Flame-retardant reinforced abs recycled plastic particles and production process thereof

Abstract

This invention relates to the field of polymer material recycling and reuse technology, and discloses flame-retardant reinforced ABS recycled plastic granules and their production process. The granules are made from recycled ABS scrap, needle-like wollastonite, decabromodiphenyl ethane, antimony trioxide, an active coating liquid, ethylene bis-stearamide, and an antioxidant. The active coating liquid is made from carboxyl-terminated butadiene-acrylonitrile copolymer, liquid epoxy resin, and an aluminate coupling agent. The process includes: first, preparing a homogeneous and transparent active coating liquid; then, rapidly heating inorganic powder, atomizing and spraying it into the coating liquid, switching to a low-speed mode, and reacting at a constant temperature of 105°C to 115°C; adding ethylene bis-stearamide during the cooling stage; and finally, melt extrusion granulation. This invention improves the dispersibility of inorganic fillers and repairs the toughness loss of recycled ABS scrap by constructing an elastic chemical coating layer in situ on the surface of inorganic powder, thus producing recycled plastics with both high flame retardancy and excellent mechanical strength.

Description

Technical Field

[0001] This invention relates to the field of polymer material recycling technology, specifically flame-retardant reinforced ABS recycled plastic granules and their production process. Background Technology

[0002] ABS (acrylonitrile-butadiene-styrene copolymer) is a thermoplastic engineering plastic with excellent comprehensive properties, widely used in appliance housings, automotive parts, and office equipment. With the development of the plastics industry, a large amount of ABS waste is generated. Recycling ABS can save petroleum resources and reduce environmental pollution. However, during the initial processing, use, and recycling and granulation of virgin ABS, recycled shredded ABS undergoes multiple thermal shearing processes and prolonged photo-oxidative aging, leading to aging, cross-linking, or degradation of the polybutadiene rubber phase within the resin, and breakage of the matrix resin molecular chains. This results in the impact strength and elongation at break of recycled ABS shredded ABS being lower than that of virgin ABS, exhibiting significant brittleness.

[0003] In applications with stringent fire safety requirements, such as electronics, electrical appliances, and automotive interiors, flame-retardant modification of recycled ABS materials is necessary. Industrially, this is achieved by adding halogenated flame retardants such as decabromodiphenyl ethane and antimony trioxide, along with inorganic reinforcing fillers like acicular wollastonite, to improve the material's flame retardancy and rigidity. However, acicular wollastonite, decabromodiphenyl ethane, and antimony trioxide are all hydrophilic polar inorganic powders, which have interfacial compatibility differences with the oleophilic non-polar ABS recycled ABS matrix.

[0004] When increasing the amount of inorganic powder to achieve higher flame retardancy and rigidity, the large specific surface area and high surface energy of the inorganic powder make it difficult to disperse uniformly in the high-viscosity ABS recycled shredded material melt, leading to agglomeration. Agglomerated inorganic powder particles not only fail to fully exert their reinforcing and flame-retardant effects but also create structural defects within the material, becoming stress concentration points. When the material is subjected to external impact, microcracks rapidly initiate and propagate at the agglomerated inorganic powder sites, further exacerbating the brittleness of the ABS recycled shredded material, resulting in the final product's mechanical properties failing to meet usage requirements. Therefore, this invention proposes flame-retardant reinforced ABS recycled plastic granules and their production process to address the shortcomings of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides flame-retardant reinforced ABS recycled plastic granules and their production process. It solves the problems of matrix degradation and embrittlement caused by thermal history during the recycling of ABS recycled crushed materials, and the decrease in material impact toughness due to inorganic powder agglomeration and poor interfacial compatibility after adding a large amount of inorganic powder to meet flame-retardant reinforcement requirements, making it difficult to achieve both high flame-retardant rating and excellent mechanical properties.

[0006] To achieve the above objectives, the present invention provides the following technical solution: Firstly, the present invention provides flame-retardant reinforced ABS recycled plastic granules, employing the following technical solution: Flame-retardant reinforced ABS recycled plastic granules are made from the following raw materials in parts by weight: 100 parts recycled ABS shreds; 20-25 parts needle-like wollastonite; 12-14 parts decabromodiphenyl ethane; 4-5 parts antimony trioxide; 3.9-5.0 parts active coating liquid; 0.5-0.8 parts ethylene bis-stearamide; and 0.3-0.5 parts antioxidant. The active coating liquid is made from carboxyl-terminated butadiene-acrylonitrile copolymer, liquid epoxy resin, and aluminate coupling agent.

[0007] By adopting the above technical solution, the following effects are achieved by using an active coating solution to modify the surface of the inorganic filler: First, the aluminate coupling agent molecules chemically bond with the hydroxyl groups on the surfaces of acicular wollastonite, decabromodiphenyl ethane, and antimony trioxide through hydrolysis or complexation, grafting lipophilic groups onto the inorganic powder surface, reducing the surface energy of the inorganic powder, and improving its dispersibility in the resin matrix. Second, the carboxyl-terminated butadiene-acrylonitrile copolymer utilizes the carboxyl groups at both ends of the molecule to undergo esterification with the epoxy groups of the liquid epoxy resin. Simultaneously, the liquid epoxy resin crosslinks with the organic functional groups of the aluminate coupling agent, thereby forming an elastomeric coating layer with a crosslinked structure in situ on the surface of the inorganic powder. When the material is subjected to external impact, the elastomeric layer coating the surface of the acicular wollastonite deforms and absorbs energy. Furthermore, the butadiene segments in the carboxyl-terminated butadiene-acrylonitrile copolymer physically entangle with the matrix resin, improving the stress transfer efficiency between the inorganic rigid particles and the resin matrix interface, and restoring the toughness of the recycled ABS material.

[0008] Preferably, the active coating solution is made from the following components in parts by weight: 30-40 parts of carboxyl-terminated butadiene-acrylonitrile copolymer; 3-5 parts of liquid epoxy resin; and 4-6 parts of aluminate coupling agent.

[0009] By employing the above technical solution and limiting the ratio of carboxyl-terminated butadiene-acrylonitrile copolymer, liquid epoxy resin, and aluminate coupling agent, the viscosity and reactivity of the active coating solution can be balanced. Under this ratio, the liquid epoxy resin can initiate chain extension of the carboxyl-terminated butadiene-acrylonitrile copolymer and bind it to the powder surface coupling agent, preventing the coating layer from becoming brittle due to excessive crosslinking or the coating layer from having insufficient adhesion to the matrix due to insufficient crosslinking.

[0010] Preferably, the antioxidant is a mixture of hindered phenolic antioxidants and phosphite antioxidants.

[0011] By adopting the above technical solution, hindered phenolic antioxidants capture free radicals generated during the processing of recycled ABS materials, and phosphite antioxidants decompose hydrogen peroxides. The two work synergistically to inhibit the thermo-oxidative degradation of the material.

