Halogen-free flame-retardant antistatic polycarbonate copolymer and preparation method thereof

Abstract

The invention provides a halogen-free flame-retardant antistatic polycarbonate copolymer and a preparation method thereof, and belongs to the technical field of materials. The preparation method comprises the following steps: loading nano black phosphorus flakes and graphene quantum dots on graphene, modifying by using polydopamine, coupling with 5, 7-dioxa-diphenyl substituted-cycloheptene phosphoryl chloride, further modifying by using tannic acid, adding into molten polycarbonate, adding an auxiliary agent, uniformly stirring and mixing, extruding and granulating, drying, and carrying out injection molding, thereby obtaining the composite material. The halogen-free flame-retardant antistatic polycarbonate copolymer is prepared. According to the halogen-free flame-retardant antistatic polycarbonate copolymer prepared by the invention, by adding the halogen-free flame-retardant antistatic modifier, the thermal conductivity, the antistatic property and the flame retardance of the material are obviously improved, meanwhile, the dispersion is uniform, the compatibility is good, the mechanical property of the material is improved to a certain extent, and the halogen-free flame-retardant antistatic polycarbonate copolymer has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, and in particular to a halogen-free flame-retardant and antistatic polycarbonate copolymer and a preparation method thereof. Background Art

[0002] Plastics and their composites offer advantages such as light weight, corrosion resistance, shock and sound absorption, excellent insulation, low thermal conductivity, easy molding, excellent colorability, low processing costs, and recyclability, making them ideally suited to modern industrial design requirements: lightweight, safe, environmentally friendly, energy-efficient, low-cost, and comfortable. Polycarbonate, a plastic with excellent transparency and comprehensive properties, has a wide range of applications, including electronics, automotive, machinery manufacturing, and computers. However, unmodified polycarbonate lacks flame retardancy and antistatic properties, making it unsuitable for applications requiring high or very high flame retardancy levels.

[0003] Chinese invention patent application CN110395034A discloses a multifunctional sound-insulating, heat-insulating, and antistatic polyester film and its preparation process, comprising: a sound-absorbing layer, a PET base film layer, an adhesive layer, a sound-insulating layer, a first heat-insulating layer, a core layer, a second heat-insulating layer, and an antistatic layer, wherein the core layer is positioned between the first and second heat-insulating layers. The present invention can block over 99% of ultraviolet absorption and over 85% of infrared absorption, exhibits excellent antistatic properties, and effectively prevents the adsorption of dust and impurities, resolving the technical problem of existing films lacking sound insulation, heat insulation, thermal insulation, and antistatic properties while maintaining good performance. This invention improves upon the multilayer film process and does not improve the flame retardancy of the material itself.

[0004] Chinese invention patent application CN107936409A discloses a polycarbonate-based nano-environmentally friendly thermal and sound-insulating packaging material and its preparation method. The packaging material is made from the following raw materials in parts by weight: 10-15 parts inorganic glass fiber, 12-20 parts water-based amino resin, 5-13 parts polycarbonate, 6-9 parts benzoyl peroxide flame retardant, 14-22 parts propylene homopolymer, 5-9 parts vinyl acetate, 22-28 parts polyvinyl chloride, 6-9 parts dispersant, 5-8 parts thermosetting resin, and 16-20 parts deionized water. The present invention combines inorganic glass fiber, water-based amino resin, polycarbonate, propylene homopolymer, polyvinyl chloride, and thermosetting resin with excellent physical properties to create a packaging material that simultaneously provides excellent thermal insulation, sound insulation, and damping properties while also achieving energy-saving, green, and environmentally friendly properties. This material meets energy-saving and environmental protection requirements and offers high economic benefits. The addition of inorganic glass fiber and thermosetting resin significantly impacts the mechanical properties and appearance of the PC material.

[0005] Chinese invention patent application CN103254609A discloses a novel polycarbonate plant fiber wood-plastic composite board. The board is cast in a mold using a heating method using a powdered material. The powdered material comprises the following components, by weight: 100 parts polycarbonate resin, 38-41 parts plant fiber, 0.5-1 part catalyst, 2-2.5 parts accelerator, 1.5-2 parts gelling agent, and 1-1.2 parts UV-resistant additive. This method improves the strength and transparency of the wood-plastic composite board, resulting in excellent sound insulation, heat insulation, light transmission, lightweight, thermal insulation, and weather resistance. The board is energy-efficient, environmentally friendly, non-toxic, and odorless. However, the heating method employed is not suitable for large-scale injection molding.

