Preparation process of high-impact flame-retardant PBT / ABS composite material

Abstract

The application belongs to the technical field of polymer materials, and particularly relates to a preparation process of high-impact flame-retardant PBT / ABS composite material. The process comprises the following steps: preparation of flame-retardant impact-resistant rubber reinforcing agent; preparation of ABS resin by compounding the flame-retardant impact-resistant rubber reinforcing agent; free segment separation and recombination; and material compounding. The flame-retardant impact-resistant rubber reinforcing agent containing a multi-arm polybutadiene structure and Br groups is prepared by adding 3-bromopropyltrimethoxysilane into a hydrogen bromide aqueous solution and anhydrous methanol, and then performing water bath heating reaction, and controlling the mass ratio of the octabromocubane coupling agent and butadiene to be (6-8):45. The flame-retardant impact-resistant rubber reinforcing agent is introduced into the preparation process of the ABS resin, so that the ABS resin is endowed with high impact resistance and tensile resistance, and is endowed with high flame retardance without affecting the physical properties. When the PBT / ABS composite material is prepared subsequently, the flame retardant does not need to be additionally added, and the PBT / ABS composite material can have good flame retardance.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and particularly relates to a preparation process of a high-impact and flame-retardant PBT / ABS composite material. Background Technology

[0002] With the rapid development of electronics, automotive lightweighting, and other fields, higher requirements are being placed on the comprehensive performance of engineering plastics. Polybutylene terephthalate (PBT) has become an important choice for high-performance engineering plastics due to its excellent mechanical strength, chemical resistance, dimensional stability, and processing performance. However, PBT itself has significant drawbacks: its high crystallinity leads to brittleness and poor impact resistance, especially at low temperatures or high strain rates where it is prone to brittle fracture, severely limiting its application in structural components. To overcome this problem, the industry often improves its toughness through blending modification. Acrylonitrile-butadiene-styrene copolymer (ABS) is considered an ideal candidate material for PBT modification due to its excellent impact resistance and processing compatibility.

[0003] However, while 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 halogenated / phosphorus flame retardants) often come at the cost of sacrificing mechanical properties and are prone to problems such as migration and precipitation. Although some processes solve the compatibility problem by modifying and processing the flame retardant surface, it is still difficult to meet the comprehensive requirements of high impact resistance, high flame retardancy and high stability of materials in high-end application scenarios. Summary of the Invention

[0004] To address the aforementioned technical deficiencies, this invention presents a preparation process for a high-impact, flame-retardant PBT / ABS composite material. By preparing flame-retardant and impact-resistant ABS resin and adding it to the composite material, the PBT / ABS composite material can possess excellent mechanical properties and flame retardancy without the need for additional flame retardants.

[0005] A preparation process for a high-impact, flame-retardant PBT / ABS composite material includes the following steps:

[0006] S1: Preparation of flame-retardant and impact-resistant rubber reinforcing agent

[0007] 3-Bromopropyltrimethoxysilane, aqueous hydrogen bromide solution, and anhydrous methanol were mixed and stirred in a water bath, then filtered, washed, and recrystallized. After drying, an octabromocage-type coupling agent was obtained. Butadiene, n-butyllithium, and anhydrous tetrahydrofuran were added to cyclohexane for polymerization to obtain a polymerization solution. The octabromocage-type coupling agent was dissolved in cyclohexane and injected into the polymerization solution for reaction. Then, steam stripping and drying were performed to obtain a flame-retardant and impact-resistant rubber reinforcing agent.

[0008] S2: ABS resin prepared by compounding flame-retardant and impact-resistant rubber reinforcing agents.

[0009] A flame-retardant and impact-resistant rubber reinforcing agent and deionized water were formulated into a rubber reinforcing agent latex. Styrene, acrylonitrile, methyl methacrylate, tert-dodecyl mercaptan and cumene hydroperoxide were mixed to form a monomer solution. Then, the rubber reinforcing agent latex and the monomer solution were mixed and reacted by the emulsion grafting method to obtain an emulsion polymer. After vacuum drying, the polymer was devolatilized to obtain flame-retardant and impact-resistant ABS resin.

[0010] S3: Free chain segment separation and recombination, and material composites

[0011] Flame-retardant and impact-resistant ABS resin and acetone were mixed and shaken, and then centrifuged to obtain flame-retardant and impact-resistant ABS resin with de-free chain segments and a free chain segment solution. Hard silicate whiskers were modified with silane and then immersed in the free chain segment solution and refluxed. The precipitate was filtered and washed to obtain surface-modified hard silicate whiskers. Polybutylene terephthalate, flame-retardant and impact-resistant ABS resin with de-free chain segments, surface-modified hard silicate whiskers and antioxidant 1098 were mixed evenly and then placed in a twin-screw extruder for extrusion granulation to obtain a high-impact and flame-retardant PBT / ABS composite material.

