Filler interface distributed PC / ABS electromagnetic shielding composite material and preparation method thereof

Abstract

The invention discloses a PC / ABS electromagnetic shielding composite material with filler interface distribution and a preparation method of the PC / ABS electromagnetic shielding composite material, and belongs to the technical field of high polymer materials. The PC / ABS electromagnetic shielding composite material is prepared from the following components in parts by mass: 65 to 80 parts of polycarbonate resin, 20 to 35 parts of acrylonitrile-butadiene-styrene copolymer resin, 5 to 15 parts of styrene grafted maleic anhydride compatibilizer, 5 to 10 parts of flexibilizer, 2 to 5 parts of carbon-based conductive filler and 1 to 3 parts of antioxidant, the content of maleic anhydride in the styrene grafted maleic anhydride compatibilizer is 15%-20%. The processing sequence that ABS and the carbon-based conductive filler are subjected to melt blending to obtain an ABS prefabricated material, and then the ABS prefabricated material and other raw materials are subjected to melt blending is adopted, so that a compatibilizer and the carbon-based conductive filler are stably distributed at a PC / ABS phase interface, the mechanical property and the processing stability of the PC / ABS composite material are greatly improved, and the effects of low filler, high conductivity and high electromagnetic shielding are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials, and in particular relates to a PC / ABS electromagnetic shielding composite material with filler interface distribution and a preparation method thereof. Background Art

[0002] PC / ABS composite is a thermoplastic engineering plastic prepared by blending and modifying polycarbonate (PC) and acrylonitrile-butadiene-styrene terpolymer (ABS). Through molecular-level synergy, this material successfully combines the high mechanical strength, excellent impact resistance, and superior heat resistance of PC resin while retaining the excellent melt flowability and molding processing advantages of ABS resin. This two-component composite system has achieved large-scale application in a variety of fields, including electronic and electrical components, automotive industrial parts, 3D digital product housings, household appliances, and architectural structural components. Its balanced performance designability and cost-effectiveness demonstrate significant economic value and broad market prospects.

[0003] Industries such as electronics and electrical appliances have high toughness requirements for PC / ABS composite materials, so that products made of PC / ABS composite materials have good impact resistance, can withstand the impact of the external environment, and are strong and durable. At the same time, carbon-based conductive fillers or conductive filler grafted polymers can give PC / ABS good electrical conductivity and excellent electromagnetic shielding properties.

[0004] For example, patent publication CN118813020A discloses a PC / ABS composite material that combines antistatic properties with high toughness. The composite comprises the following components by weight: PC, 50-90 parts by weight; ABS, 5-20 parts by weight; antistatic liquid material, 0.5-20 parts by weight; antioxidant, 0.05-2 parts by weight; toughening agent, 1-20 parts by weight; and toughening compatibilizer material, 0.2-2 parts by weight. This selection of ingredients enables the PC / ABS composite to maintain its high toughness while also maintaining and improving its fluidity. However, the conductive effect is unsatisfactory, and the processing method is complex, making it difficult to control the specific distribution of the carbon-based filler during processing. Especially at high loadings of conductive fillers, the PC / ABS composite material exhibits poor mechanical properties, making it unsuitable for most applications.

