A weather-resistant and flame-retardant reinforced polycarbonate composite board and its preparation method

Abstract

This invention discloses a weather-resistant and flame-retardant reinforced polycarbonate composite board and its preparation method. The composite board uses synergistically modified polycarbonate resin as the matrix and incorporates organic small-molecule functional additives, inorganic flame-retardant reinforcing fillers, antioxidant and weather-resistant additives, and processing stabilizers, obtained through melt blending and extrusion molding. The synergistically modified polycarbonate resin is formed by end-group addition and transesterification reactions of polycarbonate with hexaphenoxycyclotriphosphazene in the molten state. The organic small-molecule functional additive is ellagic acid. This invention significantly improves the flame-retardant properties, weather resistance, and thermal stability of the polycarbonate composite board without significantly affecting the material's processing performance and mechanical properties, making it suitable for construction, transportation, and industrial applications with high requirements for flame retardancy and weather resistance.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, specifically relating to a weather-resistant and flame-retardant reinforced polycarbonate composite board and its preparation method. Background Technology

[0002] Polycarbonate sheets are widely used in architectural lighting, rail transportation, electronic and electrical protection, and industrial structural components due to their excellent light transmittance, impact resistance, and good processing and molding properties. However, as applications shift towards long-term outdoor use and higher safety standards, the shortcomings of polycarbonate sheets in terms of weather resistance and flame retardancy are becoming increasingly apparent. Especially under ultraviolet radiation, hot and oxidative environments, and fire conditions, the material is prone to photoaging, mechanical property degradation, and dripping during combustion, making it difficult to meet increasingly stringent safety and service life requirements.

[0003] In existing technologies, to improve the flame retardant properties of polycarbonate sheets, modification with externally added phosphorus-based, nitrogen-based, or inorganic flame retardants is commonly employed. However, such solutions often suffer from drawbacks such as poor compatibility between the flame retardant and the matrix, easy migration and precipitation, and adverse effects on transparency and mechanical properties. Furthermore, improvements in weather resistance largely rely on simple compounding of hindered amine light stabilizers or antioxidants, making it difficult to achieve long-term stable synergistic effects within the flame retardant system.

[0004] Some studies have attempted to introduce flame-retardant structural units into polycarbonate through chemical modification. However, most modification methods focus on introducing a single function, and the modified systems are complex, have poor process adaptability, and struggle to simultaneously achieve flame retardancy, weather resistance, and processing stability. On the other hand, in the current field of polycarbonate sheets, there is limited research on the functional application of small organic molecule materials with multi-hydroxyl conjugated structures, and their potential synergistic effects in promoting flame-retardant char layer formation and inhibiting photo-thermal aging have not yet been fully explored.

[0005] Therefore, how to simultaneously improve weather resistance, flame retardancy, and overall performance without significantly sacrificing the original transparency and mechanical properties of polycarbonate sheets through structural synergistic design and the rational introduction of functional components remains a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To overcome the technical difficulties in the above-mentioned background technology, such as insufficient weather resistance, difficulty in maintaining long-term flame retardant performance, and difficulty in achieving synergistic balance of multiple functions in polycarbonate sheets, the present invention aims to provide a weather-resistant and flame-retardant reinforced polycarbonate composite sheet and its preparation method. This invention employs a composite technology solution that synergistically modifies polycarbonate resin and introduces specific small-molecule functional additives. While ensuring the material's processing and mechanical properties, it achieves a synergistic improvement in weather resistance and flame retardant performance. The present invention aims to enable the resulting polycarbonate composite sheet to simultaneously possess excellent weather resistance stability and highly efficient flame retardant performance.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A weather-resistant and flame-retardant reinforced polycarbonate composite board comprises the following raw materials in parts by weight: 70-88 parts of synergistically modified polycarbonate resin; 0.3-3.0 parts of organic small molecule functional additives; 5-20 parts of inorganic flame-retardant reinforcing filler; 0.2-1.5 parts of antioxidant and weather-resistant additives; and 0.1-1.0 parts of processing stabilizing additives. The synergistically modified polycarbonate resin is obtained by end-group addition and transesterification reaction of polycarbonate with hexaphenoxycyclotriphosphazene in the molten state. The organic small molecule functional additive is ellagic acid.

