A high-strength flame-retardant polycarbonate plastic and its preparation method

Abstract

The present invention belongs to the technical field of polycarbonate materials, and specifically discloses a high-strength flame-retardant polycarbonate plastic and a preparation method thereof. The high-strength flame-retardant polycarbonate plastic comprises, by weight, 60 to 80 parts of polycarbonate, 5 to 10 parts of a flame retardant, 0.1 to 2 parts of a dispersant, 0.1 to 2 parts of an antioxidant, 3 to 8 parts of a reinforcing agent, and 2 to 6 parts of a toughening agent. The flame retardant is prepared by adding 1,10-phenanthroline-4,7-diamine and triethylamine to dichloromethane, cooling to 5 to 5°C, adding a dichloromethane solution of compound A under an inert gas atmosphere, stirring the reaction, and purifying the reaction solution to obtain the obtained product. The polycarbonate plastic prepared by the present invention has both excellent mechanical properties and flame retardant properties.

Description

Technical Field

[0001] The invention belongs to the technical field of polycarbonate materials, and particularly relates to a high-strength flame-retardant polycarbonate plastic and a preparation method thereof. Background Art

[0002] Polycarbonate (PC) is a type of high molecular weight polymer containing carbonate groups in its molecular chain. The alternating structure of flexible carbonate bonds and rigid arylalkyl groups in its macromolecular chain makes it lightweight, impact-resistant, transparent, has excellent dielectric properties, and is heat and cold resistant. It is widely used in construction, medical equipment, electronic appliances, optical devices, automobiles, aerospace and other fields.

[0003] With the increasingly stringent safety standards and the continuous expansion of material application environments, higher requirements are placed on the flame retardant properties of polycarbonate materials, and it is usually necessary to introduce flame retardants to achieve the ideal flame retardant effect. There are many types of conventional flame retardants for polycarbonate, but they all have some shortcomings. Although traditional brominated flame retardants have high flame retardant efficiency, they produce thick smoke containing carcinogens when burned; low-molecular phosphate flame retardants are halogen-free and environmentally friendly, but they are volatile and cause the heat resistance of the matrix to deteriorate; sulfonate flame retardants can promote carbonization and maintain transparency, but they are not resistant to hydrolysis and are prone to flame retardant failure. At the same time, the introduction of conventional flame retardants often leads to a decrease in key mechanical indicators such as the material's impact strength and tensile properties. Therefore, it is of great significance to develop polycarbonate materials that have both high-efficiency flame retardant properties and excellent mechanical properties. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the primary purpose of the present invention is to provide a high-strength flame-retardant polycarbonate plastic having excellent flame-retardant properties and mechanical properties.

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned high-strength flame-retardant polycarbonate plastic, which has a simple process and can be produced on a large scale.

[0006] The purpose of the present invention is achieved by adopting the following technical solutions:

[0007] A high-strength flame-retardant polycarbonate plastic, comprising, by weight, 60-80 parts of polycarbonate, 5-10 parts of a flame retardant, 0.1-2 parts of a dispersant, 0.1-2 parts of an antioxidant, 3-8 parts of a reinforcing agent, and 2-6 parts of a toughening agent;

[0008] The preparation process of the flame retardant is as follows:

[0009]

[0010] 1,10-phenanthroline-4,7-diamine and triethylamine are added to dichloromethane, cooled to -5 to 5°C, and then a dichloromethane solution of compound A is added under an inert gas atmosphere. The mixture is stirred for reaction, and the reaction solution is purified to obtain the product.

[0011] Preferably, the usage ratio of the 1,10-phenanthroline-4,7-diamine, triethylamine, dichloromethane and compound A is 0.1 mol: (25-35) mL: (250-300) mL: (0.2-0.25) mol; and the stirring reaction time is 12-18 h.