[0005] And the conductive nanofiller (carbon black, graphene, carbon nanotube, etc.) is mixed into the incompatible polymer blend with a co-continuous structure, which is an effective way to reduce the percolation threshold of nanofiller. If the nanofiller is selectively distributed on one phase or interface of the incompatible polymer blend during processing, a percolation network structure is formed, which can significantly reduce the percolation threshold. There are usually three methods to promote the selective distribution on the polymer interface: first, prepare grafted nanoparticles, and control the grafting rate of the polymer on the surface of the nanoparticles to control the interfacial energy of the nanoparticles, but this method is too complex in processing, and the original performance of the carbon-based filler is easily damaged, which is difficult to industrialize; second, by strictly selecting the interfacial energy of the nanoparticles, this method only works for specific systems and is difficult to extend to other systems; the third, by dynamic regulation, this method is only suitable for specific production conditions, once the processing conditions change (such as temperature, shear rate, processing time, etc.), the carbon-based filler will migrate from the interface to a certain phase, resulting in performance failure. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application provides a filler interfacial distribution PC / ABS electromagnetic shielding composite material and a preparation method thereof. By selecting a specific compatibilizer and processing sequence, the carbon-based conductive filler is stably distributed at the phase interface of the PC / ABS electromagnetic shielding composite material. Without complex nanofiller graft modification and complex processing condition regulation, excellent mechanical properties, electrical conductivity and electromagnetic shielding performance can be achieved at a lower carbon-based filler filling.

[0007] The present application provides a filler interfacial distribution PC / ABS electromagnetic shielding composite material, which comprises, by mass fraction: polycarbonate resin 65-80 parts, acrylonitrile-butadiene-styrene copolymer resin 20-35 parts, styrene grafted maleic anhydride compatibilizer 5-15 parts, toughening agent 5-10 parts, carbon-based conductive filler 2-5 parts and antioxidant 1-3 parts. The styrene grafted maleic anhydride compatibilizer has a maleic anhydride content of 15%-20%.

[0008] The PC / ABS electromagnetic shielding composite material provided by the present invention uses a styrene-grafted maleic anhydride (SMA) compatibilizer. The maleic anhydride group in the SMA compatibilizer will undergo a ring-opening reaction with the terminal hydroxyl group of the polycarbonate resin (PC). The styrene chain segment at the other end has excellent compatibility with the styrene-acrylonitrile copolymer in the acrylonitrile-butadiene-styrene copolymer resin (ABS) and can be embedded in the ABS phase. Ultimately, the SMA compatibilizer is distributed at the PC / ABS interface, significantly reducing the interfacial tension, refining the dispersed phase size, enhancing the interfacial adhesion, and improving the overall compatibility and uniformity of the blend, which is then converted into higher impact strength (especially notched impact strength) and tensile strength. The SMA compatibilizer synergistically optimizes the electromagnetic shielding effectiveness with the toughening agent, carbon-based conductive filler and antioxidant, thereby improving the overall stability.

[0009] Selecting a styrene-grafted maleic anhydride compatibilizer with an appropriate maleic anhydride (MA) content provides a sufficiently high density of maleic anhydride-reactive groups to ensure effective chemical bonding with PC. This also maintains the good compatibility of the styrene segments in the SMA compatibilizer with ABS, enabling the SMA compatibilizer to effectively locate and act at the PC / ABS interface. Furthermore, the compatibilizer exhibits good thermal stability and dispersibility within the blend. Therefore, the maleic anhydride content of the styrene-grafted maleic anhydride compatibilizer of this invention is controlled within a range of 15%-20%.

[0010] Preferably, the weight average molecular weight of the polycarbonate resin is 1.0×10 4 ~3.0×10 4 .

[0011] The PC molecular chain ends have active hydroxyl groups (-OH), which are the reaction sites for maleic anhydride (MA) in SMA. PC segments with appropriate molecular weights have excellent mobility and are more likely to diffuse to the interface region in the melt. They then react with the MA groups of SMA to form a PC-g-SMA chemical bridge structure, strengthening the PC / ABS interfacial adhesion and forming a stable interface. This prevents filler accumulation defects at the interface and makes the conductive network more continuous. Therefore, the weight-average molecular weight of the polycarbonate resin of the present invention is 1.0×10 4 ~3.0×10 4 .

[0012] Preferably, the weight average molecular weight of the acrylonitrile-butadiene-styrene copolymer resin is 1.0×10 4 ~5.0×10 5 .

