Preparation method of flame-retardant PC / ABS composite material for automobile

Abstract

The invention relates to the technical field of engineering plastic alloys, in particular to a preparation method of a flame-retardant PC / ABS (polycarbonate / acrylonitrile butadiene styrene) composite material for automobiles, and the flame-retardant PC / ABS composite material comprises the following components: PC, ABS, LCP (liquid crystal polymer), nanofiller, a modified flame retardant, a flexibilizer, an antioxidant, a lubricant, a deodorant, an anti-dripping agent and a smoke suppressant. The preparation method of the flame-retardant PC / ABS composite material comprises the following steps: S1, mixing step by step; and S2, extruding. The modified hexaphenoxy cyclotriphosphazene and the bisphenol A-bis (diphenyl phosphate) are compounded and cooperate with the loading effect of the nano silicon dioxide, so that the damp-heat aging resistance and the ultraviolet aging resistance are improved, the tensile strength and the impact strength of the PC / ABS composite material are enhanced, and the PC / ABS composite material is suitable for the field of automobile parts.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering plastic alloys, and in particular to a method for preparing a flame-retardant PC / ABS composite material for automobiles. Background Art

[0002] Polycarbonate (PC) / acrylonitrile-butadiene-styrene (ABS) composites are widely used in electronics, automotive components, building materials, and other fields due to their excellent mechanical properties, heat resistance, processing performance, and cost advantages. Currently, the main method for improving the flame retardancy of PC / ABS is to add flame retardants, such as halogen-based flame retardants (such as brominated epoxy resins), phosphorus-based flame retardants (such as phosphate esters), and nitrogen-based flame retardants (such as melamine derivatives).

[0003] The Chinese invention application with publication number CN117820836A discloses a flame-retardant PC / ABS composite material, its preparation method and application. The invention application uses hexaphenoxy cyclotriphosphazene and bisphenol A-bis(diphenyl phosphate) as composite flame retardants, which are prepared by melt-blending and extruding with polycarbonate and ABS resin to prepare flame-retardant materials. However, after in-depth analysis, it was found that the technical solution has the following key technical problems that need to be solved: 1. Hexaphenoxy cyclotriphosphazene is a powdered crystalline material. Due to the significant polarity difference between it and the PC / ABS matrix, it is easy to agglomerate during the direct blending process, resulting in a decrease in the local flame retardant efficiency of the material. At the same time, bisphenol A-bis(diphenyl phosphate) has poor compatibility with the PC / ABS matrix, and obvious surface migration will occur during long-term use, which not only affects the appearance of the material, but also leads to a continuous decrease in flame retardant properties; 2. PC / ABS composite materials have a significant tendency to absorb moisture in hot and humid environments. The degradation of key components in the flame retardant system is accelerated: on the one hand, the PN bond in hexaphenoxycyclotriphosphazene will undergo hydrolysis under the action of moisture, and the acidic environment generated by the decomposition of bisphenol A-bis(diphenyl phosphate) will further catalyze this process; on the other hand, the ester bond in the bisphenol A-bis(diphenyl phosphate) molecule is extremely easy to break under high temperature and high humidity conditions, and the resulting acidic degradation products will trigger the hydrolysis and degradation of the PC matrix; 3. Bisphenol A-bis(diphenyl phosphate) is prone to thermal oxidation reaction under high temperature extrusion conditions, and the free radicals generated will trigger the breakage of PC molecular chains, seriously affecting the final mechanical properties of the material. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing a flame-retardant PC / ABS composite material for automobiles, so as to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions: a method for preparing a flame-retardant PC / ABS composite material for automobiles, wherein the flame-retardant PC / ABS composite material comprises the following components in parts by weight: 100 parts of PC, 40 to 60 parts of ABS, 4 to 6 parts of LCP, 8 to 12 parts of nanofillers, 8 to 10 parts of modified flame retardants, 5 to 7 parts of toughening agents, 0.3 to 0.5 parts of antioxidants, 0.3 to 0.6 parts of lubricants, 0.3 to 0.5 parts of deodorants, 0.3 to 0.5 parts of anti-dripping agents, and 0.5 to 1.0 parts of smoke suppressants; the method for preparing the modified flame retardant comprises the following steps: the method for preparing the modified flame retardant comprises the following steps: under nitrogen protection , dispersing 100 g of hexaphenoxy cyclotriphosphazene in acetone, slowly adding 6-8 g of hexamethyldisilazane and 10-12 g of nano-silica, heating to 60-65° C., reacting under mechanical stirring at 200 rpm for 6-8 hours, centrifuging, and vacuum drying to obtain modified hexaphenoxy cyclotriphosphazene; bisphenol A-bis(diphenyl phosphate), modified hexaphenoxy cyclotriphosphazene, polymethyl methacrylate, and silane coupling agent Si-69 are uniformly mixed in a mass ratio of 35:10-12:9-10:4-5, and then put into a twin-screw extruder, first pre-mixed at 185-190° C., and then melt-blended and extruded into granules at 200-210° C. to obtain the modified flame retardant;