[0012] Secondly, this invention provides a production process for flame-retardant reinforced ABS recycled plastic granules, employing the following technical solution: A production process for flame-retardant reinforced ABS recycled plastic pellets, used in the first aspect of this invention, includes the following steps: The carboxyl-terminated butadiene-acrylonitrile copolymer, liquid epoxy resin and aluminate coupling agent are mixed evenly until the material is homogeneous and transparent to obtain the active coating liquid. Needle-shaped wollastonite, decabromodiphenyl ethane, and antimony trioxide are added to a high-speed mixer and heated. The active coating liquid is then atomized and sprayed into the high-speed mixer. After spraying, the stirring speed of the high-speed mixer is reduced to a low-speed mode. The material temperature is maintained at 105℃-115℃ using the residual heat of the material and stirred at a low speed for 5.0min-8.0min to obtain thermally modified powder. The thermally modified powder is fed into a cold mixer for cooling; when the temperature of the thermally modified powder drops to 80℃-90℃, ethylene bis-stearamide is added to the cold mixer; after stirring and cooling to 40℃-50℃, the powder is discharged to obtain the modified composite powder. Modified composite powder is mixed with recycled ABS crushed material and antioxidant to obtain a premix; the premix is ​​added to a twin-screw extruder for melt extrusion and granulation to obtain flame-retardant reinforced recycled ABS plastic granules.

[0013] The process principle of adopting the above technical solution is as follows: First, in the preparation of the active coating solution, the carboxyl-terminated butadiene-acrylonitrile copolymer, liquid epoxy resin and aluminate coupling agent are mixed in advance until homogeneous and transparent to ensure that each component is evenly distributed at the molecular level and to avoid local uneven concentration caused by the addition of each component alone, thus providing conditions for subsequent synchronous reaction.

[0014] Secondly, a variable-speed temperature control process is employed in the powder modification stage. During the high-speed stirring stage, shear friction heat is used to remove moisture from the powder surface and provide initial activation energy, while atomized spraying spreads the active coating liquid on the powder surface. Subsequently, a low-speed isothermal reaction stage is adopted. Within the temperature range of 105℃-115℃, the carboxyl-terminated butadiene-acrylonitrile copolymer undergoes a chemical bonding reaction with the liquid epoxy resin, aluminate coupling agent, and the powder surface. The low-speed stirring provides a reaction residence time of 5.0-8.0 minutes, ensuring the chemical reaction proceeds while avoiding degradation of the active liquid or material agglomeration caused by continuous high-speed shearing and localized overheating, thus achieving in-situ growth of an elastic graft layer on the inorganic powder surface.

[0015] Third, a step-by-step addition process is adopted during the cooling stage. Ethylene bis-stearamide is added when the temperature of the heat-modified powder drops to 80℃-90℃. At this time, the active coating liquid has been solidified. The ethylene bis-stearamide is softened by residual heat and covers the outermost layer of the particles, forming a physical isolation layer to prevent the sticky modified composite powder from agglomerating during storage and improve the powder flowability.

[0016] Preferably, the process of uniformly mixing the carboxyl-terminated butadiene-acrylonitrile copolymer, liquid epoxy resin, and aluminate coupling agent specifically includes: adding the carboxyl-terminated butadiene-acrylonitrile copolymer into a stirred tank and heating it to 55°C-65°C; sequentially adding the liquid epoxy resin and aluminate coupling agent into the stirred tank; and continuously stirring at a stirring speed of 60 rpm-100 rpm for 15 min-20 min.

[0017] By adopting the above technical solution, the viscosity of the carboxyl-terminated butadiene-acrylonitrile copolymer is reduced by heating, which promotes the dissolution and diffusion of liquid epoxy resin and aluminate coupling agent, forming a uniform and stable mixed system.

[0018] Preferably, the mixing and heating of needle-shaped wollastonite, decabromodiphenyl ethane, and antimony trioxide in a high-speed mixer specifically includes: starting the high-speed mixing mode of the high-speed mixer, setting the mixing speed to 900 rpm-1100 rpm, and using frictional heat to raise the material temperature to 85℃-90℃; the atomization and spraying of the active coating liquid into the high-speed mixer specifically includes: maintaining the high-speed mixing mode of the high-speed mixer, uniformly spraying the active coating liquid into the high-speed mixer within 60s-90s, and continuing to maintain the high-speed mixing mode after spraying until the material temperature rises to 105℃-115℃.

[0019] By adopting the above technical solution, the spraying start temperature of 85℃-90℃ utilizes the heat of the powder to reduce the surface tension of the active coating liquid at the moment of contact, thereby increasing the wetting speed; high speed combined with short-time spraying prevents droplets from agglomerating and ensures uniform coating; the target temperature after spraying is controlled at 105℃-115℃, which is consistent with the subsequent low-speed constant temperature reaction range, ensuring a smooth reaction transition.

[0020] Preferably, the twin-screw extruder includes zones one to nine and a die head along the material conveying direction; the temperature setting range for zone one is 160℃-170℃; the temperature setting range for zones two to three is 190℃-210℃; the temperature setting range for zones four to seven is 205℃-230℃; the temperature setting range for zones eight to nine is 205℃-220℃; and the temperature setting range for the die head is 205℃-220℃.

[0021] By adopting the above technical solution, the lower temperature in Zone 1 prevents the material at the feed inlet from melting and bridging prematurely; the temperature rises in Zones 2 and 3 to achieve material melting; the high temperature section in Zones 4 to 7 promotes the chain segment diffusion and entanglement of the modified composite powder and the matrix resin; and the temperature is reduced in Zones 8 to 9 and at the die head to stabilize the melt pressure and ensure granulation stability.

[0022] This invention provides flame-retardant reinforced ABS recycled plastic pellets and their production process. It has the following beneficial effects: 1. This invention employs an active coating liquid composed of carboxyl-terminated butadiene-acrylonitrile copolymer, liquid epoxy resin, and aluminate coupling agent to chemically modify the surface of needle-shaped wollastonite and flame retardant. This constructs an elastomer coating layer with a chemically bonded structure on the surface of inorganic particles, enabling them to absorb external impact energy through their own deformation. Simultaneously, the flexible segments in the carboxyl-terminated butadiene-acrylonitrile copolymer physically entangle with the ABS recycled shredded material matrix, transferring stress and improving the molecular chain degradation and brittleness issues caused by repeated heat processing of ABS recycled shredded material. This enhances the notched impact strength and elongation at break of flame-retardant reinforced ABS recycled plastic particles.

[0023] 2. This invention utilizes the anchoring effect of aluminate coupling agents on the surface of inorganic powders and the in-situ curing reaction under specific processes to reduce the surface energy of acicular wollastonite, decabromodiphenyl ethane, and antimony trioxide. This improves the compatibility of high-filling-content inorganic powders in the organic matrix, inhibits the agglomeration of inorganic flame retardants and reinforcing fillers in the ABS recycled crushed material matrix, and ensures that the flame retardant is uniformly dispersed in the matrix. Thus, while ensuring that the material reaches the predetermined flame retardant rating, it maintains the uniformity of mechanical properties and processing rheological stability of flame-retardant reinforced ABS recycled plastic particles.