[0012] Further, the preparation of the flame-retardant and impact-resistant rubber reinforcing agent in step S1 includes the following steps:

[0013] 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 then stir the mixture at 450-500 rpm for 8-10 days in a water bath at 40-42℃. During the reaction, continuously add methanol. Then filter and collect the precipitated powder, wash it 3-4 times with anhydrous methanol, and then add n-hexane for heating and dissolution, filter to remove impurities, cool the filtrate and recrystallize to obtain a solid product. Dry the solid product at 80-85℃ for 20-24 hours to obtain an octabromocage coupling agent.

[0014] S1.2: After evacuating the stainless steel reactor to 10000-12000Pa, high-purity argon is introduced to purge the air from the reactor. Then, 200-250 parts by weight of cyclohexane are added. Under argon protection, 45 parts by weight of butadiene are injected into the cyclohexane. The mixture is heated to 50-55℃ and held for 25-30 minutes. Then, 0.01-0.02 parts by weight of n-butyllithium are injected using a syringe and stirred for 4-6 minutes. Next, 0.04-0.05 parts by weight of n-butyllithium and 1-3 parts by weight of anhydrous tetrahydrofuran are injected. The mixture is heated to 60-65℃ and held for 1.5-2 hours to carry out polymerization and obtain a polymerization solution.

[0015] S1.3: Add 6-8 parts by weight of octabromocage coupling agent to 15-20 parts by weight of cyclohexane, then heat to 55-60℃ and stir until the octabromocage coupling agent is completely dissolved to obtain an octabromocage coupling agent solution. At 60-65℃, inject the octabromocage coupling agent solution into the polymerization solution obtained in step S1.2 through a syringe, continue stirring for 1-1.5 hours, then inject 30-40 parts by weight of isopropanol to obtain a reaction solution. Remove the solvent from the reaction solution by steam stripping to obtain an aqueous solid. Place the aqueous solid in a vacuum drying oven and dry it to constant weight at 65-70℃ to obtain a flame-retardant and impact-resistant rubber reinforcing agent.

[0016] Further, step S2, the preparation of ABS resin by compounding flame-retardant and impact-resistant rubber reinforcing agents, includes the following steps:

[0017] S2.1: Mix flame-retardant and impact-resistant rubber reinforcing agent with deionized water to prepare a rubber reinforcing agent latex with a solid content of 55-60%; mix 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 to prepare a monomer solution;

[0018] 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 reaction vessel and stir until the solid dissolves. 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 cumene hydroperoxide. Start stirring under nitrogen protection at 85-95℃, 180-200 rpm, and with the monomer solution obtained in step S2.1 added dropwise by a peristaltic pump. Stir and react for 1.5-2 hours. Then add 8-10 parts by weight of dibutylhydroxytoluene and continue stirring and reacting for 25-30 minutes to obtain an emulsion polymer. Then place it in a vacuum drying oven and dry it at 80-85℃ and 8000-10000 Pa. Then transfer it to a torque rheometer for devolatilization to obtain flame-retardant and impact-resistant ABS resin.

[0019] Furthermore, step S3, the separation and recombination of free chain segments and the composite of materials, includes the following steps:

[0020] S3.1: Mix 20-30 parts by weight of flame-retardant and impact-resistant ABS resin and acetone in a constant temperature shaker, and then shake for 10-12 hours at 25-30℃ and 200-250 rpm. Then transfer to a centrifuge and centrifuge at 10000-12000 rpm for 25-30 minutes to separate the supernatant and precipitate, and obtain flame-retardant and impact-resistant ABS resin and free chain solution after defree chain segment removal.

[0021] S3.2: Dissolve γ-aminopropyltriethoxysilane in an 85-90% (v / v) aqueous ethanol solution to prepare a 2-3% (w / w) γ-aminopropyltriethoxysilane solution. Then adjust the pH to 4-5 with acetic acid. Add hard silica calcium stone whiskers at a solid-liquid ratio of 1:(20-25) g / mL. Stir at 50-60℃ for 3-4 hours to obtain silane-modified hard silica calcium stone whiskers. Take 1-2 parts by weight of silane-modified hard silica calcium stone whiskers and immerse them in the free chain segment solution prepared in step S3.1. Add 0.1-0.15 parts by weight of triethylamine. Reflux at 75-80℃ under nitrogen protection for 2-3 hours. Then filter and wash the precipitate 3-4 times with toluene. Vacuum dry to constant weight to obtain surface-modified hard silica calcium stone whiskers.

[0022] 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 de-segmentation, 10-15 parts by weight of surface-modified hard silica-calcium whiskers and 0.4-0.8 parts by weight of antioxidant 1098 evenly at room temperature, and then add it to a twin-screw extruder for extrusion granulation to obtain PBT / ABS composite material.

