Method for modifying and enhancing regenerated ABS (Acrylonitrile Butadiene Styrene) plastic

Abstract

The invention discloses a method for modifying and enhancing regenerated ABS (Acrylonitrile Butadiene Styrene) plastics, which comprises the following steps of: selecting an ABS recycled material as a regenerated ABS base material, and pretreating the ABS recycled material to remove impurities, oil stains and water to obtain regenerated ABS aggregates; the preparation method comprises the following steps: mixing a coupling agent KH-550, ethanol and water according to a ratio to prepare a KH-550 ethanol solution, and adding glass fibers for treatment to obtain modified glass fibers; the preparation method comprises the following steps: adding regenerated ABS granules, modified glass fibers, nano calcium carbonate, maleic anhydride grafted ABS and an auxiliary agent into a high-speed mixer according to a mass ratio, uniformly mixing, and screening out agglomerated granules to obtain a mixture; and feeding the mixture into a twin-screw granulator for extrusion granulation, melting and mixing the materials at high temperature, extruding into strips through a machine head, cooling through a cooling water tank, and cutting into finished regenerated ABS plastic particles through a granulator. The method disclosed by the invention is beneficial for realizing effective recovery and cyclic utilization of resources, promoting high-value utilization of the regenerated ABS plastic and reducing pollution of waste plastic to the environment, and has remarkable economic and social benefits.

Description

Technical Field

[0001] This invention relates to the field of plastic recycling and processing technology, and specifically to a method for modifying and reinforcing recycled ABS plastic. Background Technology

[0002] Plastic materials are widely used in human society and daily life, but waste plastics cause serious environmental pollution and resource waste. ABS plastic, as a thermoplastic engineering plastic with excellent comprehensive performance, is widely used in electronics, automobile manufacturing, building materials, and other fields. However, the world generates more than 8 million tons of waste ABS plastic every year. Recycling ABS plastic has become a key way to solve this problem. However, virgin ABS undergoes high-temperature melting and mechanical shearing during use and recycling, resulting in molecular chain breakage and oxidative cross-linking of the butadiene phase. This leads to a decrease in the impact strength and heat distortion temperature of recycled materials, and a significant deterioration in mechanical properties and processing stability, greatly limiting its application in high-value-added fields.

[0003] Currently, the modification and reinforcement technologies for recycled ABS plastics mainly focus on three major directions: physical blending modification, chemical grafting modification, and composite filler modification.

[0004] Physical blending modification improves the defects of recycled materials by melt blending recycled ABS with other polymers (such as PC, PBT, PVC, etc.). For example, when 5% to 15% of PC is blended with recycled ABS, the impact strength can be restored to more than 85% of that of virgin material. However, the high cost of PC leads to a decrease in economic efficiency. Elastomer toughening can effectively improve impact resistance by adding 5% to 20% of elastomer particles such as SBS and EPDM. However, this will further reduce the rigidity and heat resistance of the material, creating a contradictory relationship between performance improvement and performance enhancement.

[0005] Chemical grafting modification improves interfacial bonding and compatibility by introducing functional monomers (such as maleic anhydride and acrylates) into the molecular chains of recycled ABS. Studies have shown that grafting recycled ABS with 0.5%–2% maleic anhydride can increase the flexural strength of the composite material by 15%–25%. However, the grafting efficiency is significantly affected by reaction temperature, time, and initiator dosage. Precise control of the grafting rate is difficult in industrial production, leading to large fluctuations in product performance. Furthermore, the chemical modification process requires the use of organic solvents and initiators, posing environmental and safety risks and increasing processing costs.

[0006] Composite filler modification enhances, toughens, or functionalizes recycled ABS by adding inorganic fillers (such as glass fiber, calcium carbonate, etc.) or organic fillers (such as wood flour, starch, etc.). Glass fiber reinforced recycled ABS can increase tensile strength by 40%–60% and heat distortion temperature by 20–30°C, but uneven fiber dispersion can lead to decreased impact performance and severe wear on processing equipment. Nanofillers (such as nano-montmorillonite, carbon nanotubes, etc.) can significantly improve material properties at low addition levels (1%–5%), but the agglomeration problem of nanoparticles has not been effectively solved, and interfacial compatibility remains a key bottleneck restricting its application.