[0006] Although polycarbonate resin has a certain degree of flame retardancy, it is only UL94 V-2 grade and cannot meet the high flame retardancy requirements of the product. Brominated flame retardants are well-known for their high flame retardant efficiency, but their flame-retardant materials produce large amounts of smoke and carcinogens such as tetrabromodibenzodioxane and tetrabromodibenzofuran during combustion and thermal decomposition. Although phosphate flame retardants avoid the harmful substances produced during the combustion of brominated flame retardant systems, their low melting point and high volatility can easily cause a significant drop in the heat resistance of PC composites and volatilization losses during the molding process. Sulfonate flame retardants accelerate the charring rate of PC during combustion and promote molecular cross-linking of polymers. They are widely used due to their low addition amount, high efficiency, and ability to maintain the transparency of PC materials. However, they cannot meet the flame retardant requirements of thin-walled parts, and are not resistant to hydrolysis during actual application, making them prone to flame retardant failure. Polysiloxane flame retardants have attracted much attention from researchers for their excellent processability, flame retardancy, good mechanical properties, and especially their environmental friendliness. However, they have poor flame retardant effect when used alone, and the addition amount is large, resulting in high cost. They are generally used in combination with synergistic flame retardants.

[0007] Therefore, it is necessary to develop a halogen-free flame retardant antistatic polycarbonate copolymer material. Summary of the Invention

[0008] The purpose of the present invention is to provide a halogen-free flame-retardant and antistatic polycarbonate copolymer and a preparation method thereof. By adding a halogen-free flame-retardant and antistatic modifier, the thermal conductivity, antistatic performance and flame retardancy of the material are significantly improved. At the same time, the dispersion is uniform, the compatibility is good, and the mechanical properties of the material are improved to a certain extent, which has broad application prospects.

[0009] The technical solution of the present invention is achieved as follows: The invention provides a preparation method of a halogen-free flame-retardant and antistatic polycarbonate copolymer. The method comprises the following steps: loading nano black phosphorus sheets and graphene quantum dots on graphene, modifying the graphene with polydopamine, coupling with 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride, and further modifying the graphene with tannic acid. The resulting mixture is added to molten polycarbonate, an auxiliary agent is added, and the mixture is stirred and mixed uniformly. The mixture is extruded into granules, dried, and injection molded to obtain the halogen-free flame-retardant and antistatic polycarbonate copolymer.

[0010] As a further improvement of the present invention, the following steps are included: S1. Preparation of black phosphorus nanosheets: Blocked black phosphorus was dissolved in N-methylpyrrolidone, stirred with ultrasound in an ice bath in the dark, and subjected to gradient centrifugation. The solid was washed and dried to obtain black phosphorus nanosheets. S2. Preparation of Nano-Black Phosphorus Flakes / Graphene Quantum Dots@Graphene: Nano-black phosphorus flakes and citric acid were added to an aqueous dispersion of graphene oxide, followed by a hydrothermal reaction, centrifugation, washing, drying, and reduction with hydrazine hydrate vapor to produce nano-black phosphorus flakes / graphene quantum dots@Graphene. S3. Polydopamine modification: Adding black phosphorus nanosheets / graphene quantum dots@graphene to a Tris-HCl solution, followed by dopamine hydrochloride, heating and stirring the mixture, centrifuging, washing, and drying to obtain modified black phosphorus nanosheets / graphene quantum dots@graphene. S4. Preparation of 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride: Biphenyldiphenol, a base and phosphorus oxychloride were mixed and added to toluene, heated and stirred to react, and distilled under reduced pressure to obtain 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride; S5. Coupling: 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride, modified nano-black phosphorus flakes / graphene quantum dots@graphene, and a base were mixed in toluene, heated and stirred for reaction, centrifuged, washed, and dried to obtain modified nano-black phosphorus flakes / graphene quantum dots@graphene coupled flame retardant. S6. Tannic acid modification: The flame retardant-modified nano-black phosphorus flakes / graphene quantum dots@graphene were added to a Tris-HCl solution, followed by tannic acid. The mixture was heated and stirred for reaction, centrifuged, washed, and dried to produce a halogen-free flame retardant and antistatic modifier. S7. Preparation of a halogen-free flame-retardant and antistatic polycarbonate copolymer: Heat and melt polycarbonate, add an additive and a halogen-free flame-retardant and antistatic modifier, stir and mix uniformly, extrude and granulate, dry, and injection mold to produce a halogen-free flame-retardant and antistatic polycarbonate copolymer.

[0011] As a further improvement of the present invention, the time of the light-proof ultrasonic stirring in the ice bath in step S1 is 1-3 days, and the gradient centrifugation method is to collect the supernatant after centrifugation at a speed of 3000-5000 r / min for 5-15 minutes, and centrifuge at a speed of 12000-13000 r / min for 10-20 minutes.

[0012] As a further improvement of the present invention, the mass ratio of the nano black phosphorus sheets, citric acid and graphene oxide in step S2 is 3-4:2-3:8-12, the temperature of the hydrothermal reaction is 190-210° C., the time is 22-26 hours, and the time of the hydrazine hydrate vapor reduction is 10-12 hours.

[0013] As a further improvement of the present invention, the pH value of the Tris-HCl solution in step S3 is 8.5-9.5, the mass ratio of the nano black phosphorus sheets / graphene quantum dots@graphene and dopamine hydrochloride is 10:4-5, the temperature of the heating and stirring reaction is 45-55°C, and the time is 3-5h.