[0009] Optionally, the synergistically modified polycarbonate resin comprises the following raw materials in parts by weight: 88-97 parts of polycarbonate resin; 1-8 parts of hexaphenoxycyclotriphosphazene; 0.2-1.0 parts of tris(2,4-di-tert-butylphenyl) phosphite; 0.1-0.8 parts of pentaerythritol tetra(3,5-di-tert-butyl-4-hydroxyphenyl) propionate; and 0.05-0.5 parts of calcium stearate.

[0010] Optionally, the method for preparing the synergistically modified polycarbonate resin includes the following steps:

[0011] (1) After drying the polycarbonate resin, add it to the melt blending equipment and heat it to reach the melt state.

[0012] (2) Add hexaphenoxycyclotriphosphazene, tris(2,4-di-tert-butylphenyl) phosphite, pentaerythritol tetra(3,5-di-tert-butyl-4-hydroxyphenyl) propionate and calcium stearate to polycarbonate resin in the molten state, and carry out the melt reaction and uniform dispersion under stirring conditions;

[0013] (3) The molten system is extruded, cooled and pelletized to obtain synergistically modified polycarbonate resin.

[0014] Optionally, the reaction conditions in step (1) are to dry the polycarbonate resin at 100-130°C for 2-6 hours.

[0015] Optionally, the reaction conditions for step (2) are to perform melt blending at a melting temperature of 200-260°C, with a screw speed of 150-400 rpm and a reaction time of 3-10 min.

[0016] Optionally, the reaction conditions in step (3) are an extrusion temperature of 220-260°C, a water cooling method, and a pellet size of 2-5 mm.

[0017] Optionally, the inorganic flame-retardant reinforcing filler is a mixture of magnesium hydroxide and boron nitride in a mass ratio of 3:1 to 10:1; the antioxidant and weather-resistant additive is a mixture of bis[2,2,6,6-tetramethyl-4-piperidinyl] sebacate and pentaerythritol tetra(3,5-di-tert-butyl-4-hydroxyphenyl)propionate in a mass ratio of 1:0.5 to 1:2; and the processing stabilizing additive is a mixture of tris(2,4-di-tert-butylphenyl) phosphite and calcium stearate in a mass ratio of 1:0.2 to 1:1.

[0018] Optionally, a method for preparing a weather-resistant and flame-retardant reinforced polycarbonate composite board includes the following steps:

[0019] S1, weigh the synergistic modified polycarbonate resin, organic small molecule functional additives, inorganic flame retardant reinforcing fillers, antioxidant and weather-resistant additives and processing stabilizing additives.

[0020] S2, add the weighed components into the melt blending equipment and melt blend under heating conditions to make the components uniformly dispersed and obtain a composite melt system;

[0021] S3 involves extruding, cooling, and cutting the composite melt system to obtain a weather-resistant and flame-retardant reinforced polycarbonate composite board.

[0022] Optionally, the reaction conditions for step S2 are melt blending at 200–260°C, screw speed of 150–400 rpm, and blending time of 5–15 min.

[0023] Optionally, the reaction conditions in step S3 are: extrusion molding temperature of 220-260°C, cooling method of water cooling, and cutting after cooling to obtain the finished sheet material.

[0024] The beneficial effects of this invention are:

[0025] This invention introduces hexaphenoxycyclotriphosphazene into the polycarbonate resin structure through endogenous synergistic modification, enabling the phosphorus-nitrogen flame-retardant units to exist stably within the matrix. This avoids the defects of traditional externally added flame-retardant systems, such as easy migration and precipitation. At the same time, it is the first time that ellagic acid has been applied as an organic small molecule functional additive to weather-resistant and flame-retardant polycarbonate composite boards. Its multi-hydroxy conjugated structure promotes the formation of a dense flame-retardant char layer under thermal and ultraviolet irradiation conditions and effectively inhibits the photo-thermal aging of the polycarbonate backbone. Thus, without significantly affecting the material's processing performance, transparency, and mechanical properties, it achieves a synergistic and stable improvement in the weather resistance and flame-retardant performance of the composite board, demonstrating outstanding inventiveness and practical value. Attached Figure Description

[0026] The invention will now be further described with reference to the accompanying drawings.

