High flow halogen-free flame-retardant pc / abs material and its preparation method

Abstract

This invention provides a high-flowability halogen-free flame-retardant PC / ABS material and its preparation method, relating to the field of polymer composite materials technology. The high-flowability halogen-free flame-retardant PC / ABS material comprises the following raw materials in parts by weight: polycarbonate resin: 40-70 parts, acrylonitrile-butadiene-styrene copolymer resin: 15-40 parts, halogen-free organophosphorus flame retardant: 8-18 parts, polymer interface modifier: 4-12 parts, core-shell toughening agent: 2-8 parts, and additives: 0.5-3 parts. The high-flowability halogen-free flame-retardant PC / ABS material provided by this invention exhibits synergistic effects among its various raw materials, resulting in a PC / ABS material with high flowability, excellent flame-retardant properties, and mechanical properties, suitable for ultra-thin-walled electronic and electrical appliance housing components.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, and in particular to a high-flowability halogen-free flame-retardant PC / ABS material and its preparation method. Background Technology

[0002] Polycarbonate (PC) and acrylonitrile-butadiene-styrene copolymer (ABS) alloys (PC / ABS) have become one of the mainstream engineering plastics for electronic and electrical device housings due to their excellent comprehensive properties, such as high impact strength, good heat resistance, dimensional stability, and ease of processing and molding. As consumer electronics products, especially televisions, monitors, and laptops, continue to develop towards thinner, lighter, larger screens and more aesthetically pleasing designs, the wall thickness design of their structural components (such as back covers and frames) is constantly pushing the limits, currently generally requiring thicknesses of 0.8 mm or even thinner. This extreme trend towards thinner walls places unprecedented demands on the melt flow properties of the material to ensure perfect filling of complex and delicate cavities during injection molding, avoiding defects such as short runs and weld lines.

[0003] Flame retardancy is a core indicator of the safety of electronic and electrical materials. With increasingly stringent global environmental regulations (such as RoHS and REACH) and the growing popularity of green consumption concepts, halogen-free flame retardancy has become a mandatory requirement. In PC / ABS systems, organophosphorus flame retardants, especially bisphenol A bis(diphenyl phosphate) (BDP), have become one of the mainstream choices for achieving halogen-free flame retardancy due to their good compatibility with the PC / ABS matrix, high flame retardant efficiency, and minimal impact on material transparency.

[0004] However, applying existing commercially available BDP flame-retardant PC / ABS materials to ultra-thin-wall (≤1.6 mm) products faces a series of prominent technical contradictions and challenges: First, to achieve stringent thin-wall flame-retardant requirements (such as UL94 V-0 rating), a high BDP addition is often required, which typically significantly reduces and impairs the material's mechanical properties, directly conflicting with the high rigidity requirements of thin-walled parts. Second, as a small-molecule additive, BDP may pose a certain risk of thermal volatilization or migration during high-shear, high-temperature processing, potentially affecting the production environment and, in long-term use, potentially affecting the surface appearance and flame-retardant durability of the parts due to precipitation. Furthermore, formulation adjustments to improve flowability, such as increasing the ABS ratio or adding flow promoters, may come at the cost of sacrificing the material's heat resistance, rigidity, and impact strength. In addition, under extremely thin-walled conditions, the material's specific surface area increases, making heat accumulation more likely, placing more stringent demands on the efficiency and stability of the flame-retardant system. Ordinary BDP flame-retardant formulations often struggle to stably achieve high flame-retardant ratings at such thin dimensions.

[0005] Currently, the market for high-end PC / ABS composite materials that simultaneously meet the requirements of "ultra-high fluidity," "reliable V-0 flame retardancy at extremely thin wall thicknesses," and "good balance of mechanical properties" is mainly monopolized by a few international chemical companies. Although domestically produced similar materials have made breakthroughs in applications with conventional wall thicknesses, there is still a significant gap in the synergistic improvement of the aforementioned extreme performance characteristics. This leads to downstream high-end electronics manufacturing companies being heavily reliant on imports and facing the dual pressures of high costs and supply chain security. Summary of the Invention

[0006] Based on the technical problems existing in the background technology, this invention proposes a high-flowability halogen-free flame-retardant PC / ABS material and its preparation method. This material has ultra-high flowability, excellent thin-wall flame-retardant reliability, superior comprehensive mechanical properties and good processing thermal stability, which is of great practical significance for promoting the independent control and technological progress of my country's high-end electronic and electrical appliance industry chain.