[0007] Existing modification technologies still have many limitations in practical applications: single modification methods cannot simultaneously achieve synergistic improvements in strength, toughness, and heat resistance; the theory of ratio optimization and interface control among components in composite modification systems is incomplete; most modification processes require complex equipment and harsh reaction conditions, which contradicts the goal of low-cost recycling of recycled plastics; in addition, the sources of recycled ABS raw materials are complex, with large fluctuations in impurity content and performance, resulting in poor universality of modification formulations and difficulty in forming standardized production processes.

[0008] Therefore, developing efficient, low-cost, and environmentally friendly multi-dimensional and multi-scale synergistic modification technologies, and constructing performance regulation mechanisms and process optimization methods are the core technological requirements for promoting the high-value utilization of recycled ABS plastics. Summary of the Invention

[0009] The technical problem solved by this invention is to provide a method for modifying and reinforcing recycled ABS plastic, which is mainly used to modify and reinforce recycled ABS plastic to overcome the limitations of existing modification technologies, achieve synergistic improvement in strength, toughness and heat resistance, reduce costs, reduce environmental impact, and form a standardized production process to solve the defects in the above-mentioned technical background.

[0010] The technical problem solved by this invention is achieved by the following technical solution: A method for modifying and reinforcing recycled ABS plastic, specifically including the following steps: S1. Select recycled ABS material as the base material for recycled ABS. Pre-treat the recycled ABS material by crushing, washing and drying to remove surface impurities, oil and moisture, and obtain recycled ABS granules. S2. Mix coupling agent KH-550, ethanol and water in a mass ratio of 3:180:17, and adjust the pH of the mixture solution to 4-5 with glacial acetic acid to obtain KH-550 ethanol solution; then add glass fiber to KH-550 ethanol solution for modification treatment, and control the amount of coupling agent to be 1-1.5% of the mass of glass fiber to obtain modified glass fiber; S3. According to the mass ratio, add 70-90% recycled ABS granules, 15-20% modified glass fiber, 3-5 parts nano-calcium carbonate, 4-7 parts maleic anhydride grafted ABS, and additives to a high-speed mixer. After mixing evenly, sieve out agglomerated particles to obtain the mixture. S4. Feed the mixture obtained in step S3 into a twin-screw granulator for extrusion granulation. Set the equipment parameters as follows during granulation: Feeding section: 180~190℃, screw speed 150r / min; Compression section: 200~210℃, vacuum degree -0.07~-0.09MPa; Melting zone: 210~220℃; Die head: 215℃, die head pressure 10~15MPa; Start the equipment so that the mixture is melted and mixed at high temperature by the rotation and shearing action of the screw. Then, it is extruded into strips through the die head, cooled by the cooling water tank, and then cut into uniform finished recycled ABS plastic granules by the pelletizer.

[0011] As a further limitation, in step S1, the ABS recycled material used as raw material is preferably recycled ABS plastic for casings from the fields of electronics, automobiles and other industries.

[0012] As a further limitation, the difference in melt flow index between the recycled ABS granules and the maleic anhydride-grafted ABS is ≤5 g / 10 min, in order to avoid interfacial delamination.

[0013] As a further limitation, in step S1, when crushing the ABS recycled material, a crusher is first used to crush the ABS recycled material into particles with a particle size of 3-5 mm. Then, the crushed ABS recycled material particles are sent to a washing tank and washed with an aqueous solution containing a surfactant. The washing temperature is controlled at 40-50℃, and the washing time is 20-30 minutes. After washing, the washed particles are treated by low-temperature air drying at ≤70℃, centrifugal dehydration, or vacuum dehydration to ensure that the moisture content of the dehydrated ABS recycled material particles is reduced to below 1%.

