A polycarbonate / styrene composite material, its preparation method and application

Abstract

This invention discloses a polycarbonate / styrene composite material, its preparation method, and its applications, belonging to the field of polymer materials. The raw materials for preparing this composite material include the following substances: polycarbonate, silicon-copolymerized polycarbonate, styrene resin, halogen-free flame retardant, poly(nitrile oxide) radical compound, anti-dripping agent, antioxidant, and lubricant; the poly(nitrile oxide) radical compound has at least two nitrile oxide radicals in its molecular structure, and its molecular chain has a flexible carbon chain structure. The polycarbonate / styrene composite material provided by this invention, under the combined action of the halogen-free flame retardant and the poly(nitrile oxide) radical compound, can achieve an ultra-thin halogen-free flame retardant thickness of 0.5–1.0 mm, meeting the requirements for ultra-thin part molding. Furthermore, the prepared product exhibits excellent resistance to damp heat aging and weathering, and can be widely used in new energy battery casings, power bank casings, etc.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, and in particular relates to a polycarbonate / styrene composite material, its preparation method, and its application. Background Technology

[0002] Polycarbonate possesses advantages such as good transparency, high toughness, and creep resistance, exhibiting excellent overall performance and currently finding widespread application in electronics, electrical appliances, and new energy-related fields. Styrene-based resins mainly include acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-acrylate-styrene copolymer (ASA), and acrylonitrile-ethylene propylene diene monomer (EPDM)-styrene copolymer (AES). They possess excellent processing fluidity and impact resistance; however, styrene-based resins are prone to molecular bond breakage under prolonged light exposure, resulting in poor weather resistance. Furthermore, they have a relatively low oxygen index and poor flame retardant properties. Polycarbonate / styrene composites combine the advantages of both types of resins and are widely used in the automotive industry, home appliances, office equipment, and instrumentation. However, current polycarbonate / styrene composite materials exhibit poor resistance to humid heat, limiting their applications to these areas and often preventing direct use in humid and hot environments.

[0003] To improve the weather resistance of polycarbonate / styrene composite materials, conventional methods mainly fall into two categories. One is to enhance the moisture and heat resistance of polycarbonate / styrene composite materials through physical isolation methods such as painting and electroplating, but this method brings additional processing costs and environmental pollution. The other is to add chemical modifiers with specific properties to improve the material's weather resistance. For example, Chinese patent CN109021534A discloses a high-temperature and high-humidity resistant polycarbonate composition. In this invention, an organosilicon toughening agent and an oxazoline chain extender are added. 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 is a toxic organic compound, and its precipitates pose a certain threat to human health. Chinese Patent Publication No. CN 119798946A discloses a polycarbonate material, its preparation method, and its application. This method improves the flame retardant and weather resistance of polycarbonate materials by using a compounded flame retardant. The compounded flame retardant is an organosilicon flame retardant with nitroxide free radicals in its structure. It is obtained by reacting an organosilicon flame retardant containing active groups with a nitroxide free radical compound containing active groups. While this compounded flame retardant combines the advantages of both structures through a chemical reaction, the complexity and large size of these structures lead to uneven dispersion and poor compatibility with the matrix resin during use.

[0004] With product upgrades and iterations, lightweighting is an important development direction. Plastic products are becoming increasingly thinner, which places increasingly stringent demands on the thin-walled flame-retardant properties of materials. Existing bromine-antimony flame-retardant systems produce large amounts of toxic fumes and gases, posing serious hazards to human health and the environment. Single halogen-free phosphorus-based flame-retardant systems are insufficient to achieve flame retardancy of 0.5mm thin walls; currently, multiple flame-retardant systems need to be combined to achieve ultra-thin flame retardancy. Summary of the Invention

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

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] The first aspect of this invention is to provide a polycarbonate / styrene composite material, comprising, by weight, 30-50 parts polycarbonate, 20-40 parts silicon-copolymerized polycarbonate, 5-20 parts styrene resin, 8-15 parts halogen-free flame retardant, 0.4-1 part polynitroxide radical compound, 0.3-0.8 parts anti-dripping agent, and 0.2-0.8 parts lubricant; the polynitroxide radical compound has at least two nitroxide radicals in its molecular structure, and its molecular chain has a flexible carbon chain structure; the polynitroxide radical compound is stable in the material system and can effectively capture active free radicals generated by polymer degradation due to light, heat, and oxidative degradation. For chain-broken carbon free radicals caused by humid heat aging, the nitroxide radicals will also react with the carbon free radicals to form alkoxyamine chemical bonds. The multifunctional nitroxide radical compound acts as a chain extender.