[0023] Furthermore, the mass concentration of the hydrogen bromide aqueous solution in step S1.1 is 36-38%.

[0024] Furthermore, the concentration of the ferrous sulfate solution in step S2.2 is 1-1.5 mg / mL.

[0025] Furthermore, the conditions for devapotrering in step S2.2 of the torque rheometer are: at 150-170℃, devapotrering is performed for 4-5 minutes at a stirring speed of 60-65 rpm.

[0026] Furthermore, 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℃.

[0027] The beneficial effects are as follows: 1. In this invention, 3-bromopropyltrimethoxysilane is first added to a solvent system of hydrogen bromide aqueous solution and anhydrous methanol and heated in a water bath. During this process, 3-bromopropyltrimethoxysilane undergoes hydrolysis first, and then undergoes slow dehydration to form a hexahedral octabromocage 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 octabromocage coupling agent to butadiene is controlled to be (6-8):45. Through an active anionic polymerization reaction, the Br groups of the octabromocage coupling agent are partially replaced by polybutadiene, while some Br groups are retained, resulting in a flame-retardant and impact-resistant rubber reinforcing agent containing a multi-arm polybutadiene structure and Br groups. By introducing it into the preparation process of ABS resin, it not only endows ABS resin with high impact and tensile properties, but also endows it with high flame retardancy without affecting physical properties. In the subsequent preparation of PBT / ABS composite materials, no additional flame retardant is required to achieve good flame retardant properties.

[0028] 2. This invention involves mixing and vibrating a flame-retardant and impact-resistant rubber reinforcing agent with an acetone solution. During this process, the free segments of the styrene-acrylonitrile bonded in the flame-retardant and impact-resistant rubber reinforcing agent dissolve in the acetone solution. This prevents the free segments of styrene-acrylonitrile from becoming highly concentrated on the flame-retardant and impact-resistant rubber reinforcing agent, thereby preventing the free segments from becoming entangled with the multi-arm polybutadiene structure. This increases the complexity of subsequent crosslinking between the polybutadiene chain and PBT, increases the crosslinking density, and enhances the impact strength and tensile strength of the PBT / ABS composite material.

[0029] 3. This invention first modifies the hard silica calcium stone whiskers with silane, then immerses them in a solution of separated free chain segments for surface modification, and then co-extrudes them with PBT and flame-retardant and impact-resistant ABS resin with defree chain segments. This can significantly improve the compatibility of hard silica calcium stone whiskers in composite materials and significantly improve the impact strength and tensile strength of PBT / ABS composite materials. Attached Figure Description

[0030] Figure 1 This is a flowchart illustrating the preparation process of the high-impact, flame-retardant PBT / ABS composite material used in the embodiments of the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1: A preparation process for a high-impact, flame-retardant PBT / ABS composite material, such as... Figure 1 As shown, it includes the following steps:

[0033] S1: Preparation of flame-retardant and impact-resistant rubber reinforcing agent

[0034] S1.1: 3-bromopropyltrimethoxysilane, a 36% aqueous solution of hydrogen bromide, and anhydrous methanol were mixed in a volume ratio of 1:0.75:20 in a container. The container was sealed, and the mixture was stirred at 450 rpm for 8 days in a water bath at 40°C. Methanol was continuously added during the reaction. The precipitated powder was then collected by filtration and washed three times with anhydrous methanol. Then, n-hexane was added for heating and dissolution, followed by filtration to remove impurities. The filtrate was cooled and recrystallized to obtain a solid product. The solid product was dried at 80°C for 20 hours to obtain an octabromocage coupling agent.

[0035] S1.2: After evacuating the stainless steel reactor to 10000Pa, high-purity argon is introduced to purge the air from the reactor. Then, 200 parts by weight of cyclohexane are added. Under argon protection, 45 parts by weight of butadiene are injected into the cyclohexane. The mixture is heated to 50°C and held for 25 minutes. Then, 0.01 parts by weight of n-butyllithium is injected using a syringe and stirred for 4 minutes. Next, 0.04 parts by weight of n-butyllithium and 1 part by weight of anhydrous tetrahydrofuran are injected. The mixture is heated to 60°C and held for 1.5 hours to carry out polymerization, obtaining a polymerization solution.

[0036] S1.3: Add 6 parts by weight of octabromocage coupling agent to 15 parts by weight of cyclohexane, then heat to 55°C and stir until the octabromocage coupling agent is completely dissolved to obtain an octabromocage coupling agent solution. At 60°C, inject the octabromocage 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. Remove the solvent by steam stripping of the reaction solution to obtain an aqueous solid. Place the aqueous solid in a vacuum drying oven and dry it at 65°C to constant weight to obtain a flame-retardant and impact-resistant rubber reinforcing agent.