[0024] 3. This invention solves the problem of agglomeration or bridging of powder modified by active coating liquid due to its surface stickiness during conveying and feeding by adopting step-by-step cooling and subsequent anti-sticking treatment with ethylene bis-stearamide in the production process. The addition of ethylene bis-stearamide within a specific temperature range can form a uniform physical isolation film on the surface of the modified powder particles, improving the dryness and flowability of the modified composite powder, ensuring smooth feeding of the twin-screw extruder, and guaranteeing the continuous and stable production of flame-retardant reinforced ABS recycled plastic granules and the surface smoothness of the products. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the interface gelation rate of the present invention; Figure 2 This is a schematic diagram of the extruder current fluctuation of the present invention; Figure 3 This is a schematic diagram of the notched impact strength of the present invention. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, preparation examples, comparative examples, and test examples. 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.

[0027] Raw material source and specifications: The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0028] Carboxyl-terminated liquid nitrile butadiene rubber (CTBN), chemical name carboxyl-terminated butadiene-acrylonitrile copolymer, CAS number: 68891-46-3, bound acrylonitrile content 26%, carboxyl equivalent (EPHR) 0.07, viscosity at 27℃ 500 Pa·s, number average molecular weight Mn approximately 3500.

[0029] Preparation Examples 1-3: Preparation Example 1: This preparation example provides a method for preparing an active coating solution, including the following steps: Add 35 kg of carboxyl-terminated liquid nitrile rubber to a stirred tank with a heating jacket, raise the temperature of the material in the stirred tank to 60°C and maintain the temperature; add 4 kg of liquid epoxy resin and 5 kg of aluminate coupling agent to the stirred tank in sequence; start the stirring paddle, set the stirring speed to 80 rpm, and stir continuously for 20 min until the material in the tank becomes homogeneous and transparent, thus obtaining the active coating liquid, which is then kept warm for later use.

[0030] Preparation Example 2: This preparation example provides a method for preparing an active coating solution, including the following steps: Add 30 kg of carboxyl-terminated liquid nitrile rubber to a stirred tank with a heating jacket, raise the temperature of the material in the stirred tank to 65°C and maintain the temperature; add 5 kg of liquid epoxy resin and 4 kg of aluminate coupling agent to the stirred tank in sequence; start the stirring paddle, set the stirring speed to 100 rpm, and stir continuously for 15 min until the material in the tank becomes homogeneous and transparent, thus obtaining the active coating liquid, which is then kept warm for later use.

[0031] Preparation Example 3: This preparation example provides a method for preparing an active coating solution, including the following steps: Add 40 kg of carboxyl-terminated liquid nitrile rubber to a stirred tank with a heating jacket, raise the temperature of the material in the stirred tank to 55°C and maintain the temperature; add 3 kg of liquid epoxy resin and 6 kg of aluminate coupling agent to the stirred tank in sequence; start the stirring paddle, set the stirring speed to 60 rpm, and continue stirring for 20 min until the material in the tank becomes homogeneous and transparent, thus obtaining the active coating liquid, which is then kept warm for later use.

[0032] Examples 1-6: Example 1: This embodiment provides flame-retardant reinforced ABS recycled plastic pellets and their production process, including the following steps: High-temperature in-situ anchoring of inorganic powders: 22 kg (22 parts by weight) of needle-shaped wollastonite, 13 kg (13 parts by weight) of decabromodiphenyl ethane, and 4.5 kg (4.5 parts by weight) of antimony trioxide are added to a high-speed mixer equipped with a heating jacket and high / low speed switching function; the high-speed stirring mode of the high-speed mixer is started, and the speed is set to 1000 rpm, using frictional heat to raise the material temperature to 90°C; high-speed stirring is maintained, and the powder is evenly sprayed into the high-speed mixer through an atomizing nozzle within 80 seconds. 4.4 kg (i.e. 4.4 parts by weight) of the active coating solution prepared in Example 1 was used; after spraying, high-speed stirring was continued until the material temperature rose to 105°C; the stirring speed of the high-speed mixer was switched to low-speed mode and the speed was set to 400 rpm; the material temperature was maintained at 110°C ± 2°C under low-speed stirring by utilizing the residual heat of the material, and low-speed stirring was maintained for 6.0 min to allow the alkaline sites on the surface of the needle-shaped wollastonite to undergo interfacial grafting reaction to catalyze the active coating solution, thereby obtaining thermally modified powder; Cold mixing and surface anti-sticking treatment: The thermally modified powder is fed into a connected cold mixer; when the temperature of the thermally modified powder drops to 85°C, 0.6 kg (i.e. 0.6 parts by weight) of ethylene bis-stearamide is added to the cold mixer; the cold mixer is started to stir, and the material is discharged after cooling to 45°C to obtain a dry modified composite powder. Phase reconstruction and reactive extrusion: Modified composite powder was mixed with 100 kg (100 parts by weight) of recycled ABS crushed material and 0.4 kg (0.4 parts by weight) of antioxidant 1010 / 168 mixture (mass ratio 1:1) in a rotary drum mixer for 4 min to obtain a premix. The premix was then added to a co-rotating twin-screw extruder for melt extrusion. The length-to-diameter ratio of the co-rotating twin-screw extruder was 44:1, the screw speed was 350 rpm, and the vacuum degree was controlled at -0.09 MPa. The temperature settings of each zone of the co-rotating twin-screw extruder were as follows: Zone 1 165℃, Zone 2 195℃, Zone 3 205℃, Zone 4 210℃, Zone 5 220℃, Zone 6 225℃, Zone 7 225℃, Zone 8 215℃, Zone 9 210℃, and the die head 210℃. The extruded strip was water-cooled, air-dried, and pelletized to obtain flame-retardant reinforced recycled ABS granules.

