High-thermal-conductivity flame-retardant polycarbonate and preparation method thereof

Abstract

The invention provides high-thermal-conductivity flame-retardant polycarbonate and a preparation method thereof, and belongs to the technical field of new materials. The material is prepared from the following raw materials in parts by weight: 40-60 parts of siloxane copolymerized polycarbonate resin, 15-20 parts of a heat-conducting flame-retardant modifier, 1-3 parts of a compatible modifier and 0.5-2 parts of an auxiliary agent, the heat-conducting flame-retardant modifier is a microsphere material formed by coupling an ionic liquid and a flame retardant on the surface of the Al2O3 carbon nanotube hollow microsphere. The high-thermal-conductivity flame-retardant polycarbonate prepared by the preparation method disclosed by the invention has better mechanical properties, obviously improved thermal conductivity and antistatic property, excellent flame retardance, better antibacterial property and wide application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of new materials, and in particular to a high thermal conductivity flame retardant polycarbonate and a preparation method thereof. Background Art

[0002] In recent years, electronic consumer products have developed rapidly. Laptop computers, flat-panel displays, thin-walled large televisions, digital cameras, and other handheld electronic devices require materials with high strength, flame retardancy, and easy processing properties. However, as molded products, existing products are prone to getting hot after prolonged use, discoloring and cracking after long-term use, and are prone to burning or explosion due to improper charging or use. Therefore, flame retardants and thermal conductive materials are usually added to the materials.

[0003] Existing technologies usually use flame retardants with plasticizing properties such as BDP and RDP, or brominated flame retardants and silicone and sulfonate flame retardants. These flame retardants make the final product vulnerable to processing temperatures and have poor processability. The flame retardants are easily hydrolyzed and easily precipitated on the surface of the product. The unstable flame retardancy has a great impact on product performance.

[0004] Chinese invention patent application CN114230999A discloses a halogen-free flame-retardant and antistatic polycarbonate resin composition. The composition comprises 55-85 parts by weight of polycarbonate resin; 5-20 parts by weight of ABS resin; 5-12 parts by weight of a phosphorus-nitrogen flame retardant; 2-5 parts by weight of a polyetheresteramide compound; and other additives. Because the composition contains a high amount of ABS, the overall heat resistance of the material is relatively low.

[0005] Therefore, it is necessary to develop a high thermal conductivity flame retardant polycarbonate material. Summary of the Invention

[0006] The purpose of the present invention is to provide a high thermal conductivity flame retardant polycarbonate and a preparation method thereof, which has good mechanical properties, significantly improved thermal conductivity and antistatic properties, excellent flame retardancy, and good antibacterial properties, and has broad application prospects.

[0007] The technical solution of the present invention is achieved as follows: The present invention provides a high thermal conductivity flame retardant polycarbonate, which is prepared from the following raw materials in parts by weight: 40-60 parts of a siloxane copolymerized polycarbonate resin, 15-20 parts of a thermal conductive flame retardant modifier, 1-3 parts of a compatibility modifier, and 0.5-2 parts of an auxiliary agent; the thermal conductive flame retardant modifier is a microsphere material in which an ionic liquid and a flame retardant are coupled to the surface of Al2O3@carbon nanotube hollow microspheres.

[0008] As a further improvement of the present invention, the preparation method of the thermal conductive flame retardant modifier is as follows: S1. Preparation of polymelamine - formaldehyde resin microspheres: Melamine, formaldehyde, polyvinyl alcohol, and citric acid were added to water, heated and stirred to react, centrifuged, washed, and dried to obtain polymelamine - formaldehyde resin microspheres; S2. Preparation of Al2O3@CNT hollow microspheres: Polymelamine-formaldehyde resin microspheres were added to an ethanol-water solution, followed by the addition of aluminum isopropoxide and nickel salt. The pH of the solution was adjusted and the mixture was stirred until uniform. The mixture was centrifuged, washed, dried, and calcined under inert gas to produce Al2O3@CNT hollow microspheres. S3. Preparation of modified microspheres: Al2O3@ carbon nanotube hollow microspheres were added to ethanol, a silane coupling agent was added, the reaction was heated and stirred, centrifuged, washed, and dried to obtain modified microspheres; S4. Coupling of ionic liquids: The ionic liquid and modified microspheres were added to water, an initiator was added, the reaction was heated and stirred, centrifuged, washed, and dried to obtain ionic liquid @ modified microspheres; S5. Flame retardant coupling reaction: Biphenol, a base, and phosphorus oxychloride are reacted to produce an intermediate. The intermediate, ionic liquid@modified microspheres, and a base are then mixed and reacted to produce a thermally conductive flame retardant modifier.