[0037] ABS resin was prepared by compounding with S2 flame-retardant and impact-resistant rubber reinforcing agent.

[0038] S2.1: Mix flame-retardant and impact-resistant rubber reinforcing agent with deionized water to prepare a rubber reinforcing agent latex with a solid content of 55%; mix 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 to prepare a monomer solution.

[0039] 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 to a reaction vessel and stir until the solid dissolves. 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 cumene hydroperoxide. Start stirring at 85°C, 180 rpm, and under nitrogen protection. Add the monomer solution obtained in step S2.1 dropwise using a peristaltic pump and stir for 1.5 hours. Then add 8 parts by weight of dibutylhydroxytoluene and continue stirring for 25 minutes to obtain an emulsion polymer. Then place it in a vacuum drying oven and dry it at 80°C and 8000 Pa. Then transfer it to a torque rheometer and devolve it at 150°C with a stirring speed of 60 rpm for 4 minutes to obtain flame-retardant and impact-resistant ABS resin.

[0040] S3 free chain segment separation and recombination and material composite

[0041] S3.1: Mix 20 parts by weight of flame-retardant and impact-resistant ABS resin and acetone in a constant temperature shaker, and then shake for 10 hours at 25°C and 200 rpm. Then transfer to a centrifuge and centrifuge at 10,000 rpm for 25 minutes to separate the supernatant and precipitate, and obtain flame-retardant and impact-resistant ABS resin and free chain solution after free chain segment removal.

[0042] S3.2: Dissolve γ-aminopropyltriethoxysilane in an 85% (v / v) aqueous ethanol solution to prepare a 2% (w / w) γ-aminopropyltriethoxysilane solution. Then adjust the pH to 4 with acetic acid. Add hard silica calcium silicate whiskers at a solid-liquid ratio of 1:20 g / mL. Stir at 50°C for 3 hours to obtain silane-modified hard silica calcium silicate whiskers. Take 1 part by weight of silane-modified hard silica calcium silicate whiskers and immerse them in the free chain solution prepared in step S3.1. Add 0.1 part by weight of triethylamine. Reflux at 75°C under nitrogen protection for 2 hours. Then filter and take the precipitate. Wash it three times with toluene and vacuum dry to constant weight to obtain surface-modified hard silica calcium silicate whiskers.

[0043] S3.3: 100 parts by weight of polybutylene terephthalate, 35 parts by weight of flame-retardant and impact-resistant ABS resin with free segment removal, 10 parts by weight of surface-modified hard silicate whiskers and 0.4 parts by weight of antioxidant 1098 are mixed evenly at room temperature, and then added to a twin-screw extruder for extrusion granulation. The length-to-diameter ratio of the twin-screw extruder is 35:1, the screw speed is 200 rpm, and the extrusion temperature is 200℃ to obtain PBT / ABS composite material.

[0044] Example 2: A preparation process for a high-impact, flame-retardant PBT / ABS composite material, such as... Figure 1 As shown, it includes the following steps:

[0045] S1: Preparation of flame-retardant and impact-resistant rubber reinforcing agent

[0046] S1.1: 3-bromopropyltrimethoxysilane, a 36% aqueous solution of hydrogen bromide, and anhydrous methanol were mixed in a volume ratio of 1:0.8:25 in a container. The container was sealed, and the mixture was stirred at 450 rpm for 8 days in a water bath at 40°C. Methanol was continuously added during the reaction. The precipitated powder was then collected by filtration and washed three times with anhydrous methanol. Then, n-hexane was added for heating and dissolution, followed by filtration to remove impurities. The filtrate was cooled and recrystallized to obtain a solid product. The solid product was dried at 80°C for 20 hours to obtain an octabromocage coupling agent.

[0047] S1.2: After evacuating the stainless steel reactor to 10000Pa, high-purity argon gas is introduced to purge the air from the reactor. Then, 250 parts by weight of cyclohexane are added, and 45 parts by weight of butadiene are injected into the cyclohexane under argon protection. The mixture is heated to 50°C and held for 25 minutes. Then, 0.02 parts by weight of n-butyllithium is injected using a syringe and stirred for 4 minutes. Next, 0.05 parts by weight of n-butyllithium and 3 parts by weight of anhydrous tetrahydrofuran are injected. The mixture is heated to 60°C and held for 1.5 hours to carry out polymerization, obtaining a polymerization solution.

[0048] S1.3: Add 8 parts by weight of octabromocage coupling agent to 20 parts by weight of cyclohexane, then heat to 55°C and stir until the octabromocage coupling agent is completely dissolved to obtain an octabromocage coupling agent solution. At 60°C, inject the octabromocage 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. Remove the solvent by steam stripping of the reaction solution to obtain an aqueous solid. Place the aqueous solid in a vacuum drying oven and dry it at 65°C to constant weight to obtain a flame-retardant and impact-resistant rubber reinforcing agent.