[0014] As a further limitation, in step S2, the glass fiber used is alkali-free chopped fiber with a diameter of 10~13μm and a length of 3~5mm.

[0015] As a further limitation, in step S2, when modifying the glass fiber, the corresponding glass fiber is continuously and uniformly added to the KH-550 ethanol solution, the reaction temperature is controlled at 55~65℃ under water bath conditions, the mixture is stirred for 30~60min, filtered, and then dried in an oven at 120℃ for 2h. The resulting modified glass fiber is cooled and then sealed for storage for later use.

[0016] As a further specification, the nano-calcium carbonate used as raw material has a particle size of 50~80nm, is surface modified with stearic acid, and has an activation degree of ≥95%; the maleic anhydride grafted ABS used as raw material has a grafting rate of 1.2~1.5% and a melt index of 8~10g / 10min at 200℃ / 10kg.

[0017] As a further limitation, the additives include antioxidants and lubricants. The antioxidant is a compound antioxidant, which is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2 to 1:3, and the amount added is 0.3% of the mass of the recycled ABS granules. The lubricant is ethylene bis-stearamide, and the amount added is 0.5% of the mass of the recycled ABS granules.

[0018] As a further limitation, in step S3, when mixing materials using a high-speed mixer, the mixture is first mixed at a low speed of 300~500 r / min for 2~5 min, and then mixed at a high speed of 1000~1200 r / min for 5~10 min. During the mixing process, the material temperature is controlled to be ≤90℃, and after discharge, the material is sieved to remove agglomerated particles.

[0019] As a further limitation, in step S4, the twin-screw granulator is preferably a weak shear configuration granulator to ensure that the glass fiber retains a length of ≥2mm after extrusion.

[0020] Beneficial Effects: The modification and reinforcement method for recycled ABS plastic provided by this invention selects glass fiber and nano-calcium carbonate as reinforcing phases and maleic anhydride-grafted ABS (MAH-g-ABS) as compatibilizer. Through multi-dimensional and multi-scale synergistic modification technology, the recycled ABS plastic is modified and reinforced. This effectively overcomes the limitations of single modification methods, achieving a synergistic improvement in strength, toughness, and heat resistance. Compared with existing modification technologies, the method of this invention is more cost-effective, using relatively reasonable materials and avoiding the use of high-cost materials such as PC. Furthermore, by optimizing process and equipment parameters, energy consumption and equipment wear during production are reduced, meeting the goal of low-cost recycling of recycled plastics. In terms of environmental friendliness, the process of this invention does not rely on complex reactions and large amounts of organic solvents, reducing environmental pollution and lowering processing costs. Moreover, the modification method of this invention has strong adaptability to recycled ABS raw materials, overcoming to some extent the problems of complex raw material sources and large performance fluctuations, making it easier to form standardized production processes and showing good prospects for industrial application. Detailed Implementation

[0021] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments.

[0022] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. The above descriptions are merely implementation methods of this invention. It should be noted that those skilled in the art can make improvements without departing from the inventive concept of this invention, but these improvements all fall within the scope of protection of this invention.

[0023] In this embodiment of the invention, the method for modifying and reinforcing recycled ABS plastic is implemented in the following manner: First, prepare the ingredients: Recycled ABS substrate: Derived from crushed household appliance casings, pre-crushed into ABS recycled material particles with a particle size of 3-5mm, and then sent to a washing tank for washing with an aqueous solution containing surfactant at 45℃ for 30 minutes. After washing, it is dried at a low temperature in an oven at ≤70℃ to avoid over-drying and causing material degradation (during this period, melt flow index monitoring is used to ensure that the change rate of melt flow index after drying should be <5%), so that the moisture content of the dehydrated ABS recycled material particles is reduced to below 1%.