[0006] The preparation method of the flame retardant PC / ABS composite material comprises the following steps:

[0007] S1. Stepwise mixing: PC, ABS, nanofiller, antioxidant, and lubricant are added to a high-speed mixer and mixed at 500 rpm for 3 to 5 minutes, then increased to 1000 rpm and mixed for 7 to 10 minutes, modified flame retardant, smoke suppressant, and anti-dripping agent are added and mixed at 800 rpm for 5 to 8 minutes, and finally LCP and toughening agent are added and mixed at 600 rpm for 5 to 10 minutes to obtain a premix;

[0008] S2, extrusion: the premix was put into a twin-screw extruder, the temperature of each zone of the twin-screw extruder was set as follows: 200° C. in zone 1, 210° C. in zone 2, 230° C. in zone 3, 240° C. in zone 4, 235° C. in zone 5, and 220° C. in the die head, the screw speed of the twin-screw extruder was controlled at 280-320 rpm, a vacuum exhaust port was set in zone 4 and a vacuum degree of -0.1 MPa was maintained, the premix was melt-blended, and after pelletizing, it was vacuum-dried at 80° C. for 6 h to obtain the flame-retardant PC / ABS composite material.

[0009] Optionally, the molecular weight of the PC is 20,000 to 40,000, and the melt index of the PC is in the range of 3 to 9 g / 10 min.

[0010] Optionally, the ABS is a polymer copolymerized from 25 wt% to 40 wt% of acrylonitrile, 5 wt% to 20 wt% of butadiene, and 30 wt% to 70 wt% of styrene.

[0011] Optionally, the preparation method of the nanofiller includes the following steps: adding 20-28 g of magnesium nitrate hexahydrate and 7-10 g of aluminum nitrate nonahydrate to 400-600 mL of deionized water, adding dropwise 800-1200 mL of a NaOH / Na2CO3 mixed solution with a molar ratio of 3-5:1, hydrothermally reacting at 60-70° C. for 10-14 hours, centrifuging, washing, and drying to obtain a powder; dispersing the powder in a mixed solvent of 100-200 mL of ethanol and 30-70 mL of deionized water, adding 8-12 g of tetraethyl orthosilicate and 15-25 g of nano-alumina, and adding ammonia water at the same time, adjusting the pH value of the solution to 8.5-10.5, reacting at 50-60° C. for 5-7 hours, and centrifuging and drying to obtain the nanofiller.

[0012] Optionally, the toughening agent is one of maleic anhydride grafted ABS, maleic anhydride grafted PE, maleic anhydride grafted PP, maleic anhydride grafted PS, and maleic anhydride grafted EVA.

[0013] Optionally, the antioxidant consists of antioxidant 1010 and antioxidant 168, and the mass ratio of antioxidant 1010 to antioxidant 168 is 1:1.

[0014] Optionally, the lubricant is one of calcium stearate, polyethylene wax, and EBS.

[0015] Optionally, the deodorant is 4A zeolite molecular sieve, and the anti-dripping agent is polytetrafluoroethylene powder.

[0016] Optionally, the smoke suppressant is composed of ammonium octamolybdate and molybdenum trioxide, and the mass ratio of ammonium octamolybdate to molybdenum trioxide is 3:1.

