Polycarbonate composition and use thereof

Abstract

A polycarbonate composition and a use thereof. The product introduces a processing fluidity improver, such that the processing process fluidity of the whole product can be effectively improved, and after processing, especially after thin-wall processing, the product has good toughness, injection molding stability and appearance performance. The processing fluidity improver is a mixture of a polydimethylsiloxane containing a terminal hydroxyl group and a polystyrene containing an epoxy group.

Description

A polycarbonate composition and its application Technical Field

[0001] The present application relates to the technical field of polymer materials, and in particular to a polycarbonate composition and its application. Background Art

[0002] The molecular chain of polycarbonate is relatively rigid, so the viscous flow activation energy is relatively high, resulting in low processing fluidity and stability of most polycarbonate alloys (especially PC / ABS alloys, i.e., polycarbonate / acrylonitrile-butadiene-styrene terpolymers). The prepared products are prone to processing defects, which not only fail to meet usage requirements but may also cause appearance problems.

[0003] The current solution commonly used to solve the fluidity and stability of polycarbonate alloy processing is to introduce some fluidity improvers such as lubricants during the product preparation stage. However, these solutions have very limited performance improvement for polycarbonate alloys and may even result in the product only having an improved melt index, but the mechanical properties and appearance properties of the final product are not improved, and may even further deteriorate. In particular, when polycarbonate alloys are injection molded into thin-walled and miniaturized products, these defects become more serious. Summary of the Invention

[0004] The present application provides a polycarbonate composition, which, by introducing a specific type of polydimethylsiloxane and polystyrene compound as a processing fluidity improver, can not only effectively improve the fluidity of the overall product during the processing process, but also exhibit special toughness, injection molding stability and appearance performance after processing, especially after thin-wall processing.

[0005] The present application provides a polycarbonate composition comprising the following components in parts by weight:

[0006] 55-95 parts of polycarbonate, 10-40 parts of ABS resin, 0.5-3 parts of processing fluidity improver;

[0007] The processing fluidity improver is a mixture of polydimethylsiloxane containing terminal hydroxyl groups and polystyrene containing epoxy groups; the viscosity of the polydimethylsiloxane containing terminal hydroxyl groups is 500 to 5000 cst.

[0008] In some embodiments, the polydimethylsiloxane containing terminal hydroxyl groups has a viscosity of 2500 to 3600 cst.

[0009] In some embodiments, the mass content of the epoxy group is 0.1-3% based on the total mass of the epoxy group-containing polystyrene.

[0010] In some embodiments, in the processing fluidity improver, the mass ratio of polydimethylsiloxane containing terminal hydroxyl groups to polystyrene containing epoxy groups is (3:7) to (7:3); preferably, the mass ratio of polydimethylsiloxane containing terminal hydroxyl groups to polystyrene containing epoxy groups is (4:6) to (6:4).

[0011] In some embodiments, the non-Newtonian index of the polycarbonate is 0.2 to 0.56; preferably, the non-Newtonian index of the polycarbonate is 0.21 to 0.37.

[0012] In some embodiments, the polycarbonate has a melt flow rate of 1.7 to 28 g / 10 min at 300° C. and a load of 1.2 kg according to ISO 1133-2011.

[0013] In some embodiments, the ABS resin has a melt index of 6.5 to 50 g / 10 min at 220° C. and a load of 10 kg according to ISO 1133-2011.

[0014] In some embodiments, the components of the polycarbonate composition further include 0.1 to 10 parts by weight of a toughening agent, wherein the toughening agent is at least one of SAN grafted PB rubber (polybutadiene rubber grafted with styrene-acrylonitrile copolymer), MMA (methyl methacrylate) grafted silicone rubber, SAN (styrene-acrylonitrile copolymer) grafted silicone rubber, SEBS (styrene-ethylene-butylene-styrene block copolymer), and MBS (terpolymer of methyl methacrylate-butadiene-styrene).

[0015] The present application also provides a method for preparing the polycarbonate composition, comprising the following steps: uniformly mixing the components, and then melt-extruding and granulating the components in a screw extruder to obtain the polycarbonate composition.

[0016] The present application also provides use of the polycarbonate composition in preparing components of portable electronic products.

