High-flame-retardancy polycarbonate composition and preparation method thereof

Abstract

The invention relates to the field of macromolecules, in particular to a high-flame-retardance polycarbonate composition and a preparation method thereof. The polycarbonate composition with high flame retardance is prepared from the following components in parts by weight: 65 parts of PC, 25 to 35 parts of ABS (Acrylonitrile Butadiene Styrene), 2 to 10 parts of polysilazane, 3 to 5 parts of MBS (Methyl Methacrylate-Butadiene-Styrene) compatilizer, 0.7 part of antioxidant and 0.3 part of lubricant. The polysilazane is introduced into the polycarbonate composition, the surface temperature of the material is reduced by utilizing the endothermic effect of Si-N bond breakage, the combustible gas is diluted by nitrogen generated by decomposition, the combustion speed is slowed down by the concentration of oxygen, and a decomposition product forms a protective layer to isolate oxygen and control the transfer of heat and the combustible gas; and a carbon residue layer is generated to provide additional heat-insulating and flame-retardant effects, so that the flame-retardant property of the composition is remarkably improved.

Description

Technical Field

[0001] The present application relates to the field of polymers, and in particular to a highly flame-retardant polycarbonate composition and a preparation method thereof. Background Art

[0002] PC (polycarbonate) is a high molecular polymer containing carbonate groups in the molecular chain. It has the advantages of impact resistance, high stability, heat resistance, and non-toxicity. It is widely used in the fields of electronic appliances, mechanical equipment, etc. In order to further improve the performance of PC, it is often modified to improve the processing performance, heat resistance, impact resistance, tensile strength and flame retardancy of PC.

[0003] ABS (Acrylonitrile-Butadiene-Styrene Copolymer) is a commonly used PC blending modified material with the advantages of easy processing and high impact strength. The composition of PC and ABS combines the excellent properties of both PC and ABS, which not only improves heat resistance and tensile strength, but also reduces melt viscosity, improves processing performance, and reduces the sensitivity of product internal stress and impact strength to product thickness. Therefore, it is widely used in the fields of automobiles, electronics, communications, etc.

[0004] Although ABS-modified polycarbonate compositions have certain flame retardant properties, the flame retardant effect is poor. In order to improve the flame retardancy of polycarbonate compositions, researchers have begun to explore the use of various flame retardant additives to optimize the flame retardant properties of polycarbonate compositions. How to reasonably determine the type and amount of flame retardant additives to meet the growing demand for industrial applications is still a difficult and hot topic in current research. Summary of the invention

[0005] In order to improve the flame retardant properties of the polycarbonate composition, the present application improves the flame retardant properties of the polycarbonate composition from multiple angles, such as absorbing the surface temperature of the composition, diluting the combustible gas, and forming a protective layer to isolate oxygen.

[0006] In a first aspect, the present application provides a highly flame retardant polycarbonate composition, which adopts the following technical solution: A highly flame-retardant polycarbonate composition comprises the following components in parts by weight: 65 parts of PC, 25-35 parts of ABS, 2-10 parts of polysilazane, 3-5 parts of MBS-type compatibilizer, 0.7 parts of antioxidant and 0.3 parts of lubricant.

[0007] By adopting the above technical solution, when the polycarbonate composition is heated, the Si-N bond in the molecular structure of polysilazane will break and absorb a large amount of heat. This endothermic effect helps to reduce the surface temperature of the polycarbonate composition. During the combustion process, the polysilazane decomposes to produce nitrogen, which diffuses in the combustion area to dilute the concentration of combustible gas and oxygen, thereby reducing the combustion speed and combustion intensity. Polysilazane can also react at high temperatures to form an intermolecular cross-linked structure, thereby forming a dense protective layer on the surface of the composition, thereby isolating oxygen, preventing heat transfer and reducing the release rate of combustible gases, thereby effectively preventing the spread of combustion; polysilazane also has a high carbon residue rate during the combustion process. The resulting carbon residue layer not only has a heat-insulating effect, but also reduces the generation and release of combustible gases, further improving the flame retardant properties of the material; The present application introduces polysilazane into a polycarbonate composition, utilizes the endothermic effect of Si-N bond breaking to reduce the surface temperature of the material, dilutes the combustible gas and oxygen concentration through the decomposition-generated nitrogen to slow down the combustion rate, and the decomposition products form a protective layer to isolate oxygen and control the transfer of heat and combustible gas, and produce a high residual carbon rate to provide additional heat insulation and flame retardant effects, thereby significantly improving the flame retardant properties of the composition.

