Polycarbonate / styrene composite material as well as preparation method and application thereof

Abstract

The invention discloses a polycarbonate / styrene composite material as well as a preparation method and application thereof, and belongs to the field of high polymer materials. The composite material is prepared from the following raw materials: polycarbonate, silicon copolymerized polycarbonate, styrene resin, a halogen-free flame retardant, a polynitroxide free radical compound, an anti-dripping agent, an antioxidant and a lubricant. The molecular structure of the multi-nitroxide free radical compound contains at least two nitroxide free radicals, and the molecular chain of the multi-nitroxide free radical compound has a flexible carbon chain structure. The polycarbonate / styrene composite material provided by the invention can realize 0.5-1.0 mm ultrathin halogen-free flame retardance under the combined action of the halogen-free flame retardant and the multi-nitroxide free radical compound, and can meet the molding of ultrathin parts, and the prepared product has excellent damp-heat aging resistance and weather resistance, and is suitable for industrial production. The shell can be widely applied to new energy battery shells, power bank shells and the like.

Description

Technical Field

[0001] The present invention belongs to the field of polymer materials, and in particular relates to a polycarbonate / styrene composite material and a preparation method and application thereof. Background Art

[0002] Polycarbonate has the advantages of good transparency, high toughness, creep resistance, etc., and has excellent comprehensive performance. It is currently widely used in electronics, electrical appliances, new energy related supporting fields and other fields. Styrene resins mainly include acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-acrylate-styrene copolymer (ASA) and acrylonitrile-ethylene propylene diene monomer rubber-styrene copolymer (AES). They have excellent processing fluidity and impact resistance, but styrene resins are prone to molecular bond breakage under long-term light conditions and have poor weather resistance. Moreover, the oxygen index is relatively low and the flame retardant performance is poor. Polycarbonate / styrene composite materials have the advantages of both types of resins and have been widely used in the automotive industry, household appliances, office equipment, instruments and meters and other fields. However, the current polycarbonate / styrene composite materials have poor resistance to moisture and heat. The application of existing polycarbonate / styrene composite materials is limited to the above fields and often cannot be directly used in wet and hot usage scenarios.

[0003] In order to improve the weather resistance of polycarbonate / styrene composite materials, there are two main conventional methods. One is to improve the heat and moisture resistance of polycarbonate / styrene composite materials through physical isolation methods such as painting and electroplating, but this method will bring additional processing costs and environmental pollution. The other is to improve the weather resistance of the material by adding chemical modifiers with specific properties. For example, the Chinese patent publication number CN109021534A discloses a high-temperature and high-humidity resistant polycarbonate composition. In this invention, by adding a silicone toughening agent and an oxazoline-based chain extender, the synergistic effect of the two improves the performance retention rate of the polycarbonate composition under high temperature and high humidity conditions. However, the chain extender oxazoline used is a toxic organic compound, and its precipitates pose a certain threat to human health. Chinese patent publication number CN 119798946A discloses a polycarbonate material, its preparation method, and its application. The invention utilizes a compounded flame retardant to improve the flame retardancy and weather resistance of the polycarbonate material. The compounded flame retardant is an organosilicon flame retardant containing nitroxide radicals in its structure. The compounded flame retardant is obtained by a radical reaction between an organosilicon flame retardant containing an active group and a nitroxide radical compound containing an active group. While this compounded flame retardant, obtained through a chemical reaction between the organosilicon flame retardant and the nitroxide radical compound, combines the advantages of both structures, due to their complexity and bulkiness, problems can arise during use, such as uneven dispersion due to the large molecular structure and poor compatibility with the matrix resin.