[0017] Compared with the prior art, the present invention has the following beneficial effects: by compounding modified hexaphenoxy cyclotriphosphazene with bisphenol A-bis(diphenyl phosphate), and synergistically adding nano-silica for loading, the present invention not only improves the resistance to wet-heat aging and ultraviolet aging, but also enhances the tensile strength and impact strength of the PC / ABS composite material, making it suitable for the field of automotive parts. DETAILED DESCRIPTION

[0018] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the 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.

[0019] Example 1: The present invention provides a method for preparing a flame-retardant PC / ABS composite material for automobiles. The flame-retardant PC / ABS composite material includes the following components in parts by weight: 100 parts of PC, 40 parts of ABS, 4 parts of LCP, 8 parts of nanofiller, 8 parts of modified flame retardant, 5 parts of toughening agent, 0.3 parts of antioxidant, 0.3 parts of lubricant, 0.3 parts of deodorant, 0.3 parts of anti-dripping agent, and 0.5 parts of smoke suppressant.

[0020] The preparation method of the modified flame retardant comprises the following steps: dispersing 100g of hexaphenoxycyclotriphosphazene in acetone under nitrogen protection, slowly adding 6g of hexamethyldisilazane and 10-12g of nano-silica, heating to 60°C, reacting under mechanical stirring at 200rpm for 8h, centrifuging, and vacuum drying to obtain the modified hexaphenoxycyclotriphosphazene; and uniformly mixing bisphenol A-bis(diphenyl phosphate), the modified hexaphenoxycyclotriphosphazene, polymethyl methacrylate, and a silane coupling agent Si-69 in a mass ratio of 35:10:9:4, then putting the mixture into a twin-screw extruder, pre-mixing at 185°C, and then melt-blending and extruding at 200°C to form granules to obtain the modified flame retardant.

[0021] The preparation method of the flame retardant PC / ABS composite material comprises the following steps:

[0022] S1. Stepwise mixing: PC, ABS, nanofiller, antioxidant, and lubricant were added to a high-speed mixer and mixed at 500 rpm for 3 min, then increased to 1000 rpm and mixed for 7 min, modified flame retardant, smoke suppressant, and anti-dripping agent were added and mixed at 800 rpm for 5 min, and finally LCP and toughening agent were added and mixed at 600 rpm for 5 min to obtain a premix;

[0023] S2. Extrusion: The premix was fed into a twin-screw extruder. The temperatures of each zone of the twin-screw extruder were set as follows: 200° C. in zone 1, 210° C. in zone 2, 230° C. in zone 3, 240° C. in zone 4, 235° C. in zone 5, and 220° C. in the die head. The screw speed of the twin-screw extruder was controlled at 280 rpm. A vacuum port was set in zone 4 and a vacuum degree of -0.1 MPa was maintained. The premix was melt-blended, pelletized, and vacuum-dried at 80° C. for 6 h to obtain a flame-retardant PC / ABS composite material.

[0024] Example 2: The present invention provides a method for preparing a flame-retardant PC / ABS composite material for automobiles. The flame-retardant PC / ABS composite material includes the following components in parts by weight: 1,100 parts of PC, 45 parts of ABS, 4.5 parts of LCP, 9 parts of nanofiller, 8.5 parts of modified flame retardant, 5.5 parts of toughening agent, 0.35 parts of antioxidant, 0.4 parts of lubricant, 0.35 parts of deodorant, 0.35 parts of anti-dripping agent, and 0.6 parts of smoke suppressant.

[0025] The preparation method of the modified flame retardant comprises the following steps: dispersing 100 g of hexaphenoxycyclotriphosphazene in acetone under nitrogen protection, slowly adding 7 g of hexamethyldisilazane and 11 g of nano-silica, heating to 62° C., reacting under mechanical stirring at 200 rpm for 7 hours, centrifuging, and vacuum drying to obtain the modified hexaphenoxycyclotriphosphazene; and uniformly mixing bisphenol A-bis(diphenyl phosphate), modified hexaphenoxycyclotriphosphazene, polymethyl methacrylate, and silane coupling agent Si-69 in a mass ratio of 35:11:10:5, then placing the mixture into a twin-screw extruder, pre-mixing at 188° C., and then melt-blending and extruding at 205° C. to obtain the modified flame retardant.

