Preparation process of high-impact-resistance flame-retardant PBT / ABS (polybutylene terephthalate / acrylonitrile butadiene styrene) composite material

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to a preparation process of a high-impact-resistance flame-retardant PBT / ABS composite material. Comprising the following steps: preparing a flame-retardant impact-resistant rubber reinforcing agent; compounding a flame-retardant impact-resistant rubber reinforcing agent to prepare ABS resin; separating and recombining free chain segments and compounding the material. The preparation method comprises the following steps: adding 3-bromopropyltrimethoxysilane into a hydrogen bromide aqueous solution and absolute methanol, carrying out a water-bath heating reaction to prepare an octabromo cage type coupling agent with a hexahedral structure, and then controlling the mass ratio of the octabromo cage type coupling agent to butadiene to be 45: (6-8) to prepare the flame-retardant and impact-resistant rubber reinforcing agent containing a multi-arm polybutadiene structure and a Br group. In the preparation process of the ABS resin, the ABS resin is endowed with high impact resistance and tensile strength, and is endowed with high flame retardancy without influencing the physical properties, and the PBT / ABS composite material can also have good flame retardancy without additionally adding a flame retardant during the subsequent preparation of the PBT / ABS composite material.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a preparation process of a high-impact flame-retardant PBT / ABS composite material. Background Art

[0002] The rapid development of electronics, electrical appliances, and lightweight automobiles is placing higher demands on the comprehensive performance of engineering plastics. Polybutylene terephthalate (PBT) has become a key choice for high-performance engineering plastics due to its excellent mechanical strength, chemical resistance, dimensional stability, and processability. However, PBT itself has significant drawbacks: its high crystallinity leads to brittleness and poor impact resistance, particularly at low temperatures or high strain rates, which severely limits its application in structural parts. To overcome this problem, the industry often enhances its toughness through blending and modification. Acrylonitrile-butadiene-styrene copolymer (ABS) is considered an ideal candidate for PBT modification due to its excellent impact resistance and processing compatibility.

[0003] However, although the introduction of ABS can improve the toughness of PBT, it further reduces the flame retardancy of the material. Traditional flame retardant modification methods (such as the addition of halogen / phosphorus flame retardants) often sacrifice mechanical properties and are prone to migration, precipitation and other problems. Although some processes solve the compatibility issues of flame retardants through surface modification and processing, it is still difficult to meet the comprehensive requirements of high-end application scenarios for high impact resistance, high flame retardancy and high stability of materials. Summary of the Invention

[0004] In order to solve the above technical defects, the present invention has developed a preparation process for a high-impact and flame-retardant PBT / ABS composite material. By preparing a flame-retardant and impact-resistant ABS resin and adding it to the composite material, the PBT / ABS composite material can also have excellent mechanical properties and flame retardancy without the need for additional flame retardants.

[0005] A preparation process of a high-impact flame-retardant PBT / ABS composite material comprises the following steps: S1: Preparation of flame retardant and impact-resistant rubber reinforcing agent 3-bromopropyltrimethoxysilane, a hydrogen bromide aqueous solution, and anhydrous methanol are mixed and stirred in a water bath, then filtered, washed, and recrystallized, and dried to obtain an octabromo cage coupling agent; butadiene, n-butyl lithium, and anhydrous tetrahydrofuran are added to cyclohexane for polymerization to obtain a polymerization solution; the octabromo cage coupling agent is dissolved in cyclohexane and injected into the polymerization solution for reaction; and steam stripping and drying are performed to obtain a flame retardant and impact-resistant rubber reinforcing agent. S2: Preparation of ABS resin by compounding flame retardant and impact resistant rubber reinforcing agent A flame-retardant and impact-resistant rubber reinforcing agent and deionized water are prepared into a rubber reinforcing agent latex, styrene, acrylonitrile, methyl methacrylate, tert-dodecyl mercaptan and cumene hydroperoxide are mixed to prepare a monomer solution, and then the rubber reinforcing agent latex and the monomer solution are mixed and reacted by an emulsion grafting method to obtain an emulsion polymer, which is then vacuum-dried and devolatilized to obtain a flame-retardant and impact-resistant ABS resin; S3: Separation and reorganization of free chain segments and compounding of materials Flame-retardant impact-resistant ABS resin and acetone are mixed and shaken, and then centrifuged to obtain free-segment flame-retardant impact-resistant ABS resin and a free-segment solution. Xonotlite whiskers are silane-modified and then immersed in the free-segment solution for reflux. The precipitate is filtered and washed to obtain surface-double-modified xonotlite whiskers. Polybutylene terephthalate, free-segment flame-retardant impact-resistant ABS resin, surface-double-modified xonotlite whiskers and antioxidant 1098 are uniformly mixed and placed in a twin-screw extruder for extrusion and granulation to obtain a high-impact flame-retardant PBT / ABS composite material.

