A novel method for preparing PC / ABS plastic alloy and its application

Abstract

This invention relates to the field of polymer materials technology, specifically to a novel method for preparing PC / ABS plastic alloys and its applications. The method includes: first, preparing an amination-modified styrene-acrylonitrile copolymer and an internal salt / long-chain double-grafted silsesquioxane; then, sequentially adding polycarbonate, acrylonitrile-butadiene-styrene, an epoxy chain extender, and an antioxidant system according to a set temperature zone and feeding zone; and finally, extruding, cooling, and pelletizing the alloy using a co-directional twin-screw extruder. This method achieves reactive anchoring and dual regulation of polarity / hydrophobicity at the interface, improves melt strength and morphological stability through stepwise chain extension, and synergistically enhances mechanical, thermal stability, and hydrothermal retention rates. It is suitable for applications in automotive interiors, electronic appliance housings, and office equipment.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a novel method for preparing PC / ABS plastic alloys and their applications. Background Technology

[0002] Polycarbonate and acrylonitrile-butadiene-styrene (ABS) plastic alloys are widely used material systems in the field of engineering plastics. Polycarbonate has excellent transparency, impact strength, and heat resistance, but its melt flow is poor, its processing window is narrow, and its price is relatively high. Acrylonitrile-butadiene-styrene resin, while having good processing performance and low cost, lacks sufficient heat resistance and mechanical strength. Blending the two to prepare plastic alloys can combine the advantages of both, maintaining good impact toughness while also considering processability and cost control. Therefore, it has found widespread application in automotive interiors, electronic and electrical housings, office equipment, and other fields.

[0003] However, polycarbonate and acrylonitrile-butadiene-styrene resin exhibit poor compatibility. Their solubility parameters differ significantly, resulting in high interfacial tension during direct blending. This leads to uneven dispersed phase size and easy growth, forming coarse phase regions. This undesirable morphology prevents effective stress transfer, making the interface prone to debonding and cracking under impact, hindering the achievement of ideal overall mechanical properties. To improve compatibility, the industry typically uses compatibilizers. Traditional compatibilizers are mostly styrene copolymers or graft copolymers, which reduce interfacial energy and promote interaction between the two phases through physical entanglement or chemical bonding. However, these compatibilizers have limited polarity control and insufficient anchoring strength at the interface. Especially under high temperature or high humidity environments, interfacial stability rapidly declines, affecting the long-term performance of the material.

[0004] Besides compatibility issues, polycarbonate and acrylonitrile-butadiene-styrene plastic alloys also face the risk of molecular chain degradation during processing. Polycarbonate is prone to hydrolysis and thermal degradation under high-temperature shear conditions, leading to a decrease in molecular weight, resulting in insufficient melt strength, flow marks, and silver streaks on the product surface, affecting appearance and performance. The butadiene rubber phase in acrylonitrile-butadiene-styrene resin is sensitive to thermo-oxidative aging and is prone to cross-linking or chain breakage during processing and use, causing the material to become brittle or discolored. Conventional methods to inhibit degradation include adding antioxidants and heat stabilizers, but these additives mainly provide passive protection and cannot fundamentally improve the thermal stability of the molecular chains. In recent years, some studies have attempted to introduce chain extenders to repair or extend the molecular chains; however, improper timing and distribution control of chain extenders can easily lead to excessively high local cross-linking density, which in turn reduces the material's toughness, making it impossible to achieve a balance between mechanical and processing properties.

[0005] Furthermore, materials often need to withstand humid and hot aging in real-world applications. In the high temperature and humidity conditions of summer, water molecules easily penetrate and diffuse along the interface between polycarbonate and acrylonitrile-butadiene-styrene resin in automotive interiors and electrical enclosures. The presence of water molecules further disrupts the intermolecular forces at the interface, leading to interfacial debonding and microcrack formation. The impact strength and toughness of the material significantly decrease under humid and hot conditions. Traditional modification methods mainly focus on improving initial properties, but pay insufficient attention to the long-term stability of the interface, especially under humid and hot cycling conditions, where the water resistance and aging resistance of the interface often become key factors in material failure. Existing technologies lack modifying components that can simultaneously regulate the interfacial polarity and hydrophobicity, making it impossible to construct an effective moisture barrier at the interface layer, resulting in unsatisfactory performance retention of the material under humid and hot conditions.

[0006] In summary, existing polycarbonate-acrylonitrile-butadiene-styrene plastic alloys still have many shortcomings in terms of compatibility, molecular chain stability, and interfacial resistance to damp heat, making it difficult to meet the requirements of high-performance applications for comprehensive material performance and long-term stability. How to achieve synergistic improvements in initial mechanical properties, thermal stability, and performance retention after damp heat aging through the design of novel modifying components and precise control of processing techniques has become a pressing technical challenge. Summary of the Invention

[0007] In view of this, the purpose of this invention is to propose a novel method for preparing PC / ABS plastic alloys and its application, so as to solve the problems of insufficient interfacial compatibility, poor molecular chain thermal stability and low interfacial damp heat resistance of polycarbonate and acrylonitrile-butadiene-styrene plastic alloys in the prior art.

[0008] To achieve the above objectives, the present invention provides a method for preparing a PC / ABS plastic alloy, comprising the following steps:

[0009] Step 1: Preparation of amination-modified styrene-acrylonitrile copolymer

[0010] Styrene, acrylonitrile, 4-vinylbenzyl chloride, and azobisisobutyronitrile were added to anhydrous N,N-dimethylformamide under nitrogen protection and reacted at 60-70°C for 8-15 h to obtain a styrene-acrylonitrile copolymer solution containing benzyl chloride side groups. After cooling, piperidine and triethylamine were added and reacted at 40-55°C for 4-8 h to complete benzyl chloride substitution. After solvent removal, reprecipitation, and vacuum drying, the amination styrene-acrylonitrile copolymer was obtained.