[0008] Preferably, the weight portion of the polysilazane is 5-8 parts.

[0009] By adopting the above technical scheme, polysilazane is used as a key component to improve the flame retardant properties of the composition. When the content of polysilazane is low, the protective layer formed by the reaction of polysilazane may not be dense or complete enough, so that the isolation effect of oxygen, heat and combustible gas is not obvious, resulting in a weak flame retardant effect; when the content of polysilazane is high, due to the relatively poor compatibility of polysilazane and PC, excessive polysilazane may not be dispersed uniformly in the composition, thereby reducing the flame retardant properties of the composition; for this reason, the applicant finally determined after a lot of research and experimental verification that the weight of polysilazane in this application is preferably as above.

[0010] Preferably, the highly flame-retardant polycarbonate composition further comprises at least one of ginkgo ketone ester and R-3-hydroxybutyric acid-R-3-hydroxybutyl ester.

[0011] Preferably, the highly flame retardant polycarbonate composition further comprises ginkgo ketone ester.

[0012] By adopting the above technical solution, the ketone groups in ginkgo ketone ester and R-3-hydroxybutyric acid-R-3-hydroxybutyl ester can undergo condensation reaction with the NH bond in polysilazane, and the ester groups in ginkgo ketone ester and R-3-hydroxybutyric acid-R-3-hydroxybutyl ester can undergo ester exchange reaction with PC. Through the "bridge effect" of ginkgo ketone ester and R-3-hydroxybutyric acid-R-3-hydroxybutyl ester, the compatibility between polysilazane and PC can be greatly improved, so that the polysilazane is evenly dispersed in the composition, thereby improving the flame retardant properties of the composition; Since the high temperature stability of R-3-hydroxybutyric acid-R-3-hydroxybutyl ester is relatively weak, the improvement effect of R-3-hydroxybutyric acid-R-3-hydroxybutyl ester on the compatibility between polysilazane and PC is not as good as that of ginkgo ketone ester on the compatibility between polysilazane and PC, so ginkgo ketone ester is preferred.

[0013] Preferably, the weight ratio of the polysilazane to the ginkgo ketone ester is 2:0.2-0.3.

[0014] By adopting the above technical scheme, when the content of ginkgo biloba ketone ester is low, the content of ketone group and ester group introduced into the composition is low, and the ginkgo biloba ketone ester is insufficient to fully play a "bridge role", and the improvement of the dispersion uniformity of polysilazane in the composition is not obvious, resulting in the improvement of the flame retardant effect of the composition is not obvious; when the content of ginkgo biloba ketone ester is high, the compatibility of polysilazane and PC is difficult to continue to improve. For cost considerations, there is no need to continue to increase the content of ginkgo biloba ketone ester; for this reason, the applicant finally determined after a lot of research and experimental verification that the weight ratio of polysilazane and ginkgo biloba ketone ester in this application is preferably the above.

[0015] Preferably, the highly flame-retardant polycarbonate composition further comprises at least one of dimethylbiphenyl diisocyanate and tetramethylxylylene diisocyanate.

[0016] Preferably, the highly flame retardant polycarbonate composition further comprises dimethyl diphenyl diisocyanate.