[0006] Furthermore, step S1 of preparing the flame retardant and impact resistant rubber reinforcing agent comprises the following steps: S1.1: Mix 3-bromopropyltrimethoxysilane, aqueous hydrogen bromide solution, and anhydrous methanol in a volume ratio of 1:(0.75-0.8):(20-25) in a container, seal the container, and stir in a water bath at 40-42°C at a stirring speed of 450-500 rpm for 8-10 days. Continuously add methanol during the reaction. Then, filter and collect the precipitated powder, wash it with anhydrous methanol 3-4 times, then add n-hexane, heat and dissolve it, filter to remove impurities, and cool the filtrate to recrystallize it to obtain a solid product. Dry it at 80-85°C for 20-24 hours to obtain an octabromo cage coupling agent. S1.2: A stainless steel reactor was evacuated to a pressure of 10,000-12,000 Pa and then filled with high-purity argon to expel all air from the reactor. 200-250 parts by weight of cyclohexane was then added. 45 parts by weight of butadiene was injected into the cyclohexane under argon protection. The reaction mixture was heated to 50-55°C and kept warm for 25-30 minutes. 0.01-0.02 parts by weight of n-butyl lithium was then injected using a syringe and stirred for 4-6 minutes. 0.04-0.05 parts by weight of n-butyl lithium and 1-3 parts by weight of anhydrous tetrahydrofuran were then injected. The reaction mixture was heated to 60-65°C and kept warm for 1.5-2 hours to polymerize the mixture to obtain a polymerization solution. S1.3: Add 6-8 parts by weight of octabromo cage coupling agent to 15-20 parts by weight of cyclohexane, then heat to 55-60°C, and stir until the octabromo cage coupling agent is completely dissolved to obtain an octabromo cage coupling agent solution. At 60-65°C, inject the octabromo cage coupling agent solution into the polymerization solution obtained in step S1.2 through a syringe, continue stirring for 1-1.5 hours, and then inject 30-40 parts by weight of isopropanol to obtain a reaction solution. Steam stripping is performed on the reaction solution to remove the solvent to obtain a hydrous solid. The hydrous solid is placed in a vacuum drying oven and dried to constant weight at 65-70°C to obtain a flame retardant and impact-resistant rubber reinforcing agent.

[0007] Furthermore, step S2 of compounding the flame retardant and impact resistant rubber reinforcing agent to prepare the ABS resin comprises the following steps: S2.1: A flame retardant and impact-resistant rubber reinforcing agent and deionized water are mixed to prepare a rubber reinforcing agent latex having a solid content of 55-60%. A monomer solution is prepared by mixing 80-85 parts by weight of styrene, 28-30 parts by weight of acrylonitrile, 2.8-3 parts by weight of methyl methacrylate, 0.25-0.3 parts by weight of tert-dodecyl mercaptan, and 0.03-0.05 parts by weight of cumene hydroperoxide. S2.2: Add 0.5-1 parts by weight of glucose, 0.5-1 parts by weight of sodium pyrophosphate and 4-5 parts by weight of deionized water to a reactor and stir until the solid is dissolved. Then, add 10-12 parts by weight of ferrous sulfate solution, 240-280 parts by weight of rubber reinforcing agent latex and 0.03-0.05 parts by weight of isopropyl benzene hydroperoxide. Stirring is started at 85-95°C, 180-200 rpm and nitrogen protection. The monomer solution prepared in step S2.1 is added dropwise using a peristaltic pump. The mixture is stirred for reaction for 1.5-2 hours. Then, 8-10 parts by weight of butylated hydroxytoluene is added and the stirring reaction is continued for 25-30 minutes to obtain an emulsion polymer. The emulsion polymer is then placed in a vacuum drying oven and dried at 80-85°C and 8000-10000 Pa. The emulsion polymer is then transferred to a torque rheometer for devolatilization to obtain a flame retardant and impact-resistant ABS resin.

[0008] Furthermore, step S3 of separating and recombining free chain segments and compounding materials includes the following steps: S3.1: Mix 20-30 parts by weight of a flame-retardant and impact-resistant ABS resin and acetone in a constant temperature oscillator, and then oscillate at 25-30°C and 200-250 rpm for 10-12 hours. Then, transfer the mixture to a centrifuge and centrifuge at 10,000-12,000 rpm for 25-30 minutes. Separate the supernatant and precipitate to obtain a free-segment flame-retardant and impact-resistant ABS resin and a free-segment solution. S3.2: Dissolve γ-aminopropyltriethoxysilane in an 85-90% by volume ethanol aqueous solution to prepare a 2-3% by mass γ-aminopropyltriethoxysilane solution, then adjust the pH to 4-5 with acetic acid, add xonotlite whiskers at a solid-to-liquid ratio of 1:(20-25) g / mL, and stir at 50-60°C for 3-4 hours to obtain silane-modified xonotlite whiskers, immerse 1-2 parts by weight of the xonotlite whiskers in the free segment solution obtained in step S3.1, and then add 0.1-0.15 parts by weight of triethylamine, and reflux at 75-80°C under nitrogen for 2-3 hours. Then, filter the precipitate, wash it with toluene 3-4 times, and vacuum dry it to constant weight to obtain surface-double-modified xonotlite whiskers; S3.3: Mix 100-120 parts by weight of polybutylene terephthalate, 35-40 parts by weight of flame-retardant and impact-resistant ABS resin with free chain segments, 10-15 parts by weight of surface double-modified xonotlite whiskers and 0.4-0.8 parts by weight of antioxidant 1098 at room temperature, then add the mixture into a twin-screw extruder for extrusion and granulation to obtain a PBT / ABS composite material.

[0009] Furthermore, the mass concentration of the aqueous hydrogen bromide solution in step S1.1 is 36-38%.

[0010] Furthermore, the concentration of the ferrous sulfate solution in step S2.2 is 1-1.5 mg / mL.

[0011] Furthermore, in step S2.2, the devolatilization conditions of the torque rheometer are: devolatilization at 150-170° C. and a stirring speed of 60-65 rpm for 4-5 minutes.

[0012] Furthermore, in step S3.3, the aspect ratio of the twin-screw extruder is (35-40):1, the screw speed is 200-400 rpm, and the extrusion temperature is 200-220°C.