[0013] For ABS, the molecular weight of SAN phase (styrene-acrylonitrile) in ABS needs to be close to PC, which promotes the physical entanglement of the two phases and assists the compatibilization of SMA; and the weight average molecular weight in a suitable range can balance the flowability and mechanical properties, providing basic toughness support for the blended material, and ensuring the dispersibility and extrusion stability in the subsequent melt blending and extrusion process, significantly improving the tensile strength and impact toughness of the PC / ABS electromagnetic shielding composite material. Therefore, the weight average molecular weight of the acrylonitrile-butadiene-styrene copolymer resin in the present application is 1.0×10 4 ~5.0×10 5 .

[0014] Preferably, the weight average molecular weight of the styrene grafted maleic anhydride compatibilizer is 5.0×10 4 ~2.0×10 5 .

[0015] For SMA compatibilizer, the SMA molecular chain needs to have sufficient length, so that the terminal maleic anhydride (MA) group can deeply penetrate into the PC phase and fully contact and react (esterification) with the PC end group (-OH); and the weight average molecular weight in a suitable range can ensure that SMA quickly migrates to the interface in the melt and accurately locates at the interface, thereby improving the compatibilization reaction rate. Therefore, the weight average molecular weight of the styrene grafted maleic anhydride compatibilizer in the present application is 5.0×10 4 ~2.0×10 5 .

[0016] Preferably, the toughening agent comprises methyl methacrylate-butadiene-styrene resin.

[0017] Preferably, the carbon-based conductive filler is one or more of conductive carbon black, carbon nanotube, and graphene.

[0018] Preferably, the antioxidant is one or more of hindered phenol and phosphite.

[0019] Further preferably, the hindered phenol comprises octadecyl acrylate; The phosphite comprises one or more of triphosphite and dioctadecyl alcohol pentaerythritol diphosphite.

[0020] In another aspect, the present application also provides a preparation method of the PC / ABS electromagnetic shielding composite material, comprising the following steps: (1) According to the formula of the PC / ABS electromagnetic shielding composite material, the acrylonitrile-butadiene-styrene copolymer resin and the carbon-based conductive filler are melt blended to obtain an acrylonitrile-butadiene-styrene copolymer resin preform; (2) melt-blending acrylonitrile-butadiene-styrene copolymer resin preform, polycarbonate resin, styrene grafted maleic anhydride compatibilizer and toughening agent to obtain a flowable PC / ABS electromagnetic shielding composite material; (3) The PC / ABS electromagnetic shielding composite material in a fluid state is put into a twin-screw extruder for extrusion, and the extruded material is annealed in an inert atmosphere to obtain a PC / ABS electromagnetic shielding composite material.

[0021] The present invention prepares an acrylonitrile-butadiene-styrene copolymer resin preform (ABS preform) by first melt-blending an acrylonitrile-butadiene-styrene copolymer resin and a carbon-based conductive filler, and then melt-blending the ABS preform with other raw materials to obtain a fluid PC / ABS electromagnetic shielding composite material. Based on this preparation sequence, due to the π-π conjugation effect between the carbon-based filler and the compatibilizer, the prepared ABS preform can gradually migrate to the PC / ABS phase interface and be stably distributed under high-temperature melting, thereby achieving the effects of low filler, high conductivity, and high electromagnetic shielding.

[0022] Preferably, in step (1) and step (2), the melting temperature is 205°C to 215°C, and the melting time is 5 min to 10 min.

[0023] Preferably, in step (3), when the material is extruded through a twin-screw extruder, the screw speed is set to 80 rpm to 100 rpm.

[0024] Selecting an appropriate screw speed can provide sufficient shear force to ensure uniform dispersion of the carbon-based conductive filler, avoid agglomeration, form an effective conductive network, and fully disperse the SMA compatibilizer, promoting PC / ABS interfacial compatibility. Therefore, the screw speed of the present invention is 80 rpm to 100 rpm.