[0004] With product upgrades and iterations, lightweighting is a key development trend. Plastic products are becoming increasingly thinner, placing increasing demands on the flame retardant properties of thin-walled materials. Existing bromine-antimony flame retardant systems produce large amounts of toxic smoke and gases, posing serious hazards to humans and the environment. A single halogen-free phosphorus-based flame retardant system is unable to achieve flame retardancy at a thickness of 0.5 mm. Currently, a combination of multiple flame retardant systems is required to achieve ultra-thin flame retardancy. Summary of the Invention

[0005] The purpose of the present invention is to provide a polycarbonate / styrene composite material and its preparation method and application, so as to solve the problems of poor moisture-heat aging, weather resistance and ultra-thin halogen-free flame retardancy of polycarbonate / styrene composite materials. The polycarbonate / styrene composite material prepared by the present invention has excellent moisture-heat aging resistance and weather resistance, and achieves good halogen-free flame retardancy.

[0006] The purpose of the present invention can be achieved through the following technical solutions: The first aspect of the present invention is to provide a polycarbonate / styrene composite material. The raw materials for preparation include, by weight, 30-50 parts of polycarbonate, 20-40 parts of silicon copolymerized polycarbonate, 5-20 parts of styrene resin, 8-15 parts of halogen-free flame retardant, 0.4-1 part of a polynitroxide compound, 0.3-0.8 parts of an anti-drip agent, and 0.2-0.8 parts of a lubricant. The polynitroxide compound has at least two nitroxide radicals in its molecular structure, and its molecular chain has a flexible carbon chain structure. The polynitroxide compound can be stably present in the material system and can effectively capture active free radicals generated by light, heat, and oxidative degradation of the polymer. The nitroxide radicals can also react with carbon radicals that break the chain when the molecular chain is aged by moisture and heat, forming alkoxyamine chemical bonds. The multifunctional nitroxide compound acts as a chain extender.

[0007] As a preferred technical solution, the polycarbonate / styrene composite material further includes 0.1 to 0.4 parts of an antioxidant; the antioxidant is a mixture of at least two of Antioxidant 1076, Antioxidant 1010, Antioxidant 168, and Antioxidant 627A. Further preferably, the antioxidant is a mixture of Antioxidant 1076 and Antioxidant 168 in a mass ratio of 1:2.

[0008] As a preferred technical solution, the multi-nitrogen oxide free radical compound is at least one of bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate nitrogen oxide free radical, bis(2,2,6,6-tetramethyl-4-piperidinyl)laurate nitrogen oxide free radical, bipyridine-bridged bisTEMPO derivative, ferrocenylcarbonyl chloride-coupled bisTEMPO derivative, poly(2,2,6,6-tetramethylpiperidine-1-oxygen free radical) derivative, and dendritic TEMPO polymer.

[0009] As a preferred technical solution, the mass ratio of polycarbonate to silicon copolymerized polycarbonate is less than 2; and the silicon content of the silicon copolymerized polycarbonate is 5-20%.

[0010] As a preferred technical solution, the polycarbonate is bisphenol A polycarbonate, and the melt mass flow rate of bisphenol A polycarbonate is 3-20g / 10min at 300°C and a load of 1.2kg. The melt mass flow rate of silicon copolymer polycarbonate is 3-10g / 10min at 300°C and a load of 1.2kg. A melt mass flow rate that is too low results in poor material flowability, leading to problems in actual production and processing. A melt mass flow rate that is too high results in better material flowability, but can easily cause the material to drip and ignite, resulting in poor flame retardancy.

[0011] As a preferred technical solution, the styrene resin is at least one of acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-acrylate-styrene copolymer (ASA resin) and acrylonitrile-ethylene propylene diene monomer rubber-styrene copolymer (AES resin), and the melt mass flow rate is 20~30g / 10min; the test conditions of the melt mass flow rate are: the test conditions of ABS resin and ASA resin are 220℃, 10 kg; the test conditions of AES resin are 220℃, 5.0kg.

[0012] As a preferred technical solution, the halogen-free flame retardant is at least one of a phosphorus-based flame retardant, a nitrogen-phosphorus flame retardant, or a silicon-based flame retardant. Further preferably, the phosphorus-based flame retardant is at least one of bisphenol A-bis(diphenyl phosphate) and resorcinol bis(diphenyl phosphate); the nitrogen-phosphorus flame retardant is hexaphenoxycyclotriphosphazene; and the silicon-based flame retardant is an organosilicon flame retardant, specifically Dow Corning's silicon-based flame retardant FCA-107.