[0026] The preparation method of the flame retardant PC / ABS composite material comprises the following steps:

[0027] S1. Stepwise mixing: PC, ABS, nanofiller, antioxidant, and lubricant were added to a high-speed mixer and mixed at 500 rpm for 4 min, then increased to 1000 rpm and mixed for 8 min, modified flame retardant, smoke suppressant, and anti-dripping agent were added and mixed at 800 rpm for 6 min, and finally LCP and toughening agent were added and mixed at 600 rpm for 6 min to obtain a premix;

[0028] S2. Extrusion: The premix was fed into a twin-screw extruder. The temperatures of each zone of the twin-screw extruder were set as follows: 200° C. for zone 1, 210° C. for zone 2, 230° C. for zone 3, 240° C. for zone 4, 235° C. for zone 5, and 220° C. for the die head. The screw speed of the twin-screw extruder was controlled at 290 rpm. A vacuum port was set in zone 4 and a vacuum degree of -0.1 MPa was maintained. The premix was melt-blended, pelletized, and vacuum-dried at 80° C. for 6 h to obtain a flame-retardant PC / ABS composite material.

[0029] Example 3: The present invention provides a method for preparing a flame-retardant PC / ABS composite material for automobiles. The flame-retardant PC / ABS composite material includes the following components in parts by weight: 100 parts of PC, 50 parts of ABS, 5 parts of LCP, 10 parts of nanofiller, 9 parts of modified flame retardant, 6 parts of toughening agent, 0.4 part of antioxidant, 0.45 part of lubricant, 0.4 part of deodorant, 0.4 part of anti-dripping agent, and 0.75 part of smoke suppressant.

[0030] The preparation method of the modified flame retardant comprises the following steps: dispersing 100 g of hexaphenoxycyclotriphosphazene in acetone under nitrogen protection, slowly adding 8 g of hexamethyldisilazane and 12 g of nano-silica, heating to 65° C., reacting for 6 hours under mechanical stirring at 200 rpm, centrifuging, and vacuum drying to obtain the modified hexaphenoxycyclotriphosphazene; and uniformly mixing bisphenol A-bis(diphenyl phosphate), modified hexaphenoxycyclotriphosphazene, polymethyl methacrylate, and silane coupling agent Si-69 in a mass ratio of 35:12:10:5, then placing the mixture into a twin-screw extruder, pre-mixing at 190° C., and then melt-blending and extruding and granulating at 210° C. to obtain the modified flame retardant.

[0031] The preparation method of the flame retardant PC / ABS composite material comprises the following steps:

[0032] S1. Stepwise mixing: PC, ABS, nanofiller, antioxidant, and lubricant were added to a high-speed mixer and mixed at 500 rpm for 4 min, then increased to 1000 rpm and mixed for 8 min, modified flame retardant, smoke suppressant, and anti-dripping agent were added and mixed at 800 rpm for 6 min, and finally LCP and toughening agent were added and mixed at 600 rpm for 7 min to obtain a premix;

[0033] S2. Extrusion: The premix was fed into a twin-screw extruder. The temperatures of each zone of the twin-screw extruder were set as follows: 200° C. in zone 1, 210° C. in zone 2, 230° C. in zone 3, 240° C. in zone 4, 235° C. in zone 5, and 220° C. in the die head. The screw speed of the twin-screw extruder was controlled at 300 rpm. A vacuum exhaust port was set in zone 4 and a vacuum degree of -0.1 MPa was maintained. The premix was melt-blended, pelletized, and vacuum-dried at 80° C. for 6 h to obtain a flame-retardant PC / ABS composite material.

[0034] Example 4: The present invention provides a method for preparing a flame-retardant PC / ABS composite material for automotive use. The flame-retardant PC / ABS composite material comprises the following components in parts by weight: 100 parts PC, 55 parts ABS, 5.5 parts LCP, 11 parts nanofiller, 9.5 parts modified flame retardant, 6.5 parts toughening agent, 0.45 parts antioxidant, 0.5 parts lubricant, 0.45 parts deodorant, 0.45 parts anti-drip agent, and 0.9 parts smoke suppressant. The preparation method for the modified flame retardant is the same as that of Example 1.