[0025] Preferably, when the material is extruded through a twin-screw extruder in step (3), four temperature intervals are set, including: the temperature of zone 1 is 200°C~205°C, the temperature of zone 2 is 210°C~215°C, the temperature of zone 3 is 220°C~225°C, and the temperature of zone 4 is 230°C~235°C.

[0026] The material can be melted and extruded by step-by-step temperature increase, which can plasticize in sections to avoid thermal degradation, optimize the efficiency of the volume expansion reaction, maintain the rheological stability of the melt and protect the structural integrity of the conductive filler.

[0027] First, considering the high melting point of PC (220°C-230°C) and the poor heat resistance of ABS (easily decomposed at >240°C), a step-by-step heating strategy was designed. The first zone is kept at a low temperature (200°C-205°C) to melt the ABS first, preventing degradation under prolonged exposure to high temperatures. The third and fourth zones are heated to 220°C-235°C to ensure complete melting of the PC, while precisely controlling the temperature to avoid the decomposition temperature of ABS (<240°C). Secondly, the reaction between maleic anhydride (MA) in the SMA compatibilizer and the PC end groups requires high temperature (>220°C). The third and fourth zones (220°C-225°C) provide sufficient energy to promote the esterification reaction between MA and PC, strengthening interfacial bonding. PC has a high melt viscosity, and high temperature (230°C-235°C) can significantly reduce the viscosity and improve fluidity. Furthermore, carbon-based fillers (such as graphene) are susceptible to oxidation damage at high temperatures. Therefore, the maximum temperature is controlled to ≤235°C (below the typical oxidation threshold), and antioxidants (1-3 parts in the formulation) are used for synergistic protection. Ultimately, while avoiding material decomposition, a highly compatible matrix and a uniformly dispersed conductive network are achieved, along with optimized electromagnetic shielding performance and mechanical strength.

[0028] Furthermore, the head temperature of the twin-screw extruder was 235°C.

[0029] Selecting a high-temperature die head (235°C) can prevent the melt from cooling and solidifying prematurely, ensuring continuous and stable extrusion.

[0030] Preferably, in step (3), the inert atmosphere is nitrogen.

[0031] Preferably, in step (3), the annealing temperature is 240° C. to 250° C., and the annealing time is 10 min to 15 min.

[0032] Selecting the annealing temperature and annealing time within the above range to anneal the extruded material under nitrogen can reduce or eliminate stress cracking and warping deformation, and improve the dimensional stability, shape accuracy and long-term reliability of the product.

[0033] Compared with the prior art, the present invention has the following beneficial effects: (1) The PC / ABS electromagnetic shielding composite material formula provided by the present invention can efficiently bridge the two phases of PC and ABS through chemical reaction, greatly improving the compatibility of the composite material. In addition, the raw materials work together to achieve more efficient toughening mechanical properties (especially toughness) and significantly improve processing stability, providing a more uniform and stable dispersion environment, and potentially optimizing the electromagnetic shielding effectiveness at low filler dosage.

[0034] (2) The preparation method provided by the present invention uses a specific processing sequence (first melt-blending ABS with carbon-based conductive fillers to obtain an ABS preform, and then melt-blending with the remaining raw materials). This enables the prepared ABS preform to gradually migrate to the PC / ABS phase interface and be stably distributed under thermodynamic control, thereby achieving the effects of low filler, high conductivity, and high electromagnetic shielding.

[0035] (3) The PC / ABS electromagnetic shielding composite material prepared by the present invention has a tensile strength of up to 71 MPa and a significantly improved notched impact strength of up to 21.86 kJ / m 2 , the electromagnetic shielding performance can reach 25.2 dB, and the conductivity can reach 1.83 S / m. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a transmission electron microscope (TEM) image of the PC / ABS electromagnetic shielding composite material provided in Example 1 of the present invention.

[0037] Figure 2 This is the percolation diagram of the PC / ABS electromagnetic shielding composite material provided in Example 1 of the present invention at different carbon-based conductive filler contents.

