A g-c3n4 modified pc, a preparation method and application thereof

Abstract

The application provides a g-C3N4 modified PC and a preparation method and application thereof, the modified PC comprises the following components in mass fraction: base PC resin 96-98%, flame retardant 0.05-0.2%, toughening agent 0.1-1.5%, antioxidant 0.05-0.15%, lubricant 0.1-0.5%, maleic anhydride grafted g-C3N4 nano material 0.01-1%, and toner 0.5-1%. The modified PC has excellent antibacterial and antifouling capacity, can effectively solve the appearance problems of existing PC materials, such as easy fouling, poor wear resistance and the like in electronic and electrical products and daily packaging material products, the toughness and strength of the material are improved, and in addition, the modified PC material has certain light stability.

Description

Technical Field

[0001] This invention belongs to the field of modified polycarbonate, specifically relating to a g-C3N4 modified PC, its preparation method, and its application. Background Technology

[0002] Modified PC possesses excellent physical and mechanical properties, such as high transparency, high tensile strength, high flexural strength, as well as good heat resistance and easy processing. These characteristics enable modified PC to meet various application requirements, such as 3C electronics, new energy vehicles, and smart home fields.

[0003] Despite the numerous advantages of modified PC, several challenges remain in practical applications. These include residual stress and differences in toughness leading to stress cracking in molded parts; poor solvent and abrasion resistance resulting in a deteriorated appearance; and susceptibility to hydrolysis during high-temperature or UV aging. In the electronics and electrical packaging sector, its smooth surface is prone to organic contamination, causing cracking and scratches, potentially limiting its application in certain daily consumer and electrical packaging markets. Therefore, developing environmentally friendly, antibacterial, stain-resistant, and flame-retardant PC has become a crucial direction for modified PC products.

[0004] The existing g-C3N4 preparation technology is basically mature. g-C3N4 nanomaterials of corresponding size and thickness can be obtained through simple heat treatment and calcination. They can be widely used in photocatalysis and other fields with excellent catalytic efficiency. For example, patent CN105148744A discloses a method and application for preparing an adjustable ultrathin two-dimensional nano g-C3N4 film by high-temperature heat treatment and elongation. However, there are few reports on the application of g-C3N4 as a functional additive in the modification of polycarbonate. Therefore, this application provides a method and application for modifying polycarbonate with g-C3N4 to solve the appearance problems of existing PC materials in electronic appliances and daily packaging materials, such as easy dirt and poor wear resistance. Summary of the Invention

[0005] The purpose of this invention is to provide a g-C3N4 modified PC material and its preparation method, so as to solve the appearance problems of polycarbonate in electronic appliances and daily packaging materials, such as easy soiling and poor wear resistance.

[0006] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows:

[0007] A g-C3N4 modified PC comprises the following components by mass fraction:

[0008] Matrix PC resin 96-98%;

[0009] Flame retardant 0.05-0.2%;

[0010] Toughening agent 0.1-1.5%;

[0011] Antioxidant 0.05-0.15%;

[0012] Lubricant 0.1-0.5%;

[0013] Maleic anhydride grafted with g-C3N4 nanomaterials: 0.01-1%;

[0014] Pigment powder 0.5-1%.

[0015] Preferably, the matrix PC resin is a polycarbonate with a melt index of 7-15 g / 10 min at 300°C and 1.2 kg, more preferably a polycarbonate with a melt index of 9-10 g / 10 min;

[0016] The flame retardant is one or more of sulfonate flame retardants, preferably one or more of perfluoroalkyl sulfonates, diphenyl sulfonates, or diphenyl ether sulfonates.

[0017] The toughening agent is one or more of methyl acrylate-butadiene copolymer, methyl methacrylate-butadiene copolymer, methyl acrylate-styrene copolymer, methyl methacrylate-styrene copolymer, methyl acrylate-butadiene-styrene copolymer, and methyl methacrylate-butadiene-styrene copolymer, preferably methyl methacrylate-butadiene-styrene copolymer;

[0018] The antioxidant is one or more of phosphite antioxidants or hindered phenolic antioxidants, preferably a combination of two antioxidants;

[0019] The lubricant is one or more of stearate compounds or polyethylene waxes, preferably pentaerythritol stearate or polyethylene wax with a molecular weight of less than or equal to 2000.

[0020] The colorant is titanium dioxide or a combination of titanium dioxide and other conventional colorants;

[0021] Preferably, the maleic anhydride-grafted g-C3N4 nanoparticles are obtained by grafting modification after high-temperature calcination, and the preparation method includes the following steps:

[0022] S1: Urea or melamine is heat-treated at high temperature under N2 atmosphere and then calcined under air atmosphere to obtain g-C3N4 powder.