[0013] As a preferred technical solution, the lubricant is at least one of pentaerythritol stearate, silicone powder, and polyester wax; and the anti-drip agent is a polytetrafluoroethylene-based material. Further preferably, the anti-drip agent can be a polytetrafluoroethylene anti-drip agent coated with acrylonitrile-styrene copolymer.

[0014] The second aspect of the present invention is to provide a method for preparing the polycarbonate / styrene composite material as described in the first aspect, comprising the following steps: (1) Polycarbonate, silicon copolymer polycarbonate, styrene resin, halogen-free flame retardant, polynitrogen oxide free radical compound, anti-dripping agent, antioxidant and lubricant are mixed uniformly to obtain a mixture; preferably, the mixing is carried out uniformly using a high-speed mixer, the high-speed mixing speed is 100 to 300 r / min, and the mixing is carried out for 5 to 20 minutes; more preferably, the polycarbonate and silicon copolymer polycarbonate are dried before feeding, so that the moisture content thereof is less than 0.02%; (2) The mixed materials are melt-blended to obtain the target product. Preferably, the melt-blending adopts a screw extrusion blending process, and the equipment used is a twin-screw extruder. Further preferably, the processing temperature of each zone of the twin-screw extruder is: the temperature of zone 1 is 225℃±5℃, the temperature of zone 2 is 235℃±5℃, the temperature of zone 3 is 245℃±5℃, the temperature of zone 4 is 245℃±5℃, the temperature of zone 5 is 255℃±5℃, the temperature of zone 6 is 255℃±5℃, the temperature of zone 7 is 245±5℃, the temperature of zone 8 is 245±5℃, the temperature of zone 9 is 245±5℃, and the temperature of zone 10 is 245±5℃. The head temperature is 255℃±5℃, the screw speed is 300rpm~400rpm, and the vacuum degree is -0.5MPa~-0.9MPa.

[0015] A third aspect of the present invention provides the use of the polycarbonate / styrene composite material described in the first aspect in thin-walled, halogen-free, flame-retardant articles. These thin-walled, halogen-free, flame-retardant articles have a thickness of 0.5 to 1.0 mm, achieving ultra-thin, halogen-free, flame-retardant properties. These thin-walled, halogen-free, flame-retardant articles can be widely used in new energy battery housings, power bank casings, and other applications.

[0016] The present invention has the following beneficial effects: The polycarbonate / styrene composite material provided by the present invention, under the combined action of a halogen-free flame retardant and a polyoxyl radical compound, can achieve an ultra-thin halogen-free flame retardant thickness of 0.5 to 1.0 mm, and the prepared product has excellent resistance to wet heat aging and weathering. The working principle of the polyoxyl radical compound used in the present invention in the composite material is analyzed as follows: (1) The multiple nitroxide radicals in the polynitroxide compound structure can capture carbon radicals generated by hydrothermal aging and form multiple alkoxyamine bonds, acting as chain extenders, thereby improving the hydrothermal resistance of the composite material. Without the addition of an additional UV absorber / light stabilizer to the composite material, the nitroxide radicals in the polynitroxide compound structure of the present invention can exert a weathering principle similar to that of hindered amine light stabilizers, imparting excellent weather resistance to the composite material.

[0017] (2) Since the polyoxyl radical compound has a flexible long carbon chain structure, taking the bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate oxyl radical as an example, the flexible long carbon chain structure is eight methylene groups (-CH2-). The methylene structure is simple, internal rotation is relatively easy, and it has a certain mobility. In the composite material, the flexible carbon chain promotes molecular diffusion through movement and resists microphase separation; at the same time, the flexible carbon chain and the polymer molecular chain have similar "solubility parameters" and have a certain similar compatibility. In addition, the flexible long carbon chain structure of the polyoxyl radical compound is topologically entangled with the substrate molecular chain, which can enhance the "anchoring" ability of the polyoxyl radical compound in the matrix and inhibit migration and precipitation, so that the polyoxyl radical compound can be well dispersed in the composite material, is not easy to precipitate during use, and has good weather resistance and time aging. The polyoxyl radical compound used in the present invention can well solve the problems of uneven dispersion and poor compatibility caused by the large molecular structure of the added additive.

