A flame retardant PC composite material and its preparation method

Abstract

The present invention relates to the field of flame retardant materials, and specifically relates to a flame retardant PC composite material and a preparation method thereof. Graphite-modified polycarbonate in the present invention can improve the flame retardant properties of the polycarbonate, and the holes formed when heated can play the role of smoke elimination and heat preservation, and also make the overall compatibility better and the dispersion uniform, thereby improving the mechanical properties of the composite material. In addition, a compound of modified organic silicon balls D and modified nano silicon balls A can be used to quench the combustion chain reaction and isolate oxygen to achieve flame retardancy, and can also toughen and strengthen the polycarbonate base material. The holes in the modified carbon balls C can be used for rapid heat dissipation to prevent continued combustion, and can also dilute the oxygen that the blocking layer fails to isolate. The modified nano silicon balls B can be used for flame retardancy and smoke elimination, and can also compensate for the defect of decreased mechanical properties of the composite material caused by the formation of holes in the system, so that the composite material achieves flame retardancy and good smoke elimination while having strong mechanical properties.

Description

Technical Field

[0001] The present invention relates to the field of flame retardant materials, and in particular to a flame retardant PC composite material and a preparation method thereof. Background Art

[0002] Polycarbonate (PC) is a highly transparent amorphous thermoplastic and one of the five major engineering plastics. It has excellent mechanical properties, electrical properties, and oxidation resistance, and is widely used in industries and products such as electronics, home appliances, power tools, batteries, charging stations, and laptops. Although polycarbonate has certain flame retardancy properties, its flame retardancy still needs to be further improved in certain specific areas.

[0003] At present, traditional polycarbonate flame retardants mainly include brominated flame retardants, nitrogen-phosphorus flame retardants, sulfonates, etc. Among them, brominated flame retardants are restricted due to their high pollution when used. Therefore, it is necessary to develop new halogen-free flame retardants for polycarbonate. However, due to the addition of a large amount of additives to some existing flame-retardant polycarbonates, although the flame retardancy is improved to a certain extent, the excessive use of additives leads to a decrease in the heat resistance and mechanical properties of the polycarbonate composite materials. In addition, some composite materials will produce a lot of smoke when burning, as shown in the patent technical document CN 116790053B discloses a highly flame-retardant rubber-plastic thermal insulation material and a preparation method thereof. The invention obtains a highly flame-retardant rubber-plastic thermal insulation material by grafting a nitrogen-phosphorus flame retardant into a rubber-plastic thermal insulation material matrix, and blending the obtained modified polyvinyl chloride with a composite functional filler having a core-shell structure with a metal composite material as a shell and nanoclay as a core. Although the rubber-plastic thermal insulation material prepared by this method has high flame retardancy, since the material will produce a large amount of toxic and harmful smoke when heated and burned, the rubber-plastic thermal insulation material provided by this method is still difficult to meet application requirements.

[0004] Therefore, according to the above-mentioned related technologies, it is urgent to develop a flame retardant PC composite material and a preparation method thereof. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a flame retardant PC composite material and a preparation method thereof, so as to further improve the flame retardancy of the polycarbonate composite material.

[0006] Based on the above objectives, the present invention provides a flame retardant PC composite material and a preparation method thereof.

[0007] A flame-retardant PC composite material, comprising the following raw materials in parts by weight: 93.9-106.1 parts of a polycarbonate base material, 6-9.5 parts of a flame retardant, 0.6-1.2 parts of an antioxidant, and 0.4-0.9 parts of a smoke suppressant;

[0008] The polycarbonate base material is prepared from polycarbonate and graphite-modified polycarbonate;

[0009] The flame retardant is prepared from modified nano-silicon balls A, modified nano-silicon balls B, modified carbon balls C and modified organic silicon balls D;

[0010] The modified nano-silicon sphere A is nano-silicon dioxide modified by styrene-maleic anhydride copolymer;

[0011] The modified nano-silicon spheres B are magnesium-doped mesoporous silicon spheres;

[0012] The modified carbon balls C are prepared from straw, carboxymethyl cellulose and expanded polystyrene balls.

[0013] Preferably, the mass ratio of polycarbonate to graphite-modified polycarbonate in the polycarbonate base material is 76.4-82.5:17.5-23.6;

[0014] The preparation process of the graphite-modified polycarbonate is as follows:

[0015] Step A1. The expandable graphite was ultrasonically dispersed in tetrahydrofuran for 25-35 min, and then polycarbonate was added at a speed of 280-300 rpm to completely dissolve it in tetrahydrofuran to obtain a mixed solution A;

[0016] Step A2. The mixed solution A is placed in a refrigerator at 0-4°C for 22-24 hours, and then freeze-dried at -55-50°C and 8-10 Pa vacuum conditions for 45-48 hours to obtain a graphite-modified polycarbonate;

[0017] The usage ratio of the expandable graphite, tetrahydrofuran and polycarbonate in step A1 is 0.6-0.8 g: 38-42 mL: 2.6-3 g.

[0018] Preferably, the mass ratio of the modified nano-silicon spheres A, modified nano-silicon spheres B, modified carbon spheres C and modified organic silicon spheres D in the flame retardant is 1.7-2.3: 0.8-1.3: 0.5-0.9: 3-4.5.

[0019] Preferably, the preparation process of the modified nano-silicon spheres A is as follows:

[0020] Step B1. Add silica to the ethanol solution, ultrasonicate for 8-10 min, and then stir at 480-500 rpm at 70-75 ° C for 25-30 min to obtain a mixed solution B1;

[0021] Step B2. Aqueous ammonia and KH550 were added to the mixture B1, refluxed at 70-75 ° C for 6-8h, and then centrifuged at 8000-10000 rpm for 8-10min to obtain a mixture B2;

[0022] Step B3. Add the mixture B2 to DMF, add styrene-maleic anhydride copolymer at a speed of 480-500 rpm, reflux at 86-90 ° C for 10-12 hours, and then centrifuge at a speed of 8000-10000 rpm for 8-10 minutes to obtain modified nano-silicon spheres A.