[0007] The present invention proposes a high-flowability halogen-free flame-retardant PC / ABS material, comprising the following raw materials in parts by weight: polycarbonate resin: 40-70 parts, acrylonitrile-butadiene-styrene copolymer resin: 15-40 parts, halogen-free organophosphorus flame retardant: 8-18 parts, polymer interface modifier: 4-12 parts, core-shell toughening agent: 2-8 parts, and additives: 0.5-3 parts.

[0008] Preferably, the polycarbonate resin has a weight-average molecular weight of 18,000-25,000, and the polycarbonate resin has a melt flow rate of not less than 20 g / 10 min at 300°C and 1.2 kg.

[0009] Preferably, the rubber phase content in the acrylonitrile-butadiene-styrene copolymer resin is 10%-20% by weight, and the melt flow rate of the acrylonitrile-butadiene-styrene copolymer resin at 220℃ / 10kg is not less than 30g / 10min.

[0010] Preferably, the halogen-free organophosphorus flame retardant is selected from one or more of bisphenol A-bis(diphenyl phosphate), resorcinol bisphosphate, and aluminum diethylphosphonate.

[0011] More preferably, the phosphorus content of the bisphenol A bis(diphenyl phosphate) is 8.5 wt%-9.0 wt%, and the thermal weight loss rate of the bisphenol A bis(diphenyl phosphate) at 260°C is not greater than 5 wt%.

[0012] Preferably, the polymeric interface modifier includes methyl methacrylate-butadiene-styrene copolymer and acrylate polymer, wherein the weight-average molecular weight of the acrylate polymer is 5000-30000; and the mass ratio of the methyl methacrylate-butadiene-styrene copolymer to the acrylate polymer is (30-40):(30-60).

[0013] More preferably, the methyl methacrylate-butadiene-styrene copolymer has a weight-average molecular weight of 5,000-30,000, and the melt flow rate of the methyl methacrylate-butadiene-styrene copolymer at 260°C / 2.16kg is not less than 40g / 10min.

[0014] More preferably, the mass ratio of the rubber phase in the methyl methacrylate-butadiene-styrene copolymer to the acrylonitrile-butadiene-styrene copolymer resin is (0.1-0.3):1.

[0015] Preferably, the core-shell toughening agent is a core-shell structured polymer with cross-linked butyl acrylate rubber as the core and polymethyl methacrylate as the shell, and its average particle size is 100-300 nm.

[0016] Preferably, the additive is selected from one or more of antioxidants, light stabilizers, lubricants, and anti-dripping agents. The antioxidant includes a primary antioxidant and a secondary antioxidant. The primary antioxidant is a hindered phenolic compound, and the secondary antioxidant is a phosphite compound or a thioester compound. The mass ratio of the primary antioxidant to the secondary antioxidant is 1:(1-2).

[0017] This invention also proposes a method for preparing a high-flowability halogen-free flame-retardant PC / ABS material, comprising the following steps: mixing polycarbonate resin, acrylonitrile-butadiene-styrene copolymer resin, halogen-free organophosphorus flame retardant, core-shell toughening agent, and additives uniformly to obtain a premix; extruding, granulating, and drying the premix to obtain a high-flowability halogen-free flame-retardant PC / ABS material.

[0018] Preferably, the extrusion temperature is 210-250°C.

[0019] Preferably, the extrusion equipment is a co-rotating twin-screw extruder with a screw speed of 300-500 rpm and a vacuum degree of not less than -0.08 MPa at the vacuum exhaust port; the screw assembly of the co-rotating twin-screw extruder is configured with at least 3 kneading block zones and 2 reverse screw element zones to provide strong shear and thorough mixing; the melt passes through the vacuum exhaust port for not less than 5 seconds.

[0020] Preferably, the drying temperature is 90-110℃, and the moisture content after drying is less than 0.02%.

[0021] Application of the above-mentioned high-flowability halogen-free flame-retardant PC / ABS material or the high-flowability halogen-free flame-retardant PC / ABS material prepared by the above-mentioned method in ultra-thin-walled electronic and electrical enclosure components.