[0014] As a further improvement of the present invention, the molar ratio of biphenol, phosphorus oxychloride and base in step S4 is 1:1-1.1:3-5, the temperature of the heating and stirring reaction is 100-120°C, the time is 5-7h, and the base is selected from at least one of triethylamine, diethylamine, NaOH and KOH.

[0015] As a further improvement of the present invention, the mass ratio of 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride, modified nano black phosphorus sheets / graphene quantum dots @ graphene and base in step S5 is 4-5:10-12:5-6; the base is selected from at least one of triethylamine, diethylamine, NaOH, and KOH, and the temperature of the heating and stirring reaction is 75-85°C and the time is 3-5h.

[0016] As a further improvement of the present invention, the pH value of the Tris-HCl solution in step S6 is 8.5-9.5, the mass ratio of the modified nano black phosphorus sheets / graphene quantum dots @ graphene and tannic acid of the coupled flame retardant is 10:2-3, and the temperature of the heating and stirring reaction is 40-50°C and the time is 2-4 hours.

[0017] As a further improvement of the present invention, the heating and melting temperature in step S7 is 220-240°C, the mass ratio of the polycarbonate, the additive and the halogen-free flame retardant antistatic modifier is 70-90:1-3:7-10, and the additive includes polyethylene wax, antioxidant 1010 and polytetrafluoroethylene in a mass ratio of 2-5:1-3:2-4.

[0018] The present invention further protects a halogen-free flame-retardant and antistatic polycarbonate copolymer prepared by the above preparation method.

[0019] The present invention has the following beneficial effects: The nano-black phosphorus sheets produced by the present invention have a large specific surface area and high carrier mobility. Their unique layered structure and energy band characteristics give them excellent electrical conductivity, providing an effective channel for electron transmission. They also have high thermal conductivity. Their dense atomic arrangement and strong chemical bonds effectively conduct phonons, thereby improving the material's thermal conductivity. Furthermore, the black phosphorus nanosheets can improve the material's flame retardancy, isolating oxygen and heat to prevent further combustion of the plastic. They form a protective film on the substrate surface that effectively blocks the spread of flames and heat, reducing the release of combustible gases.

[0020] The nano black phosphorus flakes of the present invention are prepared by conjugating the lone electron pairs of phosphorus and the electron pairs of graphene oxide, and by hydrogen bonding adsorption of citric acid with the hydroxyl groups of graphene oxide. The citric acid is converted into graphene quantum dots through a hydrothermal reaction, and then reduced with hydrazine hydrate vapor to obtain nano black phosphorus flakes / graphene quantum dots@graphene. When added to polycarbonate, a structure similar to a three-dimensional network is formed in the matrix. This structure can effectively improve the electrical conductivity of the material, significantly reduce the insulation resistance of the plastic, and impart good antistatic and thermal conductivity to the plastic.

[0021] After the surface of the prepared nano-black phosphorus sheet / graphene quantum dot@graphene is modified with polydopamine, the surface has amino groups, which can undergo nucleophilic reaction with 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride. 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride can improve the flame retardant properties of the material. At the same time, the nitrogen element in polydopamine also synergistically improves the flame retardant properties of the material.

[0022] The surface is further modified with tannic acid, so that the prepared halogen-free flame retardant antistatic modifier has better dispersibility in polycarbonate resin, can be evenly dispersed by forming hydrogen bonds, improves compatibility, and avoids agglomeration of the modifier and affecting performance.

[0023] The halogen-free flame-retardant and antistatic polycarbonate copolymer prepared by the present invention significantly improves the thermal conductivity, antistatic performance and flame retardancy of the material by adding a halogen-free flame-retardant and antistatic modifier. At the same time, it is evenly dispersed and has good compatibility, which improves the mechanical properties of the material to a certain extent and has broad application prospects. DETAILED DESCRIPTION