[0023] Preferably, the ratio of silicon dioxide to ethanol solution in step B1 is 1.5-2 g: 180-200 mL, and the ethanol solution in step B1 is obtained by mixing ethanol and water in a volume ratio of 175:25;

[0024] In step B2, the ratio of the mixed solution B1, ammonia water, and KH550 is 180-200 mL: 4-5 mL: 0.8-1.2 g, and the concentration of the ammonia water is 13%-17%;

[0025] In step B3, the ratio of the mixture B2, DMF and styrene-maleic anhydride copolymer is 1.8-2 g: 145-150 mL: 0.8-1.2 g.

[0026] Preferably, the preparation process of the modified nano-silicon spheres B is as follows:

[0027] Step C1. Cetyltrimethylammonium chloride, triethanolamine, and ultrapure water were mixed in a conical flask and stirred at room temperature for 1 hour to obtain a mixed solution A. Tetraethyl silicate was added dropwise to the mixed solution A at 75-85°C with stirring. After reacting for 30 minutes, magnesium chloride solution was added and stirring was continued for 1 hour to obtain a mixed solution B.

[0028] Step C2. After the reaction, the mixture B was cooled to room temperature, washed with ethanol, and centrifuged 3-5 times. The resulting product was resuspended in a sodium chloride-methanol solution and stirred at room temperature for 6 hours. After centrifugation, it was resuspended in a sodium chloride-methanol solution and stirred at room temperature for 6 hours. It was then resuspended in ultrapure water, transferred to a sample vial, and quantified to obtain modified nanosilica spheres B.

[0029] The usage ratio of the hexadecyltrimethylammonium chloride, triethanolamine, tetraethyl silicate and magnesium chloride solution is 7-8 g:1-1.4 g:1-1.5 mL:1-1.5 mL, and the concentration of the magnesium chloride solution is 480-500 mg / mL.

[0030] Preferably, the preparation process of the modified carbon balls C is as follows:

[0031] Step D1. The straw powder, urea and ferric nitrate nonahydrate were dispersed in deionized water, and then transferred to an autoclave and maintained at 160-165°C for 8-10 hours, and then centrifuged and vacuum dried to obtain a catalyst;

[0032] Step D2. The catalyst, carboxymethyl cellulose, expanded polystyrene beads and deionized water were mixed evenly to form beads with a diameter of 2-3 mm. The beads were dried in a vacuum drying oven at 60-65°C for 12-14 hours and then calcined in a tubular furnace at 500-520°C for 2-3 hours to obtain modified carbon balls C.

[0033] Preferably, the ratio of the straw powder, urea, ferric nitrate nonahydrate and deionized water in step D1 is 3-5 g: 3-5 g: 1-2 g: 50-55 mL;

[0034] The straw powder in step D1 is any one of corn straw powder and rice straw powder;

[0035] The particle size of the urea in step D1 is 1-2 mm;

[0036] The catalyst, carboxymethyl cellulose, expanded polystyrene beads, and deionized water in step D2 are used in a ratio of 1.5-1.8 g: 0.6-0.9 g: 0.05-0.08 g: 2.2-2.6 mL;

[0037] The particle size of the expanded polystyrene beads in step D2 is 1-2 mm.

[0038] Preferably, the antioxidant is any one of antioxidant HP-136, antioxidant 1010 and antioxidant 168;

[0039] The smoke suppressant is aluminum hydroxide;

[0040] The preparation method of the modified organic silicon sphere D is as follows:

[0041] Step E1. Azobisisobutyronitrile, vinyltriethoxysilane and 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide are reacted at 75-80° C. for 8-12 h to obtain intermediate A;

[0042] Step E2. Mix concentrated hydrochloric acid, methanol, and intermediate A, react at 75-80°C for 22-25 hours, filter, and rinse with deionized water to obtain modified silicone spheres D;

[0043] The mass ratio of azobisisobutyronitrile, vinyltriethoxysilane and 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide in step E1 is 0.15-0.18:8-12:10-12;

[0044] The ratio of concentrated hydrochloric acid, methanol and intermediate A used in step E2 is 2-4 mL: 48-52 mL: 8-12 g;

[0045] The concentration of the methanol is 99.7%, and the concentration of the concentrated hydrochloric acid is 36.5%.

[0046] A method for preparing a flame-retardant PC composite material comprises the following steps:

[0047] Step S1. mixing polycarbonate and graphite-modified polycarbonate to obtain a polycarbonate base material;

[0048] Step S2. The modified nano-silicon balls A, modified nano-silicon balls B, modified carbon balls C and modified organic silicon balls D are mixed to obtain a flame retardant;

[0049] Step S3. The polycarbonate base material, flame retardant, antioxidant and smoke suppressant are mixed evenly, added into a twin-screw extruder for melt blending, extrusion and granulation to obtain a flame-retardant PC composite material.

[0050] Beneficial effects of the present invention:

[0051] The present invention provides a flame-retardant PC composite material and a preparation method thereof. The present invention introduces a flame retardant, an antioxidant and a smoke suppressant into a polycarbonate base material to prepare a PC composite material having excellent flame retardancy, dimensional stability and mechanical properties. Polycarbonate and graphite-modified polycarbonate are compounded as the polycarbonate base material, wherein a small amount of graphite-modified polycarbonate is used as a thermally conductive filler to further improve the flame retardancy of the polycarbonate, and pores formed when heated can play a role in smoke suppression and heat preservation. In addition, the pores can also serve as carriers for a relatively small amount of small molecules such as modified nano-silicon spheres B and modified carbon spheres C in the flame retardant. Combined with a relatively large amount of modified nano-silicon spheres A introduced into the flame retardant, the composite material can have better overall compatibility and uniform dispersion, thereby improving the mechanical properties of the composite material to a certain extent.