[0033] Example 2: This embodiment provides flame-retardant reinforced ABS recycled plastic pellets and their production process, including the following steps: High-temperature in-situ anchoring of inorganic powders: 25 kg (25 parts by weight) of needle-shaped wollastonite, 14 kg (14 parts by weight) of decabromodiphenyl ethane, and 5 kg (5 parts by weight) of antimony trioxide are added to a high-speed mixer equipped with a heating jacket and high / low speed switching function; the high-speed stirring mode of the high-speed mixer is started, and the speed is set to 1100 rpm, using frictional heat to raise the material temperature to 90°C; while maintaining high-speed stirring, 5.0 kg of antimony trioxide is evenly sprayed into the high-speed mixer through an atomizing nozzle within 90 seconds. The active coating solution prepared in Example 1 was prepared by mixing kg (i.e., 5.0 parts by weight); after spraying, high-speed stirring was continued until the material temperature rose to 105°C; the stirring speed of the high-speed mixer was immediately switched to low-speed mode and the speed was set to 450 rpm; the material temperature was maintained at 112°C ± 2°C by using the residual heat of the material under low-speed stirring, and low-speed stirring was maintained for 7.0 min to allow the alkaline sites on the surface of the needle-shaped wollastonite to undergo interfacial grafting reaction to catalyze the active coating solution, thereby obtaining thermally modified powder; Cold mixing and surface anti-sticking treatment: The thermally modified powder is fed into a connected cold mixer; when the temperature of the thermally modified powder drops to 88°C, 0.8 kg (i.e. 0.8 parts by weight) of ethylene bis-stearamide is added to the cold mixer; the cold mixer is started to stir, and the material is discharged after cooling to 50°C to obtain a dry modified composite powder. Phase reconstruction and reactive extrusion: The modified composite powder was mixed with 100 kg (i.e., 100 parts by weight) of recycled ABS crushed material and 0.5 kg (i.e., 0.5 parts by weight) of antioxidant 1010 / 168 mixture (mass ratio 1:1) in a rotary drum mixer for 5 min to obtain a premix; the premix was added to a co-rotating twin-screw extruder for melt extrusion; the process parameters and temperature settings of the co-rotating twin-screw extruder were consistent with those in Example 1; the extruded strip was water-cooled, air-dried, and pelletized to obtain flame-retardant reinforced recycled ABS granules.

[0034] Example 3: This embodiment provides flame-retardant reinforced ABS recycled plastic pellets and their production process, including the following steps: High-temperature in-situ anchoring of inorganic powders: 20 kg (20 parts by weight) of needle-shaped wollastonite, 12 kg (12 parts by weight) of decabromodiphenyl ethane, and 4 kg (4 parts by weight) of antimony trioxide were added to a high-speed mixer equipped with a heating jacket and high / low speed switching function; the high-speed stirring mode of the high-speed mixer was started, and the speed was set to 900 rpm, using frictional heat to raise the material temperature to 85°C; while maintaining high-speed stirring, 4.0 kg (4.0 parts by weight) of the active coating liquid prepared in Preparation Example 1 was uniformly sprayed into the high-speed mixer through an atomizing nozzle within 60 seconds; after spraying, high-speed stirring was continued until the material temperature rose to 105°C; the stirring speed of the high-speed mixer was immediately switched to low-speed mode, and the speed was set to 350 rpm; the material temperature was maintained at 105°C ± 1°C under low-speed stirring using the residual heat of the material, and low-speed stirring was maintained for 8.0 min, so that the alkaline sites on the surface of the needle-shaped wollastonite catalyzed the interfacial grafting reaction of the active coating liquid, resulting in thermally modified powder; Cold mixing and surface anti-sticking treatment: The thermally modified powder is fed into a connected cold mixer; when the temperature of the thermally modified powder drops to 80°C, 0.5 kg (i.e. 0.5 parts by weight) of ethylene bis-stearamide is added to the cold mixer; the cold mixer is started to stir, and the material is discharged after cooling to 40°C to obtain a dry modified composite powder. Phase reconstruction and reactive extrusion: The modified composite powder was mixed with 100 kg (i.e., 100 parts by weight) of recycled ABS crushed material and 0.3 kg (i.e., 0.3 parts by weight) of antioxidant 1010 / 168 mixture (mass ratio 1:1) in a rotary drum mixer for 3 min to obtain a premix; the premix was added to a co-rotating twin-screw extruder for melt extrusion; the process parameters and temperature settings of the co-rotating twin-screw extruder were consistent with those in Example 1; the extruded strip was water-cooled, air-dried, and pelletized to obtain flame-retardant reinforced recycled ABS granules.

[0035] Example 4: This embodiment provides flame-retardant reinforced ABS recycled plastic pellets and their production process, including the following steps: High-temperature in-situ anchoring of inorganic powders: 22 kg (22 parts by weight) of needle-shaped wollastonite, 13 kg (13 parts by weight) of decabromodiphenyl ethane, and 4.5 kg (4.5 parts by weight) of antimony trioxide are added to a high-speed mixer equipped with a heating jacket and high / low speed switching function; the high-speed mixing mode of the high-speed mixer is started, and the speed is set to 1000 rpm, using frictional heat to raise the material temperature to 90°C; high-speed mixing is maintained, and 4 kg (22 parts by weight) of antimony trioxide is evenly sprayed into the high-speed mixer through an atomizing nozzle within 80 seconds. The active coating solution prepared in Example 1 was prepared by using 0.4 kg (i.e., 4.4 parts by weight). After spraying, high-speed stirring was continued until the material temperature rose to 105°C. The stirring speed of the high-speed mixer was immediately switched to low-speed mode and the speed was set to 400 rpm. The material temperature was maintained at 115°C ± 1°C by using the residual heat of the material and stirring at low speed for 5.0 min. This allowed the alkaline sites on the surface of the needle-shaped wollastonite to undergo an interfacial grafting reaction with the active coating solution, resulting in thermally modified powder. Cold mixing and surface anti-sticking treatment: The thermally modified powder is fed into a connected cold mixer; when the temperature of the thermally modified powder drops to 90°C, 0.6 kg (i.e. 0.6 parts by weight) of ethylene bis-stearamide is added to the cold mixer; the cold mixer is started to stir, and the material is discharged after cooling to 45°C to obtain a dry modified composite powder. Phase reconstruction and reactive extrusion: The modified composite powder was mixed with 100 kg (i.e., 100 parts by weight) of recycled ABS crushed material and 0.4 kg (i.e., 0.4 parts by weight) of antioxidant 1010 / 168 mixture (mass ratio 1:1) in a rotary drum mixer for 4 min to obtain a premix; the premix was added to a co-rotating twin-screw extruder for melt extrusion; the process parameters and temperature settings of the co-rotating twin-screw extruder were consistent with those in Example 1; the extruded strip was water-cooled, air-dried, and pelletized to obtain flame-retardant reinforced recycled ABS granules.