[0027] Figure 1 A comparison of the infrared spectra of polycarbonate resin and synergistically modified polycarbonate resin;

[0028] Figure 2 A comparison chart showing the results of UV aging resistance and mechanical property tests for samples with different formulation ratios. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments. However, the present invention is not limited to the following embodiments. Equivalent adjustments made without departing from the spirit and essence of the present invention should also be considered to fall within the protection scope of the present invention.

[0030] Example 1: This example aims to verify the feasibility and overall performance stability of weather-resistant and flame-retardant reinforced polycarbonate composite boards under high flame retardancy and high weather resistance design conditions by using the upper limits of the dosage of each component and reaction conditions.

[0031] S1, Preparation of synergistically modified polycarbonate resin

[0032] Weigh out 97 parts by weight of polycarbonate resin, 8 parts by weight of hexaphenoxycyclotriphosphazene, 1.0 part by weight of tris(2,4-di-tert-butylphenyl) phosphite, 0.8 parts by weight of pentaerythritol tetra(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and 0.5 parts by weight of calcium stearate; after drying the polycarbonate resin at 130°C for 6 hours, add it to a melt blending device and heat it to 260°C to melt it. Add the remaining components at a screw speed of 400 rpm to carry out the melt reaction and uniform dispersion for 10 minutes. Then, extrude, cool and pelletize to obtain synergistically modified polycarbonate resin.

[0033] S2, composite melt blending

[0034] Weigh out 88 parts by weight of the above-mentioned synergistic modified polycarbonate resin, 3.0 parts of ellagic acid, 20 parts of inorganic flame retardant reinforcing filler, 1.5 parts of antioxidant and weather-resistant additive, and 1.0 part of processing stabilizing additive. Melt blend at 260℃, with a screw speed of 400 rpm and a blending time of 15 min to obtain a composite melt system.

[0035] S3, Sheet metal forming

[0036] The resulting composite melt system was extruded at 260°C, cooled and shaped by water, and then cut to obtain a weather-resistant and flame-retardant reinforced polycarbonate composite board.

[0037] Example 2: This example aims to verify the applicability and overall performance balance of the technical solution of the present invention under conventional industrial conditions by using the median range of the dosage of each component and reaction conditions.

[0038] S1, Preparation of synergistically modified polycarbonate resin

[0039] Weigh out 92.5 parts by weight of polycarbonate resin, 4.5 parts by weight of hexaphenoxycyclotriphosphazene, 0.6 parts by weight of tris(2,4-di-tert-butylphenyl)phosphite, 0.45 parts by weight of pentaerythritol tetra(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 0.275 parts by weight of calcium stearate; after drying the polycarbonate resin at 115℃ for 4 hours, add it to a melt blending device and heat it to 230℃ to melt it. Add the remaining components at a screw speed of 275 rpm to carry out the melt reaction and uniform dispersion for 6 minutes. Then, extrude, cool and pelletize to obtain synergistically modified polycarbonate resin. Figure 1 The infrared spectrum of medium-sized polycarbonate is 1770–1785 cm⁻¹ -1 The C=O stretching vibration peak of carbonate and the 1250–1150 cm⁻¹ peak. -1 The main characteristic is the COC stretching vibration peak, and the overall spectrum is relatively smooth, without the characteristic absorption peaks of phosphorus- or nitrogen-containing structures; in the modified infrared spectrum, while retaining the original polycarbonate characteristic peaks, the peaks are located at approximately 1190–1150 cm⁻¹. -1 A distinct P=O stretching vibration absorption peak appears at 1030–980 cm⁻¹. -1 and 960~900cm -1 The presence of PO-Ar and PN-related vibrational absorption peaks in the range, along with enhanced peak intensity in the COC region, indicates that hexaphenoxycyclotriphosphazene has been successfully introduced into the polycarbonate system and has a synergistic effect with it.