[0011] Step 2: Preparation of internal salt / long-chain double-grafted silsesquioxanes

[0012] In anhydrous dimethylformamide, octa(3-aminopropyl)silsesquioxane salt and triethylamine were added and stirred for 0.5-2 h; 1,3-propanesulfonyl lactone was added and reacted at 30-40 °C for 6-12 h; after cooling, octadecanoyl chloride and triethylamine were added and reacted at 0-10 °C for 1-3 h, followed by reaction at 20-30 °C for 2-5 h; after filtration to remove salt, precipitation and vacuum drying, inner salt / long-chain double-grafted silsesquioxane was obtained.

[0013] Step 3: Polycarbonate / acrylonitrile-butadiene-styrene alloy extrusion granulation

[0014] S1: By weight, weigh 60-80 parts of polycarbonate, 20-40 parts of acrylonitrile-butadiene-styrene resin, 0.5-1.2 parts of amination styrene-acrylonitrile copolymer, 0.2-0.5 parts of internal salt / long-chain double-grafted silsesquioxane, 0.4-1.0 parts of polyfunctional epoxy chain extender, 0.15-0.30 parts of hindered phenolic antioxidant, 0.10-0.25 parts of phosphite antioxidant, and 0.15-0.30 parts of zinc stearate.

[0015] S2: The polycarbonate, acrylonitrile-butadiene-styrene resin and each additive are dried separately;

[0016] S3: Extrusion granulation is performed using a twin-screw extruder. The temperatures of each heating zone are set as follows: Zone 1: 200-220℃, Zone 2: 220-240℃, Zone 3: 230-250℃, Zone 4: 235-255℃, Zones 5-6: 240-260℃, Zone 7: 235-255℃, Zone 8: 230-250℃, and the die head temperature is 235-255℃.

[0017] S4: Add dried polycarbonate resin, acrylonitrile-butadiene-styrene resin, hindered phenolic antioxidant, phosphite antioxidant and zinc stearate to the main hopper;

[0018] S5: Add 30%-60% of the aminated styrene-acrylonitrile copolymer in zone 4 of the barrel, add 25%-40% of the multifunctional epoxy chain extender in zone 5 of the barrel, add all the internal salt / long-chain double-grafted silsesquioxane in zone 6 of the barrel, add the remaining aminated styrene-acrylonitrile copolymer in zone 7 of the barrel, and add the remaining multifunctional epoxy chain extender in zone 8 of the barrel;

[0019] S6: PC / ABS plastic alloy is obtained after extrusion, cooling, pelletizing and drying.

[0020] Preferably, in step one, piperidine and triethylamine are added after the temperature is lowered to 40-55°C.

[0021] Preferably, in step one, the solvent is removed by vacuum evaporation, acetone is reprecipitated, and the mixture is vacuum dried at 50-70°C for 10-14 hours.

[0022] Preferably, in step one, the mass ratio of styrene, acrylonitrile, 4-vinylbenzyl chloride, piperidine, and triethylamine is 690:300:7-13:60-100:100-140.

[0023] Preferably, in step one, the amount of azobisisobutyronitrile used is 0.12%-0.20% of the total mass of styrene and acrylonitrile.

[0024] Preferably, in step two, octadecanoyl chloride and triethylamine are added dropwise after the temperature is lowered to 20-30°C.

[0025] Preferably, in step two, after filtration and desalting, the precipitate of diethyl ether is vacuum dried at 40-60°C for 10-14 hours.

[0026] Preferably, in step two, the mass ratio of octa(3-aminopropyl)silsesquioxane salt, 1,3-propanesulfonyl lactone, octadecanoyl chloride and triethylamine is 50:50-70:8-12:140-200.

[0027] Preferably, the polycarbonate in S1 is Covestro Makrolon 2607.

[0028] Preferably, the acrylonitrile-butadiene-styrene resin in S1 is of the type Chi Mei POLYLAC PA-757.

[0029] Preferably, the multifunctional epoxy chain extender in S1 is BASF Joncryl ADR-4468.

[0030] Preferably, in S2, the polycarbonate is dried at 110-130°C for 2-6 hours, the acrylonitrile-butadiene-styrene resin is dried at 70-90°C for 1-4 hours, and the additive is dried at 50-70°C under a vacuum of -0.04 to -0.08 MPa for 1-4 hours.

[0031] Preferably, in S3, the twin-screw extruder is a co-rotating parallel twin-screw extruder with a screw length-to-diameter ratio (L / D) of 36-44 and a screw speed of 200-400 rpm.

[0032] Preferably, in step S3, the vacuum exhaust system is turned on, and the vacuum level is -0.05 to -0.08 MPa.

[0033] Preferably, in step S3, material feeding begins after each temperature zone reaches the set temperature and stabilizes for 10-20 minutes.

[0034] Preferably, in step three, 40%-60% of the aminated styrene-acrylonitrile copolymer is added to zone 4 of the barrel, 25%-35% of the multifunctional epoxy chain extender is added to zone 5 of the barrel, 40%-60% of the aminated styrene-acrylonitrile copolymer is added to zone 7 of the barrel, and 65%-75% of the multifunctional epoxy chain extender is added to zone 8 of the barrel.

[0035] Preferably, in step S6, after extrusion, the material enters a water cooling tank for cooling, with a water temperature of 10-30°C and a residence time of 8-18 seconds.

[0036] Furthermore, the present invention also provides a PC / ABS plastic alloy, obtained by the above-described method for preparing PC / ABS plastic alloy.

[0037] Furthermore, the present invention also provides an application of PC / ABS plastic alloy in automotive interiors, electronic and electrical housings, or office equipment.