[0038] Figure 3 This is a transmission electron microscope (TEM) image of the PC / ABS / carbon-based conductive filler ternary nanocomposite material provided in Comparative Example 2 of the present invention.

[0039] Figure 4 This is a transmission electron microscope (TEM) image of the PC / ABS / carbon-based conductive filler ternary nanocomposite material provided in Comparative Example 3 of the present invention.

[0040] Figure 5 This is a transmission electron microscope (TEM) image of the PC / ABS / carbon-based conductive filler ternary nanocomposite material provided in Comparative Example 4 of the present invention.

[0041] Figure 6 This is a transmission electron microscope (TEM) image of the PC / ABS / carbon-based conductive filler ternary nanocomposite material provided in Comparative Example 6 of the present invention.

[0042] Figure 7 Conductivity stability test of the composite materials provided in Example 1 and Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0043] In order to more clearly illustrate the purpose, technical solutions and advantages of the present invention, the following will be described in detail with reference to the embodiments. Please note that these embodiments are only used to explain the content of the present invention and are not intended to limit the scope of the present invention. Modifications or equivalent substitutions made by those skilled in the art based on the understanding of the technical solutions of the present invention are all within the scope of protection of the present invention.

[0044] The raw materials were purchased from the market.

[0045] Example 1 Example 1 of the present application provides a filler interface distributed PC / ABS electromagnetic shielding composite material, which comprises the following components by weight fraction: PC resin (weight average molecular weight 1.0×10 4 ~3.0×10 4 ): 75 parts; ABS resin (weight average molecular weight 1.0×10 4 ~5.0×10 5 ): 25 parts; carbon-based conductive filler (such as carbon nanotubes, graphene, etc.): 2 parts; styrene grafted maleic anhydride compatibilizer (SMA compatibilizer, MA grafting rate about 15%~20%, weight average molecular weight 5.0×10 4 ~2.0×10 5 ): 10 parts; methyl methacrylate-butadiene-styrene resin (MBS type) toughening agent 5 parts; antioxidant: 3 parts; The antioxidant is a 3:1 compound of antioxidant 1010 (tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester) and antioxidant 168 (tris[2.4-di-tert-butylphenyl] phosphite).

[0046] Then, according to the formula of the PC / ABS electromagnetic shielding composite material, acrylonitrile-butadiene-styrene copolymer resin and carbon-based conductive filler are melted at 205℃~215℃ for 5 min~10 min, and after blending, acrylonitrile-butadiene-styrene copolymer resin preform (ABS preform) is obtained; The ABS preform, PC resin, SMA compatibilizer and MBS toughening agent are melted at 205℃~215℃ for 5 min~10 min, and after blending, the PC / ABS electromagnetic shielding composite material in a flowable state is obtained; The PC / ABS electromagnetic shielding composite material in a flowable state is put into a twin-screw extruder for extrusion, and the extruded material is annealed under nitrogen to obtain the PC / ABS electromagnetic shielding composite material.

[0047] Each flowable PC / ABS electromagnetic shielding composite material is mixed in a twin-screw extruder, and the following mixing parameters are used: The screw speed is 80-100 rpm, the temperature in zone 1 is 200-205°C, the temperature in zone 2 is 210-215°C, the temperature in zone 3 is 220-225°C, the temperature in zone 4 is 230-235°C, and the die head temperature is 235°C. After extrusion, the sample needs to be annealed at 250°C under nitrogen for 10-15 minutes to reduce or eliminate stress cracking and warping, and to improve the product's dimensional stability, shape accuracy, and long-term reliability.

[0048] Figure 1 This is a transmission electron microscope image of the PC / ABS electromagnetic shielding material prepared in Example 1. Figure 1 It can be seen that the carbon-based conductive filler is mainly distributed at the interface between the PC phase and the ABS phase, and is stably distributed at the interface.