[0008] As a preferred technical solution, the polycarbonate / styrene composite material further includes 0.1 to 0.4 parts of antioxidant; the antioxidant is a mixture of at least two of antioxidants 1076, 1010, 168, and 627A. More preferably, the antioxidant is a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 1:2.

[0009] As a preferred technical solution, the polynitrogen oxide free radical compound is at least one of the following: bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate nitroxide free radical, bis(2,2,6,6-tetramethyl-4-piperidinyl) lauryl ester nitroxide free radical, bipyridine-bridged bisTEMPO derivative, ferrocene carboxyl chloride-coupled bisTEMPO derivative, poly(2,2,6,6-tetramethylpiperidin-1-oxy radical) derivative, and dendritic TEMPO polymer.

[0010] As a preferred technical solution, the mass ratio of polycarbonate to silicon-copolymerized polycarbonate is less than 2; the silicon content of the silicon-copolymerized polycarbonate is 5-20%.

[0011] As a preferred technical solution, the polycarbonate is bisphenol A type polycarbonate, with a melt flow rate of 3~20 g / 10 min at 300℃ and 1.2 kg load. The melt flow rate of the silicon copolymer polycarbonate is also 3~10 g / 10 min at 300℃ and 1.2 kg load. A melt flow rate that is too low results in poor material fluidity, leading to problems in actual production and processing; a melt flow rate that is too high provides good material fluidity but makes the material prone to dripping and ignition, resulting in poor flame retardancy.

[0012] 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 (EPDM)-styrene copolymer (AES resin), with a melt flow rate of 20~30 g / 10 min; the test conditions for melt flow rate are as follows: for ABS resin and ASA resin, the test conditions are 220℃ and 10 kg; for AES resin, the test conditions are 220℃ and 5.0 kg.

[0013] As a preferred technical solution, the halogen-free flame retardant is at least one of phosphorus-based flame retardants, nitrogen-phosphorus flame retardants, or silicone-based flame retardants. More 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 silicone-based flame retardant is an organosilicon flame retardant, specifically Dow Corning's silicone-based flame retardant FCA-107.

[0014] As a preferred technical solution, the lubricant is at least one selected from pentaerythritol stearate, silicone powder, and polyester wax; the anti-dripping agent is polytetrafluoroethylene material. More preferably, the anti-dripping agent can be a polytetrafluoroethylene anti-dripping agent coated with acrylonitrile-styrene copolymer.

[0015] A second aspect of the present invention is to provide a method for preparing a polycarbonate / styrene composite material as described in the first aspect, comprising the following steps:

[0016] (1) Polycarbonate, silicone copolymer polycarbonate, styrene resin, halogen-free flame retardant, polynitrogen oxide free radical compound, anti-dripping agent, antioxidant and lubricant are mixed evenly to obtain a mixture; preferably, the mixture is mixed evenly using a high-speed mixer at a speed of 100-300 r / min for 5-20 min; more preferably, the polycarbonate and silicone copolymer polycarbonate are dried before feeding so that their moisture content is less than 0.02%;

[0017] (2) The mixture is melt-blended to obtain the target product. Preferably, the melt blending is performed using a screw extrusion blending process, and the equipment used is a twin-screw extruder. More preferably, the processing temperatures of each zone of the twin-screw extruder are: Zone 1: 225℃±5℃, Zone 2: 235℃±5℃, Zone 3: 245℃±5℃, Zone 4: 245℃±5℃, Zone 5: 255℃±5℃, Zone 6: 255℃±5℃, Zone 7: 245℃±5℃, Zone 8: 245℃±5℃, Zone 9: 245℃±5℃, and Zone 10: 245℃±5℃. The die head temperature is 255℃±5℃, the screw speed is 300rpm~400rpm, and the vacuum degree is -0.5MPa~-0.9MPa.