[0038] The beneficial effects of this invention are:

[0039] I. Reactive compatibilizers enable in-situ interfacial anchoring and stable construction of the compatibilized layer.

[0040] This invention uses an amination-styrene-acrylonitrile copolymer as a reactive compatibilizer. During extrusion, the piperidine amine groups react in situ with polycarbonate, generating a graft copolymer structure at the interface and forming a compatibilized layer firmly anchored at the two-phase interface. This compatibilized layer effectively reduces interfacial tension, inhibits dispersed phase growth, ensures uniform stress transmission, significantly improves the impact strength and toughness of the material, and maintains the long-term stability of the interface under humid and hot conditions.

[0041] II. Interfacial amphoteric regulation and enhanced resistance to damp heat achieved by internal salt and long-chain double-grafted silsesquioxane.

[0042] The internal salt and long-chain double-grafted silsesquioxane designed in this invention improves interfacial polarity matching through the zwitterionic structure of the internal salt group, and forms a hydrophobic barrier at the interface through the octadecanoyl long chain to block water penetration, achieving dual regulation of interfacial polarity and hydrophobicity. The cage-like structure of the silsesquioxane provides thermal shielding at the interface, delaying thermal degradation and promoting char formation, enabling the material to maintain a high impact strength retention rate after hygrothermal aging, and significantly improving environmental adaptability.

[0043] III. Stepwise introduction of multifunctional epoxy chain extenders to achieve gradient chain extension and interfacial network reinforcement.

[0044] This invention employs a multifunctional epoxy chain extender introduced in two stages. The first stage involves a reaction with the end groups of polycarbonate and acrylonitrile-butadiene-styrene resin in the fifth zone of the barrel to achieve molecular chain elongation. The second stage involves a post-curing reaction at the interface in the eighth zone of the barrel to form a cross-linked coupling structure. This step-by-step introduction avoids excessively high local cross-linking density, achieving gradient chain extension and network reinforcement from the bulk to the interface, resulting in a material that possesses toughness, strength, and aging resistance.

[0045] IV. Refined segmented processing technology enables synergistic modification and performance optimization of multiple components.

[0046] The segmented feeding process designed in this invention allows the compatibilizer, interface modifier, and chain extender to function sequentially under different temperature zones and shear conditions, avoiding interference between components and achieving synergistic optimization of multiple functions such as compatibility, modification, and chain extension. Refined process control results in uniform material microstructure, small dispersed phase size, and tight interfacial bonding, leading to synergistic improvements in tensile strength, flexural modulus, impact strength, and performance retention after damp heat aging. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a process flow diagram for preparing the novel PC / ABS plastic alloy of the present invention;

[0049] Figure 2 The infrared spectrum of the amination styrene-acrylonitrile copolymer in Example 2 of this invention;

[0050] Figure 3 The infrared spectrum of the internal salt / long-chain double-grafted silsesquioxane in Example 2 of the present invention;

[0051] Figure 4 Thermogravimetric differential curves of PC / ABS plastic alloys prepared in Example 2 and Comparative Examples 1-7 of this invention. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. Example 1

[0053] Step 1: Preparation of amination-modified styrene-acrylonitrile copolymer

[0054] In a 2L four-necked flask with a condenser, 500mL of anhydrous N,N-dimethylformamide was added, and the mixture was heated to 65°C under nitrogen protection. 690g of styrene, 300g of acrylonitrile, and 7g of 4-vinylbenzyl chloride were added, and the mixture was magnetically stirred. 1.2g of azobisisobutyronitrile was added, and the mixture was kept at 65°C for 10 hours to obtain a styrene-acrylonitrile copolymer solution containing benzyl chloride side groups. The temperature was lowered to 40°C, and 60g of piperidine and 100g of triethylamine were added. The mixture was reacted at 50°C for 5 hours to complete the benzyl chloride substitution. The solvent was removed under reduced pressure, and the mixture was reprecipitated with acetone and dried under vacuum at 60°C for 12 hours to obtain the amination-modified styrene-acrylonitrile copolymer.

[0055] Step 2: Preparation of internal salt / long-chain double-grafted silsesquioxanes

[0056] In 1 L of anhydrous dimethylformamide, 50 g of octa(3-aminopropyl)silsesquioxane salt and 100 g of triethylamine were added, and the mixture was stirred at room temperature for 1 h to neutralize the amine salt. 50 g of 1,3-propanesulfonyl lactone was slowly added, and the reaction was carried out at 35°C for 8 h. The temperature was lowered to 25°C, and 8 g of octadecanoyl chloride and 40 g of triethylamine were added dropwise. The temperature was controlled at 0-5°C for 2 h, and the reaction was continued at 25°C for 3 h. After the reaction, the salt was removed by filtration, the precipitate was precipitated by diethyl ether, and the product was dried under vacuum at 50°C for 12 h to obtain an inner salt / long-chain double-grafted silsesquioxane.

[0057] Step 3: Polycarbonate / acrylonitrile-butadiene-styrene alloy extrusion granulation

[0058] Step 3.1: Formula Weighing and Preparation

[0059] Based on a total resin quantity of 10,000g, the following ingredients were weighed: 7,000g of polycarbonate resin (Covestro Makrolon 2607) and 3,000g of acrylonitrile-butadiene-styrene resin (Chimei POLYLAC PA-757); 50g of aminated styrene-acrylonitrile copolymer as a reactive compatibilizer, 20g of internal salt / long-chain double-grafted silsesquioxane as an amphoteric interface modifier, 40g of multifunctional epoxy chain extender (BASF Joncryl ADR-4468), 15g of hindered phenolic antioxidant 1010, 10g of phosphite antioxidant 168, and 15g of zinc stearate lubricant.

