Halogen-free flame-retardant polycarbonate alloy and preparation method thereof

Abstract

The invention provides a halogen-free flame-retardant polycarbonate alloy and a preparation method thereof, and relates to the technical field of high polymer materials. The halogen-free flame-retardant polycarbonate alloy is prepared from the following raw materials in parts by mass: 55 to 93 parts of polycarbonate resin, 10 to 30 parts of silicon copolymerized polycarbonate resin, 2 to 10 parts of phosphorus flame retardant, 0 to 10 parts of modified silicon grafted sulfonate flame retardant, 0.5 to 2 parts of silicon flame retardant, 1 to 5 parts of flexibilizer, 0.5 to 1 part of compatilizer and 0.1 to 1.3 parts of other auxiliaries. The halogen-free flame-retardant polycarbonate alloy provided by the invention has excellent mechanical properties and also has flame-retardant properties meeting V0 and S.2 standards.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a halogen-free flame-retardant polycarbonate alloy and its preparation method. Background Technology

[0002] Polycarbonate (PC) is widely used in electronic and electrical enclosures, automotive interiors, and LED lighting due to its excellent optical transparency, high impact strength, and flame-retardant properties. However, with the release of the latest standard GB 4943.1-2022, the consumer electronics and electrical appliance industries face a severe challenge in the flame-retardant safety test—the S.2 needle flame test. According to the second phase of the certification validity inspection conducted by the State Administration for Market Regulation in 2024, many companies' fire-resistant protective enclosures met the requirements of UL94 V0 but failed the GB 4943.1-2022 S.2 needle flame test. The UL94 standard focuses more on the material's resistance to combustion in a vertical position. The core requirement is that after the sample is ignited, the flame must extinguish within 10 seconds, and there should be no dripping of burning material. The GB 4943.1-2022 standard assesses the integrity of finished structures (such as fireproof enclosures) under flame conditions. Its core requirement is to simulate a small, faulty flame, ensuring that the gauze covering the sample does not ignite during testing, and that the enclosure does not develop holes exceeding the standard's allowable size. Its main technical barriers lie in:

[0003] The UL94 V-0 flame retardant rating requires that there be no dripping of burning material. Currently, the only anti-dripping agent suitable for flame-retardant PC is polytetrafluoroethylene (PTFE), which prevents the dripping of burning molten material by forming a physical three-dimensional network skeleton in the molten PC. However, in the GB 4943.1-2022 S.2 standard, while the PTFE fiber network plays an anti-dripping role, it also disrupts the continuity and strength of the expanded char layer, making the formed char layer loose and brittle, thus causing combustion holes in the outer shell. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a halogen-free flame-retardant polycarbonate alloy and its preparation method.

[0005] The present invention proposes a halogen-free flame-retardant polycarbonate alloy comprising the following raw materials in parts by weight: 55-93 parts of polycarbonate resin, 10-30 parts of silicon copolymer polycarbonate resin, 2-10 parts of phosphorus-based flame retardant, 0-10 parts of modified silicon grafted sulfonate flame retardant, 0.5-2 parts of silicon-based flame retardant, 1-5 parts of toughening agent, 0.5-1 part of compatibilizer, and 0.1-1.3 parts of other additives.

[0006] This invention improves the processing performance and UL94 flame retardant performance of polycarbonate alloys by physically blending polycarbonate resins with different molecular chain lengths, silicon copolymer polycarbonate resins, and phosphorus-based flame retardants. The synergistic flame retardant effect of modified silicon grafted sulfonate flame retardants and silicon-based flame retardants can further improve the needle flame flame retardant performance of polycarbonate alloys.

[0007] Preferably, the total mass of the raw materials for the halogen-free flame-retardant polycarbonate alloy is 100 parts.

[0008] Preferably, the polycarbonate resin has a melt index of 10-12 g / 10 min under the test conditions of 300℃ / 1.2 kg.

[0009] Preferably, the melt index of the silicon copolymer polycarbonate resin is 8-12 g / 10 min under the test conditions of 300℃ / 1.2 kg, and the silicon content in the silicon copolymer polycarbonate resin is 6-8%.

[0010] By blending silicon copolymer polycarbonate resin with polycarbonate in a certain proportion, a balance between processing performance, material toughness and chemical resistance can be achieved to a certain extent. At the same time, silicon copolymer polycarbonate resin can synergistically lead to good flame retardant effect by accelerating the formation of char layer.