[0052] The present invention provides a flame-retardant PC composite material and a preparation method thereof. The present invention comprises modified nano-silicon balls A, modified nano-silicon balls B, modified carbon balls C and modified organic silicon balls D as a flame retardant. The modified organic silicon balls D release phosphorus-containing fragments and phenoxy free radicals when the system is heated, thereby quenching the combustion chain reaction. At the same time, the triethoxysilane structure therein can also combine with the modified nano-silicon balls A and other components such as a smoke suppressant within the system to form a cross-linked structure, thereby forming a denser blocking layer, reducing the release of combustible gas, and achieving a barrier effect. On the one hand, it isolates oxygen, and on the other hand, it can also seal the pores in the graphite-modified polycarbonate, preventing further heat transfer and inhibiting further combustion of the composite material. The modified nano-silicon balls A and modified organic silicon balls D are compounded and enhanced to toughen and strengthen the polycarbonate base material, and the holes contained in the modified carbon balls C in the flame retardant can be used as a heat carrier for rapid heat dissipation to prevent continued combustion, and can also dilute the oxygen that the blocking layer fails to isolate. The metal doped in the modified nano-silicon balls B in the flame retardant can be used for flame retardancy and smoke suppression, and can also make up for the defect of decreased mechanical properties of the composite material caused by the introduction of holes in the modified carbon balls C and graphite-modified polycarbonate, thereby achieving good flame retardancy and smoke suppression while having strong mechanical properties, and thus has broad application prospects. DETAILED DESCRIPTION

[0053] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0054] The sources and properties of some of the raw materials used in the present invention are as follows:

[0055] The styrene-maleic anhydride copolymer used in the present invention has a number average molecular weight Mn of 28,000 and was purchased from MacLean Chemical Reagent Co., Ltd.

[0056] The expandable graphite used in the present invention has a specification of 150 mesh and was purchased from Qingdao Yanhai Carbon Materials Co., Ltd.

[0057] The purity of azobisisobutyronitrile used in the present invention is 99.5%, and it was purchased from Beijing Chemical Plant;

[0058] The 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide used in the present invention was purchased from Eutec Trading (Shanghai) Co., Ltd.

[0059] The vinyltriethoxysilane used in the present invention was purchased from Ark Chemical Co., Ltd.

[0060] Example 1: A method for preparing a flame-retardant PC composite material, comprising the following steps:

[0061] S1. 0.6 g of expandable graphite was ultrasonically dispersed in 38 mL of tetrahydrofuran for 25 min, and then 2.6 g of polycarbonate was added at a speed of 280 rpm and completely dissolved in tetrahydrofuran to obtain a mixed solution A;

[0062] S2. The mixture A was placed in a refrigerator at 0°C for 22h, and then freeze-dried at -55°C and 8Pa under vacuum conditions for 45h to obtain graphite-modified polycarbonate;

[0063] S3 76.4g of polycarbonate and 17.5g of graphite-modified polycarbonate were mixed to obtain a polycarbonate base;

[0064] S4. 175 mL of ethanol and 25 mL of water were mixed to obtain an ethanol solution. 1.5 g of silica was added to 180 mL of the ethanol solution, ultrasonicated for 8 min, and then stirred at 480 rpm at 70°C for 25 min to obtain a mixed solution B1.

[0065] S5. To 180 mL of mixed solution B1, 4 mL of 13% aqueous ammonia and 0.8 g of KH550 were added, and the mixture was refluxed at 70°C for 6 h, and then centrifuged at 8000 rpm for 8 min to obtain mixture B2;

[0066] S6. 1.8 g of the mixture B2 was added to 145 mL of DMF, 0.8 g of styrene-maleic anhydride copolymer was added at 480 rpm, the mixture was refluxed at 86 ° C for 10 h, and then centrifuged at 8000 rpm for 8 min to obtain modified nanosilica spheres A;

[0067] S7. 7 g of hexadecyltrimethylammonium chloride, 1 g of triethanolamine, and ultrapure water were mixed in a conical flask and stirred at room temperature for 1 h to obtain a mixed solution A. 1 mL of tetraethyl silicate was added dropwise to the mixed solution A at 75°C with stirring. After reacting for 30 min, 1 mL of a 480 mg / mL magnesium chloride solution was added and stirring was continued for 1 h to obtain a mixed solution B.

[0068] S8. After the reaction, the mixture B was cooled to room temperature, washed with ethanol, and centrifuged three times. The resulting product was resuspended in a sodium chloride-methanol solution and stirred at room temperature for 6 h. After centrifugation, it was resuspended in a sodium chloride-methanol solution and stirred at room temperature for 6 h. The product was then resuspended in ultrapure water, transferred to a sample vial, and quantified to obtain modified nanosilica spheres B.

[0069] S9. 3 g corn straw powder, 3 g urea with a particle size of 1-2 mm, and 1 g ferric nitrate nonahydrate were dispersed in 50 mL of deionized water, transferred to an autoclave, and maintained at 160°C for 8 h. The catalyst was then centrifuged and dried in vacuo to obtain the catalyst.

[0070] S10. 1.5 g of catalyst, 0.6 g of carboxymethyl cellulose, 0.05 g of expanded polystyrene beads with a particle size of 1-2 mm, and 2.2 mL of deionized water were mixed to form beads with a diameter of 2-3 mm. The beads were dried in a vacuum drying oven at 60°C for 12 h and then calcined in a tube furnace at 500°C for 2 h to obtain modified carbon balls C.

[0071] S11. 0.15 g of azobisisobutyronitrile, 8 g of vinyltriethoxysilane, and 10 g of 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide were reacted at 75° C. for 8 h to obtain intermediate A;

[0072] S12. Mix 2 mL of 36.5% concentrated hydrochloric acid, 48 mL of 99.7% methanol, and 8 g of intermediate A. React at 75°C for 22 h. Filter and rinse with deionized water to obtain modified organosilicon spheres D.

[0073] S13. 1.7 g of modified nanosilicon spheres A, 0.8 g of modified nanosilicon spheres B, 0.5 g of modified carbon spheres C and 3 g of modified silicone spheres D were mixed to obtain a flame retardant;

[0074] S14. 93.9 g of polycarbonate base material, 6 g of flame retardant, 0.6 g of antioxidant HP-136 and 0.4 g of aluminum hydroxide were mixed evenly, added to a twin-screw extruder for melt blending, extrusion and granulation to obtain a flame-retardant PC composite material.