[0036] Example 5: This embodiment provides flame-retardant reinforced ABS recycled plastic pellets and their production process, including the following steps: High-temperature in-situ anchoring of inorganic powders: 22 kg (22 parts by weight) of needle-shaped wollastonite, 13 kg (13 parts by weight) of decabromodiphenyl ethane, and 4.5 kg (4.5 parts by weight) of antimony trioxide were added to a high-speed mixer equipped with a heating jacket and high / low speed switching function; the high-speed stirring mode of the high-speed mixer was started, and the speed was set to 1000 rpm, using frictional heat to raise the material temperature to 90°C; while maintaining high-speed stirring, 3.9 kg (3.9 parts by weight) of the active coating liquid prepared in Preparation Example 2 was uniformly sprayed into the high-speed mixer through an atomizing nozzle within 80 seconds; after spraying, high-speed stirring was continued until the material temperature rose to 105°C; the stirring speed of the high-speed mixer was immediately switched to low-speed mode, and the speed was set to 400 rpm; the material temperature was maintained at 110°C ± 2°C under low-speed stirring using the residual heat of the material, and low-speed stirring was maintained for 6.0 min to obtain thermally modified powder; Cold mixing and surface anti-sticking treatment: The thermally modified powder is fed into a connected cold mixer; when the temperature of the thermally modified powder drops to 85°C, 0.6 kg (i.e. 0.6 parts by weight) of ethylene bis-stearamide is added to the cold mixer; the cold mixer is started to stir, and the material is discharged after cooling to 45°C to obtain a dry modified composite powder. Phase reconstruction and reactive extrusion: The modified composite powder was mixed with 100 kg (i.e., 100 parts by weight) of recycled ABS crushed material and 0.4 kg (i.e., 0.4 parts by weight) of antioxidant 1010 / 168 mixture (mass ratio 1:1) in a rotary drum mixer for 4 min to obtain a premix; the premix was added to a co-rotating twin-screw extruder for melt extrusion; the process parameters and temperature settings of the co-rotating twin-screw extruder were consistent with those in Example 1; the extruded strip was water-cooled, air-dried, and pelletized to obtain flame-retardant reinforced recycled ABS granules.

[0037] Example 6: This embodiment provides flame-retardant reinforced ABS recycled plastic pellets and their production process, including the following steps: High-temperature in-situ anchoring of inorganic powders: 22 kg (22 parts by weight) of needle-shaped wollastonite, 13 kg (13 parts by weight) of decabromodiphenyl ethane, and 4.5 kg (4.5 parts by weight) of antimony trioxide were added to a high-speed mixer equipped with a heating jacket and high / low speed switching function; the high-speed stirring mode of the high-speed mixer was started, and the speed was set to 1000 rpm, using frictional heat to raise the material temperature to 90°C; while maintaining high-speed stirring, 4.9 kg (4.9 parts by weight) of the active coating liquid prepared in Preparation Example 3 was uniformly sprayed into the high-speed mixer through an atomizing nozzle within 80 seconds; after spraying, high-speed stirring was continued until the material temperature rose to 105°C; the stirring speed of the high-speed mixer was immediately switched to low-speed mode, and the speed was set to 400 rpm; the material temperature was maintained at 110°C ± 2°C under low-speed stirring using the residual heat of the material, and low-speed stirring was maintained for 6.0 min to obtain thermally modified powder; Cold mixing and surface anti-sticking treatment: The thermally modified powder is fed into a connected cold mixer; when the temperature of the thermally modified powder drops to 85°C, 0.6 kg (i.e. 0.6 parts by weight) of ethylene bis-stearamide is added to the cold mixer; the cold mixer is started to stir, and the material is discharged after cooling to 45°C to obtain a dry modified composite powder. Phase reconstruction and reactive extrusion: The modified composite powder was mixed with 100 kg (i.e., 100 parts by weight) of recycled ABS crushed material and 0.4 kg (i.e., 0.4 parts by weight) of antioxidant 1010 / 168 mixture (mass ratio 1:1) in a rotary drum mixer for 4 min to obtain a premix; the premix was added to a co-rotating twin-screw extruder for melt extrusion; the process parameters and temperature settings of the co-rotating twin-screw extruder were consistent with those in Example 1; the extruded strip was water-cooled, air-dried, and pelletized to obtain flame-retardant reinforced recycled ABS granules.

[0038] Comparative Examples 1-6: Comparative Example 1: Compared with Example 1, the difference is that no liquid epoxy resin was added during the preparation of the active coating liquid, and the amount of carboxyl-terminated liquid nitrile rubber was increased to 39 kg. The other raw material types, amounts and preparation process steps are consistent with Example 1.

[0039] Comparative Example 2: Compared with Example 1, the difference is that ordinary liquid nitrile rubber (with an acrylonitrile content of 26%, a viscosity of 500 Pa·s at 27°C, and no carboxyl functional groups) was used to replace the end-carboxyl liquid nitrile rubber. The other raw material types, amounts, and preparation process steps were the same as in Example 1.

[0040] Comparative Example 3: Compared with Example 1, the difference is that 1250 mesh talc powder (10% aqueous suspension with pH value of 7.0) was used to replace needle-shaped wollastonite. The other raw material types, amounts and preparation process steps are the same as in Example 1.

[0041] Comparative Example 4: Compared with Example 1, the difference is that in the high-temperature in-situ anchoring step of inorganic powder, the material temperature of the high-speed mixer is controlled to rise to a maximum of only 60°C. After spraying the active coating liquid, the mixture is mixed for 2 minutes and then discharged to the cold mixer. The low-speed constant temperature reaction stage of 105°C-115°C is eliminated. The other raw material types, dosages and subsequent extrusion process steps are consistent with Example 1.

[0042] Comparative Example 5: Compared with Example 1, the difference is that the high-speed and low-speed switching operation was cancelled in the high-temperature in-situ anchoring step, and the high-speed stirring mode of 1000 rpm was maintained throughout the process. As a result, the material temperature rose to 138°C due to frictional heat runaway during the 6.0 min holding period. The other raw material types, dosages and preparation process steps were consistent with Example 1.

[0043] Comparative Example 6: Compared with Example 1, the difference is that the addition of ethylene bis-stearamide is brought forward to the high-temperature in-situ anchoring step, that is, it is added to the high-speed mixer together with needle-shaped wollastonite. The cold mixing and surface anti-sticking treatment steps only involve cooling operations without adding any additives. The other raw material types, dosages and preparation process steps are consistent with Example 1.

[0044] Test Example 1-3: Test Example 1: Determination of Gel Content on the Surface of Modified Powder This test case aims to determine the organic grafting on the surface of thermally modified powders prepared under different process conditions using solvent extraction.

[0045] The specific experimental steps are as follows: 10.00 g of each of the thermally modified powder samples from Examples 1, 2, 3, and 4, taken after the high-temperature in-situ anchoring step of the inorganic powder but before entering the cold mixing and surface anti-sticking treatment steps, was weighed and recorded as the initial weight of the sample. Based on the feeding ratios of each embodiment and comparative example, the total weight of the theoretically contained organic coatings (including carboxyl-terminated liquid nitrile rubber or its substitutes, liquid epoxy resin, and aluminate coupling agent) in 10.00g of thermally modified powder was calculated and recorded as the theoretical organic content. .

[0046] The thermally modified powder sample was wrapped in filter paper and placed in a Soxhlet extractor. 250 mL of acetone solvent was added as the extractant. Acetone solvent can dissolve unreacted terminal carboxyl liquid nitrile rubber, liquid epoxy resin and aluminate coupling agent, but cannot dissolve gel networks and inorganic mineral fillers that have undergone chemical cross-linking or grafted onto inorganic surfaces.