[0023] S2: Disperse g-C3N4 powder in solvent A to obtain g-C3N4 solution, then add maleic anhydride solution for hydrothermal grafting modification, and finally obtain maleic anhydride-grafted g-C3N4 nanomaterials by centrifugation and freeze drying.

[0024] Preferably, in S1, after high-temperature heat treatment in N2 atmosphere, the powder is calcined in air atmosphere. Specifically, the powder is first heated to 500-600°C in N2 atmosphere at a rate of 5-10°C / min for 1-3 hours, and then calcined in air atmosphere at 450-550°C for 1-3 hours to obtain g-C3N4 powder.

[0025] Preferably, solvent A in S2 is an ethanol / water mixture, and the volume ratio of the two is 1:1-1.5;

[0026] Preferably, the mass ratio of the g-C3N4 powder to solvent A in S2 is 0.1-1:100;

[0027] Preferably, the maleic anhydride solution in S2 is an ethanol solution of maleic anhydride, with a preferred concentration of 0.1-1 g / mL, and the volume ratio of the maleic anhydride solution to the g-C3N4 solution is 1-2:1.

[0028] Preferably, the hydrothermal reaction in S2 is carried out at a temperature of 150-200°C, more preferably 160-180°C, for 5-15 hours, more preferably 8-10 hours.

[0029] Preferably, the centrifugation speed in S2 is 5000-9000 rpm and the time is 10-30 min, more preferably 6000-7000 rpm and the time is 15-20 min.

[0030] Preferably, the product after centrifugation is freeze-dried using a freeze dryer to obtain maleic anhydride-grafted g-C3N4 nanomaterials.

[0031] Preferably, the freeze-drying conditions are -10 to -40°C, vacuum degree 1.5-5 MPa, and time 18-24 h, more preferably -20 to -30°C, 2-3 MPa, and time 18-20 h.

[0032] Another objective of this invention is to provide a method for preparing g-C3N4 modified PC: a base PC resin, flame retardant, toughening agent, maleic anhydride-grafted g-C3N4 nanomaterial, antioxidant, lubricant, and colorant are mixed evenly in proportion, and then melt extruded and granulated by twin-screw extrusion to obtain g-C3N4 modified PC.

[0033] In this invention, the material mixing is performed using a high-speed mixer with a speed of 500-1000 rpm, preferably 600-700 rpm, for a time of 5-30 minutes.

[0034] Preferably, the extrusion granulation temperature is 260-300℃ and the main machine speed is 250-550rpm, with a preferred granulation temperature of 270-290℃ and a speed of 300-400rpm.

[0035] Another object of the present invention is to provide the application of the g-C3N4 modified PC in the fields of electronic appliances, daily packaging and other materials.

[0036] The beneficial effects of this invention are as follows:

[0037] (1) Applying g-C3N4 nanomaterials to modified PC materials, based on the photocatalytic degradation of organic pollutants, hydrophobicity and stable graphite sheet structure of g-C3N4, the modified PC materials are endowed with excellent antibacterial, anti-fouling and anti-wear capabilities, which can effectively solve the appearance problems of existing PC materials in electronic appliances and daily packaging materials such as easy dirt and poor wear resistance.

[0038] (2) Because g-C3N4 has a large number of amino groups on its surface, different acid anhydride polymers can be grafted based on amide reaction. After modification with maleic anhydride, the compatibility between g-C3N4 nanomaterials and the matrix can be improved, the dispersibility can be improved, and the processing and molding can be facilitated. At the same time, after maleic anhydride grafted g-C3N4 is added to the system, it can act as a flexible molecular chain and play a partial toughening and buffering effect, thereby improving the toughness and strength of the material.

[0039] (3) The composite material prepared by the present invention not only has the advantages of antibacterial and antifouling, flame retardant and wear resistant, but also the polymer material prepared by the present invention can synergistically improve the photocatalytic energy storage effect due to the addition of g-C3N4 nanomaterial and TiO2 in the color powder, which can promote the conversion of blue and ultraviolet light absorbed by the consumable material, thereby alleviating the photo-aging decomposition of polycarbonate, so that the composite material has a certain photostability. Detailed Implementation

[0040] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Locational terms such as top and bottom, mentioned or possibly used in this specification, are defined relative to the constructions shown in the accompanying drawings; they are relative concepts and may therefore vary depending on their location and usage.