[0013] The beneficial effects are as follows: 1. The present invention first adds 3-bromopropyltrimethoxysilane to a solvent system of hydrogen bromide aqueous solution and anhydrous methanol for a water bath heating reaction. During this process, the 3-bromopropyltrimethoxysilane is first hydrolyzed and then slowly dehydrated to form a hexahedral octabromo cage coupling agent with Si-O-Si short chains as edges and a bromine group attached to each Si atom. Then, the mass ratio of the octabromo cage coupling agent to butadiene is controlled to be 45:(6-8). Through a living anionic polymerization reaction, the Br groups of the octabromo cage coupling agent are partially replaced by polybutadiene, and some Br groups are retained, thereby obtaining a flame retardant and impact-resistant rubber reinforcing agent comprising a multi-arm polybutadiene structure and Br groups. By introducing the flame retardant into the preparation process of ABS resin, the ABS resin is given high impact and tensile properties and high flame retardancy without affecting the physical properties. In the subsequent preparation of PBT / ABS composite materials, good flame retardancy can be achieved without the need for additional addition of flame retardants.

[0014] 2. The present invention mixes a flame retardant and impact-resistant rubber reinforcing agent and an acetone solution and oscillates the mixture. During this process, the free chain segments of styrene-acrylonitrile in the flame retardant and impact-resistant rubber reinforcing agent will dissolve in the acetone solution, thereby avoiding high concentration of the styrene-acrylonitrile free chain segments on the flame retardant and impact-resistant rubber reinforcing agent, thereby preventing the chain entanglement of the free chain segments and the multi-arm polybutadiene structure, thereby increasing the subsequent cross-linking complexity of the polybutadiene chain and PBT, increasing the cross-linking density, and enhancing the impact strength and tensile strength of the PBT / ABS composite material.

[0015] 3. The present invention first modifies the xonotlite whiskers with silane, then immerses them in a separated free segment solution for surface modification, and then blends and extrudes them with PBT and a flame-retardant, impact-resistant ABS resin free of free segments. This can significantly improve the compatibility of the xonotlite whiskers in the composite material and significantly increase the impact strength and tensile strength of the PBT / ABS composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a flow chart of the preparation process of the high-impact flame-retardant PBT / ABS composite material used in the embodiments of the present invention. DETAILED DESCRIPTION

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 creative efforts are within the scope of protection of the present invention.

[0018] Example 1: A preparation process of a high impact flame retardant PBT / ABS composite material, such as Figure 1 As shown, the following steps are included: S1: Preparation of flame retardant and impact-resistant rubber reinforcing agent S1.1: 3-Bromopropyltrimethoxysilane, 36% aqueous hydrogen bromide solution, and anhydrous methanol were mixed in a volume ratio of 1:0.75:20 in a container, and the container was sealed. The mixture was stirred at 450 rpm in a 40°C water bath for 8 days, with methanol continuously added during the reaction. The precipitated powder was collected by filtration, washed three times with anhydrous methanol, and then dissolved in n-hexane by heating. The mixture was filtered to remove impurities, and the filtrate was cooled and recrystallized to obtain a solid product, which was then dried at 80°C for 20 hours to obtain an octabromo cage coupling agent. S1.2: A stainless steel reactor was evacuated to 10,000 Pa and then filled with high-purity argon gas to expel all air from the reactor. 200 parts by weight of cyclohexane was then added. 45 parts by weight of butadiene was injected into the cyclohexane under argon protection. The reaction mixture was heated to 50°C and held at this temperature for 25 minutes. 0.01 parts by weight of n-butyl lithium was then injected using a syringe and stirred for 4 minutes. 0.04 parts by weight of n-butyl lithium and 1 part by weight of anhydrous tetrahydrofuran were then injected. The reaction mixture was heated to 60°C and held at this temperature for 1.5 hours to polymerize the mixture to obtain a polymerization solution. S1.3: Add 6 parts by weight of octabromo cage coupling agent to 15 parts by weight of cyclohexane, then heat to 55°C and stir until the octabromo cage coupling agent is completely dissolved to obtain an octabromo cage coupling agent solution. At 60°C, inject the octabromo cage coupling agent solution into the polymerization solution obtained in step S1.2 through a syringe, continue stirring for 1 hour, and then inject 30 parts by weight of isopropanol to obtain a reaction solution. Steam stripping is performed on the reaction solution to remove the solvent to obtain a hydrous solid. The hydrous solid is placed in a vacuum drying oven and dried to constant weight at 65°C to obtain a flame retardant and impact-resistant rubber reinforcing agent.

[0019] Preparation of ABS resin by compounding S2 flame retardant and impact resistant rubber reinforcing agent S2.1: A flame-retardant and impact-resistant rubber reinforcing agent and deionized water are mixed to prepare a rubber reinforcing agent latex having a solid content of 55%. A monomer solution is prepared by mixing 80 parts by weight of styrene, 28 parts by weight of acrylonitrile, 2.8 parts by weight of methyl methacrylate, 0.25 parts by weight of tert-dodecyl mercaptan, and 0.03 parts by weight of cumene hydroperoxide. S2.2: Add 0.5 parts by weight of glucose, 0.5 parts by weight of sodium pyrophosphate and 4 parts by weight of deionized water into a reactor and stir until the solid is dissolved. Then add 10 parts by weight of ferrous sulfate solution with a concentration of 1 mg / mL, 240 parts by weight of rubber reinforcing agent latex and 0.03 parts by weight of isopropyl benzene hydroperoxide. Stirring is started at 85°C, 180 rpm and nitrogen protection. The monomer solution prepared in step S2.1 is added dropwise through a peristaltic pump. The mixture is stirred for 1.5 hours. Then 8 parts by weight of butylated hydroxytoluene is added and the stirring reaction is continued for 25 minutes to obtain an emulsion polymer. The emulsion polymer is then placed in a vacuum drying oven and dried at 80°C and 8000 Pa. The emulsion polymer is then transferred to a torque rheometer and devolatilized at 150°C and a stirring speed of 60 rpm for 4 minutes to obtain a flame retardant and impact-resistant ABS resin.