[0018] (3) Based on the halogen-free flame retardant, the nitroxide free radicals in the polynitroxide free radical compound can also play the role of capturing active free radicals, which simultaneously gives the composite material more efficient flame retardant properties. The polynitroxide free radical compound has the multiple effects of weathering agent, chain extender and flame retardant. Without the addition of ultraviolet absorbers and light stabilizers, the prepared product has excellent weather resistance. DETAILED DESCRIPTION

[0019] The preparation method, effects and uses of the present invention are further described below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0020] The specific information of the raw materials used in the following examples and comparative examples is as follows: Bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate nitroxide free radical (referred to as "Compound 1" in Table 1) Bis(2,2,6,6-tetramethyl-4-piperidinyl)laurate nitroxide free radical (referred to as "Compound 2" in Table 1) Manufacturer: Guangdong Wengjiang Chemical Reagent Co., Ltd. Polycarbonate (PC), supplier: Japan Teijin PC L1250Y; Silicon copolymer polycarbonate (Silicon PC-1), supplier: Japan Idemitsu PC FG1760 (silicon content 6%); Silicon copolymer polycarbonate (Silicon PC-2), supplier: Wanhua Silicon PC S2060 (silicon content 20%); Acrylonitrile butadiene styrene copolymer (ABS), supplier: Shanghai Gaoqiao Petrochemical Company ABS 8491; Acrylonitrile-acrylate-styrene copolymer (ASA), supplied by INEOS Styrolution Luran S®757G from Switzerland; Acrylonitrile-EPDM-styrene copolymer (AES), supplied by Shanghai KumhoSunny AES HW600G; The antioxidant is a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 1:2; the suppliers of antioxidant 1076 and antioxidant 168 are both Tianjin Li'anlong; The anti-dripping agent is PTFE DB105, and the supplier is Shanghai Puxin; The lubricant is dipentaerythritol stearate, brand PETS-AP, and the supplier is: Yidafaji; UV absorber, UV-234, supplier: Tianjin Li'anlong; Phosphorus-based flame retardant, bisphenol A-bis(diphenyl phosphate), supplier: Zhejiang Wansheng Co., Ltd. Nitrogen-phosphorus flame retardant, hexaphenoxycyclotriphosphazene, supplier: Otsuka Chemical Co., Ltd., Japan; The silicone flame retardant is FCA-107, and the supplier is Dow Corning; Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0021] Examples 1 to 14 and Comparative Examples 1 to 11 provide a polycarbonate / styrene resin composite material. The component contents are shown in Table 1. Each example and comparative example contains 0.5 parts of dipentaerythritol stearate as a lubricant and 0.4 parts of PTFE DB105 as an anti-dripping agent. The amounts of the lubricant and anti-dripping agent are not listed in Table 1. The preparation methods of the products in each example and comparative example are as follows: According to Table 1, the components (1) were mixed: the following formula components were added to a high-speed mixer and stirred for 5 minutes to obtain a mixture; (2) extrusion granulation: the mixture was added to a twin-screw extruder for granulation. The processing temperature of each section of the twin-screw extruder was as follows: the temperature of zone 1 was 225℃±5℃, the temperature of zone 2 was 235℃±5℃, the temperature of zone 3 was 245℃±5℃, the temperature of zone 4 was 245℃±5℃, the temperature of zone 5 was 255℃±5℃, the temperature of zone 6 was 255℃±5℃, the temperature of zone 7 was 245±5℃, the temperature of zone 8 was 245±5℃, the temperature of zone 9 was 245±5℃, and the temperature of zone 10 was 245±5℃. The head temperature was 255℃±5℃, the screw speed was 300rpm~400rpm, and the vacuum degree was -0.5MPa~-0.9MPa.