[0009] As a further improvement of the present invention, the mass ratio of melamine, formaldehyde, polyvinyl alcohol and citric acid in step S1 is 2-4:2-4:0.4-0.6:0.2-0.4, and the temperature of the heating and stirring reaction is 75-85° C. and the time is 15-25 minutes.

[0010] As a further improvement of the present invention, the mass ratio of the polymelamine-formaldehyde resin microspheres, aluminum isopropoxide and nickel salt in step S2 is 15-25:17-30:2-4, the nickel salt is nickel chloride, nickel sulfate or nickel nitrate, the pH value of the adjustment solution is 5-6, the calcination temperature is 850-950°C, and the time is 1-2h.

[0011] As a further improvement of the present invention, the mass ratio of the Al2O3@carbon nanotube hollow microspheres and the silane coupling agent in step S3 is 10:2-3, the silane coupling agent includes KH550 and KH570 in a mass ratio of 2-3:5-7, and the temperature of the heating and stirring reaction is 45-55°C and the time is 2-4h.

[0012] As a further improvement of the present invention, the mass ratio of the ionic liquid, modified microspheres and initiator in step S4 is 2-3:10-12:0.01-0.015, the ionic liquid is 1-vinyl-3-ethylimidazole tetrafluoroborate, the initiator is selected from at least one of potassium persulfate, sodium persulfate and ammonium persulfate, and the temperature of the heating and stirring reaction is 60-70°C and the time is 3-5 hours.

[0013] As a further improvement of the present invention, the molar ratio of biphenol, base and phosphorus oxychloride in step S5 is 1:2-4:1-1.1, the reaction temperature is 100-110°C, the time is 4-6h, the mass ratio of the intermediate, ionic liquid@modified microspheres and base is 3-5:13-15:4-6, the reaction temperature is 70-80°C, the time is 2-4h, and the base is triethylamine or NaOH.

[0014] As a further improvement of the present invention, the compatibility modifier is silicone rubber; the auxiliary agents include polyethylene wax, antioxidant 1010, and polytetrafluoroethylene, with a mass ratio of 2-5:1-3:2-4.

[0015] The present invention further protects a method for preparing the above-mentioned high thermal conductivity flame retardant polycarbonate, comprising the following steps: heating and melting a siloxane copolymerized polycarbonate resin, adding a compatibilizer, an auxiliary agent and a thermal conductive flame retardant modifier, stirring and mixing evenly, extruding and granulating, drying, and injection molding to obtain the high thermal conductive flame retardant polycarbonate.

[0016] As a further improvement of the present invention, the melting temperature is 270-280°C.

[0017] The present invention has the following beneficial effects: The invention prepares a thermally conductive flame-retardant modifier. First, polymelamine-formaldehyde resin microspheres are prepared. Then, a layer of aluminum hydroxide is coated on the surface of the microspheres through a sol-gel reaction and nickel metal ions are adsorbed. The microspheres are calcined under the protection of an inert gas. The polymelamine-formaldehyde resin is thermally decomposed into CO and NH3. Both are strongly reducing gases and can reduce nickel metal ions to single-atom nickel metal and partially reduce aluminum oxide. Under the catalytic action of a metal catalyst, CO is used as a carbon source and carbon nanotubes are generated by in-situ chemical vapor deposition. Thus, metal-atom-doped Al2O3@carbon nanotube hollow microspheres are prepared. The microspheres have good electrical and thermal conductivity and good flame retardancy. The surfaces are modified with a silane coupling agent to have amino groups and double bonds. The microspheres can be double-bonded copolymerized with the ionic liquid 1-vinyl-3-ethylimidazole tetrafluoroborate, thereby improving the antistatic property and flame retardancy of the material. The amino groups can form hydrogen bonds with the polycarbonate resin, thereby improving the compatibility with the substrate and improving the mechanical properties of the resin.

[0018] The invention uses biphenol as a raw material to first undergo a nucleophilic substitution reaction with phosphorus oxychloride to obtain 5,7-dioxa-diphenyl-substituted-cycloheptene phosphoryl chloride, and further undergoes a nucleophilic substitution reaction coupling with the imidazole group of the ionic liquid and the amino group on the surface under alkaline conditions to obtain a thermal conductive flame retardant modifier with a quaternary ammonium salt structure and an imidazole group structure, thereby improving the antibacterial and flame retardancy of the prepared polycarbonate resin.