[0020] S3 free chain segment separation and reorganization and material compounding S3.1: 20 parts by weight of a flame-retardant, impact-resistant ABS resin and acetone were mixed and added to a constant temperature shaker. The mixture was then shaken at 25°C and 200 rpm for 10 hours. The mixture was then transferred to a centrifuge and centrifuged at 10,000 rpm for 25 minutes. The supernatant and precipitate were separated to obtain a free-segment flame-retardant, impact-resistant ABS resin and a free-segment solution. S3.2: Dissolve γ-aminopropyltriethoxysilane in an 85% by volume ethanol aqueous solution to prepare a 2% by mass γ-aminopropyltriethoxysilane solution, then adjust the pH to 4 with acetic acid, add xonotlite whiskers at a solid-to-liquid ratio of 1:20 g / mL, and stir at 50°C for 3 hours to obtain silane-modified xonotlite whiskers. Immerse 1 part by weight of the xonotlite whiskers in the free segment solution prepared in step S3.1, then add 0.1 part by weight of triethylamine, and reflux at 75°C under nitrogen for 2 hours. Then, filter the precipitate, wash it three times with toluene, and vacuum dry it to constant weight to obtain surface-double-modified xonotlite whiskers. S3.3: 100 parts by weight of polybutylene terephthalate, 35 parts by weight of flame-retardant and impact-resistant ABS resin with free chain segments, 10 parts by weight of surface double-modified hard assimilate whiskers and 0.4 parts by weight of antioxidant 1098 are mixed uniformly at room temperature, and then added into a twin-screw extruder for extrusion granulation. The aspect ratio of the twin-screw extruder is 35:1, the screw speed is 200 rpm, and the extrusion temperature is 200°C to obtain a PBT / ABS composite material.

[0021] Example 2: A preparation process of a high impact flame retardant PBT / ABS composite material, such as Figure 1 As shown, the following steps are included: S1: Preparation of flame retardant and impact-resistant rubber reinforcing agent S1.1: 3-Bromopropyltrimethoxysilane, 36% aqueous hydrogen bromide solution, and anhydrous methanol were mixed in a volume ratio of 1:0.8:25 in a container, and the container was sealed. The mixture was stirred at 450 rpm in a 40°C water bath for 8 days, with methanol continuously added during the reaction. The precipitated powder was collected by filtration, washed three times with anhydrous methanol, and then dissolved in n-hexane by heating. The mixture was filtered to remove impurities, and the filtrate was cooled and recrystallized to obtain a solid product, which was then dried at 80°C for 20 hours to obtain an octabromo cage coupling agent. S1.2: A stainless steel reactor was evacuated to 10,000 Pa and filled with high-purity argon gas to expel all air from the reactor. 250 parts by weight of cyclohexane was then added. 45 parts by weight of butadiene was injected into the cyclohexane under argon protection. The reaction mixture was heated to 50°C and kept warm for 25 minutes. 0.02 parts by weight of n-butyl lithium was then injected using a syringe and stirred for 4 minutes. 0.05 parts by weight of n-butyl lithium and 3 parts by weight of anhydrous tetrahydrofuran were then injected. The reaction mixture was heated to 60°C and kept warm for 1.5 hours to polymerize the reaction mixture to obtain a polymerization solution. S1.3: Add 8 parts by weight of octabromo cage coupling agent to 20 parts by weight of cyclohexane, then heat to 55°C and stir until the octabromo cage coupling agent is completely dissolved to obtain an octabromo cage coupling agent solution. At 60°C, inject the octabromo cage coupling agent solution into the polymerization solution obtained in step S1.2 through a syringe, continue stirring for 1 hour, and then inject 40 parts by weight of isopropanol to obtain a reaction solution. Steam stripping is performed on the reaction solution to remove the solvent to obtain a hydrous solid. The hydrous solid is placed in a vacuum drying oven and dried at 65°C to constant weight to obtain a flame retardant and impact-resistant rubber reinforcing agent.

[0022] S2: Preparation of ABS resin by compounding flame retardant and impact resistant rubber reinforcing agent S2.1: A flame-retardant and impact-resistant rubber reinforcing agent and deionized water are mixed to prepare a rubber reinforcing agent latex having a solid content of 55%. A monomer solution is prepared by mixing 85 parts by weight of styrene, 30 parts by weight of acrylonitrile, 3 parts by weight of methyl methacrylate, 0.3 parts by weight of tert-dodecyl mercaptan, and 0.05 parts by weight of cumene hydroperoxide. S2.2: Add 1 part by weight of glucose, 1 part by weight of sodium pyrophosphate and 5 parts by weight of deionized water into a reactor and stir until the solid is dissolved. Then add 12 parts by weight of ferrous sulfate solution with a concentration of 1 mg / mL, 280 parts by weight of rubber reinforcing agent latex and 0.05 parts by weight of isopropyl benzene hydroperoxide. Start stirring at 85°C, 180 rpm and nitrogen protection, and add the monomer solution prepared in step S2.1 dropwise through a peristaltic pump. Stir and react for 1.5 hours. Then add 10 parts by weight of butylated hydroxytoluene and continue stirring and reacting for 25 minutes to obtain an emulsion polymer. Then put it into a vacuum drying oven and dry it at 80°C and 8000 Pa. Then transfer it to a torque rheometer and devolatilize it at 150°C and a stirring speed of 60 rpm for 4 minutes to obtain a flame retardant and impact-resistant ABS resin.