[0075] Example 2: A method for preparing a flame-retardant PC composite material, comprising the following steps:

[0076] S1. 0.7 g of expandable graphite was ultrasonically dispersed in 39 mL of tetrahydrofuran for 29 min, and then 2.7 g of polycarbonate was added at a speed of 285 rpm and completely dissolved in tetrahydrofuran to obtain a mixed solution A;

[0077] S2. The mixture A was placed in a refrigerator at 1°C for 23h, and then freeze-dried at -54°C and 9Pa under vacuum conditions for 46h to obtain graphite-modified polycarbonate;

[0078] S3 79g of polycarbonate and 19g of graphite-modified polycarbonate were mixed to obtain a polycarbonate base;

[0079] S4. 175 mL of ethanol and 25 mL of water were mixed to obtain an ethanol solution. 1.6 g of silica was added to 185 mL of the ethanol solution, ultrasonicated for 9 min, and then stirred at 485 rpm at 71°C for 26 min to obtain a mixed solution B1.

[0080] S5. To 185 mL of mixed solution B1, 4.2 mL of 14% aqueous ammonia and 0.9 g of KH550 were added, and the mixture was refluxed at 71°C for 7 h, followed by centrifugation at 8500 rpm for 9 min to obtain mixture B2.

[0081] S6. 1.9 g of mixture B2 was added to 146 mL of DMF, 0.9 g of styrene-maleic anhydride copolymer was added at 485 rpm, the mixture was refluxed at 87 ° C for 11 h, and then centrifuged at 8500 rpm for 9 min to obtain modified nanosilica spheres A;

[0082] S7. 7.4 g of hexadecyltrimethylammonium chloride, 1.2 g of triethanolamine, and ultrapure water were mixed in a conical flask and stirred at room temperature for 1 h to obtain a mixed solution A. 1.2 mL of tetraethyl silicate was added dropwise to the mixed solution A at 77°C with stirring. After reacting for 30 min, 1.2 mL of a 485 mg / mL magnesium chloride solution was added and stirring was continued for 1 h to obtain a mixed solution B.

[0083] S8. After the reaction, the mixture B was cooled to room temperature, washed with ethanol, and centrifuged four times. The resulting product was resuspended in a sodium chloride-methanol solution and stirred at room temperature for 6 h. After centrifugation, it was resuspended in a sodium chloride-methanol solution and stirred at room temperature for 6 h. The product was then resuspended in ultrapure water, transferred to a sample vial, and quantified to obtain modified nanosilica spheres B.

[0084] S9. 3.5 g of rice straw powder, 3.5 g of urea with a particle size of 1-2 mm, and 1.2 g of ferric nitrate nonahydrate were dispersed in 52 mL of deionized water, transferred to an autoclave, and maintained at 162°C for 9 h. The catalyst was then centrifuged and dried in vacuo to obtain the catalyst.

[0085] S10. 1.6 g of catalyst, 0.7 g of carboxymethyl cellulose, 0.06 g of expanded polystyrene beads with a particle size of 1-2 mm, and 2.3 mL of deionized water were mixed to form beads with a diameter of 2-3 mm. The beads were dried in a vacuum oven at 61°C for 13 h and then calcined in a tube furnace at 505°C for 2 h to obtain modified carbon balls C.

[0086] S11. 0.16 g of azobisisobutyronitrile, 9 g of vinyltriethoxysilane, and 11 g of 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide were reacted at 76° C. for 9 h to obtain intermediate A;

[0087] S12. Mix 3 mL of 36.5% concentrated hydrochloric acid, 49 mL of 99.7% methanol, and 9 g of intermediate A. React at 76°C for 23 h. Filter and rinse with deionized water to obtain modified silicone spheres D.

[0088] S13 1.8g modified nano-silicon spheres A, 0.9g modified nano-silicon spheres B, 0.6g modified carbon spheres C and 3.3g modified silicone spheres D were mixed to obtain a flame retardant;

[0089] S14. 95 g of polycarbonate base material, 7 g of flame retardant, 0.8 g of antioxidant 1010 and 0.5 g of aluminum hydroxide were mixed evenly, added to a twin-screw extruder for melt blending, extrusion and granulation to obtain a flame-retardant PC composite material.

[0090] Example 3: A method for preparing a flame-retardant PC composite material, comprising the following steps:

[0091] S1. 0.68 g of expandable graphite was ultrasonically dispersed in 40 mL of tetrahydrofuran for 29 min, and then 2.8 g of polycarbonate was added at a speed of 290 rpm and completely dissolved in tetrahydrofuran to obtain a mixed solution A;

[0092] S2. The mixture A was placed in a refrigerator at 2°C for 24 h, and then freeze-dried at -53°C and 8-10 Pa under vacuum conditions for 45-48 h to obtain graphite-modified polycarbonate;

[0093] S3. 78g of polycarbonate and 20g of graphite-modified polycarbonate were mixed to obtain a polycarbonate base;

[0094] S4. 175 mL of ethanol and 25 mL of water were mixed to obtain an ethanol solution. 1.7 g of silica was added to 190 mL of the ethanol solution, ultrasonicated for 10 min, and then stirred at 490 rpm at 72°C for 27 min to obtain a mixture B1.

[0095] S5. To 190 mL of mixed solution B1, 4.4 mL of 15% aqueous ammonia and 1 g of KH550 were added, and the mixture was refluxed at 72°C for 8 h, followed by centrifugation at 9000 rpm for 10 min to obtain mixture B2.

[0096] S6. 2 g of the mixture B2 was added to 147 mL of DMF, 1 g of styrene-maleic anhydride copolymer was added at 490 rpm, the mixture was refluxed at 88 ° C for 10 h, and then centrifuged at 9000 rpm for 10 min to obtain modified nanosilica spheres A;

[0097] S7. 7.4 g of hexadecyltrimethylammonium chloride, 1.2 g of triethanolamine, and ultrapure water were mixed in a conical flask and stirred at room temperature for 1 h to obtain a mixed solution A. 1.2 mL of tetraethyl silicate was added dropwise to the mixed solution A at 77°C with stirring. After reacting for 30 min, 1.2 mL of a 490 mg / mL magnesium chloride solution was added and stirring was continued for 1 h to obtain a mixed solution B.