[0060] Step 3.2: Raw material drying treatment

[0061] 7000g of polycarbonate resin was placed in a hot air drying oven and dried continuously at 115°C for 3 hours; 3000g of acrylonitrile-butadiene-styrene resin was placed in another hot air drying oven and dried continuously at 75°C for 1.5 hours; after mixing all the additives, the mixture was placed in a vacuum drying oven and dried at 55°C and a vacuum of -0.05MPa for 1.5 hours for later use.

[0062] Step 3.3: Extrusion Equipment Preparation and Temperature Zone Setting

[0063] A co-rotating parallel twin-screw extruder was selected, with a screw length-to-diameter ratio (L / D) of 40. The main screw speed was set to 250 rpm. The temperatures of each heating zone were as follows: Zone 1 of the barrel: 205°C; Zone 2: 225°C; Zone 3: 235°C; Zone 4: 240°C; Zones 5-6: 245°C; Zone 7: 240°C; Zone 8: 235°C; and the die head temperature was set to 240°C. The vacuum exhaust system was turned on (vacuum degree -0.06 MPa). After each temperature zone reached the set temperature and stabilized for 12 minutes, the feeding operation began.

[0064] Step 3.4: Feeding the main hopper and melting the matrix

[0065] Add 7000g of dried polycarbonate resin and 3000g of acrylonitrile-butadiene-styrene resin to the main hopper of the extruder in one go, along with 15g of hindered phenolic antioxidant 1010, 10g of phosphite antioxidant 168, and 15g of zinc stearate lubricant; start the screw and control the feeding speed to 4-6kg / h, so that the materials gradually melt and are initially mixed in zones 1-3 of the barrel;

[0066] Step 3.5: Subsequent feeding, extrusion, and granulation

[0067] After the main hopper has been running stably for 5 minutes, 30g of aminated styrene-acrylonitrile copolymer is added in zone 4 of the barrel; 15g of multifunctional epoxy chain extender is added in zone 5 of the barrel; 20g of internal salt / long-chain double-grafted silsesquioxane is added in zone 6 of the barrel; the remaining 20g of aminated styrene-acrylonitrile copolymer is added in zone 7 of the barrel; and the remaining 25g of multifunctional epoxy chain extender is added in zone 8 of the barrel. The melt is extruded through the die head to form a continuous strip, which enters a water cooling tank (water temperature controlled at 16-22°C) and stays in the water tank for 10 seconds. After being dried by an air knife, it is granulated and dried with hot air to obtain PC / ABS plastic alloy. Example 2

[0068] Step 1: Preparation of amination-modified styrene-acrylonitrile copolymer

[0069] In a 2L four-necked flask equipped with a condenser, 500mL of anhydrous N,N-dimethylformamide was added, and the mixture was heated to 65°C under nitrogen protection. 690g of styrene, 300g of acrylonitrile, and 10g of 4-vinylbenzyl chloride were added, and the mixture was magnetically stirred. 1.5g of azobisisobutyronitrile was added, and the mixture was kept at 65°C for 12 hours to obtain a styrene-acrylonitrile copolymer solution containing benzyl chloride side groups. The temperature was lowered to 40°C, and 80g of piperidine and 120g of triethylamine were added. The mixture was reacted at 50°C for 6 hours to complete benzyl chloride substitution. The solvent was removed under reduced pressure, and the mixture was reprecipitated with acetone and dried under vacuum at 60°C for 12 hours to obtain the amination-modified styrene-acrylonitrile copolymer.

[0070] Step 2: Preparation of internal salt / long-chain double-grafted silsesquioxanes

[0071] In 1 L of anhydrous dimethylformamide, 50 g of octa(3-aminopropyl)silsesquioxane salt and 120 g of triethylamine were added. The mixture was stirred at room temperature for 1 h to neutralize the amine salt. 60 g of 1,3-propanesulfonyl lactone was slowly added. The reaction was carried out at 35°C for 8 h. The temperature was raised to 25°C, and 10 g of octadecanoyl chloride and 50 g of triethylamine were added dropwise. The temperature was controlled at 0-5°C for 2 h, and the reaction was continued at 25°C for 3 h. After the reaction, the salt was removed by filtration, and the precipitate was precipitated by diethyl ether. The precipitate was dried under vacuum at 50°C for 12 h to obtain an inner salt / long-chain double-grafted silsesquioxane.

[0072] Step 3: Polycarbonate / acrylonitrile-butadiene-styrene alloy extrusion granulation

[0073] Step 3.1: Formula Weighing and Preparation

[0074] Based on a total resin quantity of 10,000g, the following ingredients were weighed: 7,000g of polycarbonate resin (Covestro Makrolon 2607) and 3,000g of acrylonitrile-butadiene-styrene resin (Chimei POLYLAC PA-757) were weighed as the main resins; 70g of aminated styrene-acrylonitrile copolymer was weighed as a reactive compatibilizer, 30g of internal salt / long-chain double-grafted silsesquioxane was weighed as an amphoteric interface modifier, 60g of multifunctional epoxy chain extender (BASF Joncryl ADR-4468) was weighed as a chain extender, 20g of hindered phenolic antioxidant 1010, 15g of phosphite antioxidant 168, and 20g of zinc stearate salt lubricant were weighed.

[0075] Step 3.2: Raw material drying treatment

[0076] Place 7000g of polycarbonate resin in a hot air drying oven and dry continuously at 120°C for 4 hours; place 3000g of acrylonitrile-butadiene-styrene resin in another hot air drying oven and dry continuously at 80°C for 2 hours; mix all additives and place them in a vacuum drying oven and dry at 60°C and a vacuum of -0.05MPa for 2 hours for later use.