[0040] S2, composite melt blending

[0041] Weigh out 79 parts by weight of the above-mentioned synergistic modified polycarbonate resin, 1.5 parts of ellagic acid, 12.5 parts of inorganic flame retardant reinforcing filler, 0.85 parts of antioxidant and weather-resistant additive, and 0.55 parts of processing stabilizing additive. Melt blend at 230°C, with a screw speed of 275 rpm and a blending time of 10 min to obtain a composite melt system.

[0042] S3, Sheet metal forming

[0043] The resulting composite melt system was extruded at 240°C, cooled and shaped by air cooling, and then cut to obtain a weather-resistant and flame-retardant reinforced polycarbonate composite board.

[0044] Example 3: This example aims to verify the feasibility and basic functional achievement of the technical solution of the present invention under low addition amount and mild process conditions by using the lower limit values ​​of the dosage of each component and reaction conditions.

[0045] S1, Preparation of synergistically modified polycarbonate resin

[0046] Weigh out 88 parts by weight of polycarbonate resin, 1 part of hexaphenoxycyclotriphosphazene, 0.2 parts of tris(2,4-di-tert-butylphenyl) phosphite, 0.1 parts of pentaerythritol tetra(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and 0.05 parts of calcium stearate; after drying the polycarbonate resin at 100°C for 2 hours, add it to a melt blending device and heat it to 200°C to melt it. Add the remaining components at a screw speed of 150 rpm to carry out the melt reaction and uniform dispersion for 3 minutes. Then, extrude, cool, and pelletize to obtain synergistically modified polycarbonate resin.

[0047] S2, composite melt blending

[0048] Weigh out 70 parts by weight of the above-mentioned synergistic modified polycarbonate resin, 0.3 parts of ellagic acid, 5 parts of inorganic flame retardant reinforcing filler, 0.2 parts of antioxidant and weather-resistant additive, and 0.1 parts of processing stabilizing additive. Melt blend at 200℃, with a screw speed of 150 rpm and a blending time of 5 min to obtain a composite melt system.

[0049] S3, Sheet metal forming

[0050] The resulting composite melt system was extruded at 220°C, cooled and shaped by air cooling, and then cut to obtain a weather-resistant and flame-retardant reinforced polycarbonate composite board.

[0051] Comparative Example 1: This comparative example aims to compare and verify the contribution of the "synergistic modification system" to the overall effect of weather resistance and flame retardancy by introducing only hexaphenoxycyclotriphosphazene into the polycarbonate resin and eliminating other stabilizing additives in the polycarbonate resin.

[0052] S1, Preparation of synergistically modified polycarbonate resin

[0053] Weigh out 92.5 parts of polycarbonate resin and 4.5 parts of hexaphenoxycyclotriphosphazene by weight; after drying the polycarbonate resin at 115℃ for 4 hours, add it to a melt blending device and heat it to 230℃ to melt it. Add hexaphenoxycyclotriphosphazene at a screw speed of 275 rpm for melt reaction and uniform dispersion. The reaction time is 6 minutes. Then, extrude, cool and pelletize to obtain synergistically modified polycarbonate resin.

[0054] S2, composite melt blending

[0055] Weigh out 79 parts by weight of the above-mentioned synergistic modified polycarbonate resin, 1.5 parts of ellagic acid, 12.5 parts of inorganic flame retardant reinforcing filler, 0.85 parts of antioxidant and weather-resistant additive, and 0.55 parts of processing stabilizing additive. Melt blend at 230°C, with a screw speed of 275 rpm and a blending time of 10 min to obtain a composite melt system.

[0056] S3, Sheet metal forming

[0057] The resulting composite melt system was extruded at 240°C, cooled and shaped by air cooling, and then cut to obtain a weather-resistant and flame-retardant reinforced polycarbonate composite board.

[0058] Comparative Example 2: This comparative example aims to use only a stabilizing additive system to modify polycarbonate resin alone, eliminating the synergistic modification effect of hexaphenoxycyclotriphosphazene on polycarbonate resin, in order to compare and verify the contribution of "introduction of phosphorus-nitrogen structural units" to the synergistic improvement of flame retardancy and weather resistance.