[0022] Table 1 Component contents of polycarbonate / styrene resin composite materials in various examples and comparative examples (parts by weight)

[0023] Performance Testing Tensile strength test: carried out in accordance with GB / T 1040 standard, with a tensile speed of 50 mm / min.

[0024] Izod notched impact test: Tensile properties test is carried out in accordance with GB / T 1843.

[0025] Flame retardancy test: The flame retardancy test was conducted according to UL-94 standard, with 0.5mm and 1.0mm standard flame retardant test strips. The oxygen index was tested according to GBT2406-1993 standard method.

[0026] Moisture and heat resistance: To test initial tensile strength and Izod impact strength, standard specimens were placed in a constant temperature and humidity aging chamber at 85°C and 85% RH for 1000 hours. After aging, the tensile strength and Izod impact strength were retested. The tensile strength and Izod impact strength retention rates were calculated based on the pre- and post-aging test values.

[0027] Xenon lamp aging test: Initial tensile strength and Izod impact strength are tested. Samples are aged for 1000 hours using a xenon lamp according to GB / T 16422.2-2014. After aging, the tensile strength and Izod impact strength are tested again. The tensile strength and Izod impact strength retention rates are calculated based on the pre- and post-aging test values.

[0028] The test results of Examples 1 to 14 and Comparative Examples 1 to 11 are shown in Tables 2 and 3.

[0029] Table 2 Performance test results of Examples 1 to 10 and Comparative Examples 1 to 3

[0030] Table 3 Performance test results of Examples 11 to 14 and Comparative Examples 4 to 11

[0031] Examples 1 and 3 differ from Comparative Examples 1 and 2 in their silicon-co-polycarbonate (Si-PC) content. As the Si-PC content decreases, the composite material's oxygen index drops to 23%, and its flame retardancy also declines, with the notched impact strength retention after damp-heat aging dropping to 31%. Comparative Example 2, which contains no Si-PC, exhibits the highest notched impact strength after damp-heat aging. Overall, Examples 1 and 3 exhibit excellent resistance to damp-heat aging, resulting in a polycarbonate (PC) to Si-PC mass ratio of less than 2. Example 4, which uses Si-PC with a 20% Si content, achieves superior overall performance compared to Example 1, demonstrating the positive effect of Si content on damp-heat aging resistance and flame retardancy.

[0032] The difference between Example 1, Example 5 and Example 6 lies in the different types of styrene resins. From the data in Table 2, the oxygen index, flame retardant properties and retention rates after wet heat aging of the three styrene composite materials, acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-acrylate-styrene copolymer (ASA) and acrylonitrile-ethylene propylene diene monomer rubber-styrene copolymer (AES) are similar, indicating that the three have excellent wet heat resistance.

[0033] The difference between Example 1, Example 7 and Example 8 is that different halogen-free flame retardants are used. The combination of nitrogen-phosphorus flame retardant, silicon-based flame retardant and polynitrogen oxide free radical compound can achieve better performance, wherein the oxygen index reaches 31%, the 0.5mm flame retardancy can reach V-0, and the retention rate after wet heat aging and xenon lamp aging can reach the level of Example 1.

[0034] Examples 1, 9, and 10 differ from Comparative Example 3 in their ABS content. As the ABS content increases, the composite material's oxygen index drops to 26%, and flame retardancy also declines. ABS contents between 5 and 20 parts per million offer the best results. In Comparative Example 3, at 30 parts per million, flame retardancy is primarily affected.

[0035] The difference between Example 1, Comparative Example 4, Comparative Example 5, and Example 11 lies in the different content of polynitroxide compounds. With the increase in the amount of polynitroxide compounds, the oxygen index of the composite material increases, and flame retardancy improves. The notched impact strength retention after damp heat aging and xenon lamp aging also shows an upward trend. In Example 11, the oxygen index reaches 31%. The notched impact strength retention after damp heat aging is 79%, and the notched impact strength retention after xenon lamp aging is 92%. This indicates that increasing the nitroxide content of the polynitroxide compounds is beneficial for damp heat resistance, flame retardancy, and weather resistance.