[0035] The preparation method of the flame retardant PC / ABS composite material comprises the following steps:

[0036] S1. Stepwise mixing: PC, ABS, nanofiller, antioxidant, and lubricant were added to a high-speed mixer and mixed at 500 rpm for 5 min, then increased to 1000 rpm and mixed for 9 min, modified flame retardant, smoke suppressant, and anti-dripping agent were added and mixed at 800 rpm for 7 min, and finally LCP and toughening agent were added and mixed at 600 rpm for 8 min to obtain a premix;

[0037] S2. Extrusion: The premix was fed into a twin-screw extruder. The temperatures of each zone of the twin-screw extruder were set as follows: 200° C. in zone 1, 210° C. in zone 2, 230° C. in zone 3, 240° C. in zone 4, 235° C. in zone 5, and 220° C. in the die head. The screw speed of the twin-screw extruder was controlled at 310 rpm. A vacuum exhaust port was set in zone 4 and a vacuum degree of -0.1 MPa was maintained. The premix was melt-blended, pelletized, and vacuum-dried at 80° C. for 6 h to obtain a flame-retardant PC / ABS composite material.

[0038] Example 5: The present invention provides a method for preparing a flame-retardant PC / ABS composite material for automotive use. The flame-retardant PC / ABS composite material comprises the following components in parts by weight: 100 parts PC, 60 parts ABS, 6 parts LCP, 12 parts nanofiller, 10 parts modified flame retardant, 7 parts toughening agent, 0.5 parts antioxidant, 0.6 parts lubricant, 0.5 parts deodorant, 0.5 parts anti-drip agent, and 1.0 parts smoke suppressant. The preparation method for the modified flame retardant is the same as that of Example 3.

[0039] The preparation method of the flame retardant PC / ABS composite material comprises the following steps:

[0040] S1. Stepwise mixing: PC, ABS, nanofiller, antioxidant, and lubricant were added to a high-speed mixer and mixed at 500 rpm for 5 min, then increased to 1000 rpm and mixed for 10 min, modified flame retardant, smoke suppressant, and anti-dripping agent were added and mixed at 800 rpm for 8 min, and finally LCP and toughening agent were added and mixed at 600 rpm for 10 min to obtain a premix;

[0041] S2. Extrusion: The premix was fed into a twin-screw extruder. The temperatures of each zone of the twin-screw extruder were set as follows: 200° C. in zone 1, 210° C. in zone 2, 230° C. in zone 3, 240° C. in zone 4, 235° C. in zone 5, and 220° C. in the die head. The screw speed of the twin-screw extruder was controlled at 320 rpm. A vacuum port was set in zone 4 and a vacuum degree of -0.1 MPa was maintained. The premix was melt-blended, pelletized, and vacuum-dried at 80° C. for 6 h to obtain a flame-retardant PC / ABS composite material.

[0042] The present invention modifies hexaphenoxycyclotriphosphazene with hexamethyldisilazane and introduces a hydrophobic group [-Si(CH3)3] onto the surface of the hexaphenoxycyclotriphosphazene. The hydrophobic group shields the phosphazene ring of the hexaphenoxycyclotriphosphazene, delaying the hydrolysis of the PN bond in a humid environment and significantly reducing its hygroscopicity. Furthermore, the hydrophobic group significantly reduces the polarity difference between the hexaphenoxycyclotriphosphazene and the PC / ABS matrix. Nanosilica has a high specific surface area, increasing the contact area between hexamethyldisilazane and hexaphenoxycyclotriphosphazene and shortening the modification reaction time. Furthermore, the porous structure of nanosilica can anchor bisphenol A-bis(diphenyl phosphate), delaying its migration and precipitation to the material surface. The silane coupling agent Si-69 enhances the interfacial compatibility of the flame retardant in polymethyl methacrylate, preventing localized aggregation of the flame retardant in the polymethyl methacrylate.