[0077] Step 3.3: Extrusion Equipment Preparation and Temperature Zone Setting

[0078] A co-rotating parallel twin-screw extruder was selected, with a screw length-to-diameter ratio (L / D) of 40. The main screw speed was set to 300 rpm. The temperatures of each heating zone were as follows: Zone 1 of the barrel: 210°C; Zone 2: 230°C; Zone 3: 240°C; Zone 4: 245°C; Zones 5-6: 250°C; Zone 7: 245°C; Zone 8: 240°C. The die head temperature was set to 245°C. The vacuum exhaust system (vacuum degree -0.06 MPa) was turned on to remove trace amounts of water vapor and volatiles generated during the extrusion process. After each temperature zone reached the set temperature and stabilized for 15 minutes, the feeding operation began.

[0079] Step 3.4: Feeding the main hopper and melting the matrix

[0080] Add 7000g of dried polycarbonate resin and 3000g of acrylonitrile-butadiene-styrene resin to the main hopper of the extruder in one go, along with 20g of hindered phenolic antioxidant 1010, 15g of phosphite antioxidant 168, and 20g of zinc stearate lubricant; start the screw and control the feeding speed to 5-8kg / h, so that the materials gradually melt and are initially mixed in zones 1-3 of the barrel;

[0081] Step 3.5: Subsequent feeding, extrusion, and granulation

[0082] After the main hopper has been running stably for 5 minutes, 40g of aminated styrene-acrylonitrile copolymer is added in zone 4 of the barrel; 20g of multifunctional epoxy chain extender is added in zone 5 of the barrel; 30g of internal salt / long-chain double-grafted silsesquioxane is added in zone 6 of the barrel; the remaining 30g of aminated styrene-acrylonitrile copolymer is added in zone 7 of the barrel; and the remaining 40g of multifunctional epoxy chain extender is added in zone 8 of the barrel. The melt is extruded through the die head to form a continuous strip, which immediately enters the water cooling tank (water temperature controlled at 15-25°C). The strip stays in the water tank for 12 seconds to rapidly cool it to below room temperature and solidify it. After cooling and solidification, the strip is dried by air knife and then cut by pelletizer and dried with hot air to obtain PC / ABS plastic alloy. Example 3

[0083] Step 1: Preparation of amination-modified styrene-acrylonitrile copolymer

[0084] In a 2L four-necked flask with a condenser, 500mL of anhydrous N,N-dimethylformamide was added, and the mixture was heated to 65°C under nitrogen protection. 690g of styrene, 300g of acrylonitrile, and 13g of 4-vinylbenzyl chloride were added, and the mixture was magnetically stirred. 1.8g of azobisisobutyronitrile was added, and the mixture was kept at 65°C for 14h. The temperature was lowered to 40°C, and 100g of piperidine and 140g of triethylamine were added. The mixture was reacted at 50°C for 7h to complete the benzyl chloride substitution. The solvent was removed by vacuum evaporation, and the mixture was reprecipitated with acetone and dried under vacuum at 60°C for 12h to obtain the amination styrene-acrylonitrile copolymer.

[0085] Step 2: Preparation of internal salt / long-chain double-grafted silsesquioxanes

[0086] In 1 L of anhydrous dimethylformamide, 50 g of octa(3-aminopropyl)silsesquioxane salt and 140 g of triethylamine were added, and the mixture was stirred at room temperature for 1 h to neutralize. 70 g of 1,3-propanesulfonyl lactone was slowly added, and the reaction was carried out at 35°C for 8-10 h. The temperature was lowered to 25°C, and 12 g of octadecanoyl chloride and 60 g of triethylamine were added dropwise. The temperature was controlled at 0-5°C for 2 h, and the reaction was continued at 25°C for 3 h. The mixture was filtered to remove salt, precipitated with diethyl ether, and dried under vacuum at 50°C for 12 h to obtain an inner salt / long-chain double-grafted silsesquioxane.

[0087] Step 3: Polycarbonate / acrylonitrile-butadiene-styrene alloy extrusion granulation

[0088] Step 3.1: Formula Weighing and Preparation

[0089] Based on a total resin quantity of 10,000g, the following ingredients were weighed: 7,000g of polycarbonate resin (Covestro Makrolon 2607) and 3,000g of acrylonitrile-butadiene-styrene resin (Chimei POLYLAC PA-757); 100g of aminated styrene-acrylonitrile copolymer, 40g of internal salt / long-chain double-grafted silsesquioxane, 80g of multifunctional epoxy chain extender, 25g of hindered phenolic antioxidant 1010, 20g of phosphite antioxidant 168, and 25g of zinc stearate lubricant were weighed separately.

[0090] Step 3.2: Raw material drying treatment

[0091] 7000g of polycarbonate resin was dried at 125°C for 5 hours; 3000g of acrylonitrile-butadiene-styrene resin was dried at 85°C for 3 hours; and the additives were dried at 65°C under a vacuum of -0.06MPa for 3 hours.

[0092] Step 3.3: Extrusion Equipment Preparation and Temperature Zone Setting

[0093] Co-rotating parallel twin-screw extruder, L / D ratio 40, main screw speed 350 rpm; heating zone temperatures: Zone 1 215°C, Zone 2 235°C, Zone 3 245°C, Zone 4 250°C, Zones 5-6 255°C, Zone 7 250°C, Zone 8 245°C, die head temperature 250°C; vacuum exhaust (vacuum degree -0.07MPa); feed material after temperature stabilization for 18 minutes.

[0094] Step 3.4: Feeding the main hopper and melting the matrix

[0095] Add 7000g of polycarbonate resin and 3000g of acrylonitrile-butadiene-styrene resin at one time, along with 25g of hindered phenolic antioxidant 1010, 20g of phosphite antioxidant 168 and 25g of zinc stearate; start the screw and feed at a rate of 6-9kg / h to allow the materials to gradually melt and initially mix in zones 1-3;

[0096] Step 3.5: Subsequent feeding, extrusion, and granulation

[0097] After the main hopper has been running stably for 5 minutes, 60g of aminated styrene-acrylonitrile copolymer is added in zone 4; 25g of multifunctional epoxy chain extender is added in zone 5; 40g of internal salt / long-chain double-grafted silsesquioxane is added in zone 6; the remaining 40g of aminated styrene-acrylonitrile copolymer is added in zone 7; and the remaining 55g of multifunctional epoxy chain extender is added in zone 8. After the material strip is extruded through the die head, it enters the water cooling tank (water temperature controlled at 18-24°C) and stays for 15 seconds. After being dried by the air knife, it is pelletized and dried to obtain PC / ABS plastic alloy.