[0019] The high thermal conductivity and flame retardant polycarbonate prepared by the present invention has good mechanical properties, significantly improved thermal conductivity and antistatic properties, and excellent flame retardancy. At the same time, it has good antibacterial properties and has broad application prospects. DETAILED DESCRIPTION

[0020] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0021] Preparation Example 1 Preparation of thermally conductive flame retardant modifier Here’s how: Preparation of polymelamine-formaldehyde resin microspheres: 2 g of melamine, 2 g of formaldehyde, 0.4 g of polyvinyl alcohol, and 0.2 g of citric acid were added to 150 mL of water, heated to 75°C, stirred for 15 minutes, centrifuged, washed, and dried to produce polymelamine-formaldehyde resin microspheres. S2. Preparation of Al2O3@CNT hollow microspheres: 1.5 g of polymelamine-formaldehyde resin microspheres were added to a 150 mL ethanol-water solution. 1.7 g of aluminum isopropoxide and 0.2 g of nickel chloride were added. The solution was adjusted to pH 5 and stirred to mix thoroughly. The mixture was centrifuged, washed, dried, and calcined at 850°C under nitrogen for 1 h to produce Al2O3@CNT hollow microspheres. S3. Preparation of modified microspheres: 1 g of Al2O3@CNT hollow microspheres was added to 100 ml of ethanol, 0.2 g of a silane coupling agent was added, and the mixture was heated to 45°C and stirred for 2 h. The mixture was centrifuged, washed, and dried to obtain modified microspheres. The silane coupling agent includes KH550 and KH570, with a mass ratio of 2:5; S4. Ionic liquid coupling: 0.2 g of 1-vinyl-3-ethylimidazolium tetrafluoroborate and 1 g of modified microspheres were added to 150 mL of water. Under nitrogen, 0.001 g of sodium persulfate was added. The mixture was heated to 60°C and stirred for 3 h. The reaction was centrifuged, washed, and dried to obtain ionic liquid@modified microspheres. S5. Flame retardant coupling reaction: 0.1 mol of biphenyl diphenol, 0.2 mol of triethylamine, and 0.1 mol of phosphorus oxychloride were mixed and added to 200 mL of toluene. The mixture was heated to 100°C and stirred for 4 h. The mixture was distilled under reduced pressure to obtain an intermediate. Then, 0.3 g of the intermediate, 1.3 g of ionic liquid@modified microspheres, and 0.4 g of triethylamine were mixed and added to 200 mL of toluene. The mixture was heated to 70°C and stirred for 2 h. The mixture was centrifuged, washed, and dried to obtain a thermally conductive flame retardant modifier.

[0022] Preparation Example 2 Preparation of thermally conductive flame retardant modifier Here’s how: Preparation of polymelamine-formaldehyde resin microspheres: 4 g of melamine, 4 g of formaldehyde, 0.6 g of polyvinyl alcohol, and 0.4 g of citric acid were added to 150 mL of water, heated to 85°C, stirred for 25 min, centrifuged, washed, and dried to produce polymelamine-formaldehyde resin microspheres. S2. Preparation of Al2O3@CNT hollow microspheres: 2.5 g of polymelamine-formaldehyde resin microspheres were added to a 150 mL ethanol-water solution. 3 g of aluminum isopropoxide and 0.4 g of nickel sulfate were added. The solution was adjusted to pH 6 and stirred to mix thoroughly. The mixture was centrifuged, washed, dried, and calcined at 950°C under nitrogen for 2 h to produce Al2O3@CNT hollow microspheres. S3. Preparation of modified microspheres: 1 g of Al2O3@CNT hollow microspheres was added to 100 ml of ethanol, 0.2 g of a silane coupling agent was added, and the mixture was heated to 55°C and stirred for 4 h. The mixture was centrifuged, washed, and dried to obtain modified microspheres. The silane coupling agent includes KH550 and KH570, with a mass ratio of 3:7; S4. Ionic liquid coupling: 0.3 g of 1-vinyl-3-ethylimidazolium tetrafluoroborate and 1.2 g of modified microspheres were added to 150 mL of water. Under nitrogen, 0.0015 g of ammonium persulfate was added. The reaction was heated to 70°C and stirred for 5 h. The reaction was centrifuged, washed, and dried to obtain ionic liquid-modified microspheres. S5. Flame retardant coupling reaction: 0.1 mol of biphenyl diphenol, 0.4 mol of NaOH, and 0.11 mol of phosphorus oxychloride were mixed and added to 200 mL of toluene. The mixture was heated to 110°C and stirred for 6 h. The mixture was then distilled under reduced pressure to obtain an intermediate. 0.5 g of the intermediate, 1.5 g of ionic liquid@modified microspheres, and 0.6 g of NaOH were then added to 200 mL of toluene. The mixture was heated to 80°C and stirred for 4 h. The mixture was centrifuged, washed, and dried to obtain a thermally conductive flame retardant modifier.