[0043] In Examples 1-2, the preparation method of the nanofiller includes the following steps: adding 20 g of magnesium nitrate hexahydrate and 7 g of aluminum nitrate nonahydrate to 400 mL of deionized water, adding dropwise 800 mL of a NaOH / Na2CO3 mixed solution with a molar ratio of 3:1, hydrothermally reacting at 50°C for 10 hours, centrifuging, washing, and drying to obtain a powder; dispersing the powder in a mixed solvent of 100 mL of ethanol and 30 mL of deionized water, adding 8 g of tetraethyl orthosilicate and 15 g of nano-alumina, and adding ammonia water at the same time, adjusting the pH value of the solution to 8.5, reacting at 40°C for 5 hours, and centrifuging and drying to obtain the nanofiller.

[0044] In Examples 3 to 4, 24.3 g of magnesium nitrate hexahydrate and 8.6 g of aluminum nitrate nonahydrate were added to 500 mL of deionized water, and 1000 mL of a NaOH / Na2CO3 mixed solution with a molar ratio of 4:1 was added dropwise. The mixture was hydrothermally reacted at 60° C. for 12 h, and the mixture was centrifuged, washed, and dried to obtain a powder. The powder was dispersed in a mixed solvent of 150 mL of ethanol and 50 mL of deionized water, and 10 g of tetraethyl orthosilicate and 20 g of nano-alumina were added. Ammonia water was also added at the same time, and the pH value of the solution was adjusted to 9.5. The mixture was reacted at 50° C. for 6 h, and centrifuged to obtain a nanofiller.

[0045] In Example 5, 24.3 g of magnesium nitrate hexahydrate and 8.6 g of aluminum nitrate nonahydrate were added to 500 mL of deionized water, 1000 mL of a Na2CO3 mixed solution with a molar ratio of 4:1 was added dropwise, and the mixture was hydrothermally reacted at 60°C for 12 h. The mixture was centrifuged, washed, and dried to obtain a powder. The powder was dispersed in a mixed solvent of 150 mL of ethanol and 50 mL of deionized water, 10 g of tetraethyl orthosilicate and 20 g of nano-alumina were added, and ammonia water was added at the same time. The pH value of the solution was adjusted to 9.5, the mixture was reacted at 50°C for 6 h, and centrifuged to obtain a nanofiller.

[0046] Ethyl orthosilicate is hydrolyzed under alkaline conditions to generate silanols, which then undergo a condensation reaction to form a silica network. Nano-alumina acts as a filler and is evenly dispersed in the silica network. The final nano-filler contains a composite structure of magnesium-aluminum hydrotalcite, silica, and nano-alumina.

[0047] In Examples 1-5, the PC melt index ranged from 3 to 9 g / 10 min. The antioxidant consisted of antioxidant 1010 and antioxidant 168, with the mass ratio of antioxidant 1010 to antioxidant 168 being 1:1. The deodorant was 4A zeolite molecular sieve, and the anti-drip agent was polytetrafluoroethylene micropowder. The smoke suppressant consisted of ammonium octamolybdate and molybdenum trioxide, with the mass ratio of ammonium octamolybdate to molybdenum trioxide being 3:1. Data for the remaining components of the flame-retardant PC / ABS composite are shown in Table 1.

[0048] Table 1

[0049]

[0050] Comparative Example 1

[0051] It is basically the same as Example 3, except that hexaphenoxy cyclotriphosphazene and bisphenol A-bis(diphenyl phosphate) are used to replace the modified flame retardant, wherein the mass ratio of hexaphenoxy cyclotriphosphazene to bisphenol A-bis(diphenyl phosphate) is 7:2.

[0052] Comparative Example 2

[0053] It is basically the same as Example 3, the only difference being that no nanofiller is used.

[0054] Test Example 1

[0055] Test content: According to the test method disclosed in GB / T 1040.2-2022, two groups of flame-retardant PC / ABS composite materials prepared in Examples 1 to 5 and two groups of comparative examples 1 to 2 were machined into 1B dumbbell-shaped specimens. The first group of specimens was not treated and was called the blank group. The second group of specimens was placed in a xenon lamp test chamber for 2000 hours and was called the control group. The ultraviolet light source in the xenon lamp test chamber was a UVA-340 lamp with an irradiation intensity of 0.76W / m 2 Environmental conditions: The blackboard temperature is set to 60±3℃, the humidity is set to 50% RH, the sample is stretched at a constant speed along the longitudinal axis of the sample until the sample breaks, and the maximum tensile stress that the sample can withstand is recorded, which is the tensile strength. The results are recorded in Table 2.