[0017] By adopting the above technical solution, dimethyl diphenyl diisocyanate and tetramethyl benzyl diisocyanate are both polyisocyanate compounds, and the isocyanate group can react with the NH bond in the polysilazane. At the same time, the other isocyanate group can also react with PC to form a carbamate bond. The "bridge effect" of dimethyl diphenyl diisocyanate and tetramethyl benzyl diisocyanate can cooperate with the "bridge effect" of ginkgo ketone ester and R-3-hydroxybutyric acid-R-3-hydroxybutyl ester to further improve the compatibility between polysilazane and PC, and promote the further improvement of the flame retardancy of the composition. At the same time, dimethylbiphenyl diisocyanate and tetramethylxylylene diisocyanate may penetrate into defects and voids of the composition, making the microstructure of the composition more dense and uniform, thereby improving the toughness of the composition; The effect of tetramethylxylylene diisocyanate on improving the compatibility between polysilazane and PC is not as good as that of dimethylbiphenyl diisocyanate on improving the compatibility between polysilazane and PC, so dimethylbiphenyl diisocyanate is preferred.

[0018] Preferably, the weight ratio of the polysilazane to dimethyl diphenyl diisocyanate is 2:0.1-0.2.

[0019] By adopting the above technical solution, when the content of dimethyl diphenyl diisocyanate is low, the isocyanate groups introduced into the composition are relatively small, and the effect of dimethyl diphenyl diisocyanate as a "bridge" to improve the compatibility of polysilazane and PC is not obvious, so that the effect of dimethyl diphenyl diisocyanate on improving the flame retardancy of the polycarbonate composition is not obvious; When the content of dimethyl diphenyl diisocyanate is high, the compatibility of polysilazane and PC is difficult to further improve. For cost considerations, there is no need to continue to increase the content of dimethyl diphenyl diisocyanate. For this reason, the applicant finally determined after a lot of research and experimental verification that the weight ratio of polysilazane and dimethyl diphenyl diisocyanate in this application is preferably as above.

[0020] In a second aspect, the present application provides a method for preparing a highly flame retardant polycarbonate composition, using the following technical solution: A method for preparing a highly flame retardant polycarbonate composition comprises the following steps: Step 1) mixing the formulated amounts of PC, ABS, polysilazane, MBS-type compatibilizer, antioxidant, lubricant and other processing aids to obtain a mixture; Step 2) Extruding and granulating the mixed material to obtain the highly flame-retardant polycarbonate composition.

[0021] By adopting the above technical solution, the present application adopts a mixing method to mix the components evenly, while ensuring the excellent performance of each component. The preparation method is simple, so that the prepared polycarbonate composition has excellent flame retardant properties.

[0022] Preferably, the temperature of the extrusion granulation in step 2) is 230-260°C.

[0023] By adopting the above technical solution, temperature is an important parameter in plastic processing, which directly affects the melting state, fluidity and viscosity of the material. When the temperature is too low, PC and ABS cannot be fully melted, and the fluidity of each component in the extruder is poor, which may lead to uneven mixing between the components, thereby reducing the overall performance of the polycarbonate composition; when the temperature is too high, components such as PC and ABS may undergo thermal decomposition, which will also lead to a decrease in the overall performance of the polycarbonate composition.

[0024] In summary, this application has the following beneficial effects: The present invention introduces polysilazane into the polycarbonate composition, utilizes the endothermic effect of Si-N bond rupture to reduce the surface temperature of the material, dilutes the combustible gas and oxygen concentration with nitrogen to slow down the combustion rate, forms a protective layer to isolate oxygen and control the transfer of heat and combustible gas, and generates a high carbon residue rate to provide additional heat insulation and flame retardant effects, thereby significantly improving the flame retardant properties of the composition; The present application can effectively improve the compatibility between polysilazane and PC by adding ginkgo biloba ketone ester and R-3-hydroxybutyric acid-R-3-hydroxybutyl ester, so that the polysilazane is evenly dispersed in the composition, thereby improving the flame retardant effect of the polysilazane in the composition; The present application further improves the compatibility between polysilazane and PC by adding dimethyl biphenyl diisocyanate and tetramethyl benzyl diisocyanate in combination with ginkgo ketone ester and R-3-hydroxybutyric acid-R-3-hydroxybutyl ester. DETAILED DESCRIPTION