[0036] The difference between Example 1, Comparative Example 6, Example 12, Comparative Example 7, and Comparative Example 8 lies in the different ratios of phosphorus-based flame retardants and polynitroxide compounds. The data show that too low a phosphorus-based flame retardant or polynitroxide compound addition level is ineffective, failing to achieve a high flame retardant effect. Furthermore, low levels of polynitroxide compounds can also affect notched impact retention after damp-heat aging and xenon lamp aging. Overall, the data from Examples 1 and 11-12 are similar, indicating that the flame retardant effect of phosphorus-based flame retardants and polynitroxide compounds has an upper limit. Further increases in addition increase formulation costs without significantly improving performance.

[0037] Compared with Example 1, the difference between Comparative Examples 9 and 10 is that both use phosphorus-based flame retardants and polynitrogen oxide free radical compounds separately, and the oxygen index of both is too low, and the flame retardant performance and moisture and heat resistance are poor. A single flame retardant system is difficult to meet the requirements of moisture and heat aging resistance and ultra-thin halogen-free flame retardancy.

[0038] The difference between Example 1 and Comparative Example 11 is that Example 1 contains a polynitroxide compound, while Comparative Example 1 contains the weathering agent UV234. The tensile strength retention and notched impact strength retention after xenon lamp aging are similar in both examples, demonstrating that the polynitroxide compound has the same weathering effect. Furthermore, the oxygen index and flame retardancy, as well as the performance retention after wet heat aging, of Example 1 are much higher than those of Comparative Example 11, demonstrating that the polynitroxide compound of the present invention has significant resistance to wet heat aging and a synergistic flame retardant effect. Furthermore, the xenon lamp aging data of the above examples and comparative examples further demonstrates that adding up to 0.5 parts of the polynitroxide compound provides excellent weathering effects.

[0039] The difference between Example 1 and Example 13 is that no antioxidant was added in Example 13, yet the overall test results were similar to those of Example 1. This demonstrates that polynitroxide compounds also possess a certain antioxidant aging resistance. Antioxidants can be omitted from the formulation to impart anti-aging and weathering properties to the composite material. Polynitroxide compounds have multiple benefits, not only reducing material costs and simplifying formulations, but also imparting high performance, offering certain advantages.

[0040] Overall, polynitrogen oxide compounds containing nitroxide radicals in their structures not only impart excellent moisture-heat and weathering resistance to composite materials, but also exhibit a highly effective synergistic flame retardant effect. These polynitrogen oxide compounds possess multiple benefits, including weathering resistance, chain extension, flame retardancy, and resistance to oxidative aging. In summary, the polycarbonate / styrene composite material provided by the present invention exhibits excellent moisture-heat aging resistance and weathering resistance, while also possessing excellent ultra-thin flame retardant properties.

[0041] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical concepts disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A polycarbonate / styrene composite material, characterized in that: The preparation raw materials include, by weight, 30 to 50 parts of polycarbonate, 20 to 40 parts of silicon copolymer polycarbonate, 5 to 20 parts of styrene resin, 8 to 15 parts of halogen-free flame retardant, 0.4 to 1 part of polynitroxide free radical compound, 0.3 to 0.8 parts of anti-dripping agent and 0.2 to 0.8 parts of lubricant; the molecular structure of the polynitroxide free radical compound contains at least two nitroxide free radicals, and the molecular chain of the polynitroxide free radical compound has a flexible carbon chain structure.

2. The polycarbonate / styrene composite material according to claim 1, characterized in that: The multi-nitrogen oxide free radical compound is at least one of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate nitrogen oxide free radical, bis(2,2,6,6-tetramethyl-4-piperidinyl) laurate nitrogen oxide free radical, bipyridine bridged bisTEMPO derivative, ferrocenylcarbonyl chloride coupled bisTEMPO derivative, poly(2,2,6,6-tetramethylpiperidine-1-oxyl free radical) derivative, and dendritic TEMPO polymer.