[0056] Table 2

[0057]

[0058] Among them, V-0: After the sample is subjected to two 10-second combustion tests, the flame is extinguished within 30 seconds. V-1: After the sample is subjected to two 10-second combustion tests, the flame is extinguished within 60 seconds.

[0059] Test Example 2

[0060] Test content: According to the test method disclosed in GB / T 1843-2008, two groups of flame-retardant PC / ABS composite materials prepared in Examples 1 to 5 and two groups of Comparative Examples 1 to 2 were machined into specimens with a size of 80 mm × 10 mm × 4 mm. The second group of specimens, referred to as the control group, were placed in a xenon lamp test chamber for 2000 h. The ultraviolet light source in the xenon lamp test chamber was a UVA-340 lamp with an irradiation intensity of 0.76 W / m2. The environmental conditions were: the blackboard temperature was set to 60±3°C, and the humidity was set to 50% RH. The absorbed energy when the specimens were broken into two or more segments was recorded. The impact strength of the specimens was calculated according to the formula: a_iN = E_C / (h×b_N)×10^3, where a_iN is the impact strength, E_C is the absorbed energy at break, h is the specimen thickness, and b_N is the remaining width of the specimen. The results are recorded in Table 2.

[0061] Test Example 3

[0062] Test content: According to the U.S. UL94 fire protection standard, two groups of flame-retardant PC / ABS composite materials prepared in Examples 1 to 5 and two groups of Comparative Examples 1 to 2 were machined into test specimens with a size of 100 mm × 12 mm × 5 mm. The first group of samples was not treated and was referred to as the blank group. The second group of samples was placed in a test chamber at a temperature of 80°C and a humidity of 90% RH for 72 hours and was referred to as the control group. The samples were subjected to the UL94HB horizontal burning test, and the results are recorded in Table 2.

[0063] Table 2 shows that replacing the modified flame retardant with hexaphenoxycyclotriphosphazene and bisphenol A-bis(diphenyl phosphate) resulted in a slight decrease in the tensile strength and a significant reduction in the impact strength of the flame-retardant PC / ABS composite, demonstrating that the modified flame retardant improved the mechanical properties of the composite. Furthermore, after 72 hours of treatment in a test chamber at 80°C and 90% relative humidity, the flame retardancy of the composite remained unchanged, demonstrating its strong resistance to wet-heat aging. Hexaphenoxycyclotriphosphazene and bisphenol A-bis(diphenyl phosphate) are generally used as flame retardants in the plastics industry and not as UV absorbers. However, after treatment in a xenon arc test chamber, the mechanical properties of the composite containing the modified flame retardant were largely retained, demonstrating that the modified flame retardant enhances the composite's resistance to UV aging and that the addition of a UV absorber is unnecessary. Nanofillers can slightly improve the tensile strength and impact strength of flame-retardant PC / ABS composites.