[0018] A third aspect of this invention is to provide the application of the polycarbonate / styrene composite material as described in the first aspect in thin-walled halogen-free flame-retardant parts, wherein the thickness of the thin-walled halogen-free flame-retardant parts is 0.5~1.0 mm, achieving ultra-thin halogen-free flame retardancy. It can be widely used in new energy battery casings, power bank casings, etc.

[0019] The present invention has the following beneficial effects:

[0020] The polycarbonate / styrene composite material provided by this invention, under the combined action of halogen-free flame retardants and polynitrogen oxide free radical compounds, can produce ultra-thin halogen-free flame-retardant parts of 0.5–1.0 mm thickness. Furthermore, the prepared products exhibit excellent resistance to damp heat aging and weathering. The working principle of the polynitrogen oxide free radical compounds used in this invention in the composite material is analyzed as follows:

[0021] (1) The multiple nitroxide radicals on the polynitroxide radical compound structure can capture carbon radicals generated by hydrothermal aging and form multiple alkoxyamine bonds, thus acting as chain extenders and improving the hydrothermal resistance of the composite material. Without adding additional ultraviolet absorbers / light stabilizers to the composite material, the nitroxide radicals on the polynitroxide radical compound structure of the present invention can exert a weathering principle similar to hindered amine light stabilizers, giving the composite material excellent weather resistance.

[0022] (2) Due to the flexible long carbon chain structure of polynitrogen oxide free radical compounds, taking the bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate nitroxide free radical as an example, the flexible long carbon chain structure consists of eight methylene groups (-CH2-). The methylene structure is simple, and internal rotation is relatively easy, giving it a certain degree of mobility. In composite materials, 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," exhibiting a certain degree of compatibility. Furthermore, the flexible long carbon chain structure of the polynitrogen oxide free radical compound forms topological entanglement with the matrix molecular chain, which can enhance the "anchoring" ability of the polynitrogen oxide free radical compound in the matrix and inhibit migration and precipitation. This allows the polynitrogen oxide free radical compound to be well dispersed in the composite material, making it less prone to precipitation during use and exhibiting good weather resistance and aging resistance. The polynitrogen oxide free radical compound used in this invention can effectively solve the problems of uneven dispersion and poor compatibility caused by the large molecular structure of added additives.

[0023] (3) Based on halogen-free flame retardants, the nitrogen and oxygen free radicals in polynitrogen oxide free radical compounds simultaneously exert their ability to capture active free radicals, thus giving the composite material more efficient flame retardant properties. Polynitrogen oxide free radical compounds have multiple effects as weathering agents, chain extenders, and flame retardants. Without the addition of ultraviolet absorbers or light stabilizers, the prepared products have excellent weather resistance. Detailed Implementation

[0024] The preparation method, effects, and uses of the present invention will be further described below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0025] The specific information of the raw materials used in the following examples and comparative examples is as follows:

[0026] Bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate nitroxide radical (referred to as "Compound 1" in Table 1)

[0027] Bis(2,2,6,6-tetramethyl-4-piperidinyl)laurate nitroxide radical (referred to as "Compound 2" in Table 1)

[0028] Manufacturer: Guangdong Wengjiang Chemical Reagent Co., Ltd.

[0029] Polycarbonate (PC), supplier: Teijin Japan PC L1250Y;

[0030] Silicon copolycarbonate (silicon PC-1), supplier: Idemitsu PC FG1760 (6% silicon content) from Japan;

[0031] Silicon copolycarbonate (silicon PC-2), supplier: Wanhua Silicon PC S2060 (silicon content 20%).

[0032] Acrylonitrile-butadiene-styrene copolymer (ABS), supplier: Shanghai Gaoqiao Petrochemical Co., Ltd. ABS 8491;

[0033] Acrylonitrile-acrylate-styrene copolymer (ASA), supplied by INEOS Styrolene Luran S®757G;

[0034] Acrylonitrile-ethylene propylene diene monomer (EPDM)-styrene copolymer (AES), supplier: Shanghai Kumho Sunny AES HW600G;

[0035] The antioxidant is a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 1:2; the suppliers of both antioxidant 1076 and antioxidant 168 are Tianjin Lianlong.