[0049] S2: ABS resin prepared by compounding flame-retardant and impact-resistant rubber reinforcing agents.

[0050] S2.1: Mix flame-retardant and impact-resistant rubber reinforcing agent with deionized water to prepare a rubber reinforcing agent latex with a solid content of 55%; mix 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 to prepare a monomer solution.

[0051] S2.2: Add 1 part by weight of glucose, 1 part by weight of sodium pyrophosphate and 5 parts by weight of deionized water to the reaction vessel and stir until the solid dissolves. 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 cumene hydroperoxide. Start stirring at 85°C, 180 rpm and under nitrogen protection. Add the monomer solution obtained in step S2.1 dropwise by a peristaltic pump and stir for 1.5 hours. Then add 10 parts by weight of dibutylhydroxytoluene and continue stirring for 25 minutes to obtain the emulsion polymer. Then place it in a vacuum drying oven and dry it at 80°C and 8000 Pa. Then transfer it to a torque rheometer and devolve it at 150°C and 60 rpm for 4 minutes to obtain flame-retardant and impact-resistant ABS resin.

[0052] S3: Free chain segment separation and recombination, and material composites

[0053] S3.1: Mix 30 parts by weight of flame-retardant and impact-resistant ABS resin and acetone in a constant temperature shaker, and then shake for 10 hours at 25°C and 200 rpm. Then transfer to a centrifuge and centrifuge at 10,000 rpm for 25 minutes to separate the supernatant and precipitate, and obtain flame-retardant and impact-resistant ABS resin and free chain solution after free chain segment removal.

[0054] S3.2: Dissolve γ-aminopropyltriethoxysilane in an 85% (v / v) aqueous ethanol solution to prepare a 2% (w / w) γ-aminopropyltriethoxysilane solution. Then adjust the pH to 4 with acetic acid. Add hard silica calcium silicate whiskers at a solid-liquid ratio of 1:20 g / mL. Stir at 50°C for 3 hours to obtain silane-modified hard silica calcium silicate whiskers. Take 2 parts by weight of silane-modified hard silica calcium silicate whiskers and immerse them in the free chain segment solution prepared in step S3.1. Add 0.15 parts by weight of triethylamine. Reflux the reaction at 75°C under nitrogen protection for 2 hours. Then filter and take the precipitate. Wash it three times with toluene and vacuum dry to constant weight to obtain surface-modified hard silica calcium silicate whiskers.

[0055] S3.3: 120 parts by weight of polybutylene terephthalate, 40 parts by weight of flame-retardant and impact-resistant ABS resin with free segment removal, 15 parts by weight of surface-modified hard silicate whiskers and 0.8 parts by weight of antioxidant 1098 are mixed evenly at room temperature, and then added to a twin-screw extruder for extrusion granulation. The length-to-diameter ratio of the twin-screw extruder is 35:1, the screw speed is 200 rpm, and the extrusion temperature is 200℃ to obtain PBT / ABS composite material.

[0056] Example 3: A preparation process for a high-impact, flame-retardant PBT / ABS composite material, such as... Figure 1 As shown, it includes the following steps:

[0057] S1: Preparation of flame-retardant and impact-resistant rubber reinforcing agent

[0058] S1.1: 3-bromopropyltrimethoxysilane, 38% aqueous hydrogen bromide solution, and anhydrous methanol were mixed in a volume ratio of 1:0.75:20 and placed in a container. The container was sealed, and the mixture was stirred at 500 rpm for 10 days in a water bath at 42°C. Methanol was continuously added during the reaction. The precipitated powder was then collected by filtration and washed four times with anhydrous methanol. Then, n-hexane was added for heating and dissolution, followed by filtration to remove impurities. The filtrate was cooled and recrystallized to obtain a solid product. The solid product was dried at 85°C for 24 hours to obtain an octabromocage coupling agent.

[0059] S1.2: After evacuating the stainless steel reactor to 12000Pa, high-purity argon gas is introduced to purge the air from the reactor. Then, 200 parts by weight of cyclohexane are added. Under argon protection, 45 parts by weight of butadiene are injected into the cyclohexane. The mixture is heated to 55°C and held for 30 minutes. Then, 0.01 parts by weight of n-butyllithium is injected using a syringe and stirred for 6 minutes. Next, 0.04 parts by weight of n-butyllithium and 1 part by weight of anhydrous tetrahydrofuran are injected. The mixture is heated to 65°C and held for 2 hours to carry out polymerization, obtaining a polymerization solution.