[0012] Preferably, the preparation process of the enhancer is as follows:

[0013]

[0014] (1) Dispersing hydroxyapatite in acetone, adding toluene-2,4-diisocyanate and stannous octoate, reacting under heating conditions, and obtaining isocyanate-treated hydroxyapatite after purification;

[0015] (2) dispersing the isocyanate-modified hydroxyapatite in ethyl acetate, adding 3-mercaptopropanol, reacting under heating conditions, and obtaining mercapto-modified hydroxyapatite after purification;

[0016] (3) Adding the mercaptolated hydroxyapatite, allyl methyl carbonate and photoinitiator into tetrahydrofuran, reacting under an inert gas atmosphere and irradiation with ultraviolet light, and obtaining the product after purification.

[0017] Preferably, in step (1), the amount ratio of hydroxyapatite, toluene diisocyanate, stannous octoate and acetone is 1 g: (1-2) g: (0.003-0.006) g: (50-75) mL; the heating temperature is 50-75° C., and the reaction time is 4-8 h.

[0018] Preferably, in step (2), the amount ratio of the isocyanated hydroxyapatite, 3-mercaptopropanol and ethyl acetate is 1 g: (3-5) g: (50-75) mL; the heating temperature is 75-85° C., and the reaction time is 3-8 h.

[0019] Preferably, in step (3), the amount ratio of the mercaptolated hydroxyapatite, allyl methyl carbonate, photoinitiator and tetrahydrofuran is 1 g: (0.6-1.2) g: (0.015-0.03) g: (50-75) mL; the photoinitiator is benzoin dimethyl ether; and the reaction time is 5-10 h.

[0020] Preferably, the polycarbonate is bisphenol A polycarbonate, and its melt index under the test conditions of 300°C and 1.2 kg is 10 to 40 g / 10 min; the antioxidant is at least one of antioxidant 1010 and antioxidant 1076; the dispersant is at least one of stearic acid monoglyceride and ethylene bisstearamide; and the toughening agent is at least one of styrene grafted maleic anhydride and methyl methacrylate-butadiene-styrene copolymer.

[0021] The preparation method of the high-strength flame-retardant polycarbonate plastic comprises the following steps: mixing polycarbonate, a flame retardant, a dispersant, an antioxidant, a reinforcing agent and a toughening agent according to the aforementioned weight proportions to obtain a mixture; adding the mixture to a twin-screw extruder, melt-extruding and granulating to obtain the high-strength flame-retardant polycarbonate plastic.

[0022] Preferably, the stirring and mixing is performed at a rotation speed of 800 to 1200 rpm and for a time of 5 to 15 minutes.

[0023] Preferably, the temperature range of each zone of the twin-screw extruder is 200-260°C, and the main engine speed is 300-850rpm. The present invention has the following effects compared with the prior art:

[0024] 1. This invention provides a high-strength, flame-retardant polycarbonate plastic, comprising polycarbonate and a flame retardant. This flame retardant significantly enhances the flame retardancy of polycarbonate through a dual mechanism: vapor-phase flame retardancy (phosphorus-nitrogen synergistically produces a free radical quenching effect) and condensed-phase flame retardancy (catalytic carbonization to form a thermally insulating layer). Furthermore, the ester structure within the flame retardant molecule improves its compatibility with the polycarbonate matrix and enhances its dispersibility. The rigid phenanthroline backbone within the flame retardant molecule not only enhances the strength of the carbon layer but also helps improve the mechanical properties of the polycarbonate material.

[0025] 2. The raw materials for the high-strength, flame-retardant polycarbonate plastic of this invention also incorporate hydroxyapatite with surface-grafted carbonate groups as a reinforcing agent, significantly improving the mechanical properties of the polycarbonate material. The introduction of carbonate groups not only effectively prevents hydroxyapatite aggregation but also significantly improves the compatibility of the reinforcing agent with the polycarbonate matrix due to their structural similarity to the matrix. Furthermore, the urethane groups generated during the reaction form a hydrogen bonding network with the polycarbonate molecular chains, further enhancing interfacial interactions. These two synergistic effects effectively enhance the reinforcing agent's dispersion within the matrix and its interfacial bonding strength, thereby further improving the mechanical properties of the polycarbonate material. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the FT-IR graph of the reinforcing agent and hydroxyapatite prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be further described below in conjunction with specific embodiments. However, it should be understood by those skilled in the art that the following examples are only intended to illustrate the present invention and should not be construed as limiting the present invention. Specific conditions not specified in the examples are to be followed according to conventional conditions or the conditions recommended by the manufacturer. All reagents or instruments used, unless otherwise specified, are conventional products obtained from commercial channels.