[0042] Main raw material sources

[0043] The main raw material sources used in the embodiments of this invention are as follows; unless otherwise specified, all other raw materials are ordinary commercially available:

[0044] Melamine: ≥99%, Shanghai Aladdin Biochemical Technology Co., Ltd. M108433;

[0045] Maleic anhydride: ≥99% (GC), Shanghai Aladdin Biochemical Technology Co., Ltd. M116389;

[0046] PC resin: Wanhua Chemical Group Co., Ltd. PC2100;

[0047] Compound antioxidant: Nanjing Milan Chemical Co., Ltd. compound antioxidant B900;

[0048] Flame retardant: Potassium perfluorobutyl sulfonate (SC4) flame retardant from Jiangxi Guohua Pharmaceutical Technology Co., Ltd.;

[0049] Toughening agent: Kanekachi M732 toughening agent from Japan;

[0050] Lubricant: PETS from Dongguan Xingyuan Chemical Co., Ltd.

[0051] Pigment: R251 titanium dioxide from Xiamen CNNC Trading Co., Ltd.

[0052] Main testing methods

[0053] Antibacterial performance: The antibacterial rate was obtained by counting and calculation using the film application method.

[0054] Tensile properties: Tested using a single-column tensile testing machine (Z0.5, Zwick), with a specimen gauge length of 50 mm and a test speed of 20 mm / min;

[0055] Impact performance: Tested using a pendulum impact tester (CEAST 9050), cantilever beam notched impact, 23℃, hammer head 5.5KJ;

[0056] Flame retardant performance: Flame retardant rating was tested using a water-based vertical burner (Sisite RH6033C) with a 1.5mm sample.

[0057] UV resistance performance: UV aging color difference was tested using a Q-Lab UV test chamber from the USA.

[0058] Example 1

[0059] The steps for preparing g-C3N4 modified PC are as follows:

[0060] (1) Take 10g of melamine and heat it to 550℃ at 5℃ / min under N2 atmosphere, keep it at the temperature for 2h, and then calcine it at 500℃ for 2h under air atmosphere to obtain g-C3N4 powder. Then disperse it in ethanol / water (volume ratio 1:1) mixed solution A at a mass ratio of 0.1:100 to obtain g-C3N4 solution. Then add an equal volume of maleic anhydride-ethanol solution and perform hydrothermal grafting modification at 180℃ for 10h. Finally, centrifuge at 7000rpm for 15min and freeze dry the remaining solid at -25℃ and 3MPa vacuum for 20h to obtain maleic anhydride grafted g-C3N4 nanomaterial.

[0061] (2) The matrix PC resin is 97.2 wt%, flame retardant is 0.15 wt%, toughening agent is 1 wt%, antioxidant is 0.15 wt%, lubricant is 0.4 wt%, maleic anhydride-grafted g-C3N4 nanomaterial obtained in step (1) is 0.1 wt%, and color powder is 1 wt%. The mixture is then mixed evenly using a high-speed mixer (550 rpm, 10 min). After that, it is melt-extruded and granulated by twin-screw extrusion (extrusion temperature is 290℃, speed is 300 rpm) to obtain g-C3N4 modified PC.

[0062] Example 2

[0063] The steps for preparing g-C3N4 modified PC are as follows:

[0064] (1) Take 10g of melamine and heat it to 550℃ at 5℃ / min under N2 atmosphere, keep it at the temperature for 2h, and then calcine it at 500℃ for 2h under air atmosphere to obtain g-C3N4 powder. Then disperse it in ethanol / water (volume ratio 1:1) mixed solution A at a mass ratio of 1:100 to obtain g-C3N4 solution. Then add an equal volume of maleic anhydride-ethanol solution and perform hydrothermal grafting modification at 160℃ for 8h. Finally, centrifuge at 6000rpm for 15min and freeze dry the remaining solid at -30℃ and 3MPa vacuum for 20h to obtain maleic anhydride grafted g-C3N4 nanomaterial.

[0065] (2) The matrix PC resin is 96.8 wt%, flame retardant is 0.15 wt%, toughening agent is 1 wt%, antioxidant is 0.15 wt%, lubricant is 0.4 wt%, maleic anhydride grafted g-C3N4 nanomaterial obtained in step (1) is 0.5 wt%, and color powder is 1 wt%. The mixture is then melt-extruded and granulated by twin-screw extrusion (extrusion temperature is 290℃, speed is 300 rpm) to obtain g-C3N4 modified PC.