[0022] Preferably, the ultra-thin wall electronic appliance housing component is manufactured by injection molding process, and the ultra-thin wall electronic appliance housing component has a thin wall area with a thickness of no more than 0.8 mm in at least one location, and the maximum thickness of the component does not exceed 1.6 mm.

[0023] Preferably, the ultra-thin wall electronic appliance housing component can be the back cover of an LCD TV or monitor, and the thickness of the thin-walled region is 0.8-1.6 mm.

[0024] The beneficial effects of this invention are as follows:

[0025] This invention aims to overcome the technical bottlenecks faced by existing BDP-flame-retardant PC / ABS materials in pursuing high flame retardancy in thin-walled applications, including decreased fluidity, impaired mechanical properties, easy migration of flame retardants, and insufficient reliability in thin-walled flame retardancy. The core of this invention lies in constructing an innovative system with multi-component, multi-scale synergistic effects, achieving systematic innovation at the molecular design, interface engineering, and processing technology levels. This provides a composite material and its preparation method that can achieve extremely high melt flow rates while maintaining excellent mechanical properties and thermal stability, and ensure stable and reliable flame retardant performance at wall thicknesses of 0.8 mm and below. The high-fluidity halogen-free flame-retardant PC / ABS material provided by this invention exhibits synergistic effects among its various raw materials, resulting in a PC / ABS material with high fluidity and excellent flame retardant and mechanical properties, suitable for ultra-thin-walled electronic and electrical enclosure components.

[0026] Innovation and Performance Enhancement of the Flame Retardant System: Using BDP as the core halogen-free flame retardant, and through precise control of the molecular weight of PC resin, the content of ABS rubber, and the polymer interface modifier, the dispersion and compatibility of BDP in the matrix are synergistically optimized, effectively inhibiting its migration and volatilization. Combined with different types of antioxidants, the thermal stability and flame retardant durability of the material during long-term use and repeated processing are significantly improved. Thus, with a relatively optimized addition amount, stable V-0 flame retardancy is achieved for the material under ultra-thin wall conditions of ≤0.8 mm.

[0027] Flow-Toughness-Rigidity Synergistic Regulation Technology: By introducing specific low molecular weight acrylate polymers as highly efficient flow promoters and combining them with MBS and core-shell toughening agents, a unique dual-functional system of "shear thinning" and "interfacial buffering" is constructed. By controlling the ratio of PC and ABS and introducing specific core-shell toughening agents, the material achieves high fluidity while maintaining a good balance between rigidity and toughness. This system significantly reduces melt viscosity during processing, imparting ultra-high fluidity (MFR ≥ 35 g / 10min), while simultaneously ensuring excellent impact strength (≥ 24 kJ / m²) even with ultra-high fluidity through enhanced interfacial bonding and energy dissipation mechanisms. 2 (and sufficient rigidity).

[0028] Process stability assurance: By optimizing the screw combination and process parameters of the twin-screw extruder (mild shearing and efficient devolatilization), the molecular structure integrity of the polymer is maintained to the greatest extent while ensuring sufficient dispersion of BDP and other components and avoiding degradation. This ensures the uniformity and repeatability of the final material properties. The optimized formulation system and process conditions ensure that the material has a wide processing window during injection molding, effectively reducing defects such as silver streaks and scorching.

[0029] Environmental and economic benefits: The raw materials of this invention are completely halogen-free, complying with international environmental regulations. The PC / ABS material developed by this invention can successfully replace imported high-end materials, reducing costs for downstream electronics manufacturing companies and ensuring supply chain security.

[0030] Through the synergistic implementation of the above technical solutions, this invention successfully solves the industry problem of simultaneously achieving ultra-high fluidity, ultra-thin walls with high flame retardancy, good mechanical properties, and processing stability. Detailed Implementation

[0031] The technical solution of the present invention will be described in detail through specific embodiments.

[0032] In the following examples and comparative examples, the specific information regarding the raw materials used is as follows:

[0033] Polycarbonate resin: Teijin PC 1225L, melt flow rate 20g / 10min.

[0034] Acrylonitrile-butadiene-styrene copolymer resin: ABS LG HP181, melt flow rate 40 g / 10 min.

[0035] Halogen-free organophosphorus flame retardant: Jiangsu Yake Technology Co., Ltd., brand name: BDP.

[0036] Polymer interface modifier: Mitsubishi, brand name: S-2001.

[0037] Core-shell toughening agent: Jia Yi Rong, brand name: SBG-001.