[0025] The raw materials in this application include the following parts: Polycarbonate (PC): a commercially available product with CAS No. 24936-68-3; Acrylonitrile butadiene styrene copolymer (ABS): a commercial product with CAS No. 9003-56-9; Polysilazane: a commercially available product with CAS No. 475645-84-2; MBS compatibilizer: a commercially available product with the brand name EM500 produced by LG Chemical Company of South Korea; Antioxidant: dilauryl thiodipropionate and distearate thiodipropionate, etc. can be used. This application uses the commercially available product of dilauryl thiodipropionate with CAS number 123-28-4; Lubricant: Oleamide and ethylene bis stearamide can be used. This application uses the commercially available oleamide product with CAS number 301-02-0; Ginkgo biloba ester: a commercially available product with CAS number 90045-36-6; R-3-hydroxybutyric acid-R-3-hydroxybutyl ester: a commercially available product with CAS number 1208313-97-6; Dimethylbiphenyl diisocyanate: a commercially available product with CAS number 91-97-4; Tetramethylxylylene diisocyanate: a commercially available product with CAS number 2778-42-9; The present application is further described in detail below in conjunction with embodiments and comparative examples.

[0026] Example 1 A method for preparing a highly flame retardant polycarbonate composition comprises the following steps: Step 1) 65 kg of PC, 30 kg of ABS, 8 kg of polysilazane, 3 kg of MBS-type compatibilizer, 0.7 kg of antioxidant, and 0.3 kg of lubricant were added into a high-speed mixer for blending, and mixed at 600 rpm for 10 minutes to obtain a uniform mixture.

[0027] Step 2) The mixed material is added into a twin-screw extruder for extrusion granulation. The screw extrusion granulation temperature is 250°C (230-260°C is acceptable) to obtain a highly flame-retardant polycarbonate composition.

[0028] Example 2 Example 2 Based on the preparation method of Example 1, the content of each component in the formula is adjusted, and the specific adjustments are shown in Table 1.

[0029] Example 3 Example 3 Based on the preparation method of Example 1, the content of each component in the formula is adjusted, and the specific adjustments are shown in Table 1.

[0030] Comparative Example 1 Comparative Example 1 Based on the preparation method of Example 1, the content of each component in the formula was adjusted, and the specific adjustments are shown in Table 1.

[0031] Table 1 Raw materials and performance test table of high flame retardant polycarbonate compositions of Examples 1-3 and Comparative Example 1

[0032] Performance testing The high flame retardant polycarbonate compositions of Examples 1-3 and Comparative Example 1 were subjected to the following performance tests, and the test results are shown in Table 1: Limiting oxygen index The highly flame retardant polycarbonate composition samples provided in Examples 1-3 and Comparative Example 1 of the present application were tested according to GB / T2406.2-2009 standard to test the limiting oxygen index of the highly flame retardant polycarbonate composition samples. The sample dimensions were: the test sample had a length of 100 mm, a width of 10 mm, and a thickness of 4 mm.

[0033] Note: The higher the limiting oxygen index, the better the flame retardant performance.

[0034] Referring to Table 1, by comparing Examples 1-3 and Comparative Example 1, it can be seen that the flame retardant properties of the highly flame retardant polycarbonate composition of Comparative Example 1 are much lower than those of the compositions of Examples 1-3, indicating that the introduction of polysilazane into the highly flame retardant polycarbonate composition can improve the flame retardant properties of the composition. This may be because the endothermic effect of the Si-N bond breakage of the polysilazane in Examples 1-3 reduces the surface temperature of the composition, and at the same time, the polysilazane decomposes and releases nitrogen to dilute the combustible gas and oxygen concentration, thereby slowing down the combustion rate, and at the same time, a protective layer is formed to isolate oxygen and control the transfer of heat and combustible gas, thereby improving the flame retardant properties of the composition.

[0035] In comparison, the highly flame-retardant polycarbonate composition of Example 1 has better flame-retardant properties and is preferred among Examples 1-3.

[0036] Example 4 Example 4 Based on the preparation method of Example 1, the amount of polysilazane added was adjusted, and the specific adjustment is shown in Table 2.

[0037] Example 5 Example 5 Based on the preparation method of Example 1, the amount of polysilazane added was adjusted, and the specific adjustment is shown in Table 2.