[0047] The Soxhlet extractor was placed on a water bath heating device, and the water bath temperature was controlled at 65°C. The extraction was carried out under reflux with acetone solvent for 48 hours to ensure complete elution of unbonded free organic matter. After extraction, the filter paper packet was removed, and the remaining solid was placed in a vacuum drying oven and dried at 80°C for 12 hours until constant weight. The weight of the remaining solid after drying was recorded as the extraction weight. .

[0048] Calculate the interfacial gelation rate using the formula: The higher the interfacial gelation rate, the more organic matter remains on the surface of the inorganic powder, and the higher the degree of interfacial chemical reaction.

[0049] The experimental data obtained are shown in the table below: Table 1. Results of interfacial gelation rate determination of thermally modified powders in different experimental groups

[0050] Conclusions and Analysis: According to Table 1 and Figure 1 According to the data, the thermally modified powder prepared in Example 1 showed an interfacial gelation rate as high as 87.2%, while the interfacial gelation rates of Comparative Examples 2, 3 and 4 were all in the low range of 10% to 22%. There were obvious differences between the data of each group, which proved the feasibility and necessity of the filler alkaline in-situ induced interfacial gelation mechanism proposed in this invention.

[0051] Specifically, in Example 1, under long-term Soxhlet extraction with strong acetone solvent, most of the organic coatings remained on the surface of the needle-shaped wollastonite, indicating that the interaction between the carboxyl-terminated liquid nitrile rubber, liquid epoxy resin and needle-shaped wollastonite was not a simple physical adsorption, but a chemical bonding reaction that formed a stable gel network insoluble in organic solvents.

[0052] Comparing the data of Example 1 and Comparative Example 2, it can be seen that when ordinary liquid nitrile rubber without terminal carboxyl groups is used to replace liquid nitrile rubber with terminal carboxyl groups, the interfacial gelation rate drops sharply from 87.2% to 16.2%. This result confirms that terminal carboxyl groups are the key active sites for constructing interfacial chemical bonds. Ordinary rubber lacking terminal carboxyl groups cannot undergo ring-opening esterification or etherification reactions with the active groups on the surface of liquid epoxy resin and needle-like wollastonite, and can only adhere in the form of physical adsorption, which is easily washed away by solvent.

[0053] Comparing the data from Example 1 and Comparative Example 3, it can be seen that when neutral talc powder is used instead of alkaline acicular wollastonite, although the system contains carboxyl-terminated liquid nitrile rubber and liquid epoxy resin, the interfacial gelation rate is only 21.6%. This significant difference confirms that the alkaline sites on the surface of acicular wollastonite play a crucial solid-phase catalyst role in the reaction system. The lack of an alkaline environment cannot effectively activate the epoxy groups and trigger the subsequent ternary grafting reaction, resulting in most of the organic matter being in a free state.

[0054] Comparing the data of Example 1 and Comparative Example 4, it can be seen that if mixing is only carried out at a low temperature of 60°C without a high-temperature reaction process of 105°C-115°C, the interfacial gelation rate is reduced to 11.5%. This indicates that the variable speed thermodynamic process designed in this invention is a necessary condition for starting the chemical reaction. Only by reaching the temperature threshold and maintaining it for a certain time can the reaction energy barrier be overcome and the physical mixture be transformed into a chemically modified powder with a core-shell structure.

[0055] In summary, the test results in Table 1 verify from the perspective of microscopic chemical reactions that the present invention constructs the interface layer through chemical bonding rather than physical encapsulation. This soft shell structure with high gelation rate is the material basis for achieving a balance between strength and toughness under high filling of recycled ABS material.

[0056] Test Example 2: Extrusion Processing Stability and Feeding Performance Test This test case aims to monitor the main machine current fluctuations and feeding status of a co-rotating twin-screw extruder during continuous production, and to compare and analyze the effects of different ethylene bis-stearamide addition processes on the processing rheological behavior and friction feeding performance of high-resin-content composite materials.

[0057] The specific experimental steps are as follows: A co-rotating twin-screw extruder with the same specifications as those in Example 1 and Comparative Example 6 was selected. The temperature of each zone of the barrel and the temperature of the die head were set to the process parameters specified in Example 1. The screw speed was set to a constant 350 rpm. The vacuum exhaust system was started and the vacuum degree was controlled to be -0.09 MPa.

[0058] The premix prepared in Example 1 was added to the loss-in-weight feeder. The feeding speed was set to 300 kg / h. After the extruder operating conditions stabilized, the timing was started, and a continuous extrusion operation lasting 120 minutes was carried out. During the operation, the main unit current value was recorded every 15 minutes, and the material bridging or feeding stagnation phenomenon was observed visually below the feed port throughout the process. The specific time point when bridging occurred was recorded.

[0059] Clean the extruder to ensure no residual material remains; add the premix prepared in Comparative Example 6 to the loss-in-weight feeder and perform continuous extrusion for 120 minutes under the same temperature, speed and feeding speed conditions; during the operation, record the main unit current value every 15 minutes, and visually observe whether there is material bridging or material stagnation below the feed port throughout the process, and record the specific time point when bridging occurs.

[0060] The host current data is statistically recorded, and the current fluctuation range is calculated to characterize the frictional gripping stability of materials in the screw conveyor section.

[0061] The experimental data obtained are shown in the table below: Table 2. Record of main machine current and feeding status during the extrusion process of Example 1 and Comparative Example 6 15 142.5 138.2 Smooth material feeding Smooth material feeding 30 143.1 121.5 Smooth material feeding Slight sticking to the wall 45 141.8 155.6 Smooth material feeding Intermittent bridging occurred 60 144.2 115.3 Smooth material feeding Bridge breaking requires manual assistance 75 143.5 162.8 Smooth material feeding Bridge construction resumes 90 142.9 108.4 Smooth material feeding Severe bridging, material shortage 105 143.8 148.7 Smooth material feeding Bridge breaking requires manual assistance 120 142.6 112.9 Smooth material feeding Frequent bridge construction Extremely poor current fluctuation 2.4 54.4 Bridgeless First bridge erection in 35 minutes Conclusions and Analysis: According to Table 2 and Figure 2 According to the data in Example 1, during the continuous extrusion process of 120 minutes, the main machine current remained stable within a narrow range of 141.8A to 144.2A, with a range of 2.4A. Furthermore, no bridging phenomenon occurred at the feed port throughout the process, indicating that a stable coefficient of friction was maintained between the material and the screw, and the solid conveying efficiency remained constant.

[0062] In contrast, the main unit current of Comparative Example 6 exhibited drastic and disordered fluctuations, with a range of 54.4A, accompanied by frequent material bridging phenomena. The sudden drop in current (e.g., dropping to 108.4A at the 90th minute) corresponds to screw slippage, at which point the material cannot be effectively gripped by the screw edges, resulting in a momentary reduction in the solid conveying volume; while the surge in current (e.g., rising to 162.8A at the 75th minute) corresponds to the instantaneous overload caused by the influx of material after the bridging collapse.

