, stirred at 250 r / min at 75 ° C for 3.5 h under a nitrogen atmosphere, filtered, and the filter residue was extracted with acetone for 48 h to obtain flame-retardant polypropylene; flame-retardant polypropylene, N-(4-hydroxyphenyl)maleimide, triethylamine, and tetrahydrofuran were mixed in a mass ratio of 1:0.25:0.2:35, stirred at 250 r / min at room temperature for 8 h under a nitrogen atmosphere, filtered, and the filter cake was washed with anhydrous ethanol 4 times and dried at 70 ° C for 5 h to obtain modified polypropylene; (3) Alkaline lignin, modified graphene oxide, and modified polypropylene were mixed in a mass ratio of 1:1:10, and extruded into granules using a twin-screw extruder. The positions of each section were set as follows: head temperature 165°C, zone 1 temperature 170°C, zone 2 temperature 175°C, zone 3 temperature 180°C, zone 4 temperature 175°C, and granule length 3.5 mm to obtain plastic granules; the plastic granules were hot-pressed using a hot press at a temperature of 150°C, a hot-pressing time of 6 min, and a pressure of 4 MPa, and then cold-pressed at room temperature for 6 min, with the pressure kept constant, to obtain weather-resistant plastic.

[0025] Comparative Example 5: A method for preparing a weather-resistant plastic comprises the following steps: (1) 3-aminopyrrole and anhydrous ethanol were mixed at a mass ratio of 1:45 to obtain an ethanol solution of 3-aminopyrrole; graphene oxide and deionized water were mixed at a mass ratio of 1:300, and graphene oxide suspension was obtained by ultrasonic dispersion. 3-aminopyrrole ethanol solution with a mass of 45 times that of graphene oxide was added, and the mixture was stirred and refluxed at 250 r / min at 90°C for 22 h, filtered, and the filter cake was washed with anhydrous ethanol for 4 times and dried at 70°C for 5 h to obtain pyrrole-modified graphene oxide; pyrrole-modified graphene oxide and chloroform were prepared into a suspension with a concentration of 2.5 mg / ml. The suspension was ultrasonically treated for 5 hours to obtain a pyrrole-modified graphene oxide suspension; pyrrole and chloroform were mixed at a mass ratio of 1:30 to obtain a chloroform solution of pyrrole; the pyrrole-modified graphene oxide suspension, anhydrous ferric chloride, and chloroform were mixed at a mass ratio of 1:2:15, stirred at room temperature at 250 r / min for 15 minutes under a nitrogen atmosphere, cooled to 0°C, and 15 times the mass of the pyrrole-modified graphene oxide suspension of chloroform solution of pyrrole was added, and the reaction was continued by stirring for 3 minutes, filtered, and the filter cake was washed with anhydrous ethanol 4 times, and dried at 70°C for 5 hours to obtain modified graphene oxide; (2) Polypropylene was irradiated with gamma rays at a radiation dose of 15 kGy and a dose rate of 2.5 kGy / h. The irradiated polypropylene, allylphosphine dichloride, and anhydrous ethanol were mixed in a mass ratio of 1:0.15:50, stirred at 250 r / min at 75 ° C for 3.5 h under a nitrogen atmosphere, filtered, and the filter residue was extracted with acetone for 48 h to obtain flame-retardant polypropylene; flame-retardant polypropylene, N-(4-hydroxyphenyl)maleimide, triethylamine, and tetrahydrofuran were mixed in a mass ratio of 1:0.25:0.2:35, stirred at 250 r / min at room temperature for 8 h under a nitrogen atmosphere, filtered, and the filter cake was washed with anhydrous ethanol 4 times and dried at 70 ° C for 5 h to obtain modified polypropylene; (3) Modified graphene oxide and modified polypropylene were mixed in a mass ratio of 1:10, and extruded into granules using a twin-screw extruder. The positions of each section were set as follows: head temperature 165°C, zone 1 temperature 170°C, zone 2 temperature 175°C, zone 3 temperature 180°C, zone 4 temperature 175°C, and granule length 3.5 mm to obtain plastic granules; the plastic granules were hot-pressed using a hot press at a temperature of 150°C, a hot-pressing time of 6 min, and a pressure of 4 MPa, and then cold-pressed at room temperature for 6 min, with the pressure kept constant, to obtain weather-resistant plastic.