[0017] The polycarbonate composition described in the present application has high processing fluidity, a long spiral line length (for example, more than 300), and good injection molding stability. When used in the preparation of some portable electronic product components with thin-walled and miniaturized requirements, it can ensure a high product yield and sufficient toughness after preparation without obvious appearance defects.

[0018] The beneficial effect of the present application is that the present application provides a polycarbonate composition, which, by introducing a specific type of polydimethylsiloxane and polystyrene compound as a processing fluidity improver, can not only effectively improve the fluidity of the overall product during the processing process, but also make the product exhibit special toughness, injection molding stability and appearance performance after processing, especially after thin-wall processing. DETAILED DESCRIPTION

[0019] The technical solution adopted in this application is: a polycarbonate composition, comprising the following components in parts by weight:

[0020] 55-95 parts of polycarbonate, 10-40 parts of ABS resin, 0.5-3 parts of processing fluidity improver;

[0021] The processing fluidity improver is a mixture of polydimethylsiloxane containing terminal hydroxyl groups and polystyrene containing epoxy groups; the viscosity of the polydimethylsiloxane is 500 to 5000 cst.

[0022] In some embodiments, the viscosity of the polydimethylsiloxane is directly tested using a viscometer at 25°C.

[0023] In some embodiments, the components of the polycarbonate composition further include 0.1 to 10 parts by weight of a toughening agent.

[0024] In some embodiments, the polycarbonate composition comprises the following components in parts by weight: 60 to 90 parts of polycarbonate, 20 to 30 parts of ABS resin, 0.2 to 3 parts of toughening agent, and 1 to 2 parts of processing fluidity improver.

[0025] In some embodiments, the weight percentage of the polycarbonate is in the range of 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, or any two of them. In some embodiments, the weight percentage of the ABS resin is in the range of 20 parts, 25 parts, 30 parts, or any two of them. In some embodiments, the weight percentage of the toughening agent is in the range of 0.2 parts, 0.5 parts, 0.8 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, or any two of them. In some embodiments, the weight percentage of the processing flow improver is in the range of 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, or any two of them.

[0026] In the polycarbonate composition product described in the present application, the polydimethylsiloxane containing terminal hydroxyl groups can react with the end groups of polycarbonate through the terminal hydroxyl groups during processing to generate polydimethylsiloxane soft segments, effectively achieving responsiveness to shear forces applied during processing. At the same time, based on the formation of the soft segments, the thermal retention stability of the overall alloy resin can be improved, so the product has ideal helix length and injection molding stability; on the other hand, the polystyrene containing epoxy groups can effectively refine the phase domains of ABS resin and toughening agent, thereby ensuring that the product maintains sufficient toughness even in a thin-walled state; the processing fluidity improver has high compatibility with the alloy resin and the toughening agent, so no appearance defects will occur, and the product has good appearance after processing and injection molding.

[0027] However, the viscosity of polydimethylsiloxane needs to be maintained within a relatively appropriate range. If the viscosity is too low, the impact strength of the matrix resin will be greatly reduced during processing due to the large viscosity difference between it and the matrix resin, and appearance defects such as precipitation will easily occur. When the viscosity of this component is too high, the compatibility of polydimethylsiloxane with the matrix resin will be poor, and it will be easy to self-polymerize and cause phase separation, further reducing the stability of the matrix resin.

[0028] In some embodiments, the viscosity of the polydimethylsiloxane is in the range of one or any two of 500 cst, 750 cst, 1000 cst, 1500 cst, 1750 cst, 2000 cst, 2500 cst, 2550 cst, 2750 cst, 3000 cst, 3250 cst, 3500 cst, 3570 cst, 3600 cst, 4000 cst, 4500 cst, and 5000 cst.

[0029] In some embodiments, the viscosity of the polydimethylsiloxane is 2500 to 3600 cst.

[0030] The inventors have found through experimental research that when the viscosity of the polydimethylsiloxane is maintained within the above range, the processing fluidity and injection molding stability of the product are higher.

[0031] In some embodiments, the weight average molecular weight of the polydimethylsiloxane is 5,000 to 25,000.

[0032] In some embodiments, the weight average molecular weight of the polydimethylsiloxane is directly measured by a small-angle laser scattering method.

[0033] In some embodiments, the weight average molecular weight of the polydimethylsiloxane is in the range of one or any two of 5000, 5400, 5500, 8000, 10000, 12000, 15000, 16000, 20000, 21000, and 23000.