[0098] S8. After the reaction, the mixture B was cooled to room temperature, washed with ethanol, and centrifuged three times. The resulting product was resuspended in a sodium chloride-methanol solution and stirred at room temperature for 6 h. After centrifugation, it was resuspended in a sodium chloride-methanol solution and stirred at room temperature for 6 h. The product was then resuspended in ultrapure water, transferred to a sample vial, and quantified to obtain modified nanosilica spheres B.

[0099] S9. 4 g of rice straw powder, 4 g of urea with a particle size of 1-2 mm, and 1.4 g of ferric nitrate nonahydrate were dispersed in 52 mL of deionized water, transferred to an autoclave, and maintained at 162°C for 8 h. The catalyst was then centrifuged and dried in vacuo to obtain the catalyst.

[0100] S10. 1.7 g of catalyst, 0.8 g of carboxymethyl cellulose, 0.07 g of expanded polystyrene beads with a particle size of 1-2 mm, and 2.4 mL of deionized water were mixed to form beads with a diameter of 2-3 mm. The beads were dried in a vacuum drying oven at 63°C for 12 h and then calcined in a tube furnace at 510°C for 2 h to obtain modified carbon balls C.

[0101] S11. 0.17 g of azobisisobutyronitrile, 10 g of vinyltriethoxysilane, and 12 g of 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide were reacted at 77° C. for 10 h to obtain intermediate A.

[0102] S12. Mix 4 mL of 36.5% concentrated hydrochloric acid, 50 mL of 99.7% methanol, and 10 g of intermediate A. React at 77°C for 22-23-24-25 hours. Filter and rinse with deionized water to obtain modified silicone spheres D.

[0103] S13 1.9g modified nanosilicon spheres A, 1.1g modified nanosilicon spheres B, 0.7g modified carbon spheres C and 3.6g modified silicone spheres D were mixed to obtain a flame retardant;

[0104] S14. 100 g of polycarbonate base material, 8 g of flame retardant, 0.8 g of antioxidant HP-136 and 0.6 g of aluminum hydroxide were mixed evenly, added to a twin-screw extruder for melt blending, extrusion and granulation to obtain a flame-retardant PC composite material.

[0105] Example 4: A method for preparing a flame-retardant PC composite material, comprising the following steps:

[0106] S1. 0.7 g of expandable graphite was ultrasonically dispersed in 41 mL of tetrahydrofuran for 34 min, and then 2.9 g of polycarbonate was added at a speed of 295 rpm and completely dissolved in tetrahydrofuran to obtain a mixed solution A;

[0107] S2. The mixture A was placed in a refrigerator at 3°C ​​for 23h, and then freeze-dried at -54°C and 9Pa under vacuum conditions for 47h to obtain graphite-modified polycarbonate;

[0108] S3. 81g of polycarbonate and 22g of graphite-modified polycarbonate were mixed to obtain a polycarbonate base;

[0109] S4. 175 mL of ethanol and 25 mL of water were mixed to obtain an ethanol solution. 1.9 g of silica was added to 195 mL of the ethanol solution, ultrasonicated for 9 min, and then stirred at 495 rpm at 74°C for 29 min to obtain a mixture B1.

[0110] S5. To 195 mL of mixed solution B1, 4.5 mL of 16% aqueous ammonia and 1.1 g of KH550 were added, and the mixture was refluxed at 74°C for 7 h, followed by centrifugation at 9500 rpm for 9 min to obtain mixture B2.

[0111] S6. 1.9 g of the mixture B2 was added to 149 mL of DMF, 1.1 g of styrene-maleic anhydride copolymer was added at 495 rpm, the mixture was refluxed at 89 ° C for 11 h, and then centrifuged at 9500 rpm for 9 min to obtain modified nanosilica spheres A;

[0112] S7. 7.8 g of hexadecyltrimethylammonium chloride, 1.3 g of triethanolamine, and ultrapure water were mixed in a conical flask and stirred at room temperature for 1 h to obtain a mixed solution A. 1.4 mL of tetraethyl silicate was added dropwise to the mixed solution A at 83°C with stirring. After reacting for 30 min, 1.4 mL of a 495 mg / mL magnesium chloride solution was added and stirring was continued for 1 h to obtain a mixed solution B.

[0113] S8. After the reaction, the mixture B was cooled to room temperature, washed with ethanol, and centrifuged 3-5 times. The resulting product was resuspended in a sodium chloride-methanol solution and stirred at room temperature for 6 hours. After centrifugation, it was resuspended in a sodium chloride-methanol solution and stirred at room temperature for 6 hours. It was then resuspended in ultrapure water, transferred to a sample vial, and quantified to obtain modified nanosilica spheres B.

[0114] S9. 4.8 g corn straw powder, 4.5 g urea with a particle size of 1-2 mm, and 1.8 g ferric nitrate nonahydrate were dispersed in 54 mL of deionized water, transferred to an autoclave, and maintained at 164°C for 9 h. The catalyst was then centrifuged and dried in vacuo to obtain a catalyst.

[0115] S10. 1.7 g of the catalyst, 0.8 g of carboxymethyl cellulose, 0.07 g of expanded polystyrene beads with a particle size of 1-2 mm, and 2.5 mL of deionized water were mixed to form beads with a diameter of 2-3 mm. The beads were dried in a vacuum drying oven at 64°C for 13 h and then calcined in a tube furnace at 518°C for 2.5 h to obtain modified carbon balls C.

[0116] S11. 0.17 g of azobisisobutyronitrile, 11 g of vinyltriethoxysilane, and 10.5 g of 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide were reacted at 79° C. for 11 h to obtain intermediate A.