[0060] S1.3: Add 6 parts by weight of octabromocage coupling agent to 15 parts by weight of cyclohexane, then heat to 60°C and stir until the octabromocage coupling agent is completely dissolved to obtain an octabromocage coupling agent solution. At 66°C, inject the octabromocage 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. Remove the solvent from the reaction solution by steam stripping to obtain an aqueous solid. Place the aqueous solid in a vacuum drying oven and dry it at 70°C to constant weight to obtain a flame-retardant and impact-resistant rubber reinforcing agent.

[0061] S2: ABS resin prepared by compounding flame-retardant and impact-resistant rubber reinforcing agents.

[0062] S2.1: Mix flame-retardant and impact-resistant rubber reinforcing agent with deionized water to prepare a rubber reinforcing agent latex with a solid content of 60%. Mix 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 to prepare a monomer solution.

[0063] 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 to the reaction vessel and stir until the solid dissolves. 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 cumene hydroperoxide. Start stirring at 95°C, 200 rpm and under nitrogen protection. Add the monomer solution obtained in step S2.1 dropwise by a peristaltic pump and stir for 2 hours. Then add 8 parts by weight of dibutylhydroxytoluene and continue stirring for 30 minutes to obtain the emulsion polymer. Then place it in a vacuum drying oven and dry it at 85°C and 10000 Pa. Then transfer it to a torque rheometer and devolve it at 170°C and 65 rpm for 4 minutes to obtain flame-retardant and impact-resistant ABS resin.

[0064] S3: Free chain segment separation and recombination, and material composites

[0065] S3.1: Mix 20 parts by weight of flame-retardant and impact-resistant ABS resin and acetone in a constant temperature shaker, and then shake for 12 hours at 30°C and 250 rpm. Then transfer to a centrifuge and centrifuge at 12,000 rpm for 30 minutes to separate the supernatant and precipitate, and obtain flame-retardant and impact-resistant ABS resin and free chain solution after free chain segment removal.

[0066] S3.2: Dissolve γ-aminopropyltriethoxysilane in a 90% (v / v) aqueous ethanol solution to prepare a 3% (w / w) γ-aminopropyltriethoxysilane solution. Then adjust the pH to 5 with acetic acid. Add hard silica calcium silicate whiskers at a solid-liquid ratio of 1:25 g / mL. Stir at 60°C for 4 hours to obtain silane-modified hard silica calcium silicate whiskers. Take 1 part by weight of silane-modified hard silica calcium silicate whiskers and immerse them in the free chain solution prepared in step S3.1. Add 0.1 part by weight of triethylamine. Reflux at 75°C under nitrogen protection for 3 hours. Then filter and take the precipitate. Wash it four times with toluene and vacuum dry to constant weight to obtain surface-modified hard silica calcium silicate whiskers.

[0067] S3.3: 100 parts by weight of polybutylene terephthalate, 35 parts by weight of flame-retardant and impact-resistant ABS resin with free segment removal, 10 parts by weight of surface-modified hard silicate whiskers and 0.4 parts by weight of antioxidant 1098 are mixed evenly at room temperature, and then added to a twin-screw extruder for extrusion granulation. The length-to-diameter ratio of the twin-screw extruder is 40:1, the screw speed is 400 rpm, and the extrusion temperature is 220℃ to obtain PBT / ABS composite material.

[0068] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that step S1 was removed, and the flame-retardant and impact-resistant rubber reinforcing agent in step S2.1 was replaced with an equal mass of polybutadiene to obtain polybutadiene latex. The subsequent rubber reinforcing agent latex was replaced with polybutadiene latex. All other specific implementation methods are the same as in Example 1.

[0069] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the amount of octabromocage coupling agent added in step S1.3 of Comparative Example 2 is 5.5 parts by weight, while the rest of the specific implementation is the same as Example 1.

[0070] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the amount of octabromocage coupling agent added in step S1.3 of Comparative Example 3 is 5 parts by weight, and the rest of the specific implementation is the same as Example 1.

[0071] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that the amount of octabromocage coupling agent added in step S1.3 is 8.5 parts by weight. All other specific implementation methods are the same as those in Example 1.

[0072] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that the amount of octabromocage coupling agent added in step S1.3 is 9 parts by weight, while the rest of the specific implementation is the same as Example 1.

[0073] Comparative Example 6: The difference between Comparative Example 6 and Example 1 is that the flame-retardant and impact-resistant ABS resin with defree chain segments in step S3.3 is replaced with an equal mass of flame-retardant and impact-resistant ABS resin. All other specific implementation methods are the same as those in Example 1.

[0074] Comparative Example 7: The difference from the implementation method of Example 1 is that in step S3.2, the hard silicate whiskers were not modified. Instead, the free segment solution obtained in step S3.1 was vacuum dried to constant weight to obtain a free segment solid. The mass difference between the surface-double-modified hard silicate whiskers and the silane-modified hard silicate whiskers in step S3.2 of Example 1 was calculated and denoted as m. The surface-double-modified hard silicate whiskers in step S3.3 were replaced with m mass of free segment solid.