[0034] In some embodiments, the mass content of terminal hydroxyl groups in the polydimethylsiloxane is 2 to 10%.

[0035] In some embodiments, the content of the polydimethylsiloxane is determined by quantitatively analyzing the terminal hydroxyl groups using infrared spectroscopy.

[0036] In some embodiments, the mass content of epoxy groups in the polystyrene is 0.1 to 3%.

[0037] In some embodiments, the mass content of epoxy groups in the polystyrene is 0.2-0.6%.

[0038] In some embodiments, the polystyrene is quantitatively analyzed for epoxy groups using infrared spectroscopy to determine its content. When the polystyrene does not contain epoxy groups, the phase domains of the ABS resin and the compatibilizer in the product cannot be effectively refined, resulting in insufficient strength at room temperature and unsatisfactory injection molding stability, processing performance, and even appearance. With the introduction of epoxy groups, the compatibility of the components is improved, and the overall performance of the product is enhanced. When the epoxy group content is maintained within the above range, the overall performance of the product is further improved.

[0039] In some embodiments, the weight average molecular weight of the polystyrene is 80,000 to 230,000.

[0040] In some embodiments, in the processing fluidity improver, the mass ratio of polydimethylsiloxane to polystyrene is (3:7) to (7:3).

[0041] In some embodiments, the mass ratio of polydimethylsiloxane to polystyrene in the processing fluidity improver is in the range of one or any two of (3:7), (4:6), (5:5), (6:4), and (7:3).

[0042] In some embodiments, in the processing fluidity improver, the mass ratio of polydimethylsiloxane to polystyrene is (4:6) to (6:4).

[0043] The inventors have found through screening that when the addition ratio of the two key components in the processing fluidity improver can be maintained within the above range, the synergistic effect of the two can enable the product to maintain optimal processing performance and injection molding performance, and the toughness and appearance performance of the processed product are optimal.

[0044] In some embodiments, the polycarbonate composition has a polycarbonate content of ≥50 wt %.

[0045] In some embodiments, the polycarbonate is bisphenol A polycarbonate.

[0046] In some embodiments, the polycarbonate has a non-Newtonian index of 0.2 to 0.56.

[0047] In some embodiments, the non-Newtonian index of the polycarbonate is in the range of one or any two of 0.2, 0.21, 0.28, 0.3, 0.33, 0.37, 0.4, 0.45, 0.5, 0.55, and 0.56.

[0048] In some embodiments, the polycarbonate has a non-Newtonian index of ≤ 0.4.

[0049] In some embodiments, the non-Newtonian index of the polycarbonate is 0.21 to 0.37.

[0050] In some embodiments, the test method for the non-Newtonian index of the polycarbonate is direct testing using a capillary rheometer: a die with an aspect ratio of 30:1 and an inlet angle of 180° is selected, and the shear rate γ is 100, 500, 1000, 2000, 3000, and 5000 s-1; the shear temperature T is fixed at 260°C; the constant temperature time is 6 minutes, and the melt is extruded from the capillary at a constant shear rate. The instrument automatically records the shear stress τ. For polymer melts, the shear rate and shear stress generally obey the power law formula (τ = Kγn; viscosity = Kγn-1). By plotting lgτ and lgγ, a straight line can be obtained, and its slope is the non-Newtonian index n.

[0051] When selecting the type of polycarbonate, the inventors found that when the non-Newtonian index of the polycarbonate is maintained in the range of ≤0.4, the processing rheological properties of the product can be further improved.

[0052] In some embodiments, the polycarbonate has a melt flow rate of 2 to 15 g / 10 min at 300° C. and a load of 1.2 kg according to ISO 1133-2011.

[0053] In some embodiments, the polycarbonate has a melt flow rate of 2.17 to 12.4 g / 10 min at 300° C. and a 1.2 kg load according to ISO 1133-2011.

[0054] In some embodiments, the weight average molecular weight described herein (eg, the weight average molecular weight of polycarbonate) can be directly measured by gel permeation chromatography.

[0055] In some embodiments, the mass content of terminal hydroxyl groups in the polycarbonate is less than 100 ppm, and the mass content of BPA (bisphenol A) is less than 20 ppm.