[0011] Preferably, the phosphorus-based flame retardant is selected from one or more of hexaphenoxycyclotriphosphazene and bisphenol A-bis(diphenyl phosphate).

[0012] Preferably, the mass ratio of the polycarbonate resin, the silicon copolymer polycarbonate resin, and the phosphorus flame retardant is (55-65):(15-25):(8-10).

[0013] Preferably, the preparation method of the modified silicon grafted sulfonate flame retardant includes the following steps: drying polycarbonate resin, silicon copolymer polycarbonate resin, sulfonate flame retardant, compatibilizer, and antioxidant, followed by premixing and melt extrusion to obtain the product.

[0014] More preferably, the sulfonate flame retardant is selected from one or more of potassium nonafluorobutyl sulfonate and potassium diphenyl sulfone-3-sulfonate.

[0015] More preferably, the compatibilizer is a maleic anhydride-grafted acrylonitrile-butadiene-styrene copolymer, and the mass fraction of maleic anhydride is 1-5 wt%.

[0016] More preferably, the mass ratio of the polycarbonate resin, the silicon copolymer polycarbonate resin, the sulfonate flame retardant, the compatibilizer, and the antioxidant is (45-50): (45-55): (1-5): (0.1-1): (0.1-1).

[0017] More preferably, the drying temperature is 70–90°C and the drying time is 4–6 hours.

[0018] More preferably, the premixing includes mixing for 5 to 15 minutes at a speed of 800 to 1500 rpm and a temperature of 10 to 30°C.

[0019] More preferably, the temperature of the melt extrusion is 220–280°C.

[0020] More preferably, the melt extrusion is carried out in a twin-screw extruder, with the temperatures of each extrusion section being 220°C, 250°C, 260°C, 280°C, 280°C, 260°C, and 260°C, respectively. The twin-screw extruder has a rotational speed of 200–500 rpm, a torque of 60–70%, and a weak-shear screw.

[0021] Preferably, the silicon-based flame retardant is an organosilicon flame retardant, and the organosilicon flame retardant is selected from Dow Corning's FCA-107.

[0022] Preferably, the mass ratio of the modified silicon grafted sulfonate flame retardant to the silicon-based flame retardant is (3-7):1.

[0023] Controlling the mass ratio of modified silicon-grafted sulfonate flame retardants and silicon-based flame retardants within a certain range helps to improve their synergistic flame retardant effect and further enhance the needle flame retardant performance of polycarbonate alloys.

[0024] Preferably, the toughening agent is selected from one or more of methyl methacrylate-butadiene-styrene terpolymer (MBS) and methyl methacrylate-acrylic acid-organosilicon core-shell copolymer.

[0025] Preferably, the compatibilizer is a maleic anhydride-grafted acrylonitrile-butadiene-styrene copolymer, and the mass fraction of maleic anhydride is 1-5 wt%.

[0026] Preferably, the other additives are selected from one or more of antioxidants, anti-dripping agents, and lubricants.

[0027] More preferably, the antioxidant is selected from one or more of hindered phenolic antioxidants and phosphite antioxidants.

[0028] More preferably, the lubricant is selected from one or more of pentaerythritol stearate and silicone.

[0029] More preferably, the anti-dripping agent is polytetrafluoroethylene (PTFE).

[0030] The present invention also provides a method for preparing the above-mentioned halogen-free flame-retardant polycarbonate alloy, comprising the following steps:

[0031] S1. Mix polycarbonate resin, silicon copolymer polycarbonate resin, phosphorus flame retardant, modified silicon grafted sulfonate flame retardant, and toughening agent evenly to obtain mixture A.

[0032] S2. Mix the silicon-based flame retardant, compatibilizer, and other additives to obtain mixture B;

[0033] S3. Mix mixture A and mixture B evenly using a high-speed mixer, then feed them into a twin-screw extruder, and after melt extrusion and granulation, the mixture is obtained.

[0034] The preparation process of the halogen-free flame-retardant polycarbonate alloy provided by this invention is simple, easy to control, and does not require high-end equipment. The equipment used is all general-purpose polymer processing equipment, which requires low investment and is conducive to industrial production.

[0035] Preferably, in S3, the speed of the high-speed mixer is 800-1500 rpm.