[0024] Reinforcing phase: Glass fiber (GF): Alkali-free short-cut fibers, 10~13μm in diameter and 3~5mm in length, with the surface pretreated with silane coupling agent KH-550 (the amount of coupling agent is 1.5% of the mass of GF). Nano calcium carbonate: Particle size 50~80nm, surface modified with stearic acid (activation degree ≥95%).

[0025] Compatibilizer: Maleic anhydride grafted ABS: grafting rate 1.2~1.5%, melt index 8~10g / 10min (200℃ / 10kg).

[0026] Antioxidant: compound system (1010:168=1:2), the total amount added is 0.3% of the mass of recycled ABS substrate.

[0027] Lubricant: Ethylene bis-stearamide (EBS), added at 0.5% of the weight of the recycled ABS substrate. Among the aforementioned raw materials, glass fiber possesses high strength and high modulus, primarily playing a role in enhancing material strength and heat resistance, and can significantly improve the tensile strength and heat distortion temperature of recycled ABS plastic.

[0028] Nano-sized calcium carbonate particles have a large specific surface area, which can strengthen and toughen materials, further enhancing their toughness and rigidity, while also improving their processing performance.

[0029] Maleic anhydride-grafted ABS acts as a bridge, strengthening the bond between glass fiber, nano-calcium carbonate, and the recycled ABS matrix, thus comprehensively improving the material's performance. It improves the interfacial compatibility between components, promotes the uniform dispersion of glass fiber and nano-calcium carbonate in the recycled ABS matrix, and fully leverages the advantages of each component.

[0030] During preparation, recycled ABS granules are added to a vacuum drying oven and dried at 60℃ and -0.09MPa for 4 hours until the moisture content is ≤0.1% (verified by weighing method, sampling is taken every hour to measure the moisture content, and drying is stopped when the difference between two consecutive values ​​is <0.02%).

[0031] Subsequently, a KH-550 ethanol solution was prepared (the ratio of coupling agent, ethanol, and water was 1.5:90:8.5, the pH was 4-5, and it was adjusted with glacial acetic acid). Glass fiber was added to this solution, stirred at 60°C for 30 minutes, filtered, and then dried in an oven at 120°C for 2 hours. After cooling, it was sealed and stored for later use.

[0032] According to the mass ratio, 70 parts of recycled ABS granules, 20 parts of glass fiber, 5 parts of nano calcium carbonate, 4 parts of maleic anhydride grafted ABS, 0.3 parts of antioxidant, and 0.5 parts of lubricant are added to a high-speed mixer. First, mix at low speed (500 r / min) for 2 minutes, and then mix at high speed (1200 r / min) for 5 minutes. During the mixing process, the material temperature is controlled to be ≤90℃ (achieved by jacket water cooling). After discharge, the material is passed through an 80-mesh sieve to remove agglomerated particles to obtain the premixed material.

[0033] The premixed material is fed into a twin-screw extruder with a screw diameter of 35mm, a length-to-diameter ratio of 40:1, and a temperature control accuracy of ±1℃. This extruder achieves a low-shear configuration by reducing the number of kneading blocks. By setting up a low-shear configuration extruder, it is ensured that the glass fibers retain a length ≥2mm after extrusion (this can be verified by microscopic observation; the length of 100 randomly selected fibers is measured, and the average length is ≥2mm).

[0034] The temperature range of the feeding section (zones 1-3) of the twin-screw extruder is set to 185℃, and the screw speed is set to 150 r / min; the temperature range of the compression section (zones 4-6) is set to 205℃, and the vacuum degree is set to -0.08 MPa; the temperature range of the melting section (zones 7-9) is set to 210℃, and the main motor current is controlled at 75% of the rated current; the temperature of the die head (zone 10) is set to 215℃, and the die head pressure range is 13 MPa; the pelletizer speed is matched with the extrusion rate (pellet length is 3-5 mm, with an error of ±0.5 mm).