[0056] In some embodiments, the ABS resin has a melt index of 10 to 30 g / 10 min at 220° C. and a load of 10 kg according to ISO 1133-2011.

[0057] In some embodiments, the ABS resin has a melt index of 10.2 to 27.8 g / 10 min at 220° C. and a load of 10 kg according to ISO 1133-2011.

[0058] In some embodiments, the relative contents of acrylonitrile, butadiene, and styrene in the ABS resin can be conventionally selected by those skilled in the art and are not limited or elaborated herein.

[0059] In some embodiments, in the polycarbonate composition, the total mass content of polycarbonate and ABS resin is not less than 60 wt %.

[0060] In some embodiments, the toughening agent is at least one of SAN grafted PB rubber, MMA grafted silicone rubber, SAN grafted silicone rubber, SEBS, and MBS.

[0061] In some embodiments, the toughening agent has a melt index of 0.1 to 5 g / 10 min at 300° C. and a load of 1.2 kg according to ISO 1133-2011.

[0062] In some embodiments, the polycarbonate composition further comprises 0.01 to 1 parts by weight of a flame retardant and 0.01 to 1 parts by weight of an anti-drip agent.

[0063] When preparing thin-walled and miniaturized products, in order to broaden their application areas, technicians in this field can introduce flame retardants and anti-dripping agents to give the products flame retardant properties without affecting the processing fluidity, injection molding stability, mechanical properties after processing, and appearance of the products.

[0064] In some embodiments, the components of the polycarbonate composition further include at least one of 0.01 to 1 parts by weight of an antioxidant, 0.01 to 1 parts by weight of a reinforcing filler, and 0.01 to 1 parts by weight of a colorant.

[0065] Based on the actual needs of the product, those skilled in the art may also appropriately introduce some other functional components commonly introduced into PC / ABS alloy products without affecting the product performance, such as antioxidants to improve the aging resistance of the product, reinforcing fillers to improve the rigidity of the product, and colorants to give the product various colors, etc.

[0066] The present application also provides a method for preparing the polycarbonate composition, comprising the following steps: uniformly mixing the components, and then melt-extruding and granulating the components in a screw extruder to obtain the polycarbonate composition.

[0067] The preparation method of the polycarbonate composition described in the present application has simple operating steps and can realize industrial-scale production.

[0068] In some embodiments, all components are fed into a twin-screw extruder from a main feeding port for melt blending, extrusion and granulation.

[0069] In some embodiments, the temperature range of the screw extruder is set to: 220-280° C., the screw speed is 200-600 r / min, and the screw length-to-diameter ratio is 36-60:1.

[0070] In some embodiments, the temperature zones of the twin-screw extruder are set to 200-220°C in zone 1, 210-230°C in zone 2, 215-235°C in zone 3, 215-235°C in zone 4, 215-235°C in zone 5, 220-245°C in zone 6, 220-245°C in zone 7, 220-245°C in zone 8, 220-245°C in zone 9, 220-240°C in zone 10, 210-230 in zone 11, and 200-220°C in zone 12. In some embodiments, the screw speed is 300-500 rpm. In some embodiments, the screw aspect ratio is 48:1.

[0071] In some embodiments, the polycarbonate composition is insulative and flame retardant. In some embodiments, the polycarbonate composition is highly processable.

[0072] The present application also provides use of the polycarbonate composition in preparing components of portable electronic products.

[0073] In order to better illustrate the purpose, technical solutions and advantages of the present application, the present application will be further described below in conjunction with specific embodiments and comparative examples. Its purpose is to understand the content of the present application in detail, rather than to limit the present application. All other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present application. The experimental reagents and instruments involved in the implementation of this application are all commonly used ordinary reagents and instruments unless otherwise specified.

[0074] Examples 1 to 17

[0075] The present application discloses a polycarbonate composition and an embodiment of its application. The components of the polycarbonate composition are shown in Table 1.

[0076] The preparation method of the polycarbonate composition comprises the following steps:

[0077] All the components in the formula are mixed uniformly in a high-speed mixer, and then fed into a twin-screw extruder from a main feeding port for melt blending, extrusion and granulation to obtain the polycarbonate composition.