[0038] Anti-dripping agent: PTFE, Shanghai Puxin Polymer Materials Co., Ltd., grade: DB105.

[0039] Lubricant: Italian brand Fagi, brand name: PETS-HS.

[0040] Antioxidant 1076, Antioxidant 168: Tianjin Lianlong.

[0041] Unless otherwise specified, all materials and reagents used in the following examples and comparative examples are commercially available.

[0042] Example 1

[0043] A high-flowability halogen-free flame-retardant PC / ABS material comprises the following raw materials in parts by weight: polycarbonate resin: 60 parts, acrylonitrile-butadiene-styrene copolymer resin: 20 parts, halogen-free organophosphorus flame retardant: 12 parts, polymer interface modifier: 4 parts, core-shell toughening agent: 2 parts, and additives: 1.8 parts, wherein the additives include antioxidant 0.3 parts, anti-dripping agent 1 part, and lubricant 0.5 parts; the antioxidant is composed of antioxidant 1076 and antioxidant 168 in a mass ratio of 1:2.

[0044] A method for preparing a high-flowability halogen-free flame-retardant PC / ABS material includes the following steps: adding polycarbonate resin, acrylonitrile-butadiene-styrene copolymer resin, halogen-free organophosphorus flame retardant, core-shell toughening agent, and additives to a high-speed mixer and mixing at 130 rpm at room temperature for 10 minutes until homogeneous to obtain a premix; adding the premix to a co-rotating twin-screw extruder through the main feed port, and subjecting it to melting, mixing, shearing, and devolatilization under set process conditions, followed by water cooling and pelletizing to obtain composite material particles; wherein, the temperature of the first temperature zone of the twin-screw extruder is 220℃, the temperature of the second temperature zone is 235℃, the temperature of the third temperature zone is 245℃, the nozzle temperature is 250℃, the screw speed is 400 rpm, and the vacuum degree of the vacuum exhaust port is not lower than -0.08. MPa; the screw assembly of the twin-screw extruder is preferably configured with 3 kneading block zones and 2 anti-thread element zones; drying: the obtained particles are dried at 100°C for 4 hours to obtain high-flowability halogen-free flame-retardant PC / ABS material.

[0045] Example 2-3

[0046] The only difference between Examples 2-3 and Example 1 is the ratio of raw materials, as detailed in Table 1. The rest is the same as Example 1.

[0047] Comparative Example 1

[0048] Comparative Example 1 uses commercially available general-purpose halogen-free flame-retardant PC / ABS material (Covestro, Germany, FR3020, nominal 1.5mm V-0) as a comparison.

[0049] Comparative Example 2

[0050] The only difference between Comparative Example 2 and Example 1 is that the core-shell toughening agent was replaced with butyl acrylate rubber (Calvin Plastics Technology KA-408), and the rest was the same as Example 1.

[0051] Comparative Example 3

[0052] The only difference between Comparative Example 3 and Example 1 is that the core-shell toughening agent was replaced with polymethyl methacrylate (Mitsubishi Rayon IRH-70), and the rest was the same as Example 1.

[0053] Comparative Example 4

[0054] The only difference between Comparative Example 4 and Example 1 is that the polymer interface modifier was replaced with MBS (Kanebuchi M-722 from Japan), and the rest is the same as Example 1.

[0055] Comparative Example 5

[0056] The only difference between Comparative Example 5 and Example 1 is the ratio of raw materials, as detailed in Table 1. The rest is the same as Example 1.

[0057] Table 1

[0058]

[0059] The above PC / ABS materials were injection molded into standard test strips, and performance tests were conducted according to the corresponding international standards. The results are shown in Table 2.

[0060] Table 2

[0061]