[0028] The particle size of the hydroxyapatite used in the present invention is 200 nm; the polycarbonate is bisphenol A polycarbonate with a melt index of 20 g / 10 min under the test conditions of 300°C and 1.2 kg, purchased from Sigma-Aldrich; styrene-grafted maleic anhydride is purchased from BASF, Germany; and methyl methacrylate-butadiene-styrene copolymer is purchased from Kabuda Chemical.

[0029] Example 1

[0030] A high-strength flame-retardant polycarbonate plastic comprises the following raw materials, calculated by weight: 70 parts of polycarbonate, 8 parts of flame retardant, 1 part of stearic acid monoglyceride, 1 part of antioxidant 1010, 5 parts of reinforcing agent, and 4 parts of styrene-grafted maleic anhydride.

[0031] The preparation process of the above flame retardant is as follows:

[0032]

[0033] According to the usage ratio of 1,10-phenanthroline-4,7-diamine, triethylamine, dichloromethane and compound A of 0.1 mol:30 mL:280 mL:0.22 mol, 1,10-phenanthroline-4,7-diamine and triethylamine were added to dichloromethane and fully dissolved. The mixture was cooled to 0°C. Under nitrogen protection, a dichloromethane solution of compound A (CAS: 5381-98-6) was added dropwise. The mixture was stirred and reacted at room temperature for 15 hours. The reaction solution was concentrated and purified by silica gel chromatography (silica gel 300-400 mesh). The eluate was collected and the solvent was removed by rotary evaporation. Finally, the mixture was dried in vacuo over P2O5 to obtain a flame retardant.

[0034] The preparation process of the above-mentioned enhancer is as follows:

[0035]

[0036] (1) Hydroxyapatite was dispersed in acetone according to the ratio of hydroxyapatite, toluene diisocyanate, stannous octoate and acetone of 1 g:1.5 g:0.004 g:60 mL, and toluene diisocyanate and stannous octoate were added, and the mixture was reacted at 60 °C for 6 h. After the reaction was completed, the mixture was filtered, and the collected crude product was washed three times with acetone and dried to obtain isocyanated hydroxyapatite.

[0037] (2) The isocyanate hydroxyapatite, 3-mercaptopropanol and ethyl acetate were used in a ratio of 1 g:4 g:65 mL. The isocyanate hydroxyapatite was ultrasonically dispersed in ethyl acetate, 3-mercaptopropanol was added, and the mixture was reacted at 80 °C for 5 h. After the reaction was completed, the mixture was filtered and the collected crude product was washed once with ethyl acetate and ethanol, and then dried in vacuo to obtain mercapto hydroxyapatite.

[0038] (3) According to the amount ratio of thiolated hydroxyapatite, allyl methyl carbonate, benzoin dimethyl ether and tetrahydrofuran of 1 g: 0.9 g: 0.02 g: 60 mL, thiolated hydroxyapatite, allyl methyl carbonate and benzoin dimethyl ether (photoinitiator) were added to tetrahydrofuran, and the mixture was reacted for 8 h under nitrogen protection and ultraviolet light irradiation; after the reaction was completed, the mixture was filtered, and the collected crude product was washed once with tetrahydrofuran and ethanol in sequence, and then dried in vacuum to obtain the enhancer.