[0026] Test Example 1: Mechanical properties testing: According to GB / T 1040-1992, the samples were tested using a DXLL-5000 electronic tensile testing machine from Shanghai Dengjie Mechanical Equipment Co., Ltd. The test temperature was 25 ± 1°C. The results are shown in Table 1.

[0027] Weather resistance test: according to GB / T3512-2014, the prepared standard sample was placed in a DHG-9245A type electric heating air drying oven for 30 days of indoor heat aging test, the temperature was set to 100 DEG C, the tensile strength retention rate of the material after 30 days of test was tested. The results are shown in Table 2.

[0028] Self-repairing performance test: each example and comparative example was cut into a sample with a size of 20mmx4mmx1mm, an original sample was prepared, the original tensile strength 1 was tested; the sample was cut at the middle position, the cut sample was gently placed together, heated to 150 DEG C and kept for 10 minutes, then cooled to room temperature, the tensile strength 2 was tested. The repair efficiency was calculated according to repair efficiency=tensile strength 2 / tensile strength 1x100%. The results are shown in Table 3.

[0029] Table 1

[0030] From the comparison of the experimental data of examples 1~3 and comparative examples 1~5 in Table 1, it can be found that the weather-resistant plastic prepared by the application has good mechanical properties.

[0031] By comparison, the tensile strength of examples 1~3 is greater than that of comparative example 2, which shows that the maleimide on the modified polypropylene can form stable chemical crosslinking with the pyrrole structure on the modified lignin through thermal reversible reaction, thereby improving the mechanical properties of the weather-resistant plastic; the tensile strength of examples 1~3 is greater than that of comparative example 3, which shows that the polypyrrole structure on the graphene oxide can form stable chemical crosslinking with the maleimide structure on the modified polypropylene through thermal reversible reaction, thereby improving the mechanical properties of the weather-resistant plastic; the tensile strength of examples 1~3 is greater than that of comparative example 4, which shows that the pyrrole structure on the modified lignin can form stable chemical crosslinking with the maleimide structure on the modified polypropylene through thermal reversible reaction, thereby improving the mechanical properties of the weather-resistant plastic.

[0032] Table 2

[0033] From the comparison of the experimental data of examples 1~3 and comparative examples 1~5 in Table 2, it can be found that the weather-resistant plastic prepared by the application has good weather resistance.

[0034] By comparison, the tensile strength retention rate of examples 1~3 is greater than that of comparative example 5, which shows that lignin contains rich phenolic hydroxyl structure, the phenolic hydroxyl structure can react with free radicals and take away the electrons of free radicals, thereby interrupting the chain reaction of free radicals and effectively improving the aging resistance of the weather-resistant plastic.

[0035] Table 3

[0036] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 3, it can be found that the weather-resistant plastic prepared by the present invention has good self-repairing properties.

[0037] By comparison, the repair efficiency of Examples 1 to 3 is significantly greater than that of Comparative Example 2, indicating that the maleimide structure on the modified polypropylene can undergo a thermally reversible reaction with the polypyrrole on the modified graphene oxide and the pyrrole on the modified lignin, disconnecting at high temperature and combining at low temperature, so that the weather-resistant plastic can achieve a self-repairing effect under heating conditions; the repair efficiency of Examples 1 to 3 is greater than that of Comparative Example 3, indicating that the polypyrrole structure on the graphene oxide can undergo a thermally reversible reaction with the maleimide structure on the modified polypropylene, thereby improving the self-repairing performance of the weather-resistant plastic; the repair efficiency of Examples 1 to 3 is significantly greater than that of Comparative Examples 4 and 5, indicating that the pyrrole on the modified lignin can undergo a thermally reversible reaction with the maleimide structure on the modified polypropylene, thereby improving the self-repairing performance of the weather-resistant plastic.