[0023] Preparation Example 3 Preparation of thermally conductive flame retardant modifier Here’s how: S1. Preparation of polymelamine-formaldehyde resin microspheres: 3 g of melamine, 3 g of formaldehyde, 0.5 g of polyvinyl alcohol, and 0.3 g of citric acid were added to 150 mL of water, heated to 80°C, stirred for 20 min, centrifuged, washed, and dried to produce polymelamine-formaldehyde resin microspheres. S2. Preparation of Al2O3@CNT hollow microspheres: 2 g of polymelamine-formaldehyde resin microspheres were added to a 150 mL ethanol-water solution. 2.5 g of aluminum isopropoxide and 0.3 g of nickel nitrate were added. The pH of the solution was adjusted to 5.5. The mixture was stirred and thoroughly mixed. The mixture was centrifuged, washed, dried, and calcined at 900°C under nitrogen for 1.5 h to produce Al2O3@CNT hollow microspheres. S3. Preparation of modified microspheres: 1 g of Al2O3@CNT hollow microspheres was added to 100 ml of ethanol, 0.2 g of a silane coupling agent was added, and the mixture was heated to 50°C and stirred for 3 h. The mixture was centrifuged, washed, and dried to obtain modified microspheres. The silane coupling agent includes KH550 and KH570, with a mass ratio of 2.5:6; S4. Ionic liquid coupling: 0.25 g of 1-vinyl-3-ethylimidazolium tetrafluoroborate and 1.1 g of modified microspheres were added to 150 mL of water. Under nitrogen, 0.0012 g of potassium persulfate was added. The mixture was heated to 65°C and stirred for 4 h. The reaction was centrifuged, washed, and dried to obtain ionic liquid-modified microspheres. S5. Flame retardant coupling reaction: 0.1 mol of biphenyl diphenol, 0.3 mol of triethylamine, and 0.105 mol of phosphorus oxychloride were mixed and added to 200 mL of toluene. The mixture was heated to 105°C and stirred for 5 h. The mixture was distilled under reduced pressure to obtain an intermediate. 0.4 g of the intermediate, 1.4 g of ionic liquid@modified microspheres, and 0.5 g of triethylamine were then mixed and added to 200 mL of toluene. The mixture was heated to 75°C and stirred for 3 h. The mixture was centrifuged, washed, and dried to obtain a thermally conductive flame retardant modifier.

[0024] Comparative Preparation Example 1 Compared with Preparation Example 3, the difference is that step S1 is not performed.

[0025] The details are as follows: S1. Preparation of Al2O3 microspheres: 4.8 g of aluminum isopropoxide was added to 150 mL of an ethanol-water solution, the pH of the solution was adjusted to 5.5, and the mixture was stirred and mixed thoroughly. The mixture was centrifuged, washed, dried, and calcined at 900°C for 1.5 h under nitrogen to produce Al2O3 microspheres. S2. Preparation of modified microspheres: 1 g of Al2O3 microspheres was added to 100 m ethanol, 0.2 g of a silane coupling agent was added, the mixture was heated to 50°C, stirred for 3 h, centrifuged, washed, and dried to obtain modified microspheres. The silane coupling agent includes KH550 and KH570, with a mass ratio of 2.5:6; S3. Ionic liquid coupling: 0.25 g of 1-vinyl-3-ethylimidazolium tetrafluoroborate and 1.1 g of modified microspheres were added to 150 mL of water. Under nitrogen, 0.0012 g of potassium persulfate was added. The mixture was heated to 65°C and stirred for 4 h. The reaction was centrifuged, washed, and dried to obtain ionic liquid-modified microspheres. S4. Flame retardant coupling reaction: 0.1 mol of biphenyl diphenol, 0.3 mol of triethylamine, and 0.105 mol of phosphorus oxychloride were mixed and added to 200 mL of toluene. The mixture was heated to 105°C and stirred for 5 h. The mixture was distilled under reduced pressure to obtain an intermediate. Then, 0.4 g of the intermediate, 1.4 g of ionic liquid@modified microspheres, and 0.5 g of triethylamine were mixed and added to 200 mL of toluene. The mixture was heated to 75°C and stirred for 3 h. The mixture was centrifuged, washed, and dried to obtain a thermally conductive flame retardant modifier.

[0026] Comparative Preparation Example 2 Compared with Preparation Example 3, the difference is that aluminum isopropoxide is not added in step S2.