[0024] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0025] Example 1 This embodiment provides a method for preparing a halogen-free flame-retardant and antistatic polycarbonate copolymer, comprising the following steps: Preparation of nano-black phosphorus flakes: 1 g of bulk black phosphorus was added to 1 L of N-methylpyrrolidone and stirred ultrasonically in an ice bath in the dark for 1 day. The supernatant was collected after centrifugation at 3000 rpm for 5 min and centrifuged at 12000 rpm for 10 min. The solid was washed and dried to obtain nano-black phosphorus flakes. S2. Preparation of nano-black phosphorus flakes / graphene quantum dots@graphene: 0.3 g of nano-black phosphorus flakes and 0.2 g of citric acid were added to 200 mL of an aqueous dispersion containing 0.8 g of graphene oxide. The mixture was hydrothermally reacted at 190°C for 22 h, followed by centrifugation, washing, drying, and reduction with hydrazine hydrate vapor for 10 h to produce nano-black phosphorus flakes / graphene quantum dots@graphene. S3. Polydopamine modification: 1 g of nano-black phosphorus flakes / graphene quantum dots@graphene was added to 200 mL of Tris-HCl solution (pH 8.5), followed by 0.4 g of dopamine hydrochloride. The mixture was heated to 45°C and stirred for 3 h. The mixture was centrifuged, washed, and dried to obtain modified nano-black phosphorus flakes / graphene quantum dots@graphene. S4. Preparation of 5,7-dioxa-diphenyl-substituted cycloheptene phosphoryl chloride: Mix 0.1 mol of biphenyldiphenol, 0.3 mol of triethylamine, and 0.1 mol of phosphorus oxychloride in 250 mL of toluene, heat to 100°C, and stir for 5 h. Distill under reduced pressure to collect the 5,7-dioxa-diphenyl-substituted cycloheptene phosphoryl chloride fraction. S5. Coupling: 0.4 g of 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride, 1 g of modified nano-black phosphorus flakes / graphene quantum dots@graphene, and 0.5 g of triethylamine were added to 200 mL of toluene. The mixture was heated to 75°C and stirred for 3 h. The mixture was centrifuged, washed, and dried to obtain the modified nano-black phosphorus flakes / graphene quantum dots@graphene coupled flame retardant. S6. Tannic acid modification: 1 g of the flame retardant-modified nano-black phosphorus flakes / graphene quantum dots@graphene was added to 200 mL of Tris-HCl solution (pH 8.5), along with 0.2 g of tannic acid. The mixture was heated to 40°C and stirred for 2 h. The mixture was centrifuged, washed, and dried to produce a halogen-free flame retardant and antistatic modifier. S7. Preparation of a halogen-free flame-retardant and antistatic polycarbonate copolymer: 7 g of polycarbonate was heated to 230°C to melt, 0.1 g of an additive and 0.7 g of a halogen-free flame-retardant and antistatic modifier were added, and the mixture was stirred and uniformly mixed. The mixture was extruded into pellets, dried, and injection molded to produce a halogen-free flame-retardant and antistatic polycarbonate copolymer. The auxiliary agents include polyethylene wax, antioxidant 1010, and polytetrafluoroethylene, with a mass ratio of 2:1:2.

[0026] Example 2 This embodiment provides a method for preparing a halogen-free flame-retardant and antistatic polycarbonate copolymer, comprising the following steps: Preparation of black phosphorus nanosheets: 1 g of bulk black phosphorus was added to 1 L of N-methylpyrrolidone, stirred ultrasonically in an ice bath in the dark for 3 days, and centrifuged at 5000 rpm for 15 min. The supernatant was collected and centrifuged at 13000 rpm for 20 min. The solid was washed and dried to obtain black phosphorus nanosheets. S2. Preparation of nano-black phosphorus flakes / graphene quantum dots@graphene: 0.4 g of nano-black phosphorus flakes and 0.3 g of citric acid were added to 200 mL of an aqueous dispersion containing 1.2 g of graphene oxide. The mixture was hydrothermally reacted at 210°C for 26 h, followed by centrifugation, washing, drying, and reduction with hydrazine hydrate vapor for 12 h to produce nano-black phosphorus flakes / graphene quantum dots@graphene. S3. Polydopamine modification: 1 g of nano-black phosphorus flakes / graphene quantum dots@graphene was added to 200 mL of Tris-HCl solution (pH 9.5), followed by 0.5 g of dopamine hydrochloride. The mixture was heated to 55°C and stirred for 5 h. The mixture was centrifuged, washed, and dried to obtain modified nano-black phosphorus flakes / graphene quantum dots@graphene. S4. Preparation of 5,7-dioxa-diphenyl-substituted cycloheptene phosphoryl chloride: Mix 0.1 mol of biphenyldiphenol, 0.5 mol of NaOH, and 0.11 mol of phosphorus oxychloride in 250 mL of toluene, heat to 110°C, and stir for 7 hours. Distill under reduced pressure to collect the 5,7-dioxa-diphenyl-substituted cycloheptene phosphoryl chloride fraction. S5. Coupling: 0.5 g of 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride, 1.2 g of modified nano-black phosphorus flakes / graphene quantum dots@graphene, and 0.6 g of NaOH were mixed in 200 mL of toluene. The mixture was heated to 85°C and stirred for 5 h. The mixture was centrifuged, washed, and dried to obtain the modified nano-black phosphorus flakes / graphene quantum dots@graphene coupled flame retardant. S6. Tannic acid modification: 1 g of flame retardant-modified nano-black phosphorus flakes / graphene quantum dots@graphene was added to 200 mL of Tris-HCl solution (pH 9.5), along with 0.3 g of tannic acid. The mixture was heated to 50°C and stirred for 4 h. The mixture was centrifuged, washed, and dried to produce a halogen-free flame retardant and antistatic modifier. S7. Preparation of a halogen-free flame-retardant and antistatic polycarbonate copolymer: 9 g of polycarbonate was heated to 240°C to melt, 0.3 g of an additive and 1 g of a halogen-free flame-retardant and antistatic modifier were added, and the mixture was stirred and uniformly mixed. The mixture was extruded into pellets, dried, and injection molded to produce a halogen-free flame-retardant and antistatic polycarbonate copolymer. The auxiliary agents include polyethylene wax, antioxidant 1010, and polytetrafluoroethylene, with a mass ratio of 5:3:4.