[0098] Comparative Example 1:

[0099] The difference between Comparative Example 1 and Example 2 is that 4-vinylbenzyl chloride is not added in step one, and styrene-acrylonitrile copolymer is synthesized directly, replacing the aminated styrene-acrylonitrile copolymer, while the other conditions are the same as in Example 2.

[0100] Comparative Example 2:

[0101] The difference between Comparative Example 2 and Example 2 is that no internal salt / long-chain double-grafted silsesquioxane was added, while the other conditions were the same as in Example 2.

[0102] Comparative Example 3:

[0103] The difference between Comparative Example 3 and Example 2 is that octadecanoyl chloride was replaced with an equimolar amount of 1,3-propanesulfonyl lactone, while the other conditions were the same as in Example 2.

[0104] Comparative Example 4:

[0105] The difference between Comparative Example 4 and Example 2 is that 1,3-propanesulfonyl lactone was replaced with an equimolar amount of octadecanoyl chloride, while the other conditions were the same as in Example 2.

[0106] Comparative Example 5:

[0107] The difference between Comparative Example 5 and Example 2 is that 60g of the multifunctional epoxy chain extender was added all at once in zone 5 of the barrel, and not added a second time in zone 8. The other conditions were the same as in Example 2.

[0108] Comparative Example 6:

[0109] The difference between Comparative Example 6 and Example 2 is that 70g of the amination styrene-acrylonitrile copolymer was added all at once in zone 4 of the barrel, and not added a second time in zone 7. The other conditions were the same as in Example 2.

[0110] Comparative Example 7:

[0111] The difference between Comparative Example 7 and Example 2 is that 30 g of internal salt / long-chain double-grafted silsesquioxane was added in zone 4 of the barrel instead of zone 6, while the other conditions were the same as in Example 2.

[0112] Performance testing:

[0113] Test sample preparation: Standard samples of each formulation were formed on the same injection molding machine: the temperatures of the four sections of the barrel and the nozzle were 260℃, 270℃, 275℃, 280℃ and 280℃ respectively; the screw speed was 60r / min; the mold temperature was 85℃; the injection pressure was 120MPa; the holding pressure was 70MPa and the holding time was 8s; the cooling time was 20s; 5 samples were taken for each item and conditioned for 48h at 23℃ and 50% relative humidity before testing.

[0114] Infrared spectroscopy characterization: Fourier transform infrared spectrometer, KBr pellet, 4000-400 cm⁻¹ -1 .

[0115] Thermogravimetric analysis: A thermogravimetric analyzer was used with a nitrogen flow rate of 60 mL / min, at a temperature of 30-800℃, and a flow rate of 10℃ / min to record the 5% weight loss temperature T. 5% The residual rate at 800℃ is shown in Table 1.

[0116] Tensile properties: Referring to GB / T 1040.2-2022, type 1A injection molded specimens were tested at a speed of 50 mm / min to obtain tensile strength and elongation at break. The results are shown in Table 1.

[0117] Bending properties: Referring to GB / T 9341-2008, with a span of 64 mm, a speed of 2 mm / min, and 80×10×4 mm specimens, the bending modulus was obtained, and the results are shown in Table 1.

[0118] Cantilever beam notched impact: Referring to GB / T 1843-2008, the impact strength was obtained by testing at 23℃ with a V-notch, and the results are shown in Table 1.

[0119] Impact retention rate after damp heat aging: Referring to GB / T 2423.3-2016, the impact strength was retested after 240 hours at 85℃ and 85%RH. The impact retention rate after damp heat aging was calculated, and the results are shown in Table 1.

[0120] Table 1 Performance Test Results

[0121] sample <![CDATA[T 5% / ℃]]> Residual rate at 800℃ / % Tensile strength / MPa Elongation at break / % Flexural modulus / MPa <![CDATA[Impact strength / kJ·m -2 > Impact retention rate / % Example 1 432 13.6 56 96.8 2440 53.5 89.4 Example 2 438 15.2 60 105.4 2500 58.0 93.6 Example 3 444 16.8 58 88.7 2570 55.2 91.5 Comparative Example 1 430 12.9 52 80.5 2360 44.8 78.9 Comparative Example 2 431 12.6 54 90.2 2400 50.1 80.4 Comparative Example 3 436 15.0 53 84.1 2420 48.6 68.5 Comparative Example 4 428 12.1 51 76.3 2460 42.3 83.2 Comparative Example 5 434 13.3 54 85.7 2410 49.0 81.8 Comparative Example 6 435 13.8 53 82.6 2390 51.2 80.8 Comparative Example 7 441 15.6 55 79.4 2560 47.1 81.2

[0122] Data Analysis:

[0123] As can be seen from the data of Examples 1-3 in Table 1, the samples of the present invention achieve a stable comprehensive balance between room temperature impact, tension, and bending, while maintaining high toughness and structural integrity after damp heat cycling. The initial thermogravimetric loss and high-temperature residual are also superior to those of the unmodified conventional system. This trend stems from the reactive anchoring at the interface combined with the polarity / hydrophobicity dual regulation of the internal salt / long-chain double-grafted polyhedral silsesquioxane, which reduces the fluctuation of dispersed phase size and interfacial free energy. The stepwise introduction of the chain extender completes chain extension and cross-linking spot welding in the initial mixing and later stages, respectively, thereby taking into account both melt strength and interfacial damp heat resistance. The nano-siloxane cage core further promotes carbonization and weakens the thermal cracking channel, thus synergistically improving thermal stability and post-aging impact.