[0038] Test Example 2: Flame retardancy testing: According to ISO 4589-2, sample dimensions were 100 mm × 6.5 mm × 3.2 mm. The limiting oxygen index (LOI) was measured using a JF-3 oxygen index meter. The results are shown in Table 4.

[0039] Table 4

[0040] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 4, it can be found that the weather-resistant plastic prepared by the present invention has good flame retardant properties.

[0041] By comparison, the limiting oxygen index of Examples 1 to 3 is significantly greater than that of Comparative Example 1, indicating that the introduction of allylphosphine dichloride into polypropylene by grafting makes the weather-resistant plastic rich in phosphorus, and phosphorus has good flame retardant properties, thereby effectively improving the flame retardant properties of the weather-resistant plastic.

[0042] Test Example 3: Antistatic testing: Antistatic performance testing was conducted in accordance with GB / T 1410-2006, with a test voltage of 100V and a charge time of 30 seconds. The specimens were placed in a constant temperature and humidity chamber for 24 hours (23°C, 45% relative humidity) before testing. Surface resistivity was then measured. Results are shown in Table 5.

[0043] Table 5

[0044] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 5, it can be found that the weather-resistant plastic prepared by the present invention has good antistatic properties.

[0045] By comparison, the surface resistivity of examples 1-3 is obviously smaller than that of comparative example 3, which indicates that polypyrrole is coated on the surface of graphene oxide, polypyrrole has a large number of conjugated structures, and conductive electrons can jump on the pyrrole ring of the conjugated structure, thereby improving the antistatic property of the weather-resistant plastic.

[0046] The above detailed description further explains the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A weather-resistant plastic, characterized in that: The weather-resistant plastic is prepared by mixing modified lignin, modified graphene oxide and modified polypropylene, followed by extrusion granulation and hot pressing. The modified lignin is prepared by reacting 2-chloromethylphenol with alkaline lignin and formaldehyde to obtain pre-modified lignin; and reacting the pre-modified lignin with 3-aminopyrrole; The modified graphene oxide is prepared by reacting graphene oxide with an ethanol solution of 3-aminopyrrole to obtain pyrrole-modified graphene oxide; and reacting the pyrrole-modified graphene oxide with anhydrous ferric chloride and a chloroform solution of pyrrole; The modified polypropylene is prepared by subjecting polypropylene to gamma ray irradiation treatment and reacting it with allylphosphine dichloride to obtain flame-retardant polypropylene, and then reacting the flame-retardant polypropylene with N-(4-hydroxyphenyl)maleimide and triethylamine.