[0063] This significant difference confirms the crucial role of the timing of ethylene bis-stearamide addition in this invention. In Comparative Example 6, ethylene bis-stearamide and needle-like wollastonite were added together during the high-temperature in-situ anchoring stage (above 105°C). Since ethylene bis-stearamide has a melting point of approximately 142°C and softens easily at high temperatures, it undergoes mutual solubility with the carboxyl-terminated liquid nitrile rubber layer or is encapsulated within the rubber layer under strong shear heat. This prevents it from forming an effective dry isolation film on the outermost layer of the powder. Instead, it acts as an internal lubricant for the rubber, reducing the viscosity of the adhesive layer. Consequently, the powder with the sticky rubber layer adheres and agglomerates, slipping on the screw surface.

[0064] In Example 1, ethylene bis-stearamide was added during the cold mixing stage when the material temperature dropped to 85°C. At this temperature, the temperature is much lower than the melting and softening points of ethylene bis-stearamide. The ethylene bis-stearamide, in a micro-powder solid form, is uniformly adsorbed onto the surface of the viscous, heat-modified powder, constructing a physical anti-sticking isolation layer. This powder structure, which is hard on the outside and soft on the inside, ensures the flowability of the powder to prevent bridging and provides sufficient solid friction before it is heated and melted in the extruder barrel, ensuring the stability of the processing.

[0065] Test Example 3: Comprehensive Test of Mechanical Properties and Flame Retardant Properties This test case aims to test the physical and mechanical properties and flammability of the flame-retardant reinforced ABS recycled granules prepared in each embodiment and comparative example after injection molding, in accordance with internationally accepted standards.

[0066] The specific experimental steps are as follows: The flame-retardant reinforced ABS recycled granules prepared in Examples 1 to 6 and Comparative Examples 1 to 6 were placed in a forced-air drying oven and dried at 80°C for 4 hours to remove surface adsorbed moisture. The dried granules were then added to the hopper of an injection molding machine. The barrel temperature of the injection molding machine was set to 230°C-250°C, the mold temperature was set to 60°C, and the injection pressure was set to 80MPa. Notched impact test specimens conforming to ASTM D256, tensile test specimens conforming to ASTM D638, and flammability test specimens conforming to UL-94 (1.6mm thick) were injection molded. The injection-molded specimens were conditioned at room temperature for 24 hours before testing.

[0067] The notched impact specimens were tested using a cantilever beam impact testing machine according to ASTM D256 standard. The notch type of the specimens was type A, and the test temperature was 23℃. The impact energy absorbed per unit cross-sectional area when the specimens fractured was recorded to characterize the toughness level of the material under high-speed impact load.

[0068] Using a universal testing machine, tensile specimens were tested according to ASTM D638 standard. The tensile speed was set to 50 mm / min. The maximum tensile load during the yielding and fracture processes of the specimens was recorded, and the tensile strength was calculated. At the same time, bending performance tests were performed according to ASTM D790 standard. The indenter speed was set to 2 mm / min, and the bending modulus was calculated to characterize the material's rigidity against deformation.

[0069] Using a vertical burning tester, vertical burning tests were conducted on the burning test strips according to the UL-94 standard. Five strips of each group of samples were ignited twice with a flame for 10 seconds each. The afterflame time and the ignition of cotton by the dripping material were recorded to evaluate the flame retardancy rating.

[0070] The experimental data obtained are shown in the table below: Table 3. Test results of mechanical and flame retardant properties of the examples and comparative samples Example 1 14.3 45.2 2750 V-0 Example 2 13.1 46.8 2910 V-0 Example 3 15.6 42.1 2580 V-0 Example 4 13.9 45.5 2760 V-0 Example 5 13.5 46.1 2820 V-0 Example 6 15.2 43.4 2640 V-0 Comparative Example 1 7.2 40.5 2680 V-0 Comparative Example 2 7.8 41.2 2690 V-0 Comparative Example 3 8.4 39.8 2450 V-0 Comparative Example 4 8.1 41.6 2620 V-0 Comparative Example 5 6.5 38.2 2710 V-0 Comparative Example 6 10.2 42.8 2650 V-0 Conclusions and Analysis: According to Table 3 and Figure 3 The data from Examples 1 to 6 show that a good balance between high rigidity and high toughness was achieved, and the flame retardant rating of all examples reached V-0. Specifically, Example 1 achieved a notched impact strength of 14.3 kJ / m². 2 The tensile strength was 45.2 MPa and the flexural modulus was 2750 MPa. This indicates that the cross-linked rubber soft shell constructed on the surface of needle-shaped wollastonite not only did not weaken the reinforcing effect of inorganic fillers on the matrix, but also dissipated the impact energy through the interfacial cavitation effect, thus solving the problem of easy brittle fracture of conventional inorganic filled ABS recycled materials.

[0071] Comparing the data of Example 1 with Comparative Examples 1 and 2, the impact strength of Example 1 (14.3 kJ / m) is... 2 (Approximately 7.2 kJ / m²) 2 ) and Comparative Example 2 (7.8kJ / m 2 Twice that of the inorganic filler. Comparative Example 1 lacked liquid epoxy resin, and Comparative Example 2 used ordinary liquid nitrile rubber without functional groups; neither could form chemical bonds on the surface of the inorganic filler. Under external impact, the physically adsorbed rubber layer easily peeled off from the filler surface, leading to rapid crack formation and propagation at the interface, failing to transfer stress and induce crazes. This result confirms the decisive role of the acid-epoxy-base ternary chemical anchoring mechanism in stress transfer and toughening.

[0072] Comparing the data of Example 1 and Comparative Example 3, the impact strength of Comparative Example 3, which uses neutral talc, is only 8.4 kJ / m. 2 This is because the surface of talc lacks the alkaline sites required for catalyzing the ring-opening of epoxy resins. Consequently, most of the carboxyl-terminated liquid nitrile rubber fails to crosslink and cure. During melt extrusion, it is easily peeled off from the filler surface by high shear forces and remains free in the ABS matrix, losing its structural advantage of a soft shell enclosing a hard core. This result verifies the key technical importance of utilizing the filler's own alkalinity as an in-situ curing catalyst.

[0073] Comparing the data from Example 1 with Comparative Examples 4 and 5 demonstrates the importance of thermodynamic control. In Comparative Example 4, due to insufficient reaction temperature (60°C), the interfacial gelation reaction did not initiate, and the toughening effect was no different from physical mixing. In Comparative Example 5, high-speed stirring throughout the process led to temperature runaway (138°C). The excessively high temperature caused thermal oxidative degradation and excessive cross-linking of the rubber molecular chains, resulting in an impact strength that dropped to the lowest level of 6.5 kJ / m. 2This indicates that only by controlling the reaction window of 105℃-115℃ and the variable rotation speed process can an elastomer coating with suitable crosslinking density be obtained.