[0027] Example 3 This embodiment provides a method for preparing a halogen-free flame-retardant and antistatic polycarbonate copolymer, comprising the following steps: Preparation of black phosphorus nanosheets: 1 g of bulk black phosphorus was added to 1 L of N-methylpyrrolidone, stirred under ultrasound in an ice bath in the dark for 2 days, and centrifuged at 4000 rpm for 10 min. The supernatant was collected and centrifuged at 12500 rpm for 15 min. The solid was washed and dried to obtain black phosphorus nanosheets. S2. Preparation of nano-black phosphorus flakes / graphene quantum dots@graphene: 0.35 g of nano-black phosphorus flakes and 0.25 g of citric acid were added to 200 mL of an aqueous dispersion containing 1 g of graphene oxide. The mixture was hydrothermally reacted at 200°C for 24 h, followed by centrifugation, washing, drying, and reduction with hydrazine hydrate vapor for 11 h to produce nano-black phosphorus flakes / graphene quantum dots@graphene. S3. Polydopamine modification: 1 g of black phosphorus nanosheets / graphene quantum dots@graphene was added to 200 mL of Tris-HCl solution (pH 9), followed by 0.45 g of dopamine hydrochloride. The mixture was heated to 50°C and stirred for 4 h. The mixture was centrifuged, washed, and dried to obtain modified black phosphorus nanosheets / graphene quantum dots@graphene. S4. Preparation of 5,7-dioxa-diphenyl-substituted cycloheptene phosphoryl chloride: Mix 0.1 mol of biphenyldiphenol, 0.4 mol of KOH, and 0.105 mol of phosphorus oxychloride in 250 mL of toluene, heat to 105°C, and stir for 6 hours. Distill under reduced pressure to collect the 5,7-dioxa-diphenyl-substituted cycloheptene phosphoryl chloride fraction. S5. Coupling: 0.45 g of 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride, 1.1 g of modified nano-black phosphorus flakes / graphene quantum dots@graphene, and 0.55 g of KOH were mixed in 200 mL of toluene. The mixture was heated to 80°C and stirred for 4 h. The mixture was centrifuged, washed, and dried to obtain the modified nano-black phosphorus flakes / graphene quantum dots@graphene coupled flame retardant. S6. Tannic acid modification: 1 g of modified nano-black phosphorus flakes / graphene quantum dots@graphene coupled with a flame retardant was added to 200 mL of Tris-HCl solution (pH 9), along with 0.25 g of tannic acid. The mixture was heated to 45°C and stirred for 3 h. The mixture was centrifuged, washed, and dried to produce a halogen-free flame retardant and antistatic modifier. S7. Preparation of a halogen-free flame-retardant and antistatic polycarbonate copolymer: 8 g of polycarbonate was heated to 235°C to melt, 0.2 g of an additive and 0.85 g of a halogen-free flame-retardant and antistatic modifier were added, and the mixture was stirred and uniformly mixed. The mixture was extruded into pellets, dried, and injection molded to produce a halogen-free flame-retardant and antistatic polycarbonate copolymer. The auxiliary agents include polyethylene wax, antioxidant 1010, and polytetrafluoroethylene, with a mass ratio of 4:2:3.

[0028] Comparative Example 1 Compared with Example 3, the difference is that no nano black phosphorus flakes are added in step S2.

[0029] The details are as follows: S2. Preparation of Graphene Quantum Dots@Graphene: 0.6 g of citric acid was added to 200 mL of an aqueous dispersion containing 1 g of graphene oxide. The mixture was hydrothermally reacted at 200°C for 24 h. The mixture was centrifuged, washed, dried, and reduced with hydrazine hydrate vapor for 11 h to obtain Graphene Quantum Dots@Graphene.

[0030] Comparative Example 2 Compared with Example 3, the difference is that citric acid is not added in step S2.

[0031] The details are as follows: S2. Preparation of nano-black phosphorus flakes@graphene: 0.6 g of nano-black phosphorus flakes were added to 200 mL of an aqueous dispersion containing 1 g of graphene oxide. The mixture was hydrothermally reacted at 200°C for 24 h. The reaction was followed by centrifugation, washing, drying, and hydrazine hydrate vapor reduction for 11 h to obtain nano-black phosphorus flakes@graphene.

[0032] Comparative Example 3 Compared with Example 3, the difference is that hydrazine hydrate vapor reduction is not performed in step S2.

