Polycarbonate material containing functionalized graphene and preparation method thereof

Abstract

The invention discloses a polycarbonate material containing functionalized graphene and a preparation method of the polycarbonate material. The polycarbonate material comprises the following components in percentage by weight: 55-75% of polycarbonate, 5-10% of functionalized graphene, 3-7% of multi-walled carbon nanotubes, 3-8% of a flame retardant, 10-20% of an elastomer, 2-5% of a compatilizer, 0.5-2% of an antioxidant, 0.5-2% of an anti-dripping agent and 0.5-2.0% of a release agent. According to the preparation method, the polycarbonate material is obtained by mixing the raw materials through a pretreatment and step-by-step mixing method and a twin-screw extrusion method. The polycarbonate material containing functionalized graphene has the problems of insufficient thermal conductivity and poor flame retardance, and can meet the comprehensive requirements of the polycarbonate material in the aspects of mechanical properties, light weight and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer functional materials, and particularly relates to a polycarbonate material containing functionalized graphene and a preparation method thereof. Background Art

[0002] With the rapid development of high-power electronic devices, intelligent transportation and electric vehicles, the application of traditional polycarbonate (PC) materials in various high-performance fields faces many challenges. Polycarbonate is widely used in electronic components, automotive battery housings, aerospace and construction due to its excellent mechanical strength, impact toughness and transparency. However, its low thermal conductivity, poor flame retardancy and heavy weight limit its application in high-power and high-safety applications. Especially in the field of high-power heat dissipation requirements such as electronic equipment and automotive batteries, the insufficient thermal conductivity and poor flame retardancy of polycarbonate make it difficult to meet the increasingly stringent technical requirements.

[0003] To improve the thermal conductivity of polycarbonate-based composite materials, thermal conductive fillers such as metal fibers, ceramic powders, and glass fibers are currently added to the polycarbonate matrix. However, these fillers have some obvious defects: first, the density of metal and ceramic fillers is relatively high, which leads to an increase in the weight of the material. Especially in industries such as automobiles and aviation that have high requirements for lightweight, this increased mass may affect the performance of the product; second, the dispersion of metal fibers and ceramic powders in the polymer matrix is ​​poor, and it is easy to form uneven heat conduction channels, thereby affecting the overall performance of the material; in addition, excessive addition of these traditional fillers will reduce the mechanical properties, toughness, and impact strength of the composite material, limiting its use in high-strength and high-performance applications.

[0004] In recent years, graphene materials have gradually attracted attention. Graphene has ultra-high thermal conductivity and good mechanical properties, and its compatibility with the polymer matrix can be significantly improved through appropriate functionalization treatment. However, ordinary graphene is prone to agglomeration when directly added to the PC matrix, which limits the improvement of thermal conductivity. In addition, graphene itself is not flame retardant and is prone to spontaneous combustion or thermal instability at high temperatures. Therefore, traditional graphene filler solutions are difficult to meet the comprehensive requirements of polycarbonate composites in terms of thermal conductivity, flame retardancy, mechanical properties and lightweight.

[0005] In order to overcome the above shortcomings of graphene, researchers have developed functionalized graphene materials in recent years, among which functionalized graphene (DOPO-GO) containing diphenyl phosphate (DOPO) groups has received special attention due to its flame retardant properties. DOPO groups have good thermal stability and antioxidant properties, and can release phosphate compounds in a flame environment, playing a flame retardant role of absorbing heat and isolating oxygen.

[0006] Therefore, in view of the above technical problems, it is necessary to provide a new type of polycarbonate material, which can overcome the problems of insufficient thermal conductivity and poor flame retardancy of the current polycarbonate materials while meeting the comprehensive requirements in terms of mechanical properties and lightweight. Summary of the invention

[0007] The purpose of the present invention is to provide a polycarbonate material containing functionalized graphene, and a preparation method and application thereof. The polycarbonate material adopts a compound of functionalized graphene (containing flame-retardant DOPO groups) and multi-walled carbon nanotubes to replace traditional metal fiber fillers, and achieves excellent electrical conductivity, thermal conductivity and flame retardancy at a lower filler dosage, thereby achieving lightweight materials and meeting high performance and flame retardancy requirements.

[0008] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:

[0009] On the one hand, the present invention provides a polycarbonate material containing functionalized graphene, wherein the polycarbonate material contains the following components in percentage by weight: 55-75% polycarbonate, 5-10% functionalized graphene, 3-7% multi-walled carbon nanotubes, 3-8% flame retardant, 10-20% elastomer, 2-5% compatibilizer, 0.5-2% antioxidant, 0.5-2% anti-dripping agent and 0.5-2.0% release agent.

[0010] In one or more embodiments of the present invention, the polycarbonate material contains the following components in percentage by weight: 61-66% polycarbonate, 6-10% functionalized graphene, 3-6% multi-walled carbon nanotubes, 3-8% flame retardant, 10-17% elastomer, 2-4% compatibilizer, 0.5-2.0% antioxidant, 0.5-2.0% anti-drip agent and 0.5-5.0% release agent