[0062] As shown in Table 2, the PC / ABS material injection-molded samples provided by this invention meet the requirements of UL94 standard regarding V-0 flame retardancy rating. Their melt flow rate at 260℃ / 2.16kg is not less than 35g / 10min, tensile strength is not less than 50MPa, and cantilever beam notched impact strength is not less than 24 kJ / m². 2The PC / ABS materials prepared in Examples 1-3 of this invention exhibit significantly higher melt flow rates (MFR ≥ 35 g / 10 min) than the commercially available general-purpose material of Comparative Example 1 (20 g / 10 min), demonstrating ultra-high fluidity. Most importantly, all the materials in these examples passed the UL94 V-0 test at an extreme thin wall thickness of 0.8 mm, while Comparative Example 1 only achieved V-1 and produced droplets at the same thickness. This proves the outstanding advantage of this invention in terms of high flame retardancy and reliability in thin-walled applications. Furthermore, while maintaining high flame retardancy in thin walls, the materials of this invention show a more balanced mechanical properties (such as impact strength) and fluidity compared to the different toughening systems in Comparative Examples 2-4, achieving an excellent balance of overall performance. As can be seen from Comparative Example 5 and Example 1, although the PC / ABS material prepared in Comparative Example 5 has slightly higher impact strength, its fluidity performance is poor. This demonstrates that the PC / ABS material obtained by controlling the raw materials within a certain range in this invention has superior performance.

[0063] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-flowability halogen-free flame-retardant PC / ABS material, characterized in that, The raw materials include the following parts by weight: polycarbonate resin: 40-70 parts, acrylonitrile-butadiene-styrene copolymer resin: 15-40 parts, halogen-free organophosphorus flame retardant: 8-18 parts, polymer interface modifier: 4-12 parts, core-shell toughening agent: 2-8 parts, and additives: 0.5-3 parts.

2. The high-flowability halogen-free flame-retardant PC / ABS material according to claim 1, characterized in that, The polycarbonate resin has a weight-average molecular weight of 18,000-25,000, and the melt flow rate of the polycarbonate resin at 300°C and 1.2 kg is not less than 20 g / 10 min.

3. The high-flowability halogen-free flame-retardant PC / ABS material according to claim 1, characterized in that, The acrylonitrile-butadiene-styrene copolymer resin has a rubber phase content of 10%-20% by weight, and the melt flow rate of the acrylonitrile-butadiene-styrene copolymer resin at 220℃ / 10kg is not less than 30g / 10min.

4. The high-flowability halogen-free flame-retardant PC / ABS material according to claim 1, characterized in that, The halogen-free organophosphorus flame retardant is selected from one or more of bisphenol A-bis(diphenyl phosphate), resorcinol bisphosphate, and aluminum diethylphosphonate.

5. The high-flowability halogen-free flame-retardant PC / ABS material according to claim 1, characterized in that, The polymeric interface modifier includes methyl methacrylate-butadiene-styrene copolymer and acrylate polymers, wherein the weight-average molecular weight of the acrylate polymers is 5000-30000; the weight-average molecular weight of the methyl methacrylate-butadiene-styrene copolymer is 5000-30000, and the melt flow rate of the methyl methacrylate-butadiene-styrene copolymer at 260℃ / 2.16kg is not less than 40g / 10min.

6. The high-flowability halogen-free flame-retardant PC / ABS material according to claim 5, characterized in that, The mass ratio of the rubber phase in the methyl methacrylate-butadiene-styrene copolymer to the acrylonitrile-butadiene-styrene copolymer resin is (0.1-0.3):

1.

7. The high-flowability halogen-free flame-retardant PC / ABS material according to claim 1, characterized in that, The core-shell toughening agent is a core-shell structured polymer with cross-linked butyl acrylate rubber as the core and polymethyl methacrylate as the shell, and its average particle size is 100-300 nm.

8. The high-flowability halogen-free flame-retardant PC / ABS material according to claim 1, characterized in that, The additives are selected from one or more of antioxidants, light stabilizers, lubricants, and anti-dripping agents. The antioxidants include primary antioxidants and secondary antioxidants. The primary antioxidant is a hindered phenolic compound, and the secondary antioxidant is a phosphite compound or a thioester compound. The mass ratio of the primary antioxidant to the secondary antioxidant is 1:(1-2).

9. A method for preparing the high-flowability halogen-free flame-retardant PC / ABS material according to any one of claims 1-8, characterized in that, Includes the following steps: Polycarbonate resin, acrylonitrile-butadiene-styrene copolymer resin, halogen-free organophosphorus flame retardant, core-shell toughening agent, and additives are mixed evenly to obtain a premix; the premix is ​​then extruded, granulated, and dried to obtain a high-flowability halogen-free flame-retardant PC / ABS material.

10. The preparation method according to claim 9, characterized in that, The extrusion temperature is 210-250℃; the drying temperature is 90-110℃, and the moisture content after drying is less than 0.02%.

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