[0033] The details are as follows: S2. Preparation of nano-black phosphorus flakes / graphene quantum dots@graphene oxide: 0.35 g of nano-black phosphorus flakes and 0.25 g of citric acid were added to 200 mL of an aqueous dispersion containing 1 g of graphene oxide. The mixture was hydrothermally reacted at 200°C for 24 h. The mixture was centrifuged, washed, and dried to obtain nano-black phosphorus flakes / graphene quantum dots@graphene oxide.

[0034] Comparative Example 4 Compared with embodiment 3, the difference is that step S3 is not performed.

[0035] The details are as follows: Preparation of black phosphorus nanosheets: 1 g of bulk black phosphorus was added to 1 L of N-methylpyrrolidone, stirred under ultrasound in an ice bath in the dark for 2 days, and centrifuged at 4000 rpm for 10 min. The supernatant was collected and centrifuged at 12500 rpm for 15 min. The solid was washed and dried to obtain black phosphorus nanosheets. S2. Preparation of nano-black phosphorus flakes / graphene quantum dots@graphene: 0.35 g of nano-black phosphorus flakes and 0.25 g of citric acid were added to 200 mL of an aqueous dispersion containing 1 g of graphene oxide. The mixture was hydrothermally reacted at 200°C for 24 h, followed by centrifugation, washing, drying, and reduction with hydrazine hydrate vapor for 11 h to produce nano-black phosphorus flakes / graphene quantum dots@graphene. S3. Preparation of 5,7-dioxa-diphenyl-substituted cycloheptene phosphoryl chloride: Mix 0.1 mol of biphenyldiphenol, 0.4 mol of KOH, and 0.105 mol of phosphorus oxychloride in 250 mL of toluene. Heat to 105°C and stir for 6 hours. Distill under reduced pressure to collect the 5,7-dioxa-diphenyl-substituted cycloheptene phosphoryl chloride fraction. S4. Coupling: 0.45 g of 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride, 1.1 g of nano-black phosphorus flakes / graphene quantum dots@graphene, and 0.55 g of KOH were mixed in 200 mL of toluene. The mixture was heated to 80°C and stirred for 4 h. The mixture was centrifuged, washed, and dried to obtain nano-black phosphorus flakes / graphene quantum dots@graphene with a coupled flame retardant. S5. Tannic acid modification: 1 g of flame retardant-coupled nano-black phosphorus flakes / graphene quantum dots@graphene was added to 200 mL of Tris-HCl solution (pH 9), along with 0.25 g of tannic acid. The mixture was heated to 45°C and stirred for 3 h. The mixture was centrifuged, washed, and dried to produce a halogen-free flame retardant and antistatic modifier. S6. Preparation of a halogen-free flame-retardant and antistatic polycarbonate copolymer: 8 g of polycarbonate was heated to 235°C to melt, 0.2 g of an additive and 0.85 g of a halogen-free flame-retardant and antistatic modifier were added, and the mixture was stirred and uniformly mixed. The mixture was extruded into pellets, dried, and injection molded to produce a halogen-free flame-retardant and antistatic polycarbonate copolymer. The auxiliary agents include polyethylene wax, antioxidant 1010, and polytetrafluoroethylene, with a mass ratio of 4:2:3.

[0036] Comparative Example 5 Compared with Example 3, the difference is that steps S3, S4 and S5 are not performed.

[0037] The details are as follows: Preparation of black phosphorus nanosheets: 1 g of bulk black phosphorus was added to 1 L of N-methylpyrrolidone, stirred under ultrasound in an ice bath in the dark for 2 days, and centrifuged at 4000 rpm for 10 min. The supernatant was collected and centrifuged at 12500 rpm for 15 min. The solid was washed and dried to obtain black phosphorus nanosheets. S2. Preparation of nano-black phosphorus flakes / graphene quantum dots@graphene: 0.35 g of nano-black phosphorus flakes and 0.25 g of citric acid were added to 200 mL of an aqueous dispersion containing 1 g of graphene oxide. The mixture was hydrothermally reacted at 200°C for 24 h, followed by centrifugation, washing, drying, and reduction with hydrazine hydrate vapor for 11 h to produce nano-black phosphorus flakes / graphene quantum dots@graphene. Tannic acid modification: 1 g of black phosphorus nanosheets / graphene quantum dots@graphene was added to 200 mL of Tris-HCl solution (pH 9), followed by 0.25 g of tannic acid. The mixture was heated to 45°C and stirred for 3 h. The mixture was centrifuged, washed, and dried to produce a halogen-free flame retardant and antistatic modifier. S4. Preparation of a halogen-free flame-retardant and antistatic polycarbonate copolymer: 8 g of polycarbonate was heated to 235°C to melt, 0.2 g of an additive and 0.85 g of a halogen-free flame-retardant and antistatic modifier were added, and the mixture was stirred and uniformly mixed. The mixture was extruded into pellets, dried, and injection molded to produce a halogen-free flame-retardant and antistatic polycarbonate copolymer. The auxiliary agents include polyethylene wax, antioxidant 1010, and polytetrafluoroethylene, with a mass ratio of 4:2:3.