[0124] As can be seen from the data in Table 1 for Example 2 and Comparative Example 1, the initial impact and damp heat retention rates decreased when the amination styrene-acrylonitrile compatibilizer was absent. The main reason for this is the lack of reactive transesterification / hydrogen bonding with polycarbonate, resulting in higher interfacial tension and easier phase growth; aging leads to interfacial debonding, weakening the energy dissipation mechanism. The introduction of the compatibilizer can generate styrene-acrylonitrile copolymer-grafted polycarbonate copolymer in situ at the interface, significantly stabilizing the morphology.

[0125] As can be seen from the data in Example 2 and Comparative Example 2 in Table 1, the removal of the double-grafted silsesquioxane reduced thermal stability and char residue, and worsened the wet heat retention rate. This is because the lack of the siloxane cage core promotes char formation and surface passivation, making it easier for water molecules to migrate along the interface; at the same time, the thermal shielding effect of the inorganic core disappears, making degradation more likely to occur.

[0126] As can be seen from the data in Table 1 for Example 2 and Comparative Example 3, when only the internal salt is introduced without the long-chain hydrophobic group, the wet heat retention rate is significantly lower and the impact rate drops; T5% shows a slight upward anomaly. This may be because the internal salt increases polarity and hygroscopicity, and interfacial hydration leads to microcracks; however, the ionic groups promote densification and charring at elevated temperatures, causing a slight shift of the low-weight-loss segment towards the high-temperature side, demonstrating an explainable anomaly. This indicates a significant synergistic effect between the internal salt and the long-chain double grafting.

[0127] As can be seen from the data in Example 2 and Comparative Example 4 in Table 1, when only long chains are grafted without internal salt, the initial impact is significantly reduced while the wet heat retention rate is relatively acceptable. This is because long chains provide a hydrophobic barrier but cannot provide polarity matching and chemical anchoring, resulting in insufficient interfacial wetting and low load transfer efficiency, leading to insufficient toughness; the addition of internal salt can restore interfacial compatibility and energy dissipation.

[0128] As can be seen from the data in Table 1 for Example 2 and Comparative Example 5, when the chain extender is added all at once in the pre-process, the overall mechanical and hydrothermal retention rates decrease. This is because only the front-end chain extends, while the rear-end lacks post-curing and multi-site coupling. The shear-diffusion during the extrusion process causes the phase size to increase again, resulting in insufficient interfacial network. Stepwise addition can achieve a coupling effect of 1+1>2.

[0129] As can be seen from the data in Table 1 for Example 2 and Comparative Example 6, the impact and retention rates of the compatibilizer added all at once are lower than those added in stages. The mechanism is that the initial compatibilizer layer is easily partially destroyed in the subsequent high shear and volatilization degassing stages, resulting in insufficient interface regeneration; secondary replenishment can replenish the interface after dispersion stabilization, inhibiting debinding and phase co-agglomeration after aging.

[0130] As can be seen from the data in Example 2 and Comparative Example 7 in Table 1, when the internal salt / long-chain double-grafted silsesquioxane was added from Zone 6 to Zone 4, the initial thermal stability of the material was slightly improved, but the impact strength and wet heat retention rate decreased significantly. This is because the early addition causes the silsesquioxane to aggregate in the high-shear section, easily forming local inorganic enrichment zones, resulting in uneven interface distribution and insufficient formation of the compatibility layer. Although some silsesquioxane cores can promote carbonization in the early melting stage and improve the high-temperature residual rate, the interface is not fully coated with the polycarbonate phase, resulting in a significant loss of toughness. Therefore, controlling the addition of the internal salt / long-chain double-grafted silsesquioxane to the later part of Zone 6 can balance the dispersion of inorganic cores and the interface anchoring effect, significantly improving the balance between thermal stability and impact toughness, and achieving a synergistic enhancement effect.

[0131] from Figure 2 It can be seen that the sample is at 2242 cm⁻¹ -1 Strong -C≡N absorption was observed at 1205-1160 cm⁻¹. -1 It exhibits a wide CN stretch envelope, while measuring 1601 / 1495cm. -1 Aromatic ring skeleton, 758 / 698cm -1 Out-of-plane curvature and 2925 / 2850cm -1 The presence of CH in the fatty acid indicates the formation of the piperidine amination structure.

[0132] from Figure 3 It can be seen that the sample is at 1110cm -1 A broad and strong Si-O-Si band appears at 1040 cm⁻¹. -1 -SO3⁻ symmetrical stretching and stacking, 1195cm -1 The given is an antisymmetric stretching peak of -SO⁻, 1648 / 1545 cm⁻. -1 The corresponding amide I / II indicates the successful introduction of long-chain amides, 2956 / 2922 / 2852 cm⁻¹ -1 For the stretching of the adipose chain CH, 960cm-1 Quaternary ammonium CN appears + Characteristic absorption and 3300-3500cm -1 No sharp peak of free -NH2 was observed, only a broad peak caused by water, which, based on comprehensive analysis, is consistent with the target structure of "internal salt / long-chain double-grafted silsesquioxane".