[0035] Start the extruder and wait for the temperature in each zone to reach the set value and stabilize for 10 minutes before turning on the feeder (feeding rate of 8-10 kg / h). After melt blending, the material is extruded through a double-strand die, and then successively cooled by water (water temperature 25±5℃), air-dried (air temperature 60℃), and then pelletized. After collecting the pellets, they are placed in an 80℃ oven to dry for 2 hours to remove surface moisture, thus obtaining the finished recycled ABS plastic pellets.

[0036] To test the performance of the prepared recycled ABS plastic granules, the corresponding finished recycled ABS plastic granules were made into standard test strips using an injection molding process. Control the barrel temperature: front section 200℃, middle section 210℃, rear section 190℃, nozzle temperature 215℃; Mold temperature: 60±5℃; Injection process: Injection pressure 80~100MPa, holding pressure 60~70MPa (holding time 15~20s), cooling time 30~40s, injection rate 50mm / s.

[0037] Tensile specimens were prepared according to GB / T1040-2006, and impact specimens (notch depth 2mm) were prepared according to GB / T1843-2008. Ten specimens were prepared in each group.

[0038] Performance tests were conducted using a universal testing machine (accuracy grade 1), a simply supported beam impact testing machine (pendulum energy 2.75J), and a heat distortion temperature measuring instrument. The specific tests included: Tensile strength: tensile rate 50 mm / min, span 50 mm, average value of sampled strips; Notched impact strength: simply supported beam method, impact velocity 3.5 m / s, notch type A; Heat distortion temperature: load 1.82MPa, heating rate 2℃ / min.

[0039] Its performance indicators are as follows: Performance indicators unit Target value actual value average value Test Standards Tensile strength MPa ≥35 36~39 36.5 GB / T 1040-2006 Elongation at break % ≥8 8.4~9.2 8.8 GB / T 1040-2006 Notched impact strength <![CDATA[kJ / m 2 ]]> ≥15 16.1~18.6 17.1 GB / T 1843-2008 Heat distortion temperature (1.82 MPa) ℃ ≥85 87.2~94.6 91.5 GB / T 1634.2-2004 Melt flow index (220℃ / 10kg) g / 10min 12~18 13~17 15.4 GB / T 3682-2000 Based on the above technical specifications, this solution adopts a "composite reinforcement + interface optimization" technical approach. Leveraging the synergistic effect of composite reinforcement and interface optimization, the overall performance of recycled ABS can be effectively improved. It can increase the tensile strength of recycled ABS to over 35 MPa and the notched impact strength to 15 kJ / m². 2 The heat distortion temperature (HDT) is increased to above 85°C.

[0040] Therefore, the recycled ABS plastic prepared by the technical solution of this embodiment is expected to be more widely used in the fields of electronics, automobile manufacturing, and building materials.

[0041] In the electronics and electrical appliance industry, this recycled ABS plastic can be used to manufacture various electrical appliance housings and components, which can both meet the performance requirements of the products and reduce production costs.

[0042] In the automotive manufacturing sector, it can be applied to the production of interior and exterior parts, helping to improve the lightweighting and environmental performance of automobiles.

[0043] In the field of building materials, it can be used to make doors, windows, pipes, etc., providing the construction industry with high-performance, low-cost plastic material options.

[0044] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A modified reinforcement method of recycling ABS plastic, characterized by, The method comprises the following steps: S1, selecting ABS recycled material as a recycled ABS base material; the recycled ABS recycled material is pretreated, impurities, oil stains and moisture on the surface are removed through crushing, cleaning and drying in the pretreatment stage, and recycled ABS granules are obtained; S2, mixing the coupling agent KH-550, ethanol and water according to a mass ratio of 3:180:17, adjusting the pH value of the mixture solution to 4-5 by using glacial acetic acid to obtain a KH-550 ethanol solution; then adding glass fibers into the KH-550 ethanol solution for modification treatment, controlling the amount of the coupling agent to be 1-1.5% of the mass of the glass fibers to obtain modified glass fibers; S3, according to the mass ratio, adding 70-90% of the recycled ABS granules, 15-20% of the modified glass fibers, 3-5 parts of nano calcium carbonate, 4-7 parts of maleic anhydride grafted ABS and an additive into a high-speed mixer, uniformly mixing, screening out agglomerated particles, and thus obtaining a mixture; S4, feeding the mixture obtained in step S3 into a double-screw granulator for extrusion granulation, and setting the equipment parameters during granulation as follows: Feeding section: 180-190℃, screw rotation speed 150r / min; Compression section: 200-210℃, vacuum degree-0.07~-0.09MPa; Melt section: 210-220℃; Die head: 215℃, die pressure 10-15MPa; Starting the equipment, so that the mixture is melted and mixed under high temperature through the rotation and shearing action of the screw, then extruded into a strip through the die head, cooled through a cooling water tank, and then cut into uniform finished product recycled ABS plastic particles by a pelletizer.