[0036] The anti-dripping agent is PTFE DB105, and the supplier is Shanghai Puxin.

[0037] The lubricant is dipentaerythritol stearate, brand name PETS-AP, and the supplier is: Italian company, PETS-AP.

[0038] Ultraviolet absorber, UV-234, supplier: Tianjin Lianlong;

[0039] Phosphorus-based flame retardant, bisphenol A-bis(diphenyl phosphate), supplier: Zhejiang Wansheng Co., Ltd.;

[0040] Nitrogen-phosphorus flame retardant, hexaphenoxycyclotriphosphazene, supplier: Otsuka Chemical Co., Ltd., Japan;

[0041] The silicone-based flame retardant is FCA-107, supplied by Dow Corning.

[0042] Unless otherwise specified, the reagents, methods and equipment used in this invention are conventional reagents, methods and equipment in this technical field.

[0043] Examples 1-14 and Comparative Examples 1-11 provide a polycarbonate / styrene resin composite material, the component contents of which are shown in Table 1. Each example and comparative example contains 0.5 parts of the lubricant dipentaerythritol stearate and 0.4 parts of the anti-dripping agent PTFE DB105. The amounts of 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:

[0044] According to Table 1, the components are mixed as follows: (1) The following formulation components are added to a high-speed mixer and stirred for 5 minutes to obtain a mixture; (2) Extrusion granulation: The mixture is added to a twin-screw extruder for granulation. The processing temperature of each section of the twin-screw extruder is as follows: Zone 1 temperature is 225℃±5℃, Zone 2 temperature is 235℃±5℃, Zone 3 temperature is 245℃±5℃, Zone 4 temperature is 245℃±5℃, Zone 5 temperature is 255℃±5℃, Zone 6 temperature is 255℃±5℃, Zone 7 temperature is 245±5℃, Zone 8 temperature is 245±5℃, Zone 9 temperature is 245±5℃, and Zone 10 temperature is 245±5℃. The die head temperature is 255℃±5℃, the screw speed is 300rpm~400rpm, and the vacuum degree is -0.5MPa~-0.9MPa.

[0045] Table 1. Component content (parts by weight) of polycarbonate / styrene resin composites in each example and comparative example.

[0046] Performance testing

[0047] Tensile strength test: conducted in accordance with GB / T 1040 standard, with a tensile speed of 50 mm / min.

[0048] Izod notched impact test: Tensile properties were tested according to GB / T 1843.

[0049] Flame retardancy testing: Flame retardancy testing was conducted according to UL-94 standard, using 0.5mm and 1.0mm standard flame retardant test strips. The oxygen index was tested according to the GBT2406-1993 standard method.

[0050] Moisture and heat resistance: Initial tensile strength and Izod impact strength were tested. Standard specimens were placed in a constant temperature and humidity aging chamber at 85℃ and 85%RH for 1000 hours. After aging, tensile strength and Izod impact strength were tested again. The retention rate of tensile strength and Izod impact strength was calculated based on the test values ​​before and after aging.

[0051] Xenon lamp aging test: Initial tensile strength and Izod impact strength were tested. The specimens were subjected to xenon lamp aging tests according to GB / T 16422.2-2014 for 1000 hours. After aging, tensile strength and Izod impact strength were tested again. The retention rate of tensile strength and Izod impact strength was calculated based on the test values ​​before and after aging.

[0052] The test results of Examples 1-14 and Comparative Examples 1-11 are shown in Tables 2 and 3.

[0053] Table 2 Performance test results of Examples 1-10 and Comparative Examples 1-3

[0054]

[0055] Table 3 Performance test results of Examples 11-14 and Comparative Examples 4-11

[0056]

[0057] The difference between Examples 1 and 3 and Comparative Examples 1 and 2 lies in the content of silicon-copolymer polycarbonate (silicon PC). As the silicon PC content decreases, the oxygen index of the composite material decreases to 23%, and the flame retardant performance also declines, with the notched impact retention rate after damp heat aging decreasing to 31%. Among these, Comparative Example 2, which does not contain silicon PC, showed the greatest impact on notched impact after damp heat aging. Overall, Examples 1 and 3 exhibit better resistance to damp heat aging; therefore, the mass ratio of polycarbonate (PC) to silicon PC is less than 2. Example 4, which uses silicon PC with a silicon content of 20%, shows a better overall effect than Example 1, indicating that silicon content has a positive effect on resistance to damp heat aging and flame retardancy.