[0039] The FT-IR images of hydroxyapatite and the reinforcing agent prepared above are as follows: Figure 1 As shown, Figure 1 Curve a in the middle corresponds to hydroxyapatite, and curve b corresponds to the enhancer. -1 The stretching vibration of -OH is assigned to 3420 cm in curve b. -1 The hydroxyl peak at 3340 cm -1 The stretching vibration peak of NH in the carbamate group appears at 1690 cm -1 The stretching vibration peak of C=O appears at 1747cm -1 The characteristic peak of C=O in the carbonate group appears at , indicating that the enhancer is successfully obtained.

[0040] This embodiment also provides a method for preparing the above-mentioned high-strength flame-retardant polycarbonate plastic, and the specific steps are as follows:

[0041] According to the above parts by weight, polycarbonate, flame retardant, monoglyceride of stearate, antioxidant 1010, reinforcing agent and styrene-grafted maleic anhydride are added to a high-speed mixer and mixed at a speed of 1000 rpm for 10 minutes to obtain a mixture; the mixture is added to a twin-screw extruder, melt-extruded and granulated, the temperatures of each section of the twin-screw extruder are as follows: 200-220°C for zone 1, 220-240°C for zone 2, 240-250°C for zone 3, and 250-260°C for zone 4, and the main engine speed is 500 rpm, thereby obtaining a high-strength flame-retardant polycarbonate plastic.

[0042] Example 2

[0043] A high-strength flame-retardant polycarbonate plastic comprises the following raw materials, calculated by weight: 60 parts of polycarbonate, 5 parts of flame retardant, 0.1 part of ethylene bisstearamide, 0.1 part of antioxidant 1076, 3 parts of reinforcing agent, 1 part of styrene-grafted maleic anhydride, and 1 part of methyl methacrylate-butadiene-styrene copolymer.

[0044] The preparation process of the above flame retardant is as follows:

[0045] According to the usage ratio of 1,10-phenanthroline-4,7-diamine, triethylamine, dichloromethane and compound A of 0.1 mol:25 mL:250 mL:0.2 mol, 1,10-phenanthroline-4,7-diamine and triethylamine were added to dichloromethane and fully dissolved. The mixture was then cooled to -5°C. Under nitrogen protection, a dichloromethane solution of compound A (CAS: 5381-98-6) was added dropwise. The mixture was stirred and reacted at room temperature for 12 h. The reaction solution was concentrated and purified by silica gel chromatography (silica gel 300-400 mesh). The eluate was collected and the solvent was removed by rotary evaporation. Finally, the mixture was dried in vacuo over P2O5 to obtain a flame retardant.

[0046] The preparation process of the above-mentioned enhancer is as follows:

[0047] (1) According to the amount ratio of hydroxyapatite, toluene diisocyanate, stannous octoate and acetone of 1 g:1 g:0.003 g:50 mL, hydroxyapatite was dispersed in acetone, and toluene diisocyanate and stannous octoate were added, and the mixture was reacted at 50 °C for 8 h. After the reaction was completed, the mixture was filtered, and the collected crude product was washed three times with acetone and dried to obtain isocyanated hydroxyapatite.

[0048] (2) The isocyanate hydroxyapatite, 3-mercaptopropanol and ethyl acetate were used in a ratio of 1 g:3 g:50 mL. The isocyanate hydroxyapatite was ultrasonically dispersed in ethyl acetate, 3-mercaptopropanol was added, and the mixture was reacted at 85 °C for 3 h. After the reaction was completed, the mixture was filtered and the collected crude product was washed once with ethyl acetate and ethanol, and then dried in vacuo to obtain the mercapto hydroxyapatite.

[0049] (3) According to the amount ratio of thiolated hydroxyapatite, allyl methyl carbonate, benzoin dimethyl ether and tetrahydrofuran of 1 g: 0.6 g: 0.0015 g: 50 mL, thiolated hydroxyapatite, allyl methyl carbonate and benzoin dimethyl ether (photoinitiator) were added to tetrahydrofuran, and reacted under nitrogen protection and ultraviolet light for 5 h; after the reaction was completed, the crude product was filtered and washed with tetrahydrofuran and ethanol in turn, and then vacuum dried to obtain the enhancer.