[0059] S1, Preparation of synergistically modified polycarbonate resin

[0060] Weigh out 92.5 parts by weight of polycarbonate resin, 0.6 parts by weight of tris(2,4-di-tert-butylphenyl) phosphite, 0.45 parts by weight of pentaerythritol tetra(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and 0.275 parts by weight of calcium stearate; after drying the polycarbonate resin at 115℃ for 4 hours, add it to a melt blending device and heat it to 230℃ to melt it. Add the remaining components at a screw speed of 275 rpm to carry out the melt reaction and uniform dispersion for 6 minutes. Then, extrude, cool and pelletize to obtain synergistically modified polycarbonate resin.

[0061] S2, composite melt blending

[0062] Weigh out 79 parts by weight of the above-mentioned synergistic modified polycarbonate resin, 1.5 parts of ellagic acid, 12.5 parts of inorganic flame retardant reinforcing filler, 0.85 parts of antioxidant and weather-resistant additive, and 0.55 parts of processing stabilizing additive. Melt blend at 230°C, with a screw speed of 275 rpm and a blending time of 10 min to obtain a composite melt system.

[0063] S3, Sheet metal forming

[0064] The resulting composite melt system was extruded at 240°C, cooled and shaped by air cooling, and then cut to obtain a weather-resistant and flame-retardant reinforced polycarbonate composite board.

[0065] Comparative Example 3: This comparative example aims to verify the contribution of ellagic acid to the synergistic enhancement of weather resistance and flame retardancy without adding the organic small molecule functional additive ellagic acid, while keeping the preparation process of synergistic modified polycarbonate resin, other components, and process conditions unchanged.

[0066] S1, Preparation of synergistically modified polycarbonate resin

[0067] Weigh out 92.5 parts by weight of polycarbonate resin, 4.5 parts by weight of hexaphenoxycyclotriphosphazene, 0.6 parts by weight of tris(2,4-di-tert-butylphenyl)phosphite, 0.45 parts by weight of pentaerythritol tetra(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 0.275 parts by weight of calcium stearate; after drying the polycarbonate resin at 115℃ for 4 hours, add it to a melt blending device and heat it to 230℃ to melt it. Add the remaining components at a screw speed of 275 rpm to carry out the melt reaction and uniform dispersion for 6 minutes. Then, extrude, cool and pelletize to obtain synergistically modified polycarbonate resin.

[0068] S2, composite melt blending

[0069] Weigh out 79 parts by weight of the above-mentioned synergistic modified polycarbonate resin, 12.5 parts by weight of inorganic flame retardant reinforcing filler, 0.85 parts by weight of antioxidant and weather-resistant additive and 0.55 parts by weight of processing stabilizing additive, and melt blend them at 230°C, with a screw speed of 275 rpm and a blending time of 10 min to obtain a composite melt system.

[0070] S3, Sheet metal forming

[0071] The resulting composite melt system was extruded at 240°C, cooled and shaped by air cooling, and then cut to obtain a weather-resistant and flame-retardant reinforced polycarbonate composite board.

[0072] Performance testing:

[0073] 1. Flame retardant performance test method

[0074] The flame retardant properties of the polycarbonate composite boards obtained in the examples and comparative examples were tested using the vertical burning method. The samples were processed to the specified dimensions according to GB / T2408 or UL-94 standards, and the samples were ignited under specified flame conditions. The burning time, extinguishing condition and whether dripping occurred were recorded. The flame retardant rating of the samples was evaluated based on their burning behavior to compare the effects of different technical solutions on the flame retardant properties of the materials.

[0075] 2. Test method for UV aging resistance

[0076] The composite boards obtained in the examples and comparative examples were placed in an accelerated UV aging test chamber and aged under UV irradiation and condensation cycling conditions according to GB / T16422.3 standard. After the set aging time, the samples were taken out and their appearance changes and mechanical property retention rates were tested to evaluate the weather resistance stability of different material systems under long-term UV irradiation conditions.

[0077] 3. Mechanical property testing methods

[0078] The polycarbonate composite panels prepared in the examples and comparative examples were tested for tensile strength, flexural strength and notched impact strength according to standards such as GB / T1040 and GB / T1043. By comparing the mechanical property values ​​of each sample, the influence of synergistic modification of polycarbonate resin and organic small molecule functional additives on the mechanical properties of the materials was analyzed.