[0023] S3: Separation and reorganization of free chain segments and compounding of materials S3.1: 30 parts by weight of a flame-retardant, impact-resistant ABS resin and acetone were mixed and added to a constant temperature shaker. The mixture was then shaken at 25°C and 200 rpm for 10 hours. The mixture was then transferred to a centrifuge and centrifuged at 10,000 rpm for 25 minutes. The supernatant and precipitate were separated to obtain a free-segment flame-retardant, impact-resistant ABS resin and a free-segment solution. S3.2: Dissolve γ-aminopropyltriethoxysilane in an 85% by volume ethanol aqueous solution to prepare a 2% by mass γ-aminopropyltriethoxysilane solution, then adjust the pH to 4 with acetic acid, add xonotlite whiskers at a solid-to-liquid ratio of 1:20 g / mL, and stir at 50°C for 3 hours to obtain silane-modified xonotlite whiskers. Immerse 2 parts by weight of the xonotlite whiskers in the free segment solution prepared in step S3.1, then add 0.15 parts by weight of triethylamine, and reflux at 75°C under nitrogen for 2 hours. Then, filter the precipitate, wash it three times with toluene, and vacuum dry it to constant weight to obtain surface-double-modified xonotlite whiskers. S3.3: 120 parts by weight of polybutylene terephthalate, 40 parts by weight of flame-retardant and impact-resistant ABS resin without free chain segments, 15 parts by weight of surface double-modified hard assimilate whiskers and 0.8 parts by weight of antioxidant 1098 are mixed uniformly at room temperature, and then added into a twin-screw extruder for extrusion granulation. The aspect ratio of the twin-screw extruder is 35:1, the screw speed is 200 rpm, and the extrusion temperature is 200°C to obtain a PBT / ABS composite material.

[0024] Example 3: A preparation process of a high impact flame retardant PBT / ABS composite material, such as Figure 1 As shown, the following steps are included: S1: Preparation of flame retardant and impact-resistant rubber reinforcing agent S1.1: 3-Bromopropyltrimethoxysilane, 38% aqueous hydrogen bromide solution, and anhydrous methanol were mixed in a volume ratio of 1:0.75:20 in a container, and the container was sealed. The mixture was stirred at 500 rpm in a water bath at 42°C for 10 days, with methanol continuously added during the reaction. The precipitated powder was collected by filtration, washed four times with anhydrous methanol, and then dissolved in n-hexane by heating. The mixture was filtered to remove impurities, and the filtrate was cooled and recrystallized to obtain a solid product, which was dried at 85°C for 24 hours to obtain an octabromo cage coupling agent. S1.2: A stainless steel reactor was evacuated to 12,000 Pa and filled with high-purity argon to expel all air from the reactor. 200 parts by weight of cyclohexane was then added. 45 parts by weight of butadiene was injected into the cyclohexane under argon protection. The reaction mixture was heated to 55°C and kept warm for 30 minutes. 0.01 parts by weight of n-butyl lithium was then injected using a syringe and stirred for 6 minutes. 0.04 parts by weight of n-butyl lithium and 1 part by weight of anhydrous tetrahydrofuran were then injected. The reaction mixture was heated to 65°C and kept warm for 2 hours to polymerize the mixture to obtain a polymerization solution. S1.3: Add 6 parts by weight of octabromo cage coupling agent to 15 parts by weight of cyclohexane, then heat to 60°C and stir until the octabromo cage coupling agent is completely dissolved to obtain an octabromo cage coupling agent solution. At 66°C, inject the octabromo cage coupling agent solution into the polymerization solution obtained in step S1.2 through a syringe, continue stirring for 1.5 hours, and then inject 30 parts by weight of isopropanol to obtain a reaction solution. Steam stripping is performed on the reaction solution to remove the solvent to obtain a water-containing solid. The water-containing solid is placed in a vacuum drying oven and dried at 70°C to constant weight to obtain a flame retardant and impact-resistant rubber reinforcing agent.

[0025] S2: Preparation of ABS resin by compounding flame retardant and impact resistant rubber reinforcing agent S2.1: A flame-retardant and impact-resistant rubber reinforcing agent and deionized water are mixed to prepare a rubber reinforcing agent latex having a solid content of 60%. A monomer solution is prepared by mixing 80 parts by weight of styrene, 28 parts by weight of acrylonitrile, 2.8 parts by weight of methyl methacrylate, 0.25 parts by weight of tert-dodecyl mercaptan, and 0.03 parts by weight of cumene hydroperoxide. S2.2: Add 0.5 parts by weight of glucose, 0.5 parts by weight of sodium pyrophosphate and 4 parts by weight of deionized water into a reactor and stir until the solid is dissolved. Then add 10 parts by weight of ferrous sulfate solution with a concentration of 1 mg / mL, 240 parts by weight of rubber reinforcing agent latex and 0.03 parts by weight of isopropyl benzene hydroperoxide. Stirring is started at 95°C, 200 rpm and nitrogen protection. The monomer solution prepared in step S2.1 is added dropwise through a peristaltic pump. Stir and react for 2 hours. Then, 8 parts by weight of dibutylhydroxytoluene is added and the stirring reaction is continued for 30 minutes to obtain an emulsion polymer. The emulsion polymer is then placed in a vacuum drying oven and dried at 85°C and 10,000 Pa. The emulsion polymer is then transferred to a torque rheometer and devolatilized at 170°C and a stirring speed of 65 rpm for 4 minutes to obtain a flame retardant and impact-resistant ABS resin.