[0117] S12. Mix 2.5 mL of 36.5% concentrated hydrochloric acid, 51 mL of 99.7% methanol, and 11 g of intermediate A. React at 79°C for 24 h. Filter and rinse with deionized water to obtain modified silicone spheres D.

[0118] S13. 2g of modified nanosilicon spheres A, 1.2g of modified nanosilicon spheres B, 0.8g of modified carbon spheres C and 4.2g of modified silicone spheres D were mixed to obtain a flame retardant;

[0119] S14. 106.1 g of polycarbonate base material, 9 g of flame retardant, 1.1 g of antioxidant 1010 and 0.8 g of aluminum hydroxide were mixed evenly, added to a twin-screw extruder for melt blending, extrusion and granulation to obtain a flame-retardant PC composite material.

[0120] Example 5: A method for preparing a flame-retardant PC composite material, comprising the following steps:

[0121] S1. 0.8 g of expandable graphite was ultrasonically dispersed in 42 mL of tetrahydrofuran for 35 min, and then 3 g of polycarbonate was added at a speed of 300 rpm and completely dissolved in tetrahydrofuran to obtain a mixed solution A;

[0122] S2. The mixture A was placed in a refrigerator at 4°C for 24 h, and then freeze-dried at -50°C and 10 Pa under vacuum conditions for 48 h to obtain graphite-modified polycarbonate;

[0123] S3. 82.5g of polycarbonate and 23.6g of graphite-modified polycarbonate were mixed to obtain a polycarbonate base;

[0124] S4. 175 mL of ethanol and 25 mL of water were mixed to obtain an ethanol solution. 2 g of silica was added to 200 mL of the ethanol solution, ultrasonicated for 10 min, and then stirred at 500 rpm at 75°C for 30 min to obtain a mixed solution B1.

[0125] S5. To 200 mL of mixed solution B1, 5 mL of 17% aqueous ammonia and 1.2 g of KH550 were added, and the mixture was refluxed at 75°C for 8 h, and then centrifuged at 10,000 rpm for 10 min to obtain mixture B2;

[0126] S6. 2 g of the mixture B2 was added to 150 mL of DMF, 1.2 g of styrene-maleic anhydride copolymer was added at 500 rpm, refluxed at 90 ° C for 12 h, and then centrifuged at 10,000 rpm for 10 min to obtain modified nanosilica spheres A;

[0127] S7. 8 g of hexadecyltrimethylammonium chloride, 1.4 g of triethanolamine, and ultrapure water were mixed in a conical flask and stirred at room temperature for 1 h to obtain a mixed solution A. 1.5 mL of tetraethyl silicate was added dropwise to the mixed solution A at 85°C with stirring. After reacting for 30 min, 1.5 mL of a 500 mg / mL magnesium chloride solution was added and stirring was continued for 1 h to obtain a mixed solution B.

[0128] S8. After the reaction, the mixture B was cooled to room temperature, washed with ethanol, and centrifuged five times. The resulting product was resuspended in a sodium chloride-methanol solution and stirred at room temperature for 6 h. After centrifugation, it was resuspended in a sodium chloride-methanol solution and stirred at room temperature for 6 h. The product was then resuspended in ultrapure water, transferred to a sample vial, and quantified to obtain modified nanosilica spheres B.

[0129] S9. 5 g of rice straw powder, 5 g of urea with a particle size of 1-2 mm, and 2 g of ferric nitrate nonahydrate were dispersed in 55 mL of deionized water, transferred to an autoclave, and maintained at 165°C for 10 h. The catalyst was then centrifuged and dried in vacuo to obtain a catalyst.

[0130] S10. 1.8 g of the catalyst, 0.9 g of carboxymethyl cellulose, 0.08 g of 2 mm expanded polystyrene beads, and 2.6 mL of deionized water were mixed to form 3 mm diameter beads. The beads were dried in a vacuum oven at 65°C for 14 h and then calcined in a tube furnace at 520°C for 3 h to obtain modified carbon beads C.

[0131] S11. 0.18 g of azobisisobutyronitrile, 12 g of vinyltriethoxysilane, and 11.5 g of 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide were reacted at 80° C. for 12 h to obtain intermediate A;

[0132] S12. Mix 3.5 mL of 36.5% concentrated hydrochloric acid, 52 mL of 99.7% methanol, and 12 g of intermediate A. React at 80°C for 25 h. Filter and rinse with deionized water to obtain modified silicone spheres D.

[0133] S13 2.3g modified nano-silicon spheres A, 1.3g modified nano-silicon spheres B, 0.9g modified carbon spheres C and 4.5g modified silicone spheres D were mixed to obtain a flame retardant;

[0134] S14. 106.1 g of polycarbonate base material, 9.5 g of flame retardant, 1.2 g of antioxidant 168 and 0.9 g of aluminum hydroxide were mixed evenly, added to a twin-screw extruder for melt blending, extrusion and granulation to obtain a flame-retardant PC composite material.

[0135] Comparative Example 1:

[0136] Compared with Example 1, this comparative example did not add graphite-modified polycarbonate during the preparation of the flame-retardant PC composite material. The remaining steps and parameters were the same and will not be repeated in this comparative example. Finally, a flame-retardant PC composite material was obtained.

[0137] Comparative Example 2:

[0138] Compared with Example 1, this comparative example did not add modified nano-silicon balls A during the preparation of the flame-retardant PC composite material. The remaining steps and parameters were the same and will not be repeated in this comparative example. Finally, a flame-retardant PC composite material was obtained.

[0139] Comparative Example 3:

[0140] Compared with Example 1, this comparative example did not add modified nano-silicon balls B during the preparation of the flame-retardant PC composite material. The remaining steps and parameters were the same and will not be repeated in this comparative example. Finally, a flame-retardant PC composite material was obtained.

[0141] Comparative Example 4:

[0142] Compared with Example 1, this comparative example did not add modified carbon balls C during the preparation of the flame-retardant PC composite material. The remaining steps and parameters were the same and will not be repeated in this comparative example. Finally, a flame-retardant PC composite material was obtained.