[0079] 4. Thermal stability test method

[0080] Thermogravimetric analysis was used to test the thermal stability of the composite boards obtained in the examples and comparative examples. The samples were heated under nitrogen protection at a set heating rate, and the initial decomposition temperature, maximum weight loss rate temperature and residual carbon content were recorded to evaluate the effects of different technical solutions on the thermal stability and carbonization ability of polycarbonate composite boards.

[0081] Table 1 Performance test results of different embodiments and comparative examples

[0082] Sample number Flame retardant rating (UL-94) Tensile strength retention rate after UV aging (%) Notched impact strength (kJ / m²) Initial decomposition temperature (°C) Carbon residue rate at 800℃ (%) Example 1 V-0 88 62 472 28.5 Example 2 V-0 93 68 485 31.2 Example 3 V-1 85 58 460 25.6 Comparative Example 1 V-1 78 54 445 21.8 Comparative Example 2 V-2 72 51 432 18.9 Comparative Example 3 V-1 70 49 438 20.1

[0083] As shown in Table 1, there are significant differences between the different embodiments and comparative examples in terms of flame retardancy, weather resistance, mechanical properties, and thermal stability. The flame retardancy ratings of Examples 1-3 reach UL-94V-0, V-0, and V-1, respectively, while Comparative Examples 1-3 only reach V-1 or V-2. This indicates that the technical solution of the present invention can significantly improve the flame retardancy of polycarbonate composite panels, with Example 2 exhibiting the best flame retardancy rating.

[0084] In terms of weather resistance, Figure 2 The tensile strength retention rates of Examples 1, 2, and 3 after UV aging were 88%, 93%, and 85%, respectively, all significantly higher than those of Comparative Example 1 (78%), Comparative Example 2 (72%), and Comparative Example 3 (70%). Among them, Example 2 showed the highest tensile strength retention rate, indicating that under the median formulation conditions, the synergistic effect of the modified polycarbonate resin and ellagic acid can most effectively inhibit the performance degradation caused by UV aging.

[0085] In terms of mechanical properties, Figure 2 The notched impact strengths of the samples in the intermediate examples were 62 kJ·m⁻², 68 kJ·m⁻², and 58 kJ·m⁻², respectively, all higher than those of Comparative Examples 1-3 (54 kJ·m⁻², 51 kJ·m⁻², and 49 kJ·m⁻²), indicating that the present invention can maintain or even improve the toughness of the material while improving flame retardancy and weather resistance. Among them, Example 2 achieved a notched impact strength of 68 kJ·m⁻², exhibiting the best overall mechanical properties.

[0086] Regarding thermal stability, the initial decomposition temperatures of Examples 1-3 were 472℃, 485℃, and 460℃, respectively, significantly higher than those of Comparative Examples 1-3 (445℃, 432℃, and 438℃). Simultaneously, the char residue rates of Examples 1-3 at 800℃ were 28.5%, 31.2%, and 25.6%, respectively, while the char residue rates of Comparative Examples 1-3 were only 21.8%, 18.9%, and 20.1%. Example 2 exhibited the highest initial decomposition temperature and char residue rate, indicating that it could form a more stable and dense flame-retardant char layer under high-temperature conditions.

[0087] In summary, based on the test data in Table 1, it can be seen that the present invention achieves a synergistic improvement in flame retardancy, weather resistance, mechanical properties, and thermal stability by synergistically modifying polycarbonate resin and introducing organic small molecule functional additives. Moreover, the overall performance of each embodiment is better than that of the comparative example, with Example 2 showing the best performance in all key performance indicators, fully demonstrating the significant inventiveness of the technical solution of the present invention and its excellent industrial application prospects.

Claims

1. A weather-resistant, flame-retardant, reinforced polycarbonate composite board, characterized in that, The raw materials include the following parts by weight: 70-88 parts of synergistic modified polycarbonate resin; 0.3-3.0 parts of organic small molecule functional additives; 5-20 parts of inorganic flame retardant reinforcing filler; 0.2-1.5 parts of antioxidant and weather-resistant additives; and 0.1-1.0 parts of processing stabilizing additives. The synergistic modified polycarbonate resin is obtained by end-group addition and transesterification reaction of polycarbonate with hexaphenoxycyclotriphosphazene in the molten state. The organic small molecule functional additive is ellagic acid.