[0058] The difference between Examples 1, 5 and 6 lies in the type of styrene resin. As shown in Table 2, the oxygen index, flame retardant properties and retention rate after damp heat aging of the three styrene composite materials, namely acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-acrylate-styrene copolymer (ASA) and acrylonitrile-ethylene propylene diene monomer (EPDM)-styrene copolymer (AES), are similar, indicating that all three have excellent damp heat resistance.

[0059] The difference between Examples 1, 7, and 8 is that they use different halogen-free flame retardants. Nitrogen-phosphorus flame retardants, silicon-based flame retardants, and polynitrogen-oxygen free radical compounds can all achieve good performance. The oxygen index of all examples reaches 31%, the flame retardancy of 0.5 mm can reach V-0, and the retention rate after damp heat aging and xenon lamp aging can reach the level of Example 1.

[0060] The difference between Examples 1, 9, and 10 and Comparative Example 3 lies in the ABS content. As the ABS content increases, the oxygen index of the composite material decreases to 26%, and the flame retardant performance also declines. An ABS content of 5-20 parts per 10 ...

[0061] The difference between Example 1, Comparative Example 4, Comparative Example 5, and Example 11 lies in the content of poly(nitrile oxygen) free radical compounds. Increased poly(nitrile oxygen) free radical compounds lead to an increased oxygen index in the composite material, resulting in improved flame retardant properties. The notched impact strength retention rates after damp heat aging and xenon lamp aging also show an upward trend. In Example 11, the oxygen index reaches 31%. The notched impact strength retention rate after damp heat aging is 79%, and after xenon lamp aging, it is 92%. This indicates that an increased content of nitrogen and oxygen free radicals on the poly(nitrile oxygen) free radical compounds is beneficial for damp heat resistance, flame retardancy, and weather resistance.

[0062] 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 retardant and polynitrile free radical compound. The data shows that adding too little phosphorus-based flame retardant or too little polynitrile free radical compound does not produce good results and fails to achieve a highly efficient flame retardant effect. Furthermore, low levels of polynitrile free radical compound also affect the notch impact retention rate after damp heat aging and xenon lamp aging. Overall, the data from Example 1 and Examples 11-12 are not significantly different, indicating that the flame retardant effect of phosphorus-based flame retardant and polynitrile free radical compound has an upper limit. Further increasing the addition amount increases the formulation design cost without significantly improving the various performance characteristics.

[0063] Compared with Example 1, Comparative Examples 9 and 10 differ in that they use phosphorus-based flame retardants and polynitrogen oxide free radical compounds separately. Both have too low oxygen index, resulting in poor flame retardant performance and resistance to damp heat. A single flame retardant system is difficult to meet the requirements for resistance to damp heat aging and ultra-thin halogen-free flame retardancy.

[0064] The difference between Example 1 and Comparative Example 11 is that Example 1 added a polynitrile oxide free radical compound, while Comparative Example 11 added the weathering agent UV234. The tensile strength retention and notched impact strength retention rates after xenon lamp aging were similar in both, indicating that the polynitrile oxide free radical compound has the same weathering effect. Furthermore, the oxygen index, flame retardant properties, and performance retention rates after damp heat aging in Example 1 were significantly higher than those in Comparative Example 11, demonstrating that the polynitrile oxide free radical compound of the present invention has significant damp heat aging resistance and a synergistic flame retardant effect. Simultaneously, the xenon lamp aging data from the above examples and comparative examples further demonstrate that adding 0.5 parts of the polynitrile oxide free radical compound results in excellent weathering performance.

[0065] The difference between Example 1 and Example 13 is that no antioxidant was added in Example 13. The overall test results were similar to those of Example 1, indicating that polynitrogen oxide free radical compounds also have a certain antioxidant aging effect. Antioxidants can be omitted from the formulation to impart anti-aging and weather-resistant properties to the composite material. Polynitrogen oxide free radical compounds have multiple functions, not only reducing material costs and simplifying formulations, but also imparting high performance to materials, thus offering certain advantages.