2. The modified reinforcement method of recycling ABS plastic according to claim 1, characterized in that, In step S1, the ABS recycled material as the raw material is a shell type ABS plastic recycled from the fields of electronic appliances and automobiles.

3. The modified reinforcement method of recycling ABS plastic according to claim 1, characterized in that, The difference between the melt indexes of the recycled ABS granules and the maleic anhydride grafted ABS is ≤5g / 10min.

4. The modified reinforcement method of recycling ABS plastic according to claim 1, characterized in that, In step S1, when the ABS recycled material is crushed, the ABS recycled material is first crushed into particles with a particle size of 3-5mm by using a crusher; then the crushed ABS recycled material particles are sent into a cleaning tank for cleaning with an aqueous solution containing a surfactant, the cleaning temperature is controlled at 40-50℃, and the cleaning time is 20-30min; after cleaning, the particles are treated by low-temperature air drying, centrifugal dewatering or vacuum dewatering at ≤70℃ to ensure that the water content of the ABS recycled material particles after dewatering is reduced to below 1%.

5. The modified reinforcement method of recycling ABS plastic according to claim 1, characterized in that, In step S2, the glass fibers used are alkali-free chopped fibers, the diameter of which is 10-13μm, and the length of which is 3-5mm.

6. The modified reinforcement method of recycling ABS plastic according to claim 1, characterized in that, In step S2, when the glass fibers are modified, the corresponding glass fibers are continuously and uniformly put into the KH-550 ethanol solution, the reaction temperature is controlled at 55-65℃ under water bath conditions, stirring is maintained for 30-60min, and after filtration, the modified glass fibers are dried in an oven at 120℃ for 2h, and then the modified glass fibers are cooled and sealed for storage.

7. The modified reinforcement method of recycling ABS plastic according to claim 1, characterized in that, The nano calcium carbonate as raw material has a particle size of 50-80 nm, is modified on the surface by stearic acid, and has an activation degree of ≥95%; the maleic anhydride grafted ABS as raw material has a grafting rate of 1.2-1.5%, and a melt index of 8-10 g / 10 min at 200 ℃ / 10 kg.

8. The modified reinforcement method of recycling ABS plastic according to claim 1, characterized in that, The auxiliary agent comprises an antioxidant and a lubricant, the antioxidant is a compounded antioxidant, is a proportion mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2-1:3, and the addition amount is 0.3% of the mass of the recycled ABS granules; the lubricant is ethylene bis-stearamide, and the addition amount is 0.5% of the mass of the recycled ABS granules.

9. The modified reinforcement method of recycling ABS plastic according to claim 1, characterized in that, In step S3, the material is mixed by using a high-speed mixer, first low-speed mixing at a speed of 300-500 r / min for 2-5 min, and then high-speed mixing at a speed of 1000-1200 r / min for 5-10 min, and the material temperature is controlled to ≤90 ℃ during the mixing process, and the agglomerated particles are removed by sieving after discharging.

10. The modified reinforcement method of recycling ABS plastic according to claim 1, characterized in that, In step S4, the double-screw granulator is a weak-shearing configuration granulator, and the glass fiber in the raw material has a reserved length of ≥2 mm after being extruded in the double-screw granulator.