[0027] The details are as follows: S1. Preparation of polymelamine-formaldehyde resin microspheres: 3 g of melamine, 3 g of formaldehyde, 0.5 g of polyvinyl alcohol, and 0.3 g of citric acid were added to 150 mL of water, heated to 80°C, stirred for 20 min, centrifuged, washed, and dried to produce polymelamine-formaldehyde resin microspheres. S2. Preparation of Al2O3@CNT hollow microspheres: 2 g of polymelamine-formaldehyde resin microspheres were added to a 150 mL ethanol-water solution. 2.5 g of aluminum isopropoxide and 0.3 g of nickel nitrate were added. The pH of the solution was adjusted to 5.5. The mixture was stirred and thoroughly mixed. The mixture was centrifuged, washed, dried, and calcined at 900°C under nitrogen for 1.5 h to produce Al2O3@CNT hollow microspheres. S3. Preparation of modified microspheres: 1 g of Al2O3@CNT hollow microspheres was added to 100 ml of ethanol, 0.2 g of a silane coupling agent was added, and the mixture was heated to 50°C and stirred for 3 h. The mixture was centrifuged, washed, and dried to obtain modified microspheres. The silane coupling agent includes KH550 and KH570, with a mass ratio of 2.5:6; S4. Ionic liquid coupling: 0.25 g of 1-vinyl-3-ethylimidazolium tetrafluoroborate and 1.1 g of modified microspheres were added to 150 mL of water. Under nitrogen, 0.0012 g of potassium persulfate was added. The mixture was heated to 65°C and stirred for 4 h. The reaction was centrifuged, washed, and dried to obtain ionic liquid-modified microspheres. S5. Flame retardant coupling reaction: 0.1 mol of biphenyl diphenol, 0.3 mol of triethylamine, and 0.105 mol of phosphorus oxychloride were mixed and added to 200 mL of toluene. The mixture was heated to 105°C and stirred for 5 h. The mixture was distilled under reduced pressure to obtain an intermediate. 0.4 g of the intermediate, 1.4 g of ionic liquid@modified microspheres, and 0.5 g of triethylamine were then mixed and added to 200 mL of toluene. The mixture was heated to 75°C and stirred for 3 h. The mixture was centrifuged, washed, and dried to obtain a thermally conductive flame retardant modifier.

[0028] Comparative Preparation Example 3 Compared with Preparation Example 3, the difference is that the silane coupling agent is a single KH550.

[0029] Comparative Preparation Example 4 Compared with Preparation Example 3, the difference is that the silane coupling agent is a single KH570.

[0030] Comparative Preparation Example 5 Compared with Preparation Example 3, the difference is that step S3 is not performed.

[0031] The details are as follows: S1. Preparation of polymelamine-formaldehyde resin microspheres: 3 g of melamine, 3 g of formaldehyde, 0.5 g of polyvinyl alcohol, and 0.3 g of citric acid were added to 150 mL of water, heated to 80°C, stirred for 20 min, centrifuged, washed, and dried to produce polymelamine-formaldehyde resin microspheres. S2. Preparation of Al2O3@CNT hollow microspheres: 2 g of polymelamine-formaldehyde resin microspheres were added to a 150 mL ethanol-water solution. 2.5 g of aluminum isopropoxide and 0.3 g of nickel nitrate were added. The pH of the solution was adjusted to 5.5. The mixture was stirred and thoroughly mixed. The mixture was centrifuged, washed, dried, and calcined at 900°C under nitrogen for 1.5 h to produce Al2O3@CNT hollow microspheres. S3. Ionic liquid coupling: 0.25 g of 1-vinyl-3-ethylimidazolium tetrafluoroborate and 1.1 g of Al2O3@carbon nanotube hollow microspheres were added to 150 mL of water. Under nitrogen, 0.0012 g of potassium persulfate was added. The mixture was heated to 65°C and stirred for 4 h. The reaction was centrifuged, washed, and dried to produce ionic liquid@microspheres. S4. Flame retardant coupling reaction: 0.1 mol of biphenyl diphenol, 0.3 mol of triethylamine, and 0.105 mol of phosphorus oxychloride were mixed and added to 200 mL of toluene. The mixture was heated to 105°C and stirred for 5 h. The mixture was distilled under reduced pressure to obtain an intermediate. Then, 0.4 g of the intermediate, 1.4 g of ionic liquid@microspheres, and 0.5 g of triethylamine were mixed and added to 200 mL of toluene. The mixture was heated to 75°C and stirred for 3 h. The mixture was centrifuged, washed, and dried to obtain a thermally conductive flame retardant modifier.

[0032] Comparative Preparation Example 6 Compared with Preparation Example 3, the difference is that step S4 is not performed.