[0075] Experiment 1: The notched impact strength, tensile strength and flame retardant properties of the PBT / ABS composite materials prepared in Examples 1-3 and Comparative Examples 1-5 were tested. The flame retardant properties were tested in accordance with GB / T2406.2-2009 "Plastics - Determination of burning behavior by oxygen index method - Part 2: Room temperature test". Three tests were conducted for each material, and the average value of the data was taken. The specific test results are shown in Table 1.

[0076] Table 1: Notched impact strength, tensile strength and flame retardant properties of PBT / ABS composite materials

[0077] 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

[0078] As shown in Table 1, the PBT / ABS composite materials prepared in this application all exhibit excellent impact strength, tensile strength, and flame retardant properties. However, as shown in Comparative Example 1, when the flame-retardant and impact-resistant rubber reinforcing agent prepared in this application is replaced with an equal mass of polybutadiene, the notched impact strength, tensile strength, and flame retardant properties of the PBT / ABS composite material all decrease. This demonstrates that when the flame-retardant and impact-resistant rubber reinforcing agent prepared in this application is introduced into ABS resin, it can improve the mechanical properties and flame retardancy of the PBT / ABS composite material. Furthermore, as shown in the data from Comparative Examples 2-5, when the mass ratio of the octabromocine 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 all decrease. This demonstrates that when the mass ratio of the octabromocine coupling agent to butadiene is 45:(6-8), a flame-retardant and impact-resistant rubber reinforcing agent with the best grafted structure can be generated, thereby significantly improving the mechanical properties and flame retardancy of the composite material.

[0079] Experiment 2: The tensile strength and impact strength of the PBT / ABS composite materials prepared in Comparative Examples 6-7 were tested. Three tests were conducted, and the average value of the data was taken. The data from Example 1 in Experiment 1 was used for comparison. The specific test results are shown in Table 2.

[0080] Table 2: Notched impact strength and tensile strength of PBT / ABS composite materials

[0081] Example 1 33.5 115.3 Comparative Example 6 29.5 108.4 Comparative Example 7 25.1 100.6

[0082] Data from Example 1 and Comparative Examples 6-7 show that separating the free segments from the flame-retardant and impact-resistant ABS resin can prevent the styrene-acrylonitrile free segments from becoming highly concentrated on the flame-retardant and impact-resistant rubber reinforcing agent, and prevent the chain entanglement of the free segments and the multi-arm polybutadiene structure. This increases the complexity of subsequent crosslinking between the polybutadiene chain and PBT, increases the crosslinking density, and enhances the impact strength and tensile strength of the PBT / ABS composite material. Furthermore, without the addition of calcium silicate whiskers, the notched impact strength and tensile strength of the PBT / ABS composite material both decrease. This demonstrates that modifying the calcium silicate whiskers and adding them to the PBT / ABS blend can improve the impact strength and tensile strength of the PBT / ABS composite material.

[0083] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A preparation process for a high-impact, flame-retardant PBT / ABS composite material, characterized in that, Includes the following steps: 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 octabromocage coupling agent. Butadiene, n-butyllithium and anhydrous tetrahydrofuran are added to cyclohexane for polymerization to obtain a polymerization solution. The octabromocage coupling agent is dissolved in cyclohexane and then injected into the polymerization solution for reaction. The mass ratio of the octabromocage coupling agent to butadiene is (6-8):