[0036] Preferably, in S3, the operating parameters of the twin-screw extruder are as follows: zone 1 temperature is 210–240℃, zone 2 temperature is 230–260℃, zone 3 temperature is 235–260℃, zone 4 temperature is 220–260℃, zone 5 temperature is 220–260℃, zone 6 temperature is 220–260℃, zone 7 temperature is 220–260℃, zone 8 temperature is 220–260℃, die temperature is 240–275℃, and screw speed is 200–400 rpm.

[0037] More preferably, the twin-screw extruder is a parallel twin-screw extruder, the screw of the parallel twin-screw extruder has a single-threaded shape, the ratio of screw length L to diameter D is 35, and the screw is provided with two meshing block areas and one reverse thread area.

[0038] Applications of the above-mentioned halogen-free flame-retardant polycarbonate alloy or the halogen-free flame-retardant polycarbonate alloy prepared by the above-mentioned method in electronic and electrical enclosures, automotive interiors, and LED lighting.

[0039] The beneficial effects of this invention are as follows:

[0040] This invention provides a halogen-free flame-retardant polycarbonate alloy that simultaneously meets the UL94 V-0 flame retardant rating and the GB 4943.1-2022 S.2 needle flame retardant rating. By physically blending polycarbonate resins, silicon copolymer polycarbonate resins, and hexaphenoxycyclotriphosphazene with different molecular chain lengths, the processing performance and UL94 flame retardant performance of the polycarbonate alloy can be improved. The synergistic flame retardant effect of modified silicon grafted sulfonate flame retardant and silicon-based flame retardant can further improve the needle flame retardant performance of the polycarbonate alloy. Detailed Implementation

[0041] The technical solution of the present invention will be described in detail through specific embodiments.

[0042] In the following examples and comparative examples, the specific information regarding the raw materials used is as follows:

[0043] Polycarbonate resin: PC 1250Y, melt index 8g / 10min, selected from Teijin Co., Ltd., Japan;

[0044] Silicon copolymer polycarbonate resin: PC AC9140, melt index 10g / 10min, selected from Formosa Plastics Idemitsu;

[0045] Phosphorus-based flame retardant: Bisphenol-A-bis(diphenyl phosphate), with a phosphorus content of 16%, selected from Zhejiang Wansheng Co., Ltd.;

[0046] Phosphorus-based flame retardant: Hexaphenoxycyclotriphosphazene SPB-110, with a phosphorus content of 13.4%, selected from Otsuka Chemical, Japan;

[0047] Silicon-based flame retardants: Organosilicon flame retardant: FCA-107, selected from Dow Corning, USA;

[0048] Toughening agent: Methyl methacrylate-acrylic acid-organosilicon core-shell copolymer: S-2030, selected from Mitsubishi Corporation, Japan;

[0049] Toughening agent: Methyl methacrylate-butadiene-styrene terpolymer: M-724, selected from Kanekachi, Japan;

[0050] Compatibilizer: Maleic anhydride-grafted acrylonitrile-butadiene-styrene copolymer: RAS-302, maleic anhydride mass fraction of 2wt%, selected from Sigma-Aldrich (Shanghai) Trading Co., Ltd.;

[0051] Hindered phenolic antioxidant: β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl ester, selected from BASF GmbH, Germany;

[0052] Phosphite antioxidant: bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate, selected from BASF GmbH, Germany;

[0053] Lubricant: Pentaerythritol stearate, selected from BASF GmbH, Germany;

[0054] Anti-dripping agent AS-PTFE: A-3800, selected from Mitsubishi Corporation, Japan.

[0055] The preparation method of the modified silicon-grafted sulfonate flame retardant includes: 47.4 parts of Teijin PC 1250Y, 50 parts of Formosa Plastics Idemitsu PC AC9140, 2 parts of Mitsubishi EF-4 potassium non-fluorobutyl sulfonate flame retardant, 0.5 parts of Rowin's maleic anhydride-grafted acrylonitrile-butadiene-styrene copolymer compatibilizer, and 0.1 parts of hindered phenolic antioxidant β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate n-octadecyl alcohol ester are dried at 80°C for approximately 5 hours to thoroughly remove moisture. The pretreated components are then added to a 1000 rpm high-speed mixer according to the formulation ratio and mixed at room temperature for 10 minutes until macroscopically homogeneous. The premixed materials are melt-blended using a twin-screw extruder. The twin-screw extruder process is as follows: the temperatures of each extrusion section are 220-250-260-280-280-260-260, the speed is 300 rpm, the torque is 60-70%, and the screw is a low-shear screw.