[0049] Figure 2 The curve of the conductivity of the PC / ABS electromagnetic shielding composite material prepared in Example 1 as a function of the content of carbon-based conductive filler. Figure 2 It can be seen that when the volume fraction of carbon-based conductive filler is added at 0.03 vol%, its conductivity is increased by 7 orders of magnitude; when the volume fraction of carbon-based conductive filler is added at 2.0 vol%, its conductivity is even increased by 13 orders of magnitude, indicating that through this processing sequence, significant conductive effects can be achieved at extremely low carbon-based conductive filler content. Figure 2 The inset in the figure shows the percolation threshold (Φc) estimated by the classical percolation model, indicating that when the carbon-based conductive filler content is about 0.023 vol%, the carbon-based conductive filler can begin to form a continuous conductive path in the matrix.

[0050] Example 2 The preparation process of Example 2 is the same as that of Example 1, except that the amount of carbon-based conductive filler (such as carbon nanotubes, graphene, etc.) is 3 parts.

[0051] Example 3 The preparation process of Example 3 is the same as that of Example 1, except that the amount of carbon-based conductive filler (such as carbon nanotubes, graphene, etc.) is 5 parts.

[0052] Comparative Example 1 The preparation process of Comparative Example 1 is the same as that of Example 1, except that the raw materials do not contain a compatibilizer.

[0053] Comparative Example 2 The preparation process of Comparative Example 2 is the same as that of Example 1, except that the compatibilizer is an acrylic ester compatibilizer, and the amount of the compatibilizer is 10 parts.

[0054] Figure 3This is a transmission electron microscope image of the PC / ABS / carbon-based conductive filler ternary nanocomposite prepared in this example. Figure 3 It can be seen from the figure that the carbon-based conductive fillers are mainly distributed in the PC phase and cannot be stably distributed at the interface.

[0055] Comparative Example 3 The preparation process of Comparative Example 3 is the same as that of Example 1, except that the compatibilizer selected is a styrene-grafted maleic anhydride compatibilizer (SMA compatibilizer, MA grafting rate of about 45% to 65%, weight average molecular weight of about 7000), and the number of compatibilizers is 10 parts.

[0056] Figure 4 This is a transmission electron microscope image of the PC / ABS / carbon-based conductive filler ternary nanocomposite prepared in this example. Figure 4 It can be seen that the carbon-based conductive fillers are still distributed in the PC phase and cannot be stably distributed at the interface.

[0057] Comparative Example 4 The preparation process of Comparative Example 4 is the same as that of Example 1, except that the compatibilizer selected is a styrene-grafted maleic anhydride compatibilizer (SMA compatibilizer, MA grafting rate of about 5% to 10%, weight average molecular weight of about 10,000), and the number of compatibilizers is 10 parts.

[0058] Figure 5 The transmission electron microscope image of the PC / ABS / carbon-based conductive filler ternary nanocomposite prepared in this example shows that the carbon-based conductive filler is mainly distributed in the PC phase. Figure 1 、 Figure 3 、 Figure 4 、 Figure 5 It can be found that the choice of compatibilizer type is crucial for whether the carbon-based conductive filler can be stably distributed at the PC / ABS interface. Although styrene-grafted maleic anhydride compatibilizer (SMA) can compatibilize PC / ABS, the maleic anhydride content in SMA greatly affects the final distribution of the carbon-based filler. Only when the maleic anhydride content is around 15%~20% can the carbon-based filler be stably distributed at the PC / ABS interface.

[0059] Comparative Example 5 The preparation process of Comparative Example 5 is the same as that of Example 1, except that, according to the formula of the PC / ABS electromagnetic shielding composite material, the SMA compatibilizer and the carbon-based conductive filler are melt-blended to obtain a compatibilizer / carbon-based conductive filler preform; then, the compatibilizer / carbon-based conductive filler preform, PC resin, ABS resin, MBS toughening agent and compounded antioxidant are melt-blended to obtain a fluidized PC / ABS electromagnetic shielding composite material.