[0066] Example 3

[0067] The steps for preparing g-C3N4 modified PC are as follows:

[0068] (1) Take 10g of melamine and heat it to 550℃ at 5℃ / min under N2 atmosphere, keep it at the temperature for 2h, and then calcine it at 500℃ for 2h under air atmosphere to obtain g-C3N4 powder. Then disperse it in ethanol / water (volume ratio 1:1) mixed solution A at a mass ratio of 0.5:100 to obtain g-C3N4 solution. Then add an equal volume of maleic anhydride-ethanol solution and perform hydrothermal grafting modification at 180℃ for 10h. Finally, centrifuge at 6000rpm for 15min and freeze dry the remaining solid at -25℃ and 3MPa vacuum for 20h to obtain maleic anhydride grafted g-C3N4 nanomaterial.

[0069] (2) The matrix PC resin is 96.8 wt%, flame retardant is 0.15 wt%, toughening agent is 1 wt%, composite antioxidant is 0.15 wt%, lubricant is 0.4 wt%, maleic anhydride grafted g-C3N4 nanomaterial obtained in step (1) is 0.5 wt%, and color powder is 1 wt%. The mixture is then uniformly mixed using a high-speed mixer (550 rpm, 10 min). After that, it is melt extruded and granulated by twin-screw extrusion (extrusion temperature is 290℃, speed is 300 rpm) to obtain g-C3N4 modified PC.

[0070] Example 4

[0071] g-C3N4 modified PC was prepared according to Example 3, except that in step (2), the proportion of maleic anhydride-grafted g-C3N4 nanomaterials added was 0.1wt%, the matrix PC resin was 97wt%, and other proportions remained unchanged; the mixture was uniformly mixed using a high-speed mixer (550 rpm, 10 min), and then melt extruded and granulated by twin-screw extrusion (extrusion temperature was 290℃, speed was 300 rpm) to obtain g-C3N4 modified PC.

[0072] Example 5

[0073] g-C3N4 modified PC was prepared according to Example 3, except that in step (2), the proportion of maleic anhydride-grafted g-C3N4 nanomaterials added was 0.8wt%, the matrix PC resin was 96.3wt%, and other proportions remained unchanged; the mixture was uniformly mixed using a high-speed mixer (550 rpm, 10 min), and then melt extruded and granulated by twin-screw extrusion (extrusion temperature was 290℃, speed was 300 rpm) to obtain g-C3N4 modified PC.

[0074] Comparative Example 1

[0075] Modified PC was prepared according to Example 3, except that maleic anhydride solution was not added to the g-C3N4 solution for hydrothermal grafting modification in step (1), and the same mass of g-C3N4 was directly added in step (2), while other ratios remained unchanged. The mixture was mixed evenly using a high-speed mixer (550 rpm, 10 min), and then melt extruded and granulated by twin-screw extrusion (extrusion temperature of 290℃, speed of 300 rpm) to obtain modified PC.

[0076] Comparative Example 2

[0077] Modified PC was prepared according to Example 3, except that step (1) was omitted, and the maleic anhydride-modified g-C3N4 nanomaterial in step (2) was replaced with the same mass of maleic anhydride at an addition ratio of 0.5 wt%, while other ratios remained unchanged. The mixture was uniformly mixed using a high-speed mixer (550 rpm for 10 min), and then melt-extruded and granulated by twin-screw extrusion (extrusion temperature of 290°C and speed of 300 rpm) to obtain modified PC.

[0078] Comparative Example 3

[0079] Modified PC was prepared according to Example 3, except that step (1) was omitted, maleic anhydride-grafted g-C3N4 nanomaterials were not added in step (2), the matrix resin ratio was adjusted to 97.3 wt%, and other ratios remained unchanged; the mixture was uniformly mixed using a high-speed mixer (550 rpm, 10 min), and then melt extruded and granulated by twin-screw extrusion (extrusion temperature was 290℃, speed was 300 rpm) to obtain modified PC.

[0080] The modified PC obtained from the above examples and comparative examples was then dried at 100°C for 4 hours and injection molded at 300°C to form standard specimens and templates. Their antibacterial rate, tensile properties, impact properties, flame retardant properties, and UV aging resistance were measured, and the results are shown in Table 1.

[0081] Table 1 Performance Test Results

[0082]

[0083] As can be seen from Table 1, the introduction of g-C3N4 nanomaterials with different maleic anhydride grafting rates into the system improved the antibacterial rate of the modified PC material, and also enhanced its tensile strength, cantilever beam notched impact strength, and UV aging resistance.