2. A method for preparing a weather-resistant plastic, characterized in that: The method comprises the following preparation steps: (1) Graphene oxide and deionized water were mixed at a mass ratio of 1:300, and ultrasonic dispersion was performed to obtain a graphene oxide suspension. An ethanol solution of 3-aminopyrrole in an amount of 40 to 50 times the mass of graphene oxide was added, and the mixture was stirred and refluxed at 200 to 300 r / min at 85 to 95 ° C for 20 to 24 h. The mixture was filtered, and the filter cake was washed with anhydrous ethanol for 3 to 5 times, and dried at 65 to 75 ° C for 4 to 6 h to obtain pyrrole-modified graphene oxide. The pyrrole-modified graphene oxide suspension and the deionized water were mixed and the mixture was ultrasonic dispersion to obtain a graphene oxide suspension. Aqueous ferric chloride and chloroform are mixed in a mass ratio of 1: (1.5-2.5): (10-20), stirred at room temperature at 200-300 r / min for 10-20 min under a nitrogen atmosphere, cooled to 0°C, and a chloroform solution of pyrrole in an amount of 14-16 times the mass of the pyrrole-modified graphene oxide suspension is added. The reaction is continued with stirring for 2.5-3.5 h, filtered, and the filter cake is washed with anhydrous ethanol 3-5 times and dried at 65-75°C for 4-6 h to obtain modified graphene oxide. (2) Polypropylene was irradiated with gamma rays at a radiation dose of 15 kGy and a dose rate of 2.5 kGy / h. The irradiated polypropylene, allylphosphine dichloride, and anhydrous ethanol were mixed in a mass ratio of 1: (0.1-0.2): (40-60), stirred at 200-300 r / min at 70-80 ° C for 3-4 hours under a nitrogen atmosphere, filtered, and the filter residue was extracted with acetone for 48 hours to obtain flame-retardant polypropylene; flame-retardant polypropylene, N-(4-hydroxyphenyl)maleimide, triethylamine, and tetrahydrofuran were mixed in a mass ratio of 1: (0.2-0.3): (0.15-0.25): (30-40), stirred at 200-300 r / min at room temperature for 7-9 hours under a nitrogen atmosphere, filtered, and the filter cake was washed with anhydrous ethanol 3-5 times and dried at 65-75 ° C for 4-6 hours to obtain modified polypropylene; (3) 2-chloromethylphenol, alkaline lignin, and 0.1 mol / L sodium hydroxide solution were mixed in a mass ratio of 1: (1-2): (10-20), stirred at 200-300 r / min at 75-85 °C for 1-2 h, cooled to 55-65 °C, and formaldehyde in an amount equal to the molar number of 2-chloromethylphenol was added to react for 1-2 h. Then, formaldehyde in an amount 0.5 times the molar number of the modified compound was added, and the temperature was raised to 75-85 °C and the reaction was continued for 1-2 h. Water was removed by rotary evaporation at 60-70 °C to obtain pre-modified lignin; 3-aminopyrrole, pre-modified lignin, sodium carbonate, and tetrahydrofuran were mixed in a mass ratio of 1: (1.2-1.7): (1.1-1.3): (20-30), stirred at 400-600 r / min at room temperature for 3-5 h, filtered, and the filter residue was dried at 40-50 °C for 5-7 h to obtain modified lignin; (4) Modified lignin, modified graphene oxide, and modified polypropylene are mixed in a mass ratio of 1: (0.8-1.2): (8-12), and granulated by extrusion using a twin-screw extruder to obtain plastic granules; the plastic granules are hot-pressed using a hot press to obtain weather-resistant plastic.

3. The method for preparing a weather-resistant plastic according to claim 2, characterized in that: The graphene oxide in step (1) is graphene oxide with a diameter of 0.5 to 3 μm.

4. The method for preparing a weather-resistant plastic according to claim 2, characterized in that: The preparation method of the ethanol solution of 3-aminopyrrole in step (1) is: 3-aminopyrrole and anhydrous ethanol are mixed in a mass ratio of 1: (40-50) to obtain the obtained product; the preparation method of the chloroform solution of pyrrole is: pyrrole and chloroform are mixed in a mass ratio of 1:30 to obtain the obtained product.

5. The method for preparing a weather-resistant plastic according to claim 2, characterized in that: The polypropylene in step (2) is K8003 type polypropylene.

6. The method for preparing a weather-resistant plastic according to claim 2, characterized in that: The alkaline lignin in step (3) is industrial grade alkaline lignin.

7. The method for preparing a weather-resistant plastic according to claim 2, characterized in that: The twin-screw extrusion process parameters in step (4) are: die head temperature 165°C, zone 1 temperature 170°C, zone 2 temperature 175°C, zone 3 temperature 180°C, zone 4 temperature 175°C, and particle length 2~5mm.

8. The method for preparing a weather-resistant plastic according to claim 2, characterized in that: The hot pressing process parameters of step (4) are as follows: hot pressing temperature of 150°C, hot pressing time of 6 minutes, pressure of 4 MPa, cold pressing temperature of room temperature, cold pressing time of 6 minutes, cold pressing pressure of 4 MPa.

9. Use of the weather-resistant plastic prepared by the method for preparing the weather-resistant plastic according to any one of claims 2 to 8 in plastic parts for electric vehicles.

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