[0060] Comparative Example 6 The preparation procedure of Comparative Example 6 is the same as that of Example 1, except that the SMA compatibilizer, carbon-based conductive filler, PC resin, ABS resin, MBS toughener and compounded antioxidant are mixed according to the formula of the PC / ABS electromagnetic shielding composite material and then directly subjected to melt processing.

[0061] Figure 6 The transmission electron microscopy (TEM) image of the PC / ABS / carbon-based conductive filler ternary nanocomposite material prepared for this example shows that a large amount of carbon-based conductive fillers are aggregated at the phase interface of PC / ABS, and a small amount of carbon-based conductive fillers still remain in the PC phase. Figure 6 It can be seen from the TEM image that, under the processing sequence of Example 1, all the carbon-based conductive fillers are stably distributed at the phase interface of PC / ABS, so the final performance of Example 1 is better than that of this example.

[0062] The following performance tests were conducted on the described examples and comparative examples, and the results are recorded in Table 1.

[0063] Tensile strength test: 25℃, tested according to ASTM D638; Notched impact strength: tested according to ISO 179:2000, and the average of three measurements was taken as the final result; Electromagnetic shielding performance test: 25℃, the electromagnetic interference (EMI) shielding effect was evaluated by a vector network analyzer in the range of 8.2-12.5 GHz. The sample size was 30×20×2 mm 3 , and the average of three measurements was taken as the final result; Conductive performance test: 25℃, the thickness of the injection-molded sample was 1 mm, the resistance value was measured by the two-point probe method under a constant current (1 mA), and the average of five measurements was taken as the final result.

[0064] Table 1 Performance test of examples and comparative examples

[0065] From the test results in Table 1, it can be seen that, compared with Comparative Examples 1-4, the present application adds a specific compatibilizer (SMA compatibilizer, MA grafting rate about 15%-20%, weight average molecular weight about 5.0×10 4 ~2.0×10 5), the tensile strength, electromagnetic shielding performance, and conductive effect of PC / ABS are greatly improved. During the processing of the SMA compatibilizer, the maleic anhydride in the compatibilizer will undergo a ring-opening reaction with the terminal hydroxyl groups of PC, causing the compatibilizer to be distributed at the PC / ABS interface, further interacting with PC and ABS, and improving its tensile properties. At the same time, the π-π conjugation effect between the carbon-based conductive filler and the compatibilizer causes the carbon-based conductive filler to be distributed within the compatibilizer, indirectly achieving the distribution of the carbon-based conductive filler at the PC / ABS two-phase interface; while acrylic compatibilizers cannot stably control the carbon-based conductive filler at the PC / ABS phase interface. The stable distribution of the carbon-based conductive filler at the interface not only greatly improves the mechanical properties of PC / ABS (compare Example 1, Comparative Example 1, and Comparative Example 2), but also has a higher conductive effect at the same carbon-based conductive filler content (compare Example 1, Comparative Example 1, and Comparative Example 2) and a better conductive effect at a lower carbon-based conductive filler content (see Example 2).

[0066] By comparing Example 1, Comparative Example 5, and Comparative Example 6, it can be seen that the processing order greatly affects the final properties of the composite material. In Example 1, the carbon-based conductive filler is first blended with ABS, and during subsequent processing, it gradually migrates to the SMA phase (i.e., the PC / ABS interface). In Comparative Example 5, because it is blended with the compatibilizer first, the carbon-based conductive filler content in the compatibilizer is too high, making it difficult to evenly disperse in the PC / ABS matrix, resulting in a decrease in conductivity, electromagnetic shielding performance, and mechanical strength. Comparative Example 6 uses a one-pot processing method, which causes some carbon-based conductive filler to remain in the PC phase and difficult to migrate to the SMA phase. As a result, the carbon-based conductive filler content at the PC / ABS interface is not as high as in Example 1, resulting in reduced conductivity and electromagnetic shielding performance.