[0066] In summary, polynitrogen oxide radical compounds with nitrogen and oxygen free radicals in their structure not only endow the composite materials with excellent resistance to damp heat and weathering, but also possess highly efficient synergistic flame-retardant effects. These polynitrogen oxide radical compounds exhibit multiple functions, including weather resistance, chain extension, flame retardancy, and resistance to oxidative aging. Therefore, the polycarbonate / styrene composite material provided by this invention possesses excellent resistance to damp heat aging and weathering, while also exhibiting excellent ultra-thin flame-retardant properties.

[0067] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can 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 those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A polycarbonate / styrene composite material, characterized in that, The raw materials, by weight, include: 30-50 parts polycarbonate, 20-40 parts silicon-copolymerized polycarbonate, 5-20 parts styrene-based resin, 8-15 parts halogen-free flame retardant, 0.4-1 part polynitrogen oxide free radical compound, 0.3-0.8 parts anti-dripping agent, and 0.2-0.8 parts lubricant; the polynitrogen oxide free radical compound has at least two nitrile oxide free radicals in its molecular structure, and the molecular chain of the polynitrogen oxide free radical compound has a flexible carbon chain structure; the polynitrogen oxide free radical compound... The oxygen free radical compound is at least one of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate nitroxide free radical and bis(2,2,6,6-tetramethyl-4-piperidinyl) lauryl ester nitroxide free radical; the mass ratio of the polycarbonate to the silicon copolymer polycarbonate is less than 2; the styrene resin is at least one of acrylonitrile-butadiene-styrene copolymer, acrylonitrile-acrylate-styrene copolymer, and acrylonitrile-ethylene propylene diene monomer (EPDM) rubber-styrene copolymer.

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

3. The polycarbonate / styrene composite material according to claim 2, 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 organosilicon flame retardant.

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

5. The polycarbonate / styrene composite material according to claim 4, characterized in that, The anti-dripping agent is a polytetrafluoroethylene anti-dripping agent coated with acrylonitrile-styrene copolymer.

6. 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 antioxidant; the antioxidant is a mixture of at least two of antioxidant 1076, antioxidant 1010, antioxidant 168, and antioxidant 627A.

7. The polycarbonate / styrene composite material according to claim 6, characterized in that, The antioxidant is a mixture of antioxidant 1076 and antioxidant 168 in a mass ratio of 1:

2.

8. 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.

9. The polycarbonate / styrene composite material according to any one of claims 1 to 8, characterized in that, The polycarbonate is bisphenol A type polycarbonate, and at 300°C and 1.2 kg load, the melt mass flow rate of the bisphenol A type polycarbonate is 3~20 g / 10 min.

10. The polycarbonate / styrene composite material according to any one of claims 1 to 8, characterized in that, The melt flow rate of the silicon copolymer polycarbonate at 300°C and 1.2 kg load is 3~10 g / 10 min.

11. The polycarbonate / styrene composite material according to claim 10, characterized in that, The silicon content of the silicon copolymer polycarbonate is 5-20%.

12. The method for preparing the polycarbonate / styrene composite material according to any one of claims 1 to 11, characterized in that, Includes the following steps: Polycarbonate, silicon copolymer polycarbonate, styrene resin, halogen-free flame retardant, polynitrogen oxide free radical compound, anti-dripping agent, antioxidant and lubricant are mixed evenly to obtain a mixture; The mixture is melt-blended to obtain the target product.

13. The method for preparing the polycarbonate / styrene composite material according to claim 12, characterized in that, The melt blending process uses a screw extrusion blending process, and the equipment used is a twin-screw extruder.

14. The method for preparing the polycarbonate / styrene composite material according to claim 12, characterized in that, The polycarbonate and silicon copolymer polycarbonate are dried before feeding to ensure that the moisture content of the polycarbonate and silicon copolymer polycarbonate is less than 0.02%.

15. The application of the polycarbonate / styrene composite material according to any one of claims 1 to 11 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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