[0038] Example 6 Example 6 Based on the preparation method of Example 1, the amount of polysilazane added was adjusted, and the specific adjustment is shown in Table 2.

[0039] The high flame retardant polycarbonate compositions of Examples 4-6 were subjected to the above performance tests, and the test results are shown in Table 2.

[0040] Table 2 Addition amount and performance test table of polysilazane in Example 1, Examples 4-6

[0041] Referring to Table 2, by comparing Example 1 with Examples 4-6, it can be seen that as the amount of polysilazane added increases, the flame retardant properties of the highly flame-retardant polycarbonate composition show a trend of first increasing and then decreasing. This may be because as the amount of polysilazane added increases, the amount of heat that can be absorbed by polysilazane during the combustion of the polycarbonate composition increases, the nitrogen generated by decomposition also increases, and the generated protective layer has a better oxygen isolation effect, thereby making the flame retardant properties of the highly flame-retardant polycarbonate composition better; when the amount of polysilazane added exceeds a certain range, due to the poor compatibility between polysilazane and PC, excessively high content of polysilazane may cause uneven dispersion of polysilazane in the highly flame-retardant polycarbonate composition, thereby reducing the flame retardant properties of the highly flame-retardant polycarbonate composition.

[0042] Example 7 Example 7 Based on the preparation method of Example 1, in step 1), 1.2 kg of ginkgo biloba ketone ester and other raw materials are added into a high-speed mixer for blending to obtain a mixture, and other conditions remain unchanged.

[0043] Example 8 Example 8 Based on the preparation method of Example 1, in step 1), 1.2 kg of R-3-hydroxybutyric acid-R-3-hydroxybutyl ester is added into a high-speed mixer together with other raw materials for blending to obtain a mixture, and other conditions remain unchanged.

[0044] The high flame retardant polycarbonate compositions of Examples 7-8 were subjected to the above performance tests, and the test results are shown in Table 3.

[0045] Table 3 Performance test table of Example 1 and Examples 7-8

[0046] Referring to Table 3, it can be seen from the comparison between Example 1 and Examples 7-8 that the addition of ginkgo ketone ester and R-3-hydroxybutyric acid-R-3-hydroxybutyl ester to the highly flame retardant polycarbonate composition can effectively improve the flame retardant properties of the composition. This may be because the ketone group in the ginkgo ketone ester and R-3-hydroxybutyric acid-R-3-hydroxybutyl ester reacts with the polysilazane, and the ester group reacts with PC, thereby achieving a "bridge" effect, greatly improving the compatibility between polysilazane and polycarbonate, so that the polysilazane can be evenly dispersed in the highly flame retardant polycarbonate composition, thereby further improving the flame retardant properties of the composition.

[0047] Comparing Examples 7 and 8, it is found that the flame retardant property of the highly flame retardant polycarbonate composition of Example 7 is better than that of the composition of Example 8, and therefore Example 7 is preferred.

[0048] Example 9 Example 9 Based on the preparation method of Example 7, the amount of ginkgo biloba ester added was adjusted, and the specific adjustment is shown in Table 4.

[0049] Example 10 Example 10 Based on the preparation method of Example 7, the amount of ginkgo biloba ester added was adjusted, and the specific adjustment is shown in Table 4.

[0050] Embodiment 11 Example 11 Based on the preparation method of Example 7, the amount of ginkgo biloba ester added was adjusted, and the specific adjustment is shown in Table 4.

[0051] Example 12 Example 12 Based on the preparation method of Example 7, the amount of ginkgo biloba ester added was adjusted, and the specific adjustment is shown in Table 4.

[0052] The high flame retardant polycarbonate compositions of Examples 9-12 were subjected to the above performance tests, and the test results are shown in Table 4.