[0143] Comparative Example 5:

[0144] Compared with Example 1, this comparative example only adjusted the amounts of "polycarbonate" and "graphite modified polycarbonate" in the "polycarbonate base material" from "76.4g" and "17.5g" to "17.5g" and "76.4g", respectively. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a flame-retardant PC composite material was obtained.

[0145] Comparative Example 6:

[0146] Compared with Example 1, this comparative example only adjusts the amount of "modified nano-silicon balls A" and "modified carbon balls C" in the "flame retardant" from "1.7g" and "0.5g" to "0.5g" and "1.7g", respectively. The remaining steps and parameters are the same and will not be repeated in this comparative example. Finally, a flame-retardant PC composite material is obtained.

[0147] Performance testing:

[0148] Mechanical properties test:

[0149] The tensile properties were tested in accordance with GB / T1040-1992 on a WDW-50E microcomputer-controlled electronic universal testing machine at a tensile rate of 200 mm / min, a gauge length of 25 mm, a dumbbell-shaped specimen thickness of 2 mm, and the test results were the average of five tests.

[0150] Limiting Oxygen Index (LOI):

[0151] The LOI test is carried out in accordance with GB / T2406-1993 on a JF-3 oxygen index tester. The standard for measuring the limiting oxygen index of rubber and plastic is that the burning length of the sample is 50mm for 3 minutes, and the sample size is 75mm×13mm×3mm. The test result is the average of 5 tests.

[0152] Horizontal and vertical burning rating (UL-94):

[0153] The UL-94 vertical combustion rating is tested in accordance with GB / T2408-1980 on a CFZ-3 vertical combustion apparatus. The rating is divided into V-0, V-1, and V-2 levels based on the degree of difficulty. The sample size is 125mm×13mm×3mm. The test result is the average of 5 tests.

[0154] Smoke Density (SD) and Smoke Density Rating (SDR) tests:

[0155] The smoke density (SD) test and smoke density rating (SDR) test were conducted in a JCY-2 building material smoke density chamber using the national standard GB / T8627-2007. The sample sizes were set to 25mm×25mm×3mm. The test results were the average of three tests. The results are shown in Tables 1 and 2 below:

[0156] Table 1 Summary of experimental results in Examples 1-5 and Comparative Examples 1-6

[0157]

[0158] Data Analysis:

[0159] As can be seen from Table 1, the flame-retardant PC composite material prepared by the present invention has higher tensile strength, more excellent flame retardant properties and lower smoke density;

[0160] This may be because the present invention compounds polycarbonate and graphite-modified polycarbonate as a polycarbonate base material, wherein a small amount of graphite-modified polycarbonate is used as a thermally conductive filler to improve the flame retardant properties of polycarbonate, and the holes formed when heated can play a role in smoke elimination and heat preservation. In addition, the holes can also serve as carriers for a small amount of small molecules such as modified nano-silicon balls B and modified carbon balls C in the flame retardant. Combined with a large amount of modified nano-silicon balls A and modified silicone balls D introduced into the flame retardant, the overall compatibility within the composite material is better and the dispersion is uniform, thereby improving the mechanical properties of the composite material to a certain extent.

[0161] In addition, the present invention mixes modified nano-silicon balls A, modified nano-silicon balls B, modified carbon balls C and modified organic silicon balls D as flame retardants. The modified organic silicon balls D release phosphorus-containing fragments and phenoxy free radicals when the system is heated, quenching the combustion chain reaction. At the same time, the triethoxysilane structure therein can also combine with the modified nano-silicon balls A and other components such as smoke suppressants inside the system to form a cross-linked structure, thereby forming a denser blocking layer, reducing the release of combustible gas and playing a barrier effect. On the one hand, it isolates oxygen, and at the same time, it can also seal the holes in the graphite-modified polycarbonate to prevent further heat transfer and inhibit further decomposition of the composite material, thereby achieving flame retardancy and heat preservation. In addition, the modified nano-silicon balls A and modified organic silicon balls D are compounded and synergistically enhanced to toughen and strengthen the polycarbonate base material, while the flame retardant On the one hand, the holes contained in the modified carbon ball C can be used as a heat carrier for rapid heat dissipation to prevent continued combustion, and at the same time, it can also dilute the oxygen that the blocking layer fails to isolate. The metal doped in the modified nano-silicon ball B in the flame retardant can be used for flame retardancy and smoke elimination, and at the same time, it can make up for the defect of decreased mechanical properties of the composite material caused by the introduction of holes in the modified carbon ball C and graphite-modified polycarbonate, thereby achieving good flame retardancy and smoke elimination while having strong mechanical properties. In Example 5, when the amount of graphene-modified polycarbonate is increased and the amount of polycarbonate is reduced, the porosity of the composite material increases and the density decreases, so the mechanical properties are significantly reduced. In Example 6, when the amount of modified nano-silicon ball A and modified carbon ball C is changed, the various properties of the composite material also decrease.