[0033] The details are as follows: S1. Preparation of polymelamine-formaldehyde resin microspheres: 3 g of melamine, 3 g of formaldehyde, 0.5 g of polyvinyl alcohol, and 0.3 g of citric acid were added to 150 mL of water, heated to 80°C, stirred for 20 min, centrifuged, washed, and dried to produce polymelamine-formaldehyde resin microspheres. S2. Preparation of Al2O3@CNT hollow microspheres: 2 g of polymelamine-formaldehyde resin microspheres were added to a 150 mL ethanol-water solution. 2.5 g of aluminum isopropoxide and 0.3 g of nickel nitrate were added. The pH of the solution was adjusted to 5.5. The mixture was stirred and thoroughly mixed. The mixture was centrifuged, washed, dried, and calcined at 900°C under nitrogen for 1.5 h to produce Al2O3@CNT hollow microspheres. S3. Preparation of modified microspheres: 1 g of Al2O3@CNT hollow microspheres was added to 100 ml of ethanol, 0.2 g of a silane coupling agent was added, and the mixture was heated to 50°C and stirred for 3 h. The mixture was centrifuged, washed, and dried to obtain modified microspheres. The silane coupling agent includes KH550 and KH570, with a mass ratio of 2.5:6; S4. Flame retardant coupling reaction: 0.1 mol of biphenyl diphenol, 0.3 mol of triethylamine and 0.105 mol of phosphorus oxychloride were mixed and added to 200 mL of toluene. The mixture was heated to 105°C and stirred for 5 h. The mixture was distilled under reduced pressure to obtain an intermediate. Then, 0.4 g of the intermediate, 1.4 g of modified microspheres and 0.5 g of triethylamine were mixed and added to 200 mL of toluene. The mixture was heated to 75°C and stirred for 3 h. The mixture was centrifuged, washed and dried to obtain a thermally conductive flame retardant modifier.

[0034] Comparative Preparation Example 7 Compared with Preparation Example 3, the difference is that step S5 is not performed.

[0035] The details are as follows: S1. Preparation of polymelamine-formaldehyde resin microspheres: 3 g of melamine, 3 g of formaldehyde, 0.5 g of polyvinyl alcohol, and 0.3 g of citric acid were added to 150 mL of water, heated to 80°C, stirred for 20 min, centrifuged, washed, and dried to produce polymelamine-formaldehyde resin microspheres. S2. Preparation of Al2O3@CNT hollow microspheres: 2 g of polymelamine-formaldehyde resin microspheres were added to a 150 mL ethanol-water solution. 2.5 g of aluminum isopropoxide and 0.3 g of nickel nitrate were added. The pH of the solution was adjusted to 5.5. The mixture was stirred and thoroughly mixed. The mixture was centrifuged, washed, dried, and calcined at 900°C under nitrogen for 1.5 h to produce Al2O3@CNT hollow microspheres. S3. Preparation of modified microspheres: 1 g of Al2O3@CNT hollow microspheres was added to 100 ml of ethanol, 0.2 g of a silane coupling agent was added, and the mixture was heated to 50°C and stirred for 3 h. The mixture was centrifuged, washed, and dried to obtain modified microspheres. The silane coupling agent includes KH550 and KH570, with a mass ratio of 2.5:6; S4. Coupling of ionic liquids: 0.25 g of 1-vinyl-3-ethylimidazolium tetrafluoroborate and 1.1 g of modified microspheres were added to 150 mL of water. Under nitrogen, 0.0012 g of potassium persulfate was added. The mixture was heated to 65°C and stirred for 4 h. The mixture was centrifuged, washed, and dried to produce a thermally conductive flame retardant modifier.

[0036] Example 1 This embodiment provides a highly thermally conductive flame-retardant polycarbonate, which is prepared from the following raw materials in parts by weight: 40 parts of siloxane copolymerized polycarbonate resin, 15 parts of the thermal conductive flame-retardant modifier prepared in Preparation Example 1, 1 part of a compatibilizer, and 0.5 parts of an auxiliary agent; the auxiliary agent includes polyethylene wax, antioxidant 1010, and polytetrafluoroethylene, with a mass ratio of 2:1:2.

[0037] The preparation method comprises the following steps: heating siloxane copolymerized polycarbonate resin to 270°C to melt, adding silicone rubber, additives and thermal conductive flame retardant modifier, stirring and mixing evenly, extruding granulation, drying, and injection molding to obtain high thermal conductive flame retardant polycarbonate.

[0038] Example 2 This embodiment provides a highly thermally conductive flame-retardant polycarbonate, which is prepared from the following raw materials in parts by weight: 60 parts of siloxane copolymerized polycarbonate resin, 20 parts of the thermal conductive flame-retardant modifier prepared in Preparation Example 2, 3 parts of a compatibility modifier, and 2 parts of an auxiliary agent; the auxiliary agent includes polyethylene wax, antioxidant 1010, and polytetrafluoroethylene, with a mass ratio of 5:3:4.

[0039] The preparation method comprises the following steps: heating siloxane copolymerized polycarbonate resin to 280°C to melt, adding silicone rubber, additives and thermal conductive flame retardant modifier, stirring and mixing evenly, extruding granulation, drying, and injection molding to obtain high thermal conductive flame retardant polycarbonate.

[0040] Example 3 This embodiment provides a highly thermally conductive flame-retardant polycarbonate, which is prepared from the following raw materials in parts by weight: 50 parts of siloxane copolymerized polycarbonate resin, 17 parts of the thermal conductive flame-retardant modifier prepared in Preparation Example 3, 2 parts of a compatibilizer, and 1 part of an auxiliary agent; the auxiliary agent includes polyethylene wax, antioxidant 1010, and polytetrafluoroethylene, with a mass ratio of 3:2:3.

[0041] The preparation method comprises the following steps: heating siloxane copolymerized polycarbonate resin to 275°C to melt, adding silicone rubber, additives and thermal conductive flame retardant modifier, stirring and mixing evenly, extruding granulation, drying, and injection molding to obtain high thermal conductive flame retardant polycarbonate.

[0042] Comparative Example 1 Compared with Example 3, the difference is that the thermal conductive flame retardant modifier is prepared by Comparative Preparation Example 1.

[0043] Comparative Example 2 Compared with Example 3, the difference is that the thermal conductive flame retardant modifier is prepared by Comparative Preparation Example 2.

[0044] Comparative Example 3 Compared with Example 3, the difference is that the thermal conductive flame retardant modifier is prepared by Comparative Preparation Example 3.

[0045] Comparative Example 4 Compared with Example 3, the difference is that the thermal conductive flame retardant modifier is prepared by Comparative Preparation Example 4.

[0046] Comparative Example 5 Compared with Example 3, the difference is that the thermal conductive flame retardant modifier is prepared by Comparative Preparation Example 5.

[0047] Comparative Example 6 Compared with Example 3, the difference is that the thermal conductive flame retardant modifier is prepared by Comparative Preparation Example 6.

[0048] Comparative Example 7 Compared with Example 3, the difference is that the thermal conductive flame retardant modifier is prepared by Comparative Preparation Example 7.

[0049] Test Example 1 The high thermal conductive flame retardant polycarbonates prepared in Examples 1-3 and Comparative Examples 1-7 were subjected to performance tests. The results are shown in Table 1.

[0050] (1) Yield strength and elongation at break are tested in accordance with the provisions of GB / T1040.2-2006, with a test speed of 50 mm / min; (2) Notched impact strength is tested in accordance with the provisions of GB / T1843-2008, and the notch type is type A; (3) HDT (heat deformation temperature) is tested in accordance with the provisions of GB / T1634.2-2004, with a load of 1.8 MPa; (4) Antistatic performance: Surface resistivity is tested according to ASTM D257.

[0051] Table 1

[0052] It can be seen from the above table that the high thermal conductivity flame retardant polycarbonate prepared in Examples 1-3 of the present invention has good comprehensive properties.

[0053] Test Example 2 The high thermal conductivity and flame retardant polycarbonates prepared in Examples 1-3 and Comparative Examples 1-7 were tested for thermal conductivity and flame retardancy. The results are shown in Table 2.

[0054] (1) Thermal conductivity (TC) was measured using an Elmer Pyris thermal conductivity probe and reported in Watts per Kelvin-meter (W / mK). Measurements were performed on injection-molded sheets at room temperature. (2) Limiting oxygen index (LOI): tested in accordance with GB / T 2406.2-2009, sample size is 80mm×10mm×4mm.

[0055] (3) Vertical burning performance: tested in accordance with GB / T 2408-2021, sample size is 125 mm × 12.5 mm × 3.2 mm.

[0056] Table 2

[0057] It can be seen from the above table that the high thermal conductivity and flame retardant polycarbonate prepared in Examples 1-3 of the present invention has good thermal conductivity and flame retardant effects.

[0058] Test Example 3 The high thermal conductive flame retardant polycarbonates prepared in Examples 1-3 and Comparative Examples 1-7 were subjected to antibacterial tests. The results are shown in Table 3.

[0059] The test was conducted according to the test method 1 of GB 21551.2-2010, and the bacteria used for detection were: Escherichia coli (ATCC25922), Staphylococcus aureus (ATCC6538) and Candida albicans (ATCC10231); 5 samples were tested in parallel for each embodiment and comparative example, and the average value was taken.

[0060] The results are shown in Table 3.

[0061]

[0062] It can be seen from the above table that the high thermal conductivity flame retardant polycarbonate prepared in Examples 1-3 of the present invention has good antibacterial effect.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A highly thermally conductive flame-retardant polycarbonate, characterized in that: The invention is prepared from the following raw materials in parts by weight: 40-60 parts of siloxane copolymerized polycarbonate resin, 15-20 parts of thermal conductive flame retardant modifier, 1-3 parts of compatibility modifier, and 0.5-2 parts of auxiliary agent; the thermal conductive flame retardant modifier is a microsphere material in which an ionic liquid and a flame retardant are coupled on the surface of Al2O3@carbon nanotube hollow microspheres.

2. The high thermal conductivity flame retardant polycarbonate according to claim 1, characterized in that: The preparation method of the thermal conductive flame retardant modifier is as follows: S1. Preparation of polymelamine - formaldehyde resin microspheres: Melamine, formaldehyde, polyvinyl alcohol, and citric acid were added to water, heated and stirred to react, centrifuged, washed, and dried to obtain polymelamine - formaldehyde resin microspheres; S2. Preparation of Al2O3@CNT hollow microspheres: Polymelamine-formaldehyde resin microspheres were added to an ethanol-water solution, followed by the addition of aluminum isopropoxide and nickel salt. The pH of the solution was adjusted and the mixture was stirred until uniform. The mixture was centrifuged, washed, dried, and calcined under inert gas to produce Al2O3@CNT hollow microspheres. S3. Preparation of modified microspheres: Al2O3@ carbon nanotube hollow microspheres were added to ethanol, a silane coupling agent was added, the reaction was heated and stirred, centrifuged, washed, and dried to obtain modified microspheres; S4. Coupling of ionic liquids: The ionic liquid and modified microspheres were added to water, an initiator was added, the reaction was heated and stirred, centrifuged, washed, and dried to obtain ionic liquid @ modified microspheres; S5. Flame retardant coupling reaction: Biphenol, a base, and phosphorus oxychloride are reacted to produce an intermediate. The intermediate, ionic liquid@modified microspheres, and a base are then mixed and reacted to produce a thermally conductive flame retardant modifier.

3. The high thermal conductivity flame retardant polycarbonate according to claim 2, characterized in that: In step S1, the mass ratio of melamine, formaldehyde, polyvinyl alcohol and citric acid is 2-4:2-4:0.4-0.6:0.2-0.4, and the temperature of the heating and stirring reaction is 75-85° C. and the time is 15-25 minutes.

4. The high thermal conductivity flame retardant polycarbonate according to claim 2, characterized in that: In step S2, the mass ratio of the polymelamine-formaldehyde resin microspheres, aluminum isopropoxide and nickel salt is 15-25:17-30:2-4, the nickel salt is nickel chloride, nickel sulfate or nickel nitrate, the pH value of the adjusted solution is 5-6, the calcination temperature is 850-950° C., and the time is 1-2 hours.

5. The high thermal conductivity flame retardant polycarbonate according to claim 2, characterized in that: In step S3, the mass ratio of the Al2O3@ carbon nanotube hollow microspheres to the silane coupling agent is 10:2-3, the silane coupling agent includes KH550 and KH570, and the mass ratio is 2-3:5-7. The temperature of the heating and stirring reaction is 45-55°C and the time is 2-4h.

6. The high thermal conductivity flame retardant polycarbonate according to claim 2, characterized in that: In step S4, the mass ratio of the ionic liquid, modified microspheres and initiator is 2-3:10-12:0.01-0.015, the ionic liquid is 1-vinyl-3-ethylimidazolium tetrafluoroborate, the initiator is selected from at least one of potassium persulfate, sodium persulfate and ammonium persulfate, the temperature of the heating and stirring reaction is 60-70° C., and the time is 3-5 hours.

7. The high thermal conductivity flame retardant polycarbonate according to claim 2, characterized in that: In step S5, the molar ratio of biphenol, base and phosphorus oxychloride is 1:2-4:1-1.1, the reaction temperature is 100-110°C, the time is 4-6 hours, the mass ratio of the intermediate, ionic liquid@modified microspheres and base is 3-5:13-15:4-6, the reaction temperature is 70-80°C, the time is 2-4 hours, and the base is triethylamine or NaOH.

8. The high thermal conductivity flame retardant polycarbonate according to claim 1, characterized in that: The compatibility modifier is silicone rubber; the auxiliary agents include polyethylene wax, antioxidant 1010, and polytetrafluoroethylene, with a mass ratio of 2-5:1-3:2-4.

9. A method for preparing the highly thermally conductive flame-retardant polycarbonate according to any one of claims 1 to 8, characterized in that: The following steps are involved: The siloxane copolymerized polycarbonate resin is heated and melted, a compatibility modifier, an auxiliary agent and a thermal conductive flame retardant modifier are added, the mixture is stirred and evenly mixed, extruded into granules, dried and injection molded to obtain a high thermal conductive flame retardant polycarbonate.

10. The preparation method according to claim 9, characterized in that The melting temperature is 270-280°C.

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