2. The weather-resistant and flame-retardant reinforced polycarbonate composite board according to claim 1, characterized in that, The synergistically modified polycarbonate resin comprises the following raw materials in parts by weight: 88-97 parts of polycarbonate resin; 1-8 parts of hexaphenoxycyclotriphosphazene; 0.2-1.0 parts of tris(2,4-di-tert-butylphenyl) phosphite; 0.1-0.8 parts of pentaerythritol tetra(3,5-di-tert-butyl-4-hydroxyphenyl) propionate; and 0.05-0.5 parts of calcium stearate.

3. A weather-resistant and flame-retardant reinforced polycarbonate composite board according to claim 1 or 2, characterized in that, The preparation method of the synergistically modified polycarbonate resin includes the following steps: (1) After drying the polycarbonate resin, add it to the melt blending equipment and heat it to reach the melt state. (2) Add hexaphenoxycyclotriphosphazene, tris(2,4-di-tert-butylphenyl) phosphite, pentaerythritol tetra(3,5-di-tert-butyl-4-hydroxyphenyl) propionate and calcium stearate to polycarbonate resin in the molten state, and carry out the melt reaction and uniform dispersion under stirring conditions; (3) The molten system is extruded, cooled and pelletized to obtain synergistically modified polycarbonate resin.

4. The weather-resistant and flame-retardant reinforced polycarbonate composite board according to claim 3, characterized in that, The reaction conditions for step (1) are to dry the polycarbonate resin at 100-130°C for 2-6 hours.

5. The weather-resistant and flame-retardant reinforced polycarbonate composite board according to claim 3, characterized in that, The reaction conditions for step (2) are as follows: melt blending is carried out at a melting temperature of 200-260°C, screw speed is 150-400 rpm, and reaction time is 3-10 min.

6. The weather-resistant and flame-retardant reinforced polycarbonate composite board according to claim 3, characterized in that, The reaction conditions for step (3) are an extrusion temperature of 220-260°C, a water cooling method, and a pellet size of 2-5 mm.

7. The weather-resistant and flame-retardant reinforced polycarbonate composite board according to claim 1, characterized in that, The inorganic flame-retardant reinforcing filler is a mixture of magnesium hydroxide and boron nitride in a mass ratio of 3:1 to 10:1; the antioxidant and weather-resistant additive is a mixture of bis[2,2,6,6-tetramethyl-4-piperidinyl] sebacate and pentaerythritol tetra(3,5-di-tert-butyl-4-hydroxyphenyl)propionate in a mass ratio of 1:0.5 to 1:2; and the processing stabilizing additive is a mixture of tris(2,4-di-tert-butylphenyl) phosphite and calcium stearate in a mass ratio of 1:0.2 to 1:

1.

8. A method for preparing a weather-resistant and flame-retardant reinforced polycarbonate composite board, characterized in that, The preparation method includes the following steps: S1, weigh the synergistic modified polycarbonate resin, organic small molecule functional additives, inorganic flame retardant reinforcing fillers, antioxidant and weather-resistant additives and processing stabilizing additives. S2, add the weighed components into the melt blending equipment and melt blend under heating conditions to obtain a composite melt system; S3 involves extruding, cooling, and cutting the composite melt system to obtain a weather-resistant and flame-retardant reinforced polycarbonate composite board.

9. The method for preparing a weather-resistant and flame-retardant reinforced polycarbonate composite board according to claim 8, characterized in that, The reaction conditions for step S2 are as follows: melt blending at 200–260°C, screw speed of 150–400 rpm, and blending time of 5–15 min.

10. The method for preparing a weather-resistant and flame-retardant reinforced polycarbonate composite board according to claim 8, characterized in that, The reaction conditions for step S3 are: extrusion molding temperature of 220-260℃, cooling method of water cooling, and cutting after cooling to obtain the finished board.

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