[0038] Comparative Example 6 Compared with embodiment 3, the difference is that step S6 is not performed.

[0039] The details are as follows: Preparation of black phosphorus nanosheets: 1 g of bulk black phosphorus was added to 1 L of N-methylpyrrolidone, stirred under ultrasound in an ice bath in the dark for 2 days, and centrifuged at 4000 rpm for 10 min. The supernatant was collected and centrifuged at 12500 rpm for 15 min. The solid was washed and dried to obtain black phosphorus nanosheets. S2. Preparation of nano-black phosphorus flakes / graphene quantum dots@graphene: 0.35 g of nano-black phosphorus flakes and 0.25 g of citric acid were added to 200 mL of an aqueous dispersion containing 1 g of graphene oxide. The mixture was hydrothermally reacted at 200°C for 24 h, followed by centrifugation, washing, drying, and reduction with hydrazine hydrate vapor for 11 h to produce nano-black phosphorus flakes / graphene quantum dots@graphene. S3. Polydopamine modification: 1 g of black phosphorus nanosheets / graphene quantum dots@graphene was added to 200 mL of Tris-HCl solution (pH 9), followed by 0.45 g of dopamine hydrochloride. The mixture was heated to 50°C and stirred for 4 h. The mixture was centrifuged, washed, and dried to obtain modified black phosphorus nanosheets / graphene quantum dots@graphene. S4. Preparation of 5,7-dioxa-diphenyl-substituted cycloheptene phosphoryl chloride: Mix 0.1 mol of biphenyldiphenol, 0.4 mol of KOH, and 0.105 mol of phosphorus oxychloride in 250 mL of toluene, heat to 105°C, and stir for 6 hours. Distill under reduced pressure to collect the 5,7-dioxa-diphenyl-substituted cycloheptene phosphoryl chloride fraction. S5. Coupling: 0.45 g of 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride, 1.1 g of modified nano-black phosphorus flakes / graphene quantum dots@graphene, and 0.55 g of KOH were mixed in 200 mL of toluene. The mixture was heated to 80°C and stirred for 4 h. The mixture was centrifuged, washed, and dried to obtain the modified nano-black phosphorus flakes / graphene quantum dots@graphene coupled flame retardant. S6. Preparation of a halogen-free flame-retardant and antistatic polycarbonate copolymer: 8 g of polycarbonate was melted by heating to 235°C, adding 0.2 g of an additive and 0.85 g of a flame retardant-modified nano-black phosphorus flake / graphene quantum dot@graphene. The mixture was stirred and uniformly mixed. The mixture was extruded and pelletized, dried, and injection molded to produce a halogen-free flame-retardant and antistatic polycarbonate copolymer. The auxiliary agents include polyethylene wax, antioxidant 1010, and polytetrafluoroethylene, with a mass ratio of 4:2:3.

[0040] Test Example 1 The halogen-free flame-retardant and antistatic polycarbonate copolymers prepared in Examples 1-3 and Comparative Examples 1-6 were tested for thermal conductivity and flame retardancy. The results are shown in Table 1.

[0041] (1) Thermal conductivity (TC) was measured using an Elmer Pyris thermal conductivity probe and reported in Watts per Kelvin-meter (W / mK). Measurements were performed on injection-molded sheets at room temperature. (2) Limiting oxygen index (LOI): tested in accordance with GB / T 2406.2-2009, sample size 80 mm × 10 mm × 4 mm; (3) Vertical burning performance: tested in accordance with GB / T 2408-2021, sample size: 125 mm × 12.5 mm × 3.2 mm; (4) HDT (heat deformation temperature) is tested in accordance with the provisions of GB / T1634.2-2004, with a load of 1.8 MPa.

[0042] Table 1

[0043] It can be seen from the above table that the halogen-free flame-retardant and antistatic polycarbonate copolymers prepared in Examples 1-3 of the present invention have good thermal conductivity, heat resistance and flame retardancy.

[0044] Test Example 2 The halogen-free flame retardant and antistatic polycarbonate copolymers prepared in Examples 1-3 and Comparative Examples 1-6 were subjected to mechanical property and antistatic tests. The results are shown in Table 2.

[0045] (1) Notched impact strength is tested in accordance with the provisions of GB / T1843-2008, and the notch type is type A; (2) Tensile strength and elongation at break: measured in accordance with the provisions of GB / T 1040.2-2022, with a tensile rate of 50.00 mm / min, a 4 mm thick 1A dumbbell-shaped standard specimen, and a test temperature of 22 ± 3 °C.

[0046] (3) Antistatic performance: Surface resistivity is tested according to ASTM D257.

[0047] Table 2

[0048] It can be seen from the above table that the halogen-free flame retardant and antistatic polycarbonate copolymers prepared in Examples 1-3 of the present invention have good mechanical properties.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a halogen-free flame-retardant and antistatic polycarbonate copolymer, characterized in that: Nano-black phosphorus sheets and graphene quantum dots are loaded on graphene, modified with polydopamine, coupled with 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride, and further modified with tannic acid. The resultant is added to molten polycarbonate, and the mixture is stirred and mixed evenly. The mixture is extruded into granules, dried, and injection molded to obtain a halogen-free flame-retardant and antistatic polycarbonate copolymer.