3. The polycarbonate / styrene composite material according to claim 1, characterized in that: The mass ratio of the polycarbonate to the silicon copolymerized polycarbonate is less than 2.

4. The polycarbonate / styrene composite material according to claim 1, characterized in that: The styrene resin is at least one of acrylonitrile-butadiene-styrene copolymer, acrylonitrile-acrylate-styrene copolymer, and acrylonitrile-ethylene propylene diene monomer rubber-styrene copolymer.

5. The polycarbonate / styrene composite material according to claim 1, characterized in that: The halogen-free flame retardant is at least one of a phosphorus-based flame retardant, a nitrogen-phosphorus flame retardant or a silicon-based flame retardant.

6. The polycarbonate / styrene composite material according to claim 5, characterized in that: The phosphorus-based flame retardant is at least one of bisphenol A-bis(diphenyl phosphate) and resorcinol bis(diphenyl phosphate); the nitrogen-phosphorus flame retardant is hexaphenoxycyclotriphosphazene; and the silicon-based flame retardant is an organic silicon flame retardant.

7. The polycarbonate / styrene composite material according to claim 1, characterized in that: The anti-dripping agent is a polytetrafluoroethylene-based material.

8. The polycarbonate / styrene composite material according to claim 7, characterized in that: The anti-dripping agent is a polytetrafluoroethylene anti-dripping agent coated with acrylonitrile-styrene copolymer.

9. The polycarbonate / styrene composite material according to claim 1, characterized in that: The polycarbonate / styrene composite material further includes 0.1 to 0.4 parts of an antioxidant; the antioxidant is a mixture of at least two of antioxidant 1076, antioxidant 1010, antioxidant 168, and antioxidant 627A.

10. The polycarbonate / styrene composite material according to claim 9, characterized in that: The antioxidant is a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 1:

2.

11. The polycarbonate / styrene composite material according to claim 1, characterized in that: The lubricant is at least one of pentaerythritol stearate, silicone powder and polyester wax.

12. The polycarbonate / styrene composite material according to any one of claims 1 to 11, characterized in that: The polycarbonate is bisphenol A polycarbonate, and at 300° C. and a load of 1.2 kg, the melt mass flow rate of the bisphenol A polycarbonate is 3-20 g / 10 min.

13. The polycarbonate / styrene composite material according to any one of claims 1 to 11, characterized in that: The silicon copolymer polycarbonate has a melt mass flow rate of 3-10 g / 10 min at 300° C. and a load of 1.2 kg.

14. The polycarbonate / styrene composite material according to claim 13, characterized in that: The silicon content of the silicon copolymer polycarbonate is 5-20%.

15. The method for preparing a polycarbonate / styrene composite material according to any one of claims 1 to 14, wherein: The following steps are involved: The polycarbonate, the silicon copolymer polycarbonate, the styrene resin, the halogen-free flame retardant, the polynitrogen oxide free radical compound, the anti-dripping agent, the antioxidant and the lubricant are uniformly mixed to obtain a mixture; The mixed materials are melt-blended to obtain a target product.

16. The method for preparing a polycarbonate / styrene composite material according to claim 15, wherein: The melt blending adopts a screw extrusion blending process, and the equipment used is a twin-screw extruder.

17. The method for preparing a polycarbonate / styrene composite material according to claim 15, wherein: The polycarbonate and silicon copolymerized polycarbonate are dried before feeding, so that the moisture content of the polycarbonate and silicon copolymerized polycarbonate is lower than 0.02%.

18. Use of the polycarbonate / styrene composite material according to any one of claims 1 to 14 in thin-walled halogen-free flame-retardant parts, characterized in that: The thickness of the thin-walled halogen-free flame-retardant component is 0.5-1.0 mm.

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