[0056] Unless otherwise specified, all materials and reagents used in the following examples and comparative examples are commercially available.

[0057] Examples 1-10

[0058] The raw material ratios for halogen-free flame-retardant polycarbonate alloys are detailed in Table 1.

[0059] A method for preparing halogen-free flame-retardant polycarbonate alloys includes the following steps:

[0060] S1. Mix polycarbonate resin, silicon copolymer polycarbonate resin, phosphorus flame retardant, modified silicon grafted sulfonate flame retardant, and toughening agent evenly to obtain mixture A.

[0061] S2. Mix the silicon-based flame retardant, compatibilizer, antioxidant, lubricant, and anti-dripping agent to obtain mixture B;

[0062] S3. After mixing mixture A and mixture B evenly through a high-speed mixer, the mixture is fed into a twin-screw extruder and subjected to melt extrusion and granulation to obtain the final product. The process parameters include: zone 1 temperature 230℃, zone 2 temperature 240℃, zone 3 temperature 250℃, zone 4 temperature 250℃, zone 5 temperature 250℃, zone 6 temperature 250℃, zone 7 temperature 245℃, zone 8 temperature 245℃, die temperature 260℃, and screw speed 400 rpm. The screw of the parallel twin-screw extruder has a single-threaded shape, and the ratio of screw length L to diameter D, L / D, is 35. The screw has two meshing block areas and one reverse thread area.

[0063] Comparative Examples 1-7

[0064] The raw material ratios for halogen-free flame-retardant polycarbonate alloys are detailed in Table 2.

[0065] The preparation method of the halogen-free flame-retardant polycarbonate alloy is the same as that in the examples.

[0066] Table 1

[0067]

[0068] Table 2

[0069]

[0070] The halogen-free flame-retardant polycarbonate alloys prepared in the above examples and comparative examples were subjected to the following performance tests:

[0071] Melt flow index: Tested according to GB / T 3682-2018 standard, test temperature is 300℃, load is 1.2kg;

[0072] Needle flame test: Tested according to GB 4943.1-2022 standard;

[0073] Mechanical properties: tested according to GB / T 1843-2008 standard;

[0074] Flame retardant performance: Tested according to UL-94 standard, with a sample thickness of 1.5mm / 3.0mm. The shorter the total burning time T1+T2 of the 5 test samples, the better the flame retardant performance. Record its flame retardant rating.

[0075] The performance test results are shown in Table 3.

[0076] Table 3

[0077]

[0078] As shown in Table 3, in Examples 1-4, the mechanical properties of hexaphenoxycyclotriphosphazene decreased slightly with increasing addition, but its flame retardant properties significantly improved, increasing from 3.0 mmV2 to 3.0 mmV0. When the addition amount of hexaphenoxycyclotriphosphazene reached 6 parts, combined with 0.1 parts PTFE, 3.0 mmV0 could be achieved while maintaining good material properties. This is because hexaphenoxycyclotriphosphazene decomposes upon heating into phosphorus-containing free radicals, which efficiently quench hydrogen ions and hydroxyl free radicals in the flame, thereby interrupting the chain combustion reaction. Simultaneously, the thermal decomposition of hexaphenoxycyclotriphosphazene produces strongly dehydrating acidic substances such as phosphoric acid and polyphosphoric acid, catalyzing polymer dehydration and cross-linking to form a dense and stable expanded char layer, which can hinder the combustion reaction. Furthermore, hexaphenoxycyclotriphosphazene also forms a superior thermal and material barrier through a phosphorus-nitrogen synergistic effect, interrupting the combustion reaction. Under high temperature and shear force, PTFE fibrils and forms a three-dimensional network structure. This three-dimensional network acts like countless tiny "fishing lines" or "spider webs" embedded in the melt, greatly increasing its viscosity and strength. This transforms the melt from a "flowable liquid" into a "viscous, gel-like solid," thus resisting gravity and preventing it from dripping easily. However, due to insufficient PTFE addition, when the sample thickness is too thin, the three-dimensional network cannot completely prevent melt dripping, resulting in a UL94 V2 rating. When PTFE is increased from 0.1 to 0.3 parts, a 1.5 mmV0 can be achieved through the synergistic effect of hexaphenoxycyclotriphosphazene and PTFE, but the needle flame performance shows a significant decrease.