[0026] S3: Separation and reorganization of free chain segments and compounding of materials S3.1: 20 parts by weight of a flame-retardant, impact-resistant ABS resin and acetone were mixed and added to a constant temperature shaker. The mixture was shaken at 30°C and 250 rpm for 12 hours. The mixture was then transferred to a centrifuge and centrifuged at 12,000 rpm for 30 minutes. The supernatant and precipitate were separated to obtain a free-segment flame-retardant, impact-resistant ABS resin and a free-segment solution. S3.2: Dissolve γ-aminopropyltriethoxysilane in a 90% by volume ethanol aqueous solution to prepare a 3% by mass γ-aminopropyltriethoxysilane solution, then adjust the pH to 5 with acetic acid, add xonotlite whiskers at a solid-to-liquid ratio of 1:25 g / mL, and stir at 60°C for 4 hours to obtain silane-modified xonotlite whiskers. Take 1 part by weight of the xonotlite whiskers and immerse them in the free segment solution prepared in step S3.1. Then, add 0.1 part by weight of triethylamine, and reflux at 75°C under nitrogen for 3 hours. Then, filter the precipitate, wash it four times with toluene, and vacuum dry it to constant weight to obtain surface-double-modified xonotlite whiskers. S3.3: 100 parts by weight of polybutylene terephthalate, 35 parts by weight of flame-retardant and impact-resistant ABS resin with free chain segments, 10 parts by weight of surface double-modified hard assimilate whiskers and 0.4 parts by weight of antioxidant 1098 are mixed uniformly at room temperature, and then added into a twin-screw extruder for extrusion granulation. The aspect ratio of the twin-screw extruder is 40:1, the screw speed is 400 rpm, and the extrusion temperature is 220°C to obtain a PBT / ABS composite material.

[0027] Comparative Example 1: The difference from the implementation method of Example 1 is that Comparative Example 1 removes step S1, replaces the flame retardant and impact-resistant rubber reinforcing agent in step S2.1 with polybutadiene of equal mass to prepare polybutadiene latex, and replaces the subsequent rubber reinforcing agent latex with polybutadiene latex. The remaining specific implementation methods are the same as Example 1.

[0028] Comparative Example 2: The difference from the implementation of Example 1 is that the amount of octabromo cage coupling agent added in step S1.3 of Comparative Example 2 is 5.5 parts by weight, and the other specific implementation methods are the same as those of Example 1.

[0029] Comparative Example 3: The difference from the implementation of Example 1 is that the amount of octabromo cage coupling agent added in step S1.3 of Comparative Example 3 is 5 parts by weight, and the other specific implementation methods are the same as those of Example 1.

[0030] Comparative Example 4: The difference from the implementation method of Example 1 is that the amount of octabromo cage coupling agent added in step S1.3 of Comparative Example 4 is 8.5 parts by weight, and the other specific implementation methods are the same as those of Example 1.

[0031] Comparative Example 5: The difference from the implementation of Example 1 is that the amount of octabromo cage coupling agent added in step S1.3 of Comparative Example 5 is 9 parts by weight, and the other specific implementation methods are the same as those of Example 1.

[0032] Comparative Example 6: The difference from the implementation method of Example 1 is that in Comparative Example 6, the flame-retardant and impact-resistant ABS resin for removing the free chain segments in step S3.3 is replaced with a flame-retardant and impact-resistant ABS resin of equal mass, and the rest of the specific implementation methods are the same as those of Example 1.

[0033] Comparative Example 7: The difference from the implementation method of Example 1 is that in Comparative Example 7, the xonotlite whiskers are not modified in step S3.2. Only the free segment solution obtained in step S3.1 is vacuum dried to constant weight to obtain a free segment solid. The mass difference between the surface double-modified xonotlite whiskers and the silane-modified xonotlite whiskers in step S3.2 of Example 1 is calculated and recorded as m. The surface double-modified xonotlite whiskers in step S3.3 are replaced with m mass of free segment solid.

[0034] Experiment 1: The PBT / ABS composite materials prepared in Examples 1-3 and Comparative Examples 1-5 were tested for notched impact strength, tensile strength, and flame retardancy. The flame retardancy test was conducted in accordance with GB / T 2406.2-2009 "Plastics - Determination of Combustion Behavior by Oxygen Index Method - Part 2: Room Temperature Tests". Three tests were performed, and the data were averaged. The specific test results are shown in Table 1. Table 1: Notched impact strength, tensile strength and flame retardancy of PBT / ABS composites 　 <![CDATA[Notch impact strength (KJ / m 2 )]]> Tensile strength (MPa) Oxygen index (%) Example 1 33.5 115.3 29.5 Example 2 32.9 114.8 29.1 Example 3 33.7 115.5 29.7 Comparative Example 1 24.8 96.1 20.7 Comparative Example 2 29.4 106.4 24.3 Comparative Example 3 30.3 109.3 23.7 Comparative Example 4 26.9 102.2 26.9 Comparative Example 5 25.7 100.3 27.5 It can be seen from the data of Examples 1-3 in Table 1 that the PBT / ABS composite materials prepared in the examples of the present application all have excellent impact strength, tensile strength and flame retardant properties. However, it can be seen from Comparative Example 1 that when the flame retardant impact-resistant rubber reinforcing agent prepared in the present application is replaced with polybutadiene of equal mass, the notched impact strength, tensile strength and flame retardant properties of the PBT / ABS composite material are all reduced, proving that when the flame retardant impact-resistant rubber reinforcing agent prepared in the present application is introduced into ABS resin, it can improve the mechanical properties and flame retardancy of the PBT / ABS composite material. It can be seen from the data of Comparative Examples 2-5 that when the mass ratio of the octabromo cage coupling agent to butadiene is not within the range of 45:(6-8), the notched impact strength, tensile strength and flame retardant properties of the PBT / ABS composite material are all reduced, proving that when the mass ratio of the octabromo cage coupling agent to butadiene is 45:(6-8), a flame retardant impact-resistant rubber reinforcing agent with the best graft structure can be generated, thereby greatly improving the mechanical properties and flame retardancy of the composite material.