[0078] When the components are melt-blended and extruded, the temperature zones of the twin-screw extruder are set to 200-220°C in zone 1, 210-230°C in zone 2, 215-235°C in zone 3, 215-235°C in zone 4, 215-235°C in zone 5, 220-245°C in zone 6, 220-245°C in zone 7, 220-245°C in zone 8, 220-240°C in zone 9, 220-240°C in zone 10, 210-230 in zone 11, and 200-220°C in zone 12. The screw speed is 400 rpm and the screw aspect ratio is 48:1.

[0079] Comparative Examples 1 to 9

[0080] The difference between the comparative examples and the examples is only in the types and proportions of the components, as shown in Table 2.

[0081] Among the components described in each embodiment and comparative example,

[0082] The polycarbonate 1 is 7030PJ, produced by Mitsubishi, Japan, with a melt flow rate (ISO 1133-2011) of 3.43 g / 10 min at 300° C. and a load of 1.2 kg, and a non-Newtonian index of 0.33;

[0083] The polycarbonate 2 is WY111BR, produced by Lihuayi, with a melt flow rate (ISO 1133-2011) of 12.4 g / 10 min at 300° C. and a load of 1.2 kg, and a non-Newtonian index of 0.37;

[0084] The polycarbonate 3 is 2100, produced by Wanhua Chemical, with a melt flow rate (ISO 1133-2011) of 9.82 g / 10 min at 300° C. and a load of 1.2 kg, and a non-Newtonian index of 0.45;

[0085] The polycarbonate 4 is FB2560, produced by Idemitsu, Japan, with a melt flow rate (ISO 1133-2011) of 2.83 g / 10 min at 300° C. and a load of 1.2 kg, and a non-Newtonian index of 0.28;

[0086] The polycarbonate 5 is 3026, produced by Mitsubishi of Japan, with a melt flow rate (ISO 1133-2011) of 2.17 g / 10 min at 300° C. and a load of 1.2 kg, and a non-Newtonian index of 0.21;

[0087] The ABS resin 1 is ABS8434, produced in Shanghai Gaoqiao, and has a melt index of 10.2 g / 10 min at 220° C. and a load of 10 kg according to ISO 1133-2011.

[0088] The ABS resin 2 is PA757, produced by Chi Mei, and has a melt index of 27.8 g / 10 min at 220° C. and a load of 10 kg according to ISO 1133-2011;

[0089] The toughening agent 1 is M521, MBS, produced by Kaneka, Japan, and has a measured melt index of 1.3 g / 10 min at 300° C. and 1.2 kg load according to ISO1133-2011;

[0090] The toughening agent 2 is S2501, which is an MMA grafted silicone rubber with a core composed of a cross-linked acrylate copolymer and an organosilicon copolymer and a grafted polymethyl methacrylate as a shell. It is produced by Mitsubishi Chemical of Japan and has a melt index of 4.4 g / 10 min at 300°C and a load of 1.2 kg according to ISO1133.

[0091] The polydimethylsiloxane 1 is P433355 produced by Aladdin, containing terminal hydroxyl groups, with a viscosity of 2700 cst and a weight-average molecular weight of 16000;

[0092] The polydimethylsiloxane 2 is FR240 produced by SiKe, containing terminal hydroxyl groups, with a viscosity of 3500 cst and a weight-average molecular weight of 21000;

[0093] The polydimethylsiloxane 3 is P433353 produced by Aladdin, containing terminal hydroxyl groups, with a viscosity of 750cst and a weight-average molecular weight of 5000;

[0094] The polydimethylsiloxane 4 is FR202 produced by Silicon Science, containing terminal hydroxyl groups, with a viscosity of 4500 cst and a weight-average molecular weight of 23000;

[0095] The polydimethylsiloxane 5 is P433351 produced by Aladdin, containing terminal hydroxyl groups, a viscosity of 25 cst, and a weight-average molecular weight of 1200;

[0096] The polydimethylsiloxane 6 is P433354 produced by Aladdin, containing terminal hydroxyl groups, a viscosity of 20,000 cst, and a weight-average molecular weight of 42,000;

[0097] The phenyl polysiloxane is DC8008 produced by Kangdaoning, which does not contain terminal hydroxyl groups, has a viscosity of 3000 cst and a weight-average molecular weight of 13000;

[0098] The polystyrenes 1 to 3 are homemade, and the polystyrene 4 is PS8265 produced by Total of France, with a weight average molecular weight of 100,000. The preparation methods of the polystyrenes 1 to 3 are as follows:

[0099] Glycidyl methacrylate and polystyrene 4 were mixed in a compound ratio corresponding to the epoxy group grafting content, and then the mixture was melt-extruded in a twin-screw extruder at 155-165° C. for 20-30 minutes to prepare polystyrenes 1-3 with different epoxy group contents, wherein the epoxy group content of polystyrene 1 was 0.2%, the epoxy group content of polystyrene 2 was 0.5%, and the epoxy group content of polystyrene 3 was 3%. The weight average molecular weight of polystyrenes 1-3 was tested, and the change rate compared with polystyrene 4 was less than 5%, so they could be considered to have the same weight average molecular weight as polystyrene 4.

[0100] The existing processing fluidity improver 1 is BDP, produced by Aidico;

[0101] The existing processing fluidity improver 2 is MMA, produced by Mitsubishi Chemical.

[0102] Unless otherwise specified, the components and raw materials used in the examples and comparative examples of the present application are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0103] Table 1

[0104] Table 2

[0105] In order to verify the performance of the polycarbonate composition described in this application, the products prepared in each embodiment and comparative example were subjected to the following performance tests. The specific steps are as follows:

[0106] (1) Room temperature thin-wall strength test: Refer to ISO 6603-2-2000 and injection mold a 1.5 mm × 100 mm × 100 mm test plate. The fixed hammer weight is 1.0 kg, the drop speed is 4.4 m / s, and the test environment temperature is room temperature (25°C) and the humidity is 50%. The experimental phenomena and data recorded are the puncture energy Ep (kJ) and the failure mode (toughness or brittleness).

[0107] (2) Injection molding stability test: According to ISO 1133-2011 standard, the test temperature is fixed at 260 ° C and the load is 2.16 kg. The MI (melt index) of the pellets produced by extrusion before injection molding is compared with the MI growth rate of the injection molded parts after injection molding. The larger the MI growth rate, the worse the injection molding stability.

[0108] (3) Spiral length test: Fixed injection temperature of 260°C, injection pressure of 50%, injection speed of 50%, holding time of 3s, cooling time of 5s, mold temperature of 80°C, after 20 consecutive injections, read the spiral length scale from the 15th to the 20th mold and record and calculate the average value as the final result. Under the same test conditions, the longer the spiral length, the better the injection molding processability and the more suitable it is for thin-wall injection molding applications;

[0109] (4) Appearance performance test: Each product was injection molded with a fixed injection temperature of 280°C, injection pressure of 90%, injection speed of 90%, holding time of 3s, cooling time of 5s, mold temperature of 80°C, and a 1.5mm large plate splash mold. The defects at the end and on the surface of the large plate were observed. When the large plate had no defects or only sporadic short defects appeared at the end and the number was less than 5, it was rated as Level 1; when sporadic defects appeared on the large plate and at the end and the number was between 5 and 15, it was rated as Level 2; when sporadic defects appeared on the large plate and at the end and the number was between 15 and 25, it was rated as Level 3; when the defects were clustered into blocks or the surface was foggy, it was rated as Level 4.

[0110] The test results are shown in Tables 3 and 4.