[0053] Table 4: Addition amount and performance test table of ginkgo biloba esters in Examples 7 and 9-12

[0054] Referring to Table 4, it can be seen from the comparison of Examples 7 and 9-12 that as the amount of ginkgo ketone ester added increases, the flame retardant properties of the highly flame retardant polycarbonate composition show a trend of increasing and then flattening. This may be because as the amount of ginkgo ketone ester added increases, the ketone group and ester group in the ginkgo ketone ester react with the polysilazane and the polycarbonate respectively and connect the two, thereby continuously improving the compatibility of the polysilazane and the polycarbonate, and then the polysilazane is evenly dispersed in the composition, so that the polysilazane can fully exert its flame retardant effect; When the addition amount of ginkgo ketone ester exceeds a certain range, the flame retardant properties of the highly flame retardant polycarbonate composition no longer continue to improve. This may be because the content of ginkgo ketone ester introduced into the composition is sufficient to evenly disperse the polysilazane in the composition, making it difficult to improve the flame retardant properties of the highly flame retardant polycarbonate composition.

[0055] Embodiment 13 Example 13 Based on the preparation method of Example 7, in step 1), 0.8 kg of dimethylbiphenyl diisocyanate is added into a high-speed mixer together with other raw materials for blending to obtain a mixture, and other conditions remain unchanged.

[0056] Embodiment 14 Example 14 Based on the preparation method of Example 7, in step 1), 0.8 kg of tetramethylxylene diisocyanate is added into a high-speed mixer together with other raw materials for blending to obtain a mixture, and other conditions remain unchanged.

[0057] The highly flame retardant polycarbonate composition samples provided in Examples 1, 7 and 13-14 of the present application were tested according to ISO 527-2 standard to test the tensile strength and elongation at break of the highly flame retardant polycarbonate composition samples. The sample dimensions were as follows: the test sample had a length of 170 mm, a width of 10 mm and a thickness of 4 mm.

[0058] The high flame retardant polycarbonate compositions of Examples 13-14 were subjected to performance tests, and the test results are shown in Table 5.

[0059] Table 5 Performance test table of Example 1, Example 7, and Examples 13-14

[0060] Referring to Table 5, by comparing Example 1, Example 7, and Examples 13-14, it can be seen that adding dimethyl diphenyl diisocyanate and tetramethyl benzyl diisocyanate to the highly flame retardant polycarbonate composition can effectively improve the flame retardant properties of the composition. This may be because multiple isocyanate groups in dimethyl diphenyl diisocyanate and tetramethyl benzyl diisocyanate can react with polysilazane and PC, respectively, to achieve the effect of a "bridge", thereby cooperating with ginkgo ketone ester and R-3-hydroxybutyric acid-R-3-hydroxybutyl ester to further improve the compatibility between polysilazane and polycarbonate, so that polysilazane can be dispersed more evenly in the highly flame retardant polycarbonate composition, thereby further improving the flame retardant properties of the composition.

[0061] In addition, by comparing Example 1, Example 7 and Examples 13-14, it can be seen that adding dimethyl diphenyl diisocyanate and tetramethyl benzyl diisocyanate to the highly flame retardant polycarbonate composition can improve the tensile strength and elongation at break of the composition. This may be because dimethyl diphenyl diisocyanate and tetramethyl benzyl diisocyanate penetrate into the defects and voids of the composition, making the microstructure of the composition more dense and uniform, thereby improving the tensile strength and elongation at break of the composition.

[0062] Comparing Examples 13 and 14, it is found that the flame retardant property of the highly flame retardant polycarbonate composition of Example 13 is better than that of the composition of Example 14, and therefore Example 13 is preferred.

[0063] Embodiment 15 Example 15 Based on the preparation method of Example 13, the addition amount of dimethylbiphenyl diisocyanate is adjusted, and the specific adjustment is shown in Table 6.

[0064] Example 16 Example 16 Based on the preparation method of Example 13, the addition amount of dimethylbiphenyl diisocyanate is adjusted, and the specific adjustment is shown in Table 6.

[0065] Embodiment 17 Example 17 Based on the preparation method of Example 13, the addition amount of dimethylbiphenyl diisocyanate is adjusted, and the specific adjustment is shown in Table 6.

[0066] Embodiment 18 Example 18 Based on the preparation method of Example 13, the addition amount of dimethylbiphenyl diisocyanate is adjusted, and the specific adjustment is shown in Table 6.

[0067] The high flame retardant polycarbonate compositions of Examples 15-18 were subjected to the above performance tests, and the test results are shown in Table 6.