[0050] This embodiment also provides a method for preparing the above-mentioned high-strength flame-retardant polycarbonate plastic, and the specific steps are as follows:

[0051] According to the above parts by weight, polycarbonate, flame retardant, ethylene bisstearamide, antioxidant 1076, reinforcing agent and methyl methacrylate-butadiene-styrene copolymer are added to a high-speed mixer and mixed at a speed of 800 rpm for 15 minutes to obtain a mixture; the mixture is added to a twin-screw extruder, melt-extruded and granulated, the temperatures of each section of the twin-screw extruder are as follows: 200-220°C for zone 1, 220-240°C for zone 2, 240-250°C for zone 3, and 250-260°C for zone 4, and the main engine speed is 300 rpm, thereby obtaining a high-strength flame-retardant polycarbonate plastic.

[0052] Example 3

[0053] A high-strength flame-retardant polycarbonate plastic comprises the following raw materials, calculated by weight: 80 parts of polycarbonate, 10 parts of flame retardant, 1 part of stearic acid monoglyceride, 1 part of ethylene bisstearamide, 1 part of antioxidant 1010, 1 part of antioxidant 1076, 8 parts of reinforcing agent, and 6 parts of methyl methacrylate-butadiene-styrene copolymer.

[0054] The preparation process of the above flame retardant is as follows:

[0055] According to the usage ratio of 1,10-phenanthroline-4,7-diamine, triethylamine, dichloromethane and compound A of 0.1 mol:35 mL:300 mL:0.25 mol, 1,10-phenanthroline-4,7-diamine and triethylamine were added to dichloromethane and fully dissolved. The mixture was then cooled to 5°C. Under nitrogen protection, a dichloromethane solution of compound A (CAS: 5381-98-6) was added dropwise. The mixture was stirred and reacted at room temperature for 18 h. The reaction solution was concentrated and purified by silica gel chromatography (silica gel 300-400 mesh). The eluate was collected and the solvent was removed by rotary evaporation. Finally, the mixture was dried in vacuo over P2O5 to obtain a flame retardant.

[0056] The preparation process of the above-mentioned enhancer is as follows:

[0057] (1) According to the amount ratio of hydroxyapatite, toluene diisocyanate, stannous octoate and acetone of 1 g:2 g:0.006 g:75 mL, hydroxyapatite was dispersed in acetone, and toluene diisocyanate and stannous octoate were added, and the mixture was reacted at 75°C for 4 h. After the reaction was completed, the mixture was filtered, and the collected crude product was washed three times with acetone and dried to obtain isocyanated hydroxyapatite.

[0058] (2) The isocyanate hydroxyapatite, 3-mercaptopropanol and ethyl acetate were used in a ratio of 1 g:5 g:75 mL. The isocyanate hydroxyapatite was ultrasonically dispersed in ethyl acetate, 3-mercaptopropanol was added, and the mixture was reacted at 75 °C for 8 h. After the reaction was completed, the mixture was filtered and the collected crude product was washed once with ethyl acetate and ethanol in sequence. After vacuum drying, the mercapto hydroxyapatite was obtained.

[0059] (3) According to the amount ratio of thiolated hydroxyapatite, allyl methyl carbonate, benzoin dimethyl ether and tetrahydrofuran of 1 g:1.2 g:0.03 g:75 mL, thiolated hydroxyapatite, allyl methyl carbonate and benzoin dimethyl ether (photoinitiator) were added to tetrahydrofuran, and reacted for 10 h under nitrogen protection and ultraviolet light irradiation; after the reaction was completed, the crude product was filtered and washed with tetrahydrofuran and ethanol in turn, and then vacuum dried to obtain the enhancer.