[0111] Table 3

[0112] Table 4

[0113] As can be seen from Tables 3 and 4, the polycarbonate composition of the product described in this application has a spiral length of more than 300 and high processing fluidity, which is very suitable for processing thin-walled parts used in some portable electronic products. In the thin-walled state, it can reach at least greater than 30kJ and the fracture form is toughness. The injection molding stability can reach within 3.5%, the appearance grade reaches level 2 or above, and the comprehensive performance is excellent. Among the components of the product described in this application, the processing fluidity improver is very important. As shown in Comparative Examples 8 to 9, if some fluidity improving components used in the prior art are used, they cannot achieve the same improvement effect. It is necessary to use a specific type of polydimethylsiloxane and polystyrene compound to make the product have the expected comprehensive performance. If the types used are inappropriate, as shown in Comparative Examples 6 and 7, the processing fluidity improver obtained after the two are compounded cannot synergistically and effectively act in the resin system. According to Comparative Example 4, Example 1, Examples 9-11, and Comparative Example 5, it can be seen that when the viscosity of polydimethylsiloxane is low, the processing performance of the product is poor, which has a negative impact on the quality of the thin-wall surface. As the viscosity increases, the comprehensive performance of the product improves, especially when it is in the range of 2500-3600 cst, the performance of the product is the best. However, as the viscosity further increases beyond the specified range, the appearance performance of the product fails to meet the standard and exhibits brittle failure. On the other hand, when the epoxy group content of polystyrene is maintained in the range of 0.2-0.6%, the performance of the corresponding products of Example 1 and Example 12 is better than that of Example 13. In the processing flow improver, both components are indispensable. The products of Comparative Examples 1 and 2, in which either one is missing, have poor thin-wall toughness and poor processing stability, and also have a relatively obvious negative impact on the appearance quality of the product. The ratio of the two components will also have a certain impact on the performance of the product. As shown in Examples 1 and Examples 16-19, when the ratio of the two components is (4:6) to (6:4), the two can exert the greatest synergistic effect. At the same time, the amount of processing fluidity improver added needs to be maintained within a certain range. As can be seen from Example 1, Examples 14-15 and Comparative Example 3, as the amount of processing fluidity improver added increases, the performance of the product is further improved. However, if the amount added is too much, the toughness and processing stability of the product will decrease. In addition to the processing fluidity improver, the choice of polycarbonate itself will also have a certain impact on the performance of the product. As recorded in Example 1 and Examples 4-7, when the non-Newtonian index of the polycarbonate is preferably ≤0.4, and further 0.33-0.37, the product can obtain the best processing fluidity, injection molding stability and appearance performance.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A polycarbonate composition, characterized in that The composition comprises the following components in parts by weight: 55-95 parts of polycarbonate, 10-40 parts of ABS (terpolymer of acrylonitrile-butadiene-styrene) resin, and 0.5-3 parts of processing fluidity improver; The processing fluidity improver is a mixture of polydimethylsiloxane containing terminal hydroxyl groups and polystyrene containing epoxy groups; the viscosity of the polydimethylsiloxane containing terminal hydroxyl groups is 500-5000 cst.

2. The polycarbonate composition according to claim 1, characterized in that The viscosity of the polydimethylsiloxane containing terminal hydroxyl groups is 2500 to 3600 cst.

3. The polycarbonate composition according to claim 1, wherein The mass content of the epoxy group is 0.1-3% based on the total mass of the polystyrene containing the epoxy group.

4. The polycarbonate composition according to claim 1, wherein In the processing fluidity improver, the mass ratio of the polydimethylsiloxane containing terminal hydroxyl groups to the polystyrene containing epoxy groups is (3:7) to (7:3); preferably, the mass ratio of the polydimethylsiloxane containing terminal hydroxyl groups to the polystyrene containing epoxy groups is (4:6) to (6:4).

5. The polycarbonate composition according to claim 1, wherein The non-Newtonian index of the polycarbonate is 0.2 to 0.56; preferably, the non-Newtonian index of the polycarbonate is 0.21 to 0.

37.

6. The polycarbonate composition according to claim 1, wherein The polycarbonate has a melt flow rate of 1.7 to 28 g / 10 min at 300° C. and a load of 1.2 kg according to ISO 1133-2011.

7. The polycarbonate composition according to claim 1, wherein The ABS resin has a melt index of 6.5 to 50 g / 10 min at 220° C. and a load of 10 kg according to ISO 1133-2011.

8. The polycarbonate composition according to claim 1, wherein The components of the polycarbonate composition also include 0.1 to 10 parts by weight of a toughening agent, wherein the toughening agent is at least one of SAN grafted PB rubber (polybutadiene rubber grafted with styrene-acrylonitrile copolymer), MMA (methyl methacrylate) grafted silicone rubber, SAN (styrene-acrylonitrile copolymer) grafted silicone rubber, SEBS (styrene-ethylene-butylene-styrene block copolymer), and MBS (terpolymer of methyl methacrylate-butadiene-styrene).

9. The method for preparing the polycarbonate composition according to any one of claims 1 to 8, characterized in that: The following steps are involved: After the components are uniformly mixed, they are melt-extruded and granulated in a screw extruder to obtain the polycarbonate composition.

10. Use of the polycarbonate composition according to any one of claims 1 to 8 in preparing parts for portable electronic products.

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