[0084] Under illumination, as the amount of maleic anhydride-grafted g-C3N4 nanomaterials added increases, the number of colonies decreases due to the catalytic conversion of organic matter, reducing the colony growth environment and creating an antibacterial effect on the material surface. Furthermore, the maleic anhydride-grafted g-C3N4 nanomaterials, after being introduced into the system, can insert into the PC molecular chain network based on the principle of like dissolves like, forming flexible branches with a shield-like structure that can provide partial buffering and toughening effects, thus improving the material's impact strength. Moreover, the insertion of maleic anhydride-grafted g-C3N4 nanomaterials into the PC molecular chain forms anchor points, increasing the entanglement of the PC molecular chains and improving the tensile strength of the material. In addition, in titanium dioxide-dyed modified PC products, because g-C3N4 and TiO2 can synergistically amplify the blue-ultraviolet photocatalytic conversion ability, the UV radiation energy received by the material can be rapidly consumed, thereby alleviating the photodegradation of PC and improving the material's UV aging resistance. After 600 hours of aging, the color difference change is small, thus the composite material also has a certain degree of photostability.

[0085] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom remain within the scope of protection of this invention.

Claims

1. A method for preparing maleic anhydride-grafted g-C3N4 nanomaterials, characterized in that, Includes the following steps: S1: Urea or melamine is heat-treated at high temperature under N2 atmosphere and then calcined under air atmosphere to obtain g-C3N4 powder. S2: Prepare g-C3N4 solution, mix with maleic anhydride solution for hydrothermal grafting modification, and obtain maleic anhydride-grafted g-C3N4 nanomaterials by centrifugation and freeze-drying.

2. The preparation method according to claim 1, characterized in that, Step S1 specifically involves heating the powder to 400-600℃ at a rate of 1-10℃ / min under a N2 atmosphere for 1-3 hours, and then calcining it at 400-550℃ for 1-3 hours under an air atmosphere to obtain g-C3N4 powder.

3. According to the preparation method of claim 1, in step S2, the maleic anhydride solution is an ethanol solution of maleic anhydride, preferably with a concentration of 0.1-1 g / mL; Preferably, the solvent for the g-C3N4 solution is an ethanol / water mixture with a volume ratio of 1:1-1.

5.

4. The preparation method according to claim 1 or 3, characterized in that, In step S2, the volume ratio of maleic anhydride solution to g-C3N4 solution is 1-2:1; Preferably, in step S2, the reaction temperature for hydrothermal grafting modification is 150-200℃, more preferably 160-180℃, and the reaction time is 5-15h, more preferably 8-10h. Preferably, in step S2, the freeze-drying temperature is -10 to -40°C, the vacuum degree is 1.5-5 MPa, and the time is 18-24 hours. More preferably, the temperature is -20 to -30°C and the vacuum degree is 2-3 MPa.

5. A g-C3N4 modified PC, characterized in that, The components include the following mass fractions: Matrix PC resin 96-98%; Flame retardant 0.05-0.2%; Toughening agent 0.1-1.5%; Antioxidant 0.05-0.15%; Lubricant 0.1-0.5%; Maleic anhydride grafted with g-C3N4 nanomaterials: 0.01-1%; Pigment powder 0.5-1%.

6. The g-C3N4 modified PC according to claim 5, characterized in that, The base PC resin is a polycarbonate with a melt index of 7-15 g / 10 min at 300℃ and 1.2 kg, more preferably a polycarbonate with a melt index of 9-10 g / 10 min; Preferably, the flame retardant is one or more of sulfonate flame retardants, and more preferably one or more of perfluoroalkyl sulfonate, diphenyl sulfonate, or diphenyl ether sulfonate; Preferably, the toughening agent is one or more of the following: methyl acrylate-butadiene copolymer, methyl methacrylate-butadiene copolymer, methyl acrylate-styrene copolymer, methyl methacrylate-styrene copolymer, methyl acrylate-butadiene-styrene copolymer, and methyl methacrylate-butadiene-styrene copolymer. Preferably, the antioxidant is one or more of phosphite antioxidants or hindered phenolic antioxidants; Preferably, the lubricant is one or more of stearate compounds or polyethylene wax compounds, preferably pentaerythritol stearate or polyethylene wax with a molecular weight of less than or equal to 2000.

7. A method for preparing g-C3N4 modified PC, characterized in that, The process includes the following steps: mixing the base PC resin, flame retardant, toughening agent, maleic anhydride-grafted g-C3N4 nanomaterial, antioxidant, lubricant, and colorant in a specific ratio, and then melting and extruding the mixture to obtain g-C3N4 modified PC.

8. The preparation method according to claim 7, characterized in that, The extrusion granulation temperature is 260-300℃ and the rotation speed is 250-550rpm, with the preferred granulation temperature being 270-290℃ and the rotation speed being 300-400rpm.

9. The application of g-C3N4 modified PC according to claim 5 or 6 in the fields of electronic appliances and daily packaging materials.

Images