[0035] Experiment 2: The tensile strength and impact strength of the PBT / ABS composite materials prepared in Comparative Examples 6-7 were tested three times respectively. The data were averaged and compared with the data of Example 1 in Experiment 1. The specific test results are shown in Table 2. Table 2: Notched impact strength and tensile strength of PBT / ABS composites 　 <![CDATA[Notch impact strength (KJ / m 2 )]]> Tensile strength (MPa) Example 1 33.5 115.3 Comparative Example 6 29.5 108.4 Comparative Example 7 25.1 100.6 The data from Example 1 and Comparative Examples 6-7 indicate that separation of the free chain segments from the flame-retardant, impact-resistant ABS resin can prevent high concentration of the styrene-acrylonitrile free chain segments on the flame-retardant, impact-resistant rubber reinforcing agent, and prevent chain entanglement between the free chain segments and the multi-arm polybutadiene structure. This increases the complexity of subsequent crosslinking between the polybutadiene chains and PBT, increases the crosslinking density, and enhances the impact strength and tensile strength of the PBT / ABS composite. Furthermore, when xonotlite whiskers are not added, the notched impact strength and tensile strength of the PBT / ABS composite decrease. This demonstrates that modifying xonotlite whiskers and adding them to PBT / ABS for blending can improve the impact strength and tensile strength of the PBT / ABS composite.

[0036] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by persons skilled in the art without departing from the spirit and technical concepts disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A preparation process of a high impact flame retardant PBT / ABS composite material, characterized in that: The following steps are involved: Preparation of S1 flame-retardant and impact-resistant rubber reinforcing agent: 3-bromopropyltrimethoxysilane, aqueous hydrogen bromide solution, and anhydrous methanol are mixed and stirred in a water bath, then filtered, washed, and recrystallized, and dried to obtain an octabromo cage coupling agent; butadiene, n-butyl lithium, and anhydrous tetrahydrofuran are added to cyclohexane for polymerization to obtain a polymerization solution; the octabromo cage coupling agent is dissolved in cyclohexane and injected into the polymerization solution for reaction, followed by steam stripping and drying to obtain a flame-retardant and impact-resistant rubber reinforcing agent; S2 flame retardant and impact resistant rubber reinforcing agent is compounded to prepare ABS resin: flame retardant and impact resistant rubber reinforcing agent and deionized water are mixed to prepare rubber reinforcing agent latex, styrene, acrylonitrile, methyl methacrylate, tert-dodecyl mercaptan and isopropylbenzene hydroperoxide are mixed to prepare monomer solution, and then the rubber reinforcing agent latex and monomer solution are mixed and reacted by emulsion grafting method to obtain emulsion polymer, which is vacuum dried and then devolatilized to obtain flame retardant and impact resistant ABS resin; S3 free chain segment separation and reorganization and material compounding: the flame retardant impact-resistant ABS resin and acetone are mixed and shaken, and then centrifuged to obtain the flame retardant impact-resistant ABS resin without free chain segments and the free chain segment solution. The hard notacite whiskers are silane-modified and then immersed in the free chain segment solution and refluxed. The precipitate is filtered and washed to obtain surface double-modified hard notacite whiskers. Polybutylene terephthalate, the flame retardant impact-resistant ABS resin without free chain segments, the surface double-modified hard notacite whiskers and antioxidant 1098 are mixed evenly and placed in a twin-screw extruder for extrusion and granulation to obtain a high impact and flame retardant PBT / ABS composite material.

2. The preparation process of a high impact flame retardant PBT / ABS composite material according to claim 1, characterized in that: Step S1: Preparation of flame retardant and impact resistant rubber reinforcing agent, comprising the following steps: S1.1: Mix 3-bromopropyltrimethoxysilane, aqueous hydrogen bromide solution, and anhydrous methanol in a volume ratio of 1:(0.75-0.8):(20-25) in a container, seal the container, and stir in a water bath at 40-42°C at a stirring speed of 450-500 rpm for 8-10 days. Continuously add methanol during the reaction. Then, filter and collect the precipitated powder, wash it with anhydrous methanol 3-4 times, then add n-hexane, heat and dissolve it, filter to remove impurities, and cool the filtrate to recrystallize it to obtain a solid product. Dry it at 80-85°C for 20-24 hours to obtain an octabromo cage coupling agent. S1.2: A stainless steel reactor was evacuated to a pressure of 10,000-12,000 Pa and then filled with high-purity argon to expel all air from the reactor. 200-250 parts by weight of cyclohexane was then added. 45 parts by weight of butadiene was injected into the cyclohexane under argon protection. The reaction mixture was heated to 50-55°C and kept warm for 25-30 minutes. 0.01-0.02 parts by weight of n-butyl lithium was then injected using a syringe and stirred for 4-6 minutes. 0.04-0.05 parts by weight of n-butyl lithium and 1-3 parts by weight of anhydrous tetrahydrofuran were then injected. The reaction mixture was heated to 60-65°C and kept warm for 1.5-2 hours to polymerize the mixture to obtain a polymerization solution. S1.3: Add 6-8 parts by weight of octabromo cage coupling agent to 15-20 parts by weight of cyclohexane, then heat to 55-60°C, and stir until the octabromo cage coupling agent is completely dissolved to obtain an octabromo cage coupling agent solution. At 60-65°C, inject the octabromo cage coupling agent solution into the polymerization solution obtained in step S1.2 through a syringe, continue stirring for 1-1.5 hours, and then inject 30-40 parts by weight of isopropanol to obtain a reaction solution. Steam stripping is performed on the reaction solution to remove the solvent to obtain a hydrous solid. The hydrous solid is placed in a vacuum drying oven and dried to constant weight at 65-70°C to obtain a flame retardant and impact-resistant rubber reinforcing agent.