[0074] Comparing the data from Example 1 and Comparative Example 6, the impact strength of Comparative Example 6 decreased significantly to 10.2 kJ / m. 2 Based on the analysis of Test Example 2, this is because the premature addition of ethylene bis-stearamide caused feed slippage, which prevented the screw from establishing a stable melt pressure. As a result, the material was unevenly plasticized in the barrel, the dispersion of each component deteriorated, and macroscopic defects were formed inside the material, leading to a decrease in mechanical properties.

[0075] In summary, the data in Table 3 further confirms the advanced nature of the technical solution of this invention from the perspective of macroscopic performance: through interfacial chemical design and segmented process control, high performance with high filler content has been successfully achieved in the field of waste plastic recycling, which is significantly better than the traditional physical blending modification technology.

Claims

1. Flame-retardant reinforced ABS recycled plastic granules, characterized in that, Made from the following ingredients in parts by weight: 100 parts recycled ABS material; 20-25 parts acicular wollastonite; 12-14 parts decabromodiphenyl ethane; 4-5 parts antimony trioxide; 3.9-5.0 parts of active coating solution; 0.5-0.8 parts of ethylene bis-stearamide; 0.3-0.5 parts of antioxidant; The active coating solution is made of carboxyl-terminated butadiene-acrylonitrile copolymer, liquid epoxy resin and aluminate coupling agent; The active coating solution is made from the following components in parts by weight: 30-40 parts of carboxyl-terminated butadiene-acrylonitrile copolymer; 3-5 parts of liquid epoxy resin; 4-6 parts of aluminate coupling agent; The preparation process of the flame-retardant reinforced ABS recycled plastic granules is as follows: The carboxyl-terminated butadiene-acrylonitrile copolymer, liquid epoxy resin and aluminate coupling agent are mixed evenly until the material is homogeneous and transparent to obtain the active coating liquid. Needle-shaped wollastonite, decabromodiphenyl ethane, and antimony trioxide are added to a high-speed mixer and heated. The active coating liquid is then atomized and sprayed into the high-speed mixer. After spraying, the high-speed stirring mode is maintained until the material temperature rises to 105℃-115℃. The stirring speed of the high-speed mixer is then reduced to a low-speed mode, and the material temperature is maintained at 105℃-115℃ using the residual heat of the material. The low-speed stirring is maintained for 5.0 min-8.0 min to obtain the thermally modified powder. The thermally modified powder is fed into a cold mixer for cooling; when the temperature of the thermally modified powder drops to 80℃-90℃, ethylene bis-stearamide is added to the cold mixer; after stirring and cooling to 40℃-50℃, the powder is discharged to obtain the modified composite powder. The modified composite powder is mixed with recycled ABS material and antioxidant to obtain a premix; the premix is ​​added to a twin-screw extruder for melt extrusion and granulation to obtain flame-retardant reinforced recycled ABS plastic granules.

2. The flame retardant reinforced ABS recycled plastic particles as claimed in claim 1 wherein, The antioxidant is a mixture of hindered phenolic antioxidants and phosphite antioxidants.

3. A process for the production of flame retardant reinforced ABS recycled plastic granules, characterized by, The method for preparing flame-retardant reinforced ABS recycled plastic pellets as described in any one of claims 1-2 includes the following steps: The carboxyl-terminated butadiene-acrylonitrile copolymer, liquid epoxy resin and aluminate coupling agent are mixed evenly until the material is homogeneous and transparent to obtain the active coating liquid. Needle-shaped wollastonite, decabromodiphenyl ethane, and antimony trioxide are added to a high-speed mixer and heated. The active coating liquid is then atomized and sprayed into the high-speed mixer. After spraying, the high-speed stirring mode is maintained until the material temperature rises to 105℃-115℃. The stirring speed of the high-speed mixer is then reduced to a low-speed mode, and the material temperature is maintained at 105℃-115℃ using the residual heat of the material. The low-speed stirring is maintained for 5.0 min-8.0 min to obtain the thermally modified powder. The thermally modified powder is fed into a cold mixer for cooling; when the temperature of the thermally modified powder drops to 80℃-90℃, ethylene bis-stearamide is added to the cold mixer; after stirring and cooling to 40℃-50℃, the powder is discharged to obtain the modified composite powder. The modified composite powder is mixed with recycled ABS material and antioxidant to obtain a premix; the premix is ​​added to a twin-screw extruder for melt extrusion and granulation to obtain flame-retardant reinforced recycled ABS plastic granules.

4. The process for the production of flame retardant reinforced ABS recycled plastic granules as claimed in claim 3 wherein, The process of uniformly mixing the carboxyl-terminated butadiene-acrylonitrile copolymer, liquid epoxy resin, and aluminate coupling agent specifically includes: The carboxyl-terminated butadiene-acrylonitrile copolymer was added to a stirred tank and heated to 55°C-65°C. The liquid epoxy resin and the aluminate coupling agent were added to the stirred tank in sequence, and the mixture was stirred continuously at a stirring speed of 60 rpm-100 rpm for 15 min-20 min.

5. The process for the production of flame retardant reinforced ABS recycled plastic granules as claimed in claim 3 wherein, The specific steps of adding needle-shaped wollastonite, decabromodiphenyl ethane, and antimony trioxide into a high-speed mixer for mixing and heating include: Start the high-speed mixing mode of the high-speed mixer and set the mixing speed to 900rpm-1100rpm. The frictional heat of needle-shaped wollastonite, decabromodiphenyl ethane and antimony trioxide will raise the material temperature to 85℃-90℃.

6. The process for the production of flame retardant reinforced ABS recycled plastic granules as claimed in claim 3 wherein, The process of atomizing and spraying the active coating liquid into the high-speed mixer specifically includes: Maintain the high-speed mixing mode of the high-speed mixer and spray the active coating liquid evenly into the high-speed mixer within 60s-90s.

7. The process for the production of flame retardant reinforced ABS recycled plastic granules as claimed in claim 3 wherein, Reducing the stirring speed of the high-speed mixer to a low-speed mode specifically includes: Switch the stirring speed of the high-speed mixer to 350rpm-450rpm.

8. The process for the production of flame retardant reinforced ABS recycled plastic granules as claimed in claim 3 wherein, The premix obtained by mixing the modified composite powder with recycled ABS material and the antioxidant specifically includes: The modified composite powder, the recycled ABS material, and the antioxidant are added to a rotary drum mixer and mixed for 3-5 minutes.

9. The process for the production of flame retardant reinforced ABS recycled plastic granules as claimed in claim 3 wherein, The twin-screw extruder includes zones one through nine and a die head along the material conveying direction. The temperature setting range for Zone 1 is 160℃-170℃; for Zones 2 and 3, it is 190℃-210℃; for Zones 4 to 7, it is 205℃-230℃; for Zones 8 and 9, it is 205℃-220℃; and for the machine head, it is 205℃-220℃.

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