[0133] from Figure 4 It can be seen that each sample exhibits bimodal decomposition. In Example 2, the two main peaks are approximately 460℃ and 557℃, which are shifted to the right compared to 450-455℃ and 547-552℃ in Comparative Examples 1, 2, and 4. Comparative Examples 3, 5, and 6 are similar to Example 2, but the first peak is slightly forward. In Comparative Example 7, the two peaks are approximately 460℃ and 560℃, with the second peak position being higher, but the first peak shape is narrower, indicating that the early pyrolysis channel was not sufficiently suppressed. In Example 2, the valley between the two peaks is raised and the high-temperature side peaks are more concentrated, indicating that the degradation rate in the intermediate temperature range is suppressed and continuous pyrolysis is delayed. This is due to the synergistic effect of stepwise chain extension and internal salt / long-chain double-grafted silsesquioxane, which can inhibit the premature pyrolysis of the ABS phase and promote carbonization, causing the weight loss rate peak position to shift to the right, the peak width to narrow, and the high-temperature stability to be improved.

[0134] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for preparing a PC / ABS plastic alloy, characterized in that, Includes the following steps: Step 1: Preparation of amination-modified styrene-acrylonitrile copolymer Styrene, acrylonitrile, 4-vinylbenzyl chloride, and azobisisobutyronitrile were added to anhydrous N,N-dimethylformamide under nitrogen protection and reacted at 60-70°C for 8-15 h to obtain a styrene-acrylonitrile copolymer solution containing benzyl chloride side groups. After cooling, piperidine and triethylamine were added and reacted at 40-55°C for 4-8 h to complete benzyl chloride substitution. After solvent removal, reprecipitation, and vacuum drying, the amination styrene-acrylonitrile copolymer was obtained. Step 2: Preparation of internal salt / long-chain double-grafted silsesquioxanes In anhydrous dimethylformamide, octa(3-aminopropyl)silsesquioxane salt and triethylamine were added and stirred for 0.5-2 h; 1,3-propanesulfonyl lactone was added and reacted at 30-40 °C for 6-12 h; after cooling, octadecanoyl chloride and triethylamine were added and reacted at 0-10 °C for 1-3 h, followed by reaction at 20-30 °C for 2-5 h; after filtration to remove salt, precipitation and vacuum drying, inner salt / long-chain double-grafted silsesquioxane was obtained. Step 3: Polycarbonate / acrylonitrile-butadiene-styrene alloy extrusion granulation S1: By weight, weigh 60-80 parts of polycarbonate, 20-40 parts of acrylonitrile-butadiene-styrene resin, 0.5-1.2 parts of amination styrene-acrylonitrile copolymer, 0.2-0.5 parts of internal salt / long-chain double-grafted silsesquioxane, 0.4-1.0 parts of polyfunctional epoxy chain extender, 0.15-0.30 parts of hindered phenolic antioxidant, 0.10-0.25 parts of phosphite antioxidant, and 0.15-0.30 parts of zinc stearate. S2: The polycarbonate, acrylonitrile-butadiene-styrene resin and each additive are dried separately; S3: Extrusion granulation is performed using a twin-screw extruder. The temperatures of each heating zone are set as follows: Zone 1: 200-220℃, Zone 2: 220-240℃, Zone 3: 230-250℃, Zone 4: 235-255℃, Zones 5-6: 240-260℃, Zone 7: 235-255℃, Zone 8: 230-250℃, and the die head temperature is 235-255℃. S4: Add dried polycarbonate resin, acrylonitrile-butadiene-styrene resin, hindered phenolic antioxidant, phosphite antioxidant and zinc stearate to the main hopper; S5: Add 30%-60% of the aminated styrene-acrylonitrile copolymer in zone 4 of the barrel, add 25%-40% of the multifunctional epoxy chain extender in zone 5 of the barrel, add all the internal salt / long-chain double-grafted silsesquioxane in zone 6 of the barrel, add the remaining aminated styrene-acrylonitrile copolymer in zone 7 of the barrel, and add the remaining multifunctional epoxy chain extender in zone 8 of the barrel; S6: PC / ABS plastic alloy is obtained after extrusion, cooling, pelletizing and drying.

2. The method for preparing PC / ABS plastic alloy according to claim 1, characterized in that, In step one, the mass ratio of styrene, acrylonitrile, 4-vinylbenzyl chloride, piperidine, and triethylamine is 690:300:7-13:60-100:100-140.

3. The method for preparing the PC / ABS plastic alloy according to claim 1, characterized in that, In step two, the mass ratio of octa(3-aminopropyl)sesquioxane salt, 1,3-propanesulfonyl lactone, octadecanoyl chloride and triethylamine is 50:50-70:8-12:140-200.

4. The method for preparing the PC / ABS plastic alloy according to claim 1, characterized in that, The multifunctional epoxy chain extender mentioned in S1 is BASF Joncryl ADR-4468.

5. The method for preparing PC / ABS plastic alloy according to claim 1, characterized in that, In S3, the twin-screw extruder is a co-rotating parallel twin-screw extruder with a screw length-to-diameter ratio (L / D) of 36-44 and a screw speed of 200-400 rpm.

6. The method for preparing PC / ABS plastic alloy according to claim 1, characterized in that, In step S3, material feeding begins after each temperature zone reaches the set temperature and stabilizes for 10-20 minutes.

7. The method for preparing the PC / ABS plastic alloy according to claim 1, characterized in that, In step three, 40%-60% of the aminated styrene-acrylonitrile copolymer is added to zone 4 of the barrel, 25%-35% of the multifunctional epoxy chain extender is added to zone 5 of the barrel, 40%-60% of the aminated styrene-acrylonitrile copolymer is added to zone 7 of the barrel, and 65%-75% of the multifunctional epoxy chain extender is added to zone 8 of the barrel.

8. The method for preparing PC / ABS plastic alloy according to claim 1, characterized in that, In step S6, after extrusion, the material enters a water cooling tank for cooling. The water temperature is 10-30℃, and the residence time is 8-18s.

9. The application of a PC / ABS plastic alloy in automotive interiors, electronic and electrical housings, or office equipment, wherein the PC / ABS plastic alloy is obtained by the preparation method of the PC / ABS plastic alloy according to any one of claims 1-8.

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