3. The preparation process of a high impact flame retardant PBT / ABS composite material according to claim 2, characterized in that: Step S2: compounding a flame retardant and impact resistant rubber reinforcing agent to prepare ABS resin, comprising the following steps: S2.1: A flame retardant and impact-resistant rubber reinforcing agent and deionized water are mixed to prepare a rubber reinforcing agent latex having a solid content of 55-60%. A monomer solution is prepared by mixing 80-85 parts by weight of styrene, 28-30 parts by weight of acrylonitrile, 2.8-3 parts by weight of methyl methacrylate, 0.25-0.3 parts by weight of tert-dodecyl mercaptan, and 0.03-0.05 parts by weight of cumene hydroperoxide. S2.2: Add 0.5-1 parts by weight of glucose, 0.5-1 parts by weight of sodium pyrophosphate and 4-5 parts by weight of deionized water to a reactor and stir until the solid is dissolved. Then, add 10-12 parts by weight of ferrous sulfate solution, 240-280 parts by weight of rubber reinforcing agent latex and 0.03-0.05 parts by weight of isopropyl benzene hydroperoxide. Stirring is started at 85-95°C, 180-200 rpm and nitrogen protection. The monomer solution prepared in step S2.1 is added dropwise using a peristaltic pump. The mixture is stirred for reaction for 1.5-2 hours. Then, 8-10 parts by weight of butylated hydroxytoluene is added and the stirring reaction is continued for 25-30 minutes to obtain an emulsion polymer. The emulsion polymer is then placed in a vacuum drying oven and dried at 80-85°C and 8000-10000 Pa. The emulsion polymer is then transferred to a torque rheometer for devolatilization to obtain a flame retardant and impact-resistant ABS resin.

4. The process for preparing a high impact flame retardant PBT / ABS composite material according to claim 3, characterized in that: Step S3, separation and reorganization of free chain segments and compounding of materials, includes the following steps: S3.1: Mix 20-30 parts by weight of a flame-retardant and impact-resistant ABS resin and acetone in a constant temperature oscillator, and then oscillate at 25-30°C and 200-250 rpm for 10-12 hours. Then, transfer the mixture to a centrifuge and centrifuge at 10,000-12,000 rpm for 25-30 minutes. Separate the supernatant and precipitate to obtain a free-segment flame-retardant and impact-resistant ABS resin and a free-segment solution. S3.2: Dissolve γ-aminopropyltriethoxysilane in an 85-90% by volume ethanol aqueous solution to prepare a 2-3% by mass γ-aminopropyltriethoxysilane solution, then adjust the pH to 4-5 with acetic acid, add xonotlite whiskers at a solid-to-liquid ratio of 1:(20-25) g / mL, and stir at 50-60°C for 3-4 hours to obtain silane-modified xonotlite whiskers, immerse 1-2 parts by weight of the xonotlite whiskers in the free segment solution obtained in step S3.1, and then add 0.1-0.15 parts by weight of triethylamine, and reflux at 75-80°C under nitrogen for 2-3 hours. Then, filter the precipitate, wash it with toluene 3-4 times, and vacuum dry it to constant weight to obtain surface-double-modified xonotlite whiskers; S3.3: Mix 100-120 parts by weight of polybutylene terephthalate, 35-40 parts by weight of flame-retardant and impact-resistant ABS resin with free chain segments, 10-15 parts by weight of surface double-modified xonotlite whiskers and 0.4-0.8 parts by weight of antioxidant 1098 at room temperature, then add the mixture into a twin-screw extruder for extrusion and granulation to obtain a PBT / ABS composite material.

5. The process for preparing a high impact flame retardant PBT / ABS composite material according to claim 2, characterized in that: The mass concentration of the aqueous hydrogen bromide solution in step S1.1 is 36-38%.

6. The process for preparing a high impact flame retardant PBT / ABS composite material according to claim 3, characterized in that: The concentration of the ferrous sulfate solution in step S2.2 is 1-1.5 mg / mL.

7. The process for preparing a high impact flame retardant PBT / ABS composite material according to claim 3, characterized in that: Step S2.2 The devolatilization conditions of the torque rheometer are: devolatilization at 150-170° C. and a stirring speed of 60-65 rpm for 4-5 minutes.

8. The process for preparing a high impact flame retardant PBT / ABS composite material according to claim 4, characterized in that: In step S3.3, the length-to-diameter ratio of the twin-screw extruder is (35-40):1, the screw speed is 200-400 rpm, and the extrusion temperature is 200-220°C.

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