[0068] Table 6 Addition amount and performance test data of dimethyl biphenyl diisocyanate in Example 13 and Examples 15-18

[0069] Referring to Table 6, it can be seen from the comparison of Example 13 and Examples 15-18 that as the amount of dimethyl diphenyl diisocyanate added continues to increase, the flame retardant properties of the highly flame retardant polycarbonate composition show a trend of continuously increasing and then tending to a flattening trend. This may be because as the amount of dimethyl diphenyl diisocyanate added continues to increase, the two isocyanate groups in the dimethyl diphenyl diisocyanate continue to react with the polysilazane and the polycarbonate respectively and connect the two, thereby further improving the compatibility of the polysilazane and the polycarbonate, thereby more evenly dispersing the polysilazane in the highly flame retardant polycarbonate composition, so that the polysilazane can more fully exert its flame retardant effect.

[0070] When the addition amount of dimethyl diphenyl diisocyanate exceeds a certain range, it is difficult to further improve the flame retardant properties of the highly flame retardant polycarbonate composition. This may be because the content of dimethyl diphenyl diisocyanate introduced into the highly flame retardant polycarbonate composition is sufficient to completely disperse the polysilazane in the composition, and therefore it is difficult to further improve the flame retardant properties of the composition.

[0071] In addition, by comparing Example 13 and Examples 15-18, it can be seen that as the amount of dimethyl diphenyl diisocyanate added continues to increase, the tensile strength and elongation at break of the high flame retardant polycarbonate composition both show a trend of continuously increasing and then tending to a flattening trend. This may be because as the amount of dimethyl diphenyl diisocyanate added continues to increase, dimethyl diphenyl diisocyanate continues to penetrate into the defects and voids of the composition, making the microstructure of the composition more dense and uniform.

[0072] When the addition amount of dimethyl diphenyl diisocyanate exceeds a certain range, the tensile strength and elongation at break of the highly flame retardant polycarbonate composition are difficult to continue to increase. This may be because the content of dimethyl diphenyl diisocyanate introduced into the highly flame retardant polycarbonate composition has fully filled the defects and gaps of the composition.

[0073] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A highly flame retardant polycarbonate composition, characterized in that: The invention comprises the following components in parts by weight: 65 parts of PC, 25-35 parts of ABS, 2-10 parts of polysilazane, 3-5 parts of MBS-type compatibilizer, 0.7 parts of antioxidant and 0.3 parts of lubricant.

2. The highly flame retardant polycarbonate composition according to claim 1, characterized in that: The weight portion of the polysilazane is 5-8 parts.

3. The highly flame retardant polycarbonate composition according to claim 1, characterized in that: It also includes at least one of ginkgo biloba ketone ester and R-3-hydroxybutyric acid-R-3-hydroxybutyl ester.

4. The highly flame retardant polycarbonate composition according to claim 3, characterized in that: Also included are Ginkgo biloba esters.

5. The highly flame retardant polycarbonate composition according to claim 4, characterized in that: The weight ratio of the polysilazane to the ginkgo ketone ester is 2:0.2-0.

3.

6. The highly flame retardant polycarbonate composition according to claim 3, characterized in that: It also includes at least one of dimethylbiphenyl diisocyanate and tetramethylxylylene diisocyanate.

7. The highly flame retardant polycarbonate composition according to claim 6, characterized in that: Also included is dimethylbiphenyl diisocyanate.

8. The highly flame retardant polycarbonate composition according to claim 7, characterized in that: The weight ratio of the polysilazane to dimethylbiphenyl diisocyanate is 2:0.1-0.

2.

9. The method for preparing the highly flame-retardant polycarbonate composition according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1) mixing the formulated amounts of PC, ABS, polysilazane, MBS-type compatibilizer, antioxidant, lubricant and other processing aids to obtain a mixture; Step 2) Extruding and granulating the mixed material to obtain the highly flame-retardant polycarbonate composition.

10. The method for preparing a highly flame-retardant polycarbonate composition according to claim 9, characterized in that: The temperature of the extrusion granulation in step 2) is 230-260°C.

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