2. The preparation method according to claim 1, characterized in that The following steps are involved: S1. Preparation of black phosphorus nanosheets: Blocked black phosphorus was dissolved in N-methylpyrrolidone, stirred with ultrasound in an ice bath in the dark, and subjected to gradient centrifugation. The solid was washed and dried to obtain black phosphorus nanosheets. S2. Preparation of Nano-Black Phosphorus Flakes / Graphene Quantum Dots@Graphene: Nano-black phosphorus flakes and citric acid were added to an aqueous dispersion of graphene oxide, followed by a hydrothermal reaction, centrifugation, washing, drying, and reduction with hydrazine hydrate vapor to produce nano-black phosphorus flakes / graphene quantum dots@Graphene. S3. Polydopamine modification: Adding black phosphorus nanosheets / graphene quantum dots@graphene to a Tris-HCl solution, followed by dopamine hydrochloride, heating and stirring the mixture, centrifuging, washing, and drying to obtain modified black phosphorus nanosheets / graphene quantum dots@graphene. S4. Preparation of 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride: Biphenyldiphenol, a base and phosphorus oxychloride were mixed and added to toluene, heated and stirred to react, and distilled under reduced pressure to obtain 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride; S5. Coupling: 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride, modified nano-black phosphorus flakes / graphene quantum dots@graphene, and a base were mixed in toluene, heated and stirred for reaction, centrifuged, washed, and dried to obtain modified nano-black phosphorus flakes / graphene quantum dots@graphene coupled flame retardant. S6. Tannic acid modification: The flame retardant-modified nano-black phosphorus flakes / graphene quantum dots@graphene were added to a Tris-HCl solution, followed by tannic acid. The mixture was heated and stirred for reaction, centrifuged, washed, and dried to produce a halogen-free flame retardant and antistatic modifier. S7. Preparation of a halogen-free flame-retardant and antistatic polycarbonate copolymer: Heat and melt polycarbonate, add an additive and a halogen-free flame-retardant and antistatic modifier, stir and mix uniformly, extrude and granulate, dry, and injection mold to produce a halogen-free flame-retardant and antistatic polycarbonate copolymer.

3. The preparation method according to claim 2, characterized in that The time of the ice bath light-proof ultrasonic stirring in step S1 is 1-3 days, and the gradient centrifugation method is to collect the supernatant after centrifugation at a speed of 3000-5000 r / min for 5-15 minutes, and centrifuge at a speed of 12000-13000 r / min for 10-20 minutes.

4. The preparation method according to claim 2, characterized in that In step S2, the mass ratio of the nano black phosphorus sheet, citric acid and graphene oxide is 3-4:2-3:8-12, the temperature of the hydrothermal reaction is 190-210° C., the time is 22-26 hours, and the time of the hydrazine hydrate vapor reduction is 10-12 hours.

5. The preparation method according to claim 2, characterized in that The pH value of the Tris-HCl solution in step S3 is 8.5-9.5, the mass ratio of the nano black phosphorus sheets / graphene quantum dots@graphene and dopamine hydrochloride is 10:4-5, the temperature of the heating and stirring reaction is 45-55° C., and the time is 3-5 hours.

6. The preparation method according to claim 2, characterized in that In step S4, the molar ratio of biphenol, phosphorus oxychloride and base is 1:1-1.1:3-5, the temperature of the heating and stirring reaction is 100-120° C., and the time is 5-7 hours. The base is selected from at least one of triethylamine, diethylamine, NaOH and KOH.

7. The preparation method according to claim 2, characterized in that In step S5, the mass ratio of 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride, modified nano black phosphorus sheets / graphene quantum dots@graphene, and base is 4-5:10-12:5-6; the base is selected from at least one of triethylamine, diethylamine, NaOH, and KOH, and the heating and stirring reaction temperature is 75-85° C. and the time is 3-5 hours.

8. The preparation method according to claim 2, characterized in that The pH value of the Tris-HCl solution in step S6 is 8.5-9.5, the mass ratio of the modified nano black phosphorus sheet / graphene quantum dots@graphene of the coupled flame retardant and tannic acid is 10:2-3, the temperature of the heating and stirring reaction is 40-50° C., and the time is 2-4 hours.

9. The preparation method according to claim 2, characterized in that The heating and melting temperature in step S7 is 220-240° C., the mass ratio of the polycarbonate, the additive and the halogen-free flame retardant antistatic modifier is 70-90:1-3:7-10, and the additive includes polyethylene wax, antioxidant 1010 and polytetrafluoroethylene in a mass ratio of 2-5:1-3:2-4.

10. A halogen-free flame-retardant and antistatic polycarbonate copolymer prepared by the preparation method according to any one of claims 1 to 9.

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