[0079] In Examples 5-7, with the increase of the amount of silicon copolymer PC added, the needle flame performance showed a conventional improvement while maintaining other stable properties. This is because siloxanes have extremely low surface energy. At the high temperatures generated by combustion, the mobility of the entire molecular chain is enhanced, and the polysiloxane segments block within them spontaneously migrate and accumulate to the surface. The siloxanes accumulated on the surface undergo self-crosslinking at high temperatures and react with the carbon layer formed by PC to generate chemical bonds such as Si-C and Si-OC, ultimately forming a silicon-carbon composite carbon layer. The introduction of silicon into this carbon layer greatly improves the stability of the carbon layer at high temperatures, preventing the carbon layer from burning through, while also protecting the unburned matrix inside and slowing down the pyrolysis process. In Examples 8-10, as the amount of modified silicon-grafted sulfonate flame retardant increased, its needle flame performance was synergistically improved while maintaining other stable properties. This is because the sulfonate flame retardant decomposes at the processing and combustion temperatures of PC, producing strong protic acids or Lewis acids. Under the catalysis of these acids, the phenolic hydroxyl groups at the PC terminals undergo Friedel-Crafts alkylation with the aromatic rings on adjacent PC chains, forming methylene bridges. This reaction rapidly expands throughout the PC matrix, forming a highly cross-linked three-dimensional network structure. Through the synergistic effect of these three flame-retardant properties, a halogen-free polycarbonate alloy with simultaneous V0 and S.2 was achieved.

[0080] Compared with Comparative Example 1, Example 9 did not add silicon copolymer PC. The flame retardant properties of the polycarbonate alloy obtained in Comparative Example 1 could only reach 1.5mmV2 / 3.0mmV0, and the needle flame performance was significantly reduced. This shows that silicon copolymer PC can simultaneously promote UL94 V0 flame retardant performance and needle flame S.2 flame retardant performance in the system.

[0081] Compared with Comparative Example 2, Example 9 did not contain hexaphenoxycyclotriphosphazene, and the flame retardant performance of the material could only reach 1.5 mmV2. At the same time, the needle flame performance could not meet S.2. This shows that the advantage of hexaphenoxycyclotriphosphazene in this invention is that it can meet the vertical flame retardant performance of UL94 at a low PTFE content, achieve the V0 rating by blocking the combustion chain reaction, and has a certain effect on hindering the continuous combustion of the needle flame effect.

[0082] Compared with Comparative Example 3, Comparative Example 3 did not add modified silicon grafted sulfonate flame retardant. The flame retardant performance of the material could reach 1.5 mm V0, but the needle flame performance could not meet S.2. This shows that the modified silicon grafted sulfonate flame retardant in this invention is mainly used to further synergistically improve the needle flame performance without affecting the V0 rating.

[0083] Compared with Comparative Example 4, Example 9 did not contain PTFE, and the resulting polycarbonate alloy would drip during combustion, thus failing to meet the UL94V0 requirement. This indicates that in this invention, PTFE mainly achieves the V0 flame retardant rating by forming a network structure to block the molten material from dripping.

[0084] Compared with Comparative Example 5, Example 9 did not contain any silicon-based flame retardant. The resulting polycarbonate alloy maintained its mechanical properties well, but its combustion performance was reduced to some extent. This indicates that the silicon-based flame retardant played a synergistic flame retardant role in this system.

[0085] Compared with Comparative Example 6, Example 9 shows that no toughening agent was added in Comparative Example 6, and the resulting polycarbonate alloy had lower mechanical properties. This indicates that the toughening agent in this system can effectively improve the mechanical properties of the material while maintaining the V0 and S.2 flame retardant properties, thus enabling it to have a wider range of applications.

[0086] Compared with Comparative Example 7, Example 9 did not add modified silicon grafted sulfonate flame retardant, but instead used nonafluorobutyl sulfonate flame retardant in the same proportion. It can be seen that the flame retardant performance of the material can reach 1.5 mmV0, but the needle flame performance still cannot meet S.2. This shows that the modified silicon grafted sulfonate flame retardant can better improve the S.2 flame retardant performance of the material in this invention.

[0087] In summary, the halogen-free flame-retardant polycarbonate alloy provided by this invention has excellent mechanical properties, while also meeting the flame-retardant properties required by V0 and S.2 standards.