[0060] This embodiment also provides a method for preparing the above-mentioned high-strength flame-retardant polycarbonate plastic, and the specific steps are as follows:

[0061] The raw materials are weighed according to the above parts by weight, and then polycarbonate, flame retardant, ethylene bisstearamide, antioxidant 1010, antioxidant 1076, reinforcing agent and methyl methacrylate-butadiene-styrene copolymer are added to a high-speed mixer and mixed at a speed of 1200 rpm for 5 minutes to obtain a mixture. The mixture is added to a twin-screw extruder, melt-extruded and granulated. The temperatures of each section of the twin-screw extruder are as follows: 200-220°C for zone 1, 220-240°C for zone 2, 240-250°C for zone 3, and 250-260°C for zone 4. The main engine speed is 850 rpm, thereby obtaining a high-strength flame-retardant polycarbonate plastic.

[0062] Comparative Example 1

[0063] Comparative Example 1 is substantially the same as Example 1, except that when preparing the reinforcing agent, steps (2) and (3) are omitted, that is, isocyanate-treated hydroxyapatite is used as the reinforcing agent.

[0064] Comparative Example 2

[0065] Comparative Example 2 is substantially the same as Example 1, except that the flame retardant in Example 1 is omitted.

[0066] Test example

[0067] The polycarbonate plastics prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were subjected to flame retardancy tests according to the UL94 standard, and to tensile strength, flexural strength, and impact strength tests according to the ASTM D638, ASTM D790, and ASTM D256 standards. The test results are shown in Table 1, where NR in Table 1 indicates no rating.

[0068] Table 1 Performance results of polycarbonate plastics obtained in Examples 1-3 and Comparative Examples 1-2

[0069]

[0070] It can be seen from the test results in Table 1 that the polycarbonate plastics prepared in Examples 1 to 3 of the present invention have both excellent mechanical properties and flame retardancy, are suitable for preparing flame retardant products, and have wide applicability.

[0071] Compared to Comparative Example 2, which did not include the addition of a flame retardant, the polycarbonate plastics prepared in Examples 1-3 of the present invention all achieved a flame retardancy rating of V0, and none of the mechanical properties showed a significant decrease. Analysis reveals that the flame retardant prepared in this invention significantly improves the flame retardancy of polycarbonate through both vapor-phase flame retardancy (phosphorus-nitrogen synergistically produces a free radical quenching effect) and condensed-phase flame retardancy (catalytic carbonization to form a thermal insulation layer). Furthermore, the ester structure in the flame retardant molecules improves their compatibility with the polycarbonate matrix and enhances its dispersibility. The rigid phenanthroline skeleton in the flame retardant molecules not only enhances the strength of the carbon layer but also helps improve the mechanical properties of the polycarbonate material.

[0072] Compared to Comparative Example 1, which used isocyanated hydroxyapatite as a reinforcing agent, Examples 1-3 of the present invention, which used hydroxyapatite with surface-grafted carbonate groups as a reinforcing agent, significantly improved the mechanical properties of polycarbonate plastics. This is because, on the one hand, the introduction of carbonate groups not only effectively prevents hydroxyapatite agglomeration, but also significantly improves the compatibility of the reinforcing agent with the polycarbonate matrix due to the structural similarity between the carbonate groups and the matrix. On the other hand, the urethane groups generated during the reaction can form a hydrogen bond network with the polycarbonate molecular chains, further enhancing interfacial interactions. The synergistic effect of these two factors effectively improves the dispersion of the reinforcing agent in the matrix and the interfacial bonding strength, thereby further enhancing the mechanical properties of the polycarbonate material.

[0073] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the same. The basic principles and main features of the present invention have been described above using specific implementation schemes. Modifications or substitutions may be made based on the present invention, but such modifications or substitutions do not detract from the essence of the corresponding technical solutions from the scope of protection claimed by the present invention.