45. Then, steam stripping and drying are performed to obtain the flame-retardant and impact-resistant rubber reinforcing agent. ABS resin is prepared by compounding S2 flame-retardant and impact-resistant rubber reinforcing agent: The flame-retardant and impact-resistant rubber reinforcing agent and deionized water are formulated into a rubber reinforcing agent latex with a solid content of 55-60%. 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 are mixed to prepare a monomer solution. Then, 240-280 parts by weight of the rubber reinforcing agent latex and the monomer solution are mixed and reacted using an emulsion grafting method to obtain an emulsion polymer. After vacuum drying, the polymer is devolatilized to obtain the flame-retardant and impact-resistant ABS resin. S3 Free Segment Separation and Recombination of Materials: Flame-retardant and impact-resistant ABS resin and acetone are mixed and shaken, then centrifuged to obtain de-segmented flame-retardant and impact-resistant ABS resin and free segment solution. Hard silicate whiskers are modified with silane and then immersed in the free segment solution for reflux. The precipitate is filtered and washed to obtain surface-modified hard silicate whiskers. 100-120 parts by weight of polybutylene terephthalate, 35-40 parts by weight of de-segmented flame-retardant and impact-resistant ABS resin, 10-15 parts by weight of surface-modified hard silicate whiskers and 0.4-0.8 parts by weight of antioxidant 1098 are mixed evenly and then placed in a twin-screw extruder for extrusion 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, the preparation of the flame-retardant and impact-resistant rubber reinforcing agent, includes 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 then stir the mixture at 450-500 rpm for 8-10 days in a water bath at 40-42℃. During the reaction, continuously add methanol. Then filter and collect the precipitated powder, wash it 3-4 times with anhydrous methanol, and then add n-hexane for heating and dissolution, filter to remove impurities, cool the filtrate and recrystallize to obtain a solid product. Dry the solid product at 80-85℃ for 20-24 hours to obtain an octabromocage coupling agent. S1.2: After evacuating the stainless steel reactor to 10000-12000Pa, high-purity argon is introduced to purge the air from the reactor. Then, 200-250 parts by weight of cyclohexane are added. Under argon protection, 45 parts by weight of butadiene are injected into the cyclohexane. The mixture is heated to 50-55℃ and held for 25-30 minutes. Then, 0.01-0.02 parts by weight of n-butyllithium are injected using a syringe and stirred for 4-6 minutes. Next, 0.04-0.05 parts by weight of n-butyllithium and 1-3 parts by weight of anhydrous tetrahydrofuran are injected. The mixture is heated to 60-65℃ and held for 1.5-2 hours to carry out polymerization and obtain a polymerization solution. S1.3: Add 6-8 parts by weight of octabromocage coupling agent to 15-20 parts by weight of cyclohexane, then heat to 55-60℃ and stir until the octabromocage coupling agent is completely dissolved to obtain an octabromocage coupling agent solution. At 60-65℃, inject the octabromocage coupling agent solution into the polymerization solution obtained in step S1.2 through a syringe, continue stirring for 1-1.5 hours, then inject 30-40 parts by weight of isopropanol to obtain a reaction solution. Remove the solvent from the reaction solution by steam stripping to obtain an aqueous solid. Place the aqueous solid in a vacuum drying oven and dry it to constant weight at 65-70℃ 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 involves compounding flame-retardant and impact-resistant rubber reinforcing agents to prepare ABS resin, including the following steps: S2.1: Mix flame-retardant and impact-resistant rubber reinforcing agent with deionized water to prepare a rubber reinforcing agent latex with a solid content of 55-60%; mix 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 to prepare a monomer solution; 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 reaction vessel and stir until the solid dissolves. 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 cumene hydroperoxide. Start stirring under nitrogen protection at 85-95℃, 180-200 rpm, and with the monomer solution obtained in step S2.1 added dropwise by a peristaltic pump. Stir and react for 1.5-2 hours. Then add 8-10 parts by weight of dibutylhydroxytoluene and continue stirring and reacting for 25-30 minutes to obtain an emulsion polymer. Then place it in a vacuum drying oven and dry it at 80-85℃ and 8000-10000 Pa. Then transfer it to a torque rheometer for devolatilization to obtain flame-retardant and impact-resistant ABS resin.

4. The preparation process of a high-impact flame-retardant PBT / ABS composite material according to claim 3, characterized in that, Step S3, the separation and recombination of free chain segments and the composite of materials, includes the following steps: S3.1: Mix 20-30 parts by weight of flame-retardant and impact-resistant ABS resin and acetone in a constant temperature shaker, and then shake for 10-12 hours at 25-30℃ and 200-250 rpm. Then transfer to a centrifuge and centrifuge at 10000-12000 rpm for 25-30 minutes to separate the supernatant and precipitate, and obtain flame-retardant and impact-resistant ABS resin and free chain solution after defree chain segment removal. S3.2: Dissolve γ-aminopropyltriethoxysilane in an 85-90% (v / v) aqueous ethanol solution to prepare a 2-3% (w / w) γ-aminopropyltriethoxysilane solution. Then adjust the pH to 4-5 with acetic acid. Add hard silica calcium stone whiskers at a solid-liquid ratio of 1:(20-25) g / mL. Stir at 50-60℃ for 3-4 hours to obtain silane-modified hard silica calcium stone whiskers. Take 1-2 parts by weight of silane-modified hard silica calcium stone whiskers and immerse them in the free chain segment solution prepared in step S3.

1. Add 0.1-0.15 parts by weight of triethylamine. Reflux at 75-80℃ under nitrogen protection for 2-3 hours. Then filter and wash the precipitate 3-4 times with toluene. Vacuum dry to constant weight to obtain surface-modified hard silica calcium stone 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 de-segmentation, 10-15 parts by weight of surface-modified hard silica-calcium whiskers and 0.4-0.8 parts by weight of antioxidant 1098 evenly at room temperature, and then add it to a twin-screw extruder for extrusion granulation to obtain PBT / ABS composite material.

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

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

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

8. The preparation process of 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℃.

Images