[0064] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a flame-retardant PC / ABS composite material for automobiles, characterized by: The flame retardant PC / ABS composite material comprises the following components in parts by weight: 100 parts of PC, 40 to 60 parts of ABS, 4 to 6 parts of LCP, 8 to 12 parts of nanofillers, 8 to 10 parts of modified flame retardants, 5 to 7 parts of toughening agents, 0.3 to 0.5 parts of antioxidants, 0.3 to 0.6 parts of lubricants, 0.3 to 0.5 parts of deodorants, 0.3 to 0.5 parts of anti-dripping agents, and 0.5 to 1.0 parts of smoke suppressants; the preparation method of the modified flame retardant comprises the following steps: under nitrogen protection, dispersing 100 g of hexaphenoxy cyclotriphosphazene in acetone, slowly adding 6 to 8 g of hexamethyl The modified flame retardant is prepared by heating disilazane and 10-12g of nano-silica to 60-65°C, reacting for 6-8h under mechanical stirring at 200rpm, centrifuging, and vacuum drying to obtain a modified hexaphenoxy cyclotriphosphazene. Bisphenol A-bis(diphenyl phosphate), modified hexaphenoxy cyclotriphosphazene, polymethyl methacrylate, and silane coupling agent Si-69 are uniformly mixed in a mass ratio of 35:10-12:9-10:4-5, and then feeding into a twin-screw extruder, pre-mixing at 185-190°C, and then melt-blending and extruding granulation at 200-210°C to obtain the modified flame retardant. The preparation method of the flame retardant PC / ABS composite material comprises the following steps: S1. Stepwise mixing: PC, ABS, nanofiller, antioxidant, and lubricant are added to a high-speed mixer and mixed at 500 rpm for 3 to 5 minutes, then increased to 1000 rpm and mixed for 7 to 10 minutes, modified flame retardant, smoke suppressant, and anti-dripping agent are added and mixed at 800 rpm for 5 to 8 minutes, and finally LCP and toughening agent are added and mixed at 600 rpm for 5 to 10 minutes to obtain a premix; S2, extrusion: the premix was put into a twin-screw extruder, the temperature of each zone of the twin-screw extruder was set as follows: 200° C. in zone 1, 210° C. in zone 2, 230° C. in zone 3, 240° C. in zone 4, 235° C. in zone 5, and 220° C. in the die head, the screw speed of the twin-screw extruder was controlled at 280-320 rpm, a vacuum exhaust port was set in zone 4 and a vacuum degree of -0.1 MPa was maintained, the premix was melt-blended, and after pelletizing, it was vacuum-dried at 80° C. for 6 h to obtain the flame-retardant PC / ABS composite material.

2. The method for preparing a flame-retardant PC / ABS composite material for automobiles according to claim 1, wherein: The molecular weight of the PC is 20,000 to 40,000, and the melt index of the PC is in the range of 3 to 9 g / 10 min.

3. The method for preparing a flame-retardant PC / ABS composite material for automobiles according to claim 1, wherein: The ABS is a polymer formed by copolymerizing 25 wt% to 40 wt% of acrylonitrile, 5 wt% to 20 wt% of butadiene, and 30 wt% to 70 wt% of styrene.

4. The method for preparing a flame-retardant PC / ABS composite material for automobiles according to claim 1, wherein: The preparation method of the nanofiller comprises the following steps: adding 20-28 g of magnesium nitrate hexahydrate and 7-10 g of aluminum nitrate nonahydrate into 400-600 mL of deionized water, dropwise adding 800-1200 mL of a NaOH / Na2CO3 mixed solution with a molar ratio of 3-5:1, hydrothermally reacting at 60-70° C. for 10-14 hours, centrifugally washing and drying to obtain a powder; dispersing the powder in a mixed solvent of 100-200 mL of ethanol and 30-70 mL of deionized water, adding 8-12 g of tetraethyl orthosilicate and 15-25 g of nano-alumina, and simultaneously adding ammonia water, adjusting the pH value of the solution to 8.5-10.5, reacting at 50-60° C. for 5-7 hours, and centrifugally drying to obtain the nanofiller.

5. The method for preparing a flame-retardant PC / ABS composite material for automobiles according to claim 1, characterized in that: The toughening agent is one of maleic anhydride grafted ABS, maleic anhydride grafted PE, maleic anhydride grafted PP, maleic anhydride grafted PS, and maleic anhydride grafted EVA.

6. The method for preparing a flame-retardant PC / ABS composite material for automobiles according to claim 1, wherein: The antioxidant consists of antioxidant 1010 and antioxidant 168, and the mass ratio of antioxidant 1010 to antioxidant 168 is 1:

1.

7. The method for preparing a flame-retardant PC / ABS composite material for automobiles according to claim 1, wherein: The lubricant is one of calcium stearate, polyethylene wax and EBS.

8. The method for preparing a flame-retardant PC / ABS composite material for automobiles according to claim 1, characterized in that: The deodorant is 4A type zeolite molecular sieve, and the anti-dripping agent is polytetrafluoroethylene powder.

9. The method for preparing a flame-retardant PC / ABS composite material for automobiles according to claim 1, wherein: The smoke suppressant consists of ammonium octamolybdate and molybdenum trioxide, and the mass ratio of ammonium octamolybdate to molybdenum trioxide is 3:1.

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