[0067] In terms of thermal stability, compared with Example 1 and Comparative Example 2, the SMA compatibilizer is also better than the acrylate compatibilizer (see Figure 7 ), annealed at 250°C for a long time, the conductivity of Example 1 reached a high conductivity state in less than 100 s and did not change significantly in the later period, while that of Comparative Example 2 required a longer time and the conductivity gradually decreased during the annealing process.

[0068] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; under the idea of the present application, the technical features in the above examples or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above, which are not provided in details for simplicity; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A PC / ABS electromagnetic shielding composite material with filler interface distribution, characterized in that: The composition comprises, by mass, 65-80 parts of polycarbonate resin, 20-35 parts of acrylonitrile-butadiene-styrene copolymer resin, 5-15 parts of styrene-grafted maleic anhydride compatibilizer, 5-10 parts of toughening agent, 2-5 parts of carbon-based conductive filler and 1-3 parts of antioxidant; The maleic anhydride content of the styrene-grafted maleic anhydride compatibilizer is 15% to 20%.

2. The PC / ABS electromagnetic shielding composite material according to claim 1, characterized in that: The weight average molecular weight of the polycarbonate resin is 1.0×10 4 ~3.0×10 4 ; The weight average molecular weight of the acrylonitrile-butadiene-styrene copolymer resin is 1.0×10 4 ~5.0×10 5 ; The weight average molecular weight of the styrene grafted maleic anhydride compatibilizer is 5.0×10 4 ~2.0×10 5 .

3. The PC / ABS electromagnetic shielding composite material according to claim 1, characterized in that: The toughening agent includes methyl methacrylate-butadiene-styrene resin.

4. The PC / ABS electromagnetic shielding composite material according to claim 1, characterized in that: The carbon-based conductive filler is one or more of conductive carbon black, carbon nanotubes, and graphene.

5. The PC / ABS electromagnetic shielding composite material according to claim 1, characterized in that: The antioxidant is one or more of hindered phenols and phosphites.

6. The PC / ABS electromagnetic shielding composite material according to claim 5, characterized in that: The hindered phenols include octadecyl acrylate; The phosphites include one or more of triphosphite and dioctadecyl pentaerythritol diphosphite.

7. A method for preparing the PC / ABS electromagnetic shielding composite material according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) According to the formula of the PC / ABS electromagnetic shielding composite material, an acrylonitrile-butadiene-styrene copolymer resin and a carbon-based conductive filler are melt-blended to obtain an acrylonitrile-butadiene-styrene copolymer resin prefabricated material; (2) melt-blending acrylonitrile-butadiene-styrene copolymer resin preform, polycarbonate resin, styrene grafted maleic anhydride compatibilizer and toughening agent to obtain a flowable PC / ABS electromagnetic shielding composite material; (3) The PC / ABS electromagnetic shielding composite material in a fluid state is put into a twin-screw extruder for extrusion, and the extruded material is annealed in an inert atmosphere to obtain a PC / ABS electromagnetic shielding composite material.

8. The method for preparing the PC / ABS electromagnetic shielding composite material according to claim 7, characterized in that: In step (1) and step (2), the melting temperature is 205°C to 215°C, and the melting time is 5 min to 10 min.

9. The method for preparing the PC / ABS electromagnetic shielding composite material according to claim 7, characterized in that: In step (3), when the material is extruded through a twin-screw extruder, the screw speed is set to 80 rpm~100 rpm; When the material is extruded through a twin-screw extruder, four temperature zones are set, including: the temperature of zone one is 200℃~205℃, the temperature of zone two is 210℃~215℃, the temperature of zone three is 220℃~225℃, and the temperature of zone four is 230℃~235℃.

10. The preparation method according to claim 8, characterized in that In step (3), the annealing temperature is 240°C to 250°C, and the annealing time is 10 min to 15 min.

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