Claims

1. A high-strength flame-retardant polycarbonate plastic, characterized in that: The high-strength flame-retardant polycarbonate plastic comprises, by weight: 60-80 parts of polycarbonate, 5-10 parts of flame retardant, 0.1-2 parts of dispersant, 0.1-2 parts of antioxidant, 3-8 parts of reinforcing agent, and 2-6 parts of toughening agent; The preparation process of the flame retardant is as follows: 1,10-phenanthroline-4,7-diamine and triethylamine are added to dichloromethane, cooled to -5 to 5°C, and then a dichloromethane solution of compound A is added under an inert gas atmosphere. The mixture is stirred for reaction, and the reaction solution is purified to obtain the product.

2. The high-strength flame-retardant polycarbonate plastic according to claim 1, characterized in that: The usage ratio of the 1,10-phenanthroline-4,7-diamine, triethylamine, dichloromethane and compound A is 0.1 mol: (25-35) mL: (250-300) mL: (0.2-0.25) mol; and the stirring reaction time is 12-18 h.

3. The high-strength flame-retardant polycarbonate plastic according to claim 1, characterized in that: The preparation process of the enhancer is as follows: (1) Dispersing hydroxyapatite in acetone, adding toluene-2,4-diisocyanate and stannous octoate, reacting under heating conditions, and obtaining isocyanate-treated hydroxyapatite after purification; (2) dispersing the isocyanate-modified hydroxyapatite in ethyl acetate, adding 3-mercaptopropanol, reacting under heating conditions, and obtaining mercapto-modified hydroxyapatite after purification; (3) Adding the mercaptolated hydroxyapatite, allyl methyl carbonate and photoinitiator into tetrahydrofuran, reacting under an inert gas atmosphere and irradiation with ultraviolet light, and obtaining the product after purification.

4. The high-strength flame-retardant polycarbonate plastic according to claim 3, characterized in that: The amount ratio of hydroxyapatite, toluene diisocyanate, stannous octoate and acetone in step (1) is 1 g: (1-2) g: (0.003-0.006) g: (50-75) mL; the heating temperature is 50-75° C., and the reaction time is 4-8 h.

5. The high-strength flame-retardant polycarbonate plastic according to claim 3, characterized in that: In step (2), the amount ratio of isocyanate-treated hydroxyapatite, 3-mercaptopropanol and ethyl acetate is 1 g: (3-5) g: (50-75) mL; the heating temperature is 75-85° C., and the reaction time is 3-8 h.

6. The high-strength flame-retardant polycarbonate plastic according to claim 3, characterized in that: In step (3), the amount ratio of thiolated hydroxyapatite, allyl methyl carbonate, photoinitiator and tetrahydrofuran is 1 g: (0.6-1.2) g: (0.015-0.03) g: (50-75) mL; the photoinitiator is benzoin dimethyl ether; and the reaction time is 5-10 h.

7. The high-strength flame-retardant polycarbonate plastic according to claim 1, characterized in that: The polycarbonate is bisphenol A polycarbonate, and its melt index under test conditions of 300° C. and 1.2 kg is 10 to 40 g / 10 min; the antioxidant is at least one of antioxidant 1010 and antioxidant 1076; the dispersant is at least one of stearic acid monoglyceride and ethylene bisstearamide; and the toughening agent is at least one of styrene grafted maleic anhydride and methyl methacrylate-butadiene-styrene copolymer.

8. The method for preparing the high-strength flame-retardant polycarbonate plastic according to any one of claims 1 to 7, characterized in that: Polycarbonate, flame retardant, dispersant, antioxidant, reinforcing agent and toughening agent are stirred and mixed according to the weight proportions to obtain a mixture; the mixture is added into a twin-screw extruder, melt-extruded and granulated to obtain the high-strength flame-retardant polycarbonate plastic.

9. The method for preparing high-strength flame-retardant polycarbonate plastic according to claim 8, characterized in that: The stirring and mixing is performed at a rotation speed of 800 to 1200 rpm and for a time of 5 to 15 minutes.

10. The method for preparing high-strength flame-retardant polycarbonate plastic according to claim 8, characterized in that: The temperature range of each zone of the twin-screw extruder is 200-260° C., and the main engine speed is 300-850 rpm.

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