[0088] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A halogen-free flame-retardant polycarbonate alloy, characterized in that, The raw materials include the following parts by weight: 55-93 parts of polycarbonate resin, 10-30 parts of silicon copolymer polycarbonate resin, 2-10 parts of phosphorus flame retardant, 0-10 parts of modified silicon grafted sulfonate flame retardant, 0.5-2 parts of silicon flame retardant, 1-5 parts of toughening agent, 0.5-1 part of compatibilizer, and 0.1-1.3 parts of other additives.

2. The halogen-free flame-retardant polycarbonate alloy according to claim 1, characterized in that, The polycarbonate resin has a melt index of 10-12 g / 10 min under the test conditions of 300℃ / 1.2 kg; the silicon copolymer polycarbonate resin has a melt index of 8-12 g / 10 min under the test conditions of 300℃ / 1.2 kg, and the silicon content in the silicon copolymer polycarbonate resin is 6-8%; the phosphorus flame retardant is selected from one or more of hexaphenoxycyclotriphosphazene and bisphenol A-bis(diphenyl phosphate); the mass ratio of the polycarbonate resin, silicon copolymer polycarbonate resin and phosphorus flame retardant is (55-65):(15-25):(8-10).

3. The halogen-free flame-retardant polycarbonate alloy according to claim 1, characterized in that, The preparation method of the modified silicon grafted sulfonate flame retardant includes the following steps: drying polycarbonate resin, silicon copolymer polycarbonate resin, sulfonate flame retardant, compatibilizer, and antioxidant, followed by premixing and melt extrusion to obtain the product.

4. The halogen-free flame-retardant polycarbonate alloy according to claim 3, characterized in that, The sulfonate flame retardant is selected from one or more of potassium nonafluorobutyl sulfonate and potassium diphenyl sulfone-3-sulfonate; the compatibilizer is a maleic anhydride-grafted acrylonitrile-butadiene-styrene copolymer, with a maleic anhydride mass fraction of 1-5 wt%; the mass ratio of polycarbonate resin, silicon copolymer polycarbonate resin, sulfonate flame retardant, compatibilizer, and antioxidant is (45-50):(45-55):(1-5):(0.1-1):(0.1-1); the drying temperature is 70-90℃, and the drying time is 4-6 h; the premixing includes mixing for 5-15 min at a speed of 800-1500 rpm and a temperature of 10-30℃; the melt extrusion temperature is 220-280℃.

5. The halogen-free flame-retardant polycarbonate alloy according to claim 1, characterized in that, The silicon-based flame retardant is an organosilicon flame retardant; the toughening agent is selected from one or more of methyl methacrylate-butadiene-styrene terpolymer and methyl methacrylate-acrylic acid-organosilicon core-shell copolymer.

6. The halogen-free flame-retardant polycarbonate alloy according to claim 1, characterized in that, The compatibilizer is a maleic anhydride-grafted acrylonitrile-butadiene-styrene copolymer, with a maleic anhydride mass fraction of 1-5 wt%.

7. The halogen-free flame-retardant polycarbonate alloy according to claim 1, characterized in that, The other additives are selected from one or more of antioxidants, anti-dripping agents, and lubricants; the antioxidants are selected from one or more of hindered phenolic antioxidants and phosphite antioxidants; the lubricants are selected from one or more of pentaerythritol stearate and silicone; and the anti-dripping agent is polytetrafluoroethylene.

8. A method for preparing the halogen-free flame-retardant polycarbonate alloy according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Mix polycarbonate resin, silicon copolymer polycarbonate resin, phosphorus flame retardant, modified silicon grafted sulfonate flame retardant, and toughening agent evenly to obtain mixture A. S2. Mix the silicon-based flame retardant, compatibilizer, and other additives to obtain mixture B; S3. Mix mixture A and mixture B evenly using a high-speed mixer, then feed them into a twin-screw extruder, and after melt extrusion and granulation, the mixture is obtained.

9. The preparation method according to claim 8, characterized in that, In S3, the operating parameters of the twin-screw extruder are as follows: zone 1 temperature is 210-240℃, zone 2 temperature is 230-260℃, zone 3 temperature is 235-260℃, zone 4 temperature is 220-260℃, zone 5 temperature is 220-260℃, zone 6 temperature is 220-260℃, zone 7 temperature is 220-260℃, zone 8 temperature is 220-260℃, die temperature is 240-275℃, and screw speed is 200-400 rpm.

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