[0162] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Within the scope of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0163] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A flame retardant PC composite material, characterized in that: The invention comprises the following raw materials in parts by weight: 93.9-106.1 parts of polycarbonate base material, 6-9.5 parts of flame retardant, 0.6-1.2 parts of antioxidant, and 0.4-0.9 parts of smoke suppressant; The polycarbonate base material is prepared from polycarbonate and graphite-modified polycarbonate; The mass ratio of polycarbonate to graphite-modified polycarbonate in the polycarbonate base material is 76.4-82.5:17.5-23.6; The preparation process of the graphite-modified polycarbonate is as follows: Step A1. The expandable graphite was ultrasonically dispersed in tetrahydrofuran for 25-35 min, and then polycarbonate was added at a speed of 280-300 rpm to completely dissolve it in tetrahydrofuran to obtain a mixed solution A; Step A2. The mixed solution A is placed in a refrigerator at 0-4°C for 22-24 hours, and then freeze-dried at -55-50°C and 8-10 Pa vacuum conditions for 45-48 hours to obtain a graphite-modified polycarbonate; The flame retardant is prepared from modified nano-silicon balls A, modified nano-silicon balls B, modified carbon balls C and modified organic silicon balls D; The mass ratio of modified nano-silicon spheres A, modified nano-silicon spheres B, modified carbon spheres C and modified organic silicon spheres D in the flame retardant is 1.7-2.3:0.8-1.3:0.5-0.9:3-4.5; The preparation process of the modified nano-silicon sphere A is as follows: Step B1. Add silica to the ethanol solution, ultrasonicate for 8-10 min, and then stir at 480-500 rpm at 70-75 ° C for 25-30 min to obtain a mixed solution B1; Step B2. Aqueous ammonia and KH550 were added to the mixture B1, refluxed at 70-75 ° C for 6-8h, and then centrifuged at 8000-10000 rpm for 8-10min to obtain a mixture B2; Step B3. The mixture B2 was added to DMF, styrene-maleic anhydride copolymer was added at a speed of 480-500 rpm, refluxed at 86-90 ° C for 10-12h, and then centrifuged at a speed of 8000-10000 rpm for 8-10min to obtain modified nano-silicon spheres A; The modified nano-silicon spheres B are magnesium-doped mesoporous silicon spheres; The preparation process of the modified carbon ball C is as follows: Step D1. The straw powder, urea and ferric nitrate nonahydrate were dispersed in deionized water, and then transferred to an autoclave and maintained at 160-165°C for 8-10 hours, and then centrifuged and vacuum dried to obtain a catalyst; Step D2. The catalyst, carboxymethyl cellulose, expanded polystyrene beads and deionized water were mixed uniformly to form beads with a diameter of 2-3 mm. The beads were dried in a vacuum drying oven at 60-65°C for 12-14 h and then calcined in a tube furnace at 500-520°C for 2-3 h to obtain modified carbon balls C. The modified organic silicon sphere D is a cage-type polysilsesquioxane containing vinyl and phosphorus.

2. The flame retardant PC composite material according to claim 1, characterized in that: The usage ratio of the expandable graphite, tetrahydrofuran and polycarbonate in step A1 is 0.6-0.8 g: 38-42 mL: 2.6-3 g.

3. The flame retardant PC composite material according to claim 1, characterized in that: The amount ratio of the silicon dioxide and the ethanol solution in step B1 is 1.5-2 g: 180-200 mL, and the ethanol solution in step B1 is obtained by mixing ethanol and water in a volume ratio of 175:25; In step B2, the ratio of the mixed solution B1, ammonia water, and KH550 is 180-200 mL: 4-5 mL: 0.8-1.2 g, and the concentration of the ammonia water is 13%-17%; In step B3, the ratio of the mixture B2, DMF and styrene-maleic anhydride copolymer is 1.8-2 g: 145-150 mL: 0.8-1.2 g.

4. The flame retardant PC composite material according to claim 1, characterized in that: The preparation process of the modified nano-silicon sphere B is as follows: Step C1. Cetyltrimethylammonium chloride, triethanolamine, and ultrapure water were mixed in a conical flask and stirred at room temperature for 1 hour to obtain a mixed solution A. Tetraethyl silicate was added dropwise to the mixed solution A at 75-85°C with stirring. After reacting for 30 minutes, magnesium chloride solution was added and stirring was continued for 1 hour to obtain a mixed solution B. Step C2. After the reaction, the mixture B was cooled to room temperature, washed with ethanol, and centrifuged 3-5 times. The resulting product was resuspended in a sodium chloride-methanol solution and stirred at room temperature for 6 hours. After centrifugation, it was resuspended in a sodium chloride-methanol solution and stirred at room temperature for 6 hours. It was then resuspended in ultrapure water, transferred to a sample vial, and quantified to obtain modified nanosilica spheres B. The usage ratio of the hexadecyltrimethylammonium chloride, triethanolamine, tetraethyl silicate and magnesium chloride solution is 7-8 g:1-1.4 g:1-1.5 mL:1-1.5 mL, and the concentration of the magnesium chloride solution is 480-500 mg / mL.

5. The flame retardant PC composite material according to claim 1, characterized in that: In step D1, the ratio of straw powder, urea, ferric nitrate nonahydrate, and deionized water is 3-5 g: 3-5 g: 1-2 g: 50-55 mL; The straw powder in step D1 is any one of corn straw powder and rice straw powder; The particle size of the urea in step D1 is 1-2 mm; The catalyst, carboxymethyl cellulose, expanded polystyrene beads, and deionized water in step D2 are used in a ratio of 1.5-1.8 g: 0.6-0.9 g: 0.05-0.08 g: 2.2-2.6 mL; The particle size of the expanded polystyrene beads in step D2 is 1-2 mm.

6. The flame retardant PC composite material according to claim 1, characterized in that: The antioxidant is any one of antioxidant HP-136, antioxidant 1010 and antioxidant 168; The smoke suppressant is aluminum hydroxide; The preparation method of the modified organic silicon sphere D is as follows: Step E1. Azobisisobutyronitrile, vinyltriethoxysilane and 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide are reacted at 75-80° C. for 8-12 h to obtain intermediate A; Step E2. Mix concentrated hydrochloric acid, methanol, and intermediate A, react at 75-80°C for 22-25 hours, filter, and rinse with deionized water to obtain modified silicone spheres D; The mass ratio of azobisisobutyronitrile, vinyltriethoxysilane and 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide in step E1 is 0.15-0.18:8-12:10-12; The ratio of concentrated hydrochloric acid, methanol and intermediate A used in step E2 is 2-4 mL: 48-52 mL: 8-12 g; The concentration of the methanol is 99.7%, and the concentration of the concentrated hydrochloric acid is 36.5%.

7. A method for preparing the flame-retardant PC composite material according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step S1. mixing polycarbonate and graphite-modified polycarbonate to obtain a polycarbonate base material; Step S2. The modified nano-silicon balls A, modified nano-silicon balls B, modified carbon balls C and modified organic silicon balls D are mixed to obtain a flame retardant; Step S3. The polycarbonate base material, flame retardant, antioxidant and smoke suppressant are mixed evenly, added into a twin-screw extruder for melt blending, extrusion and granulation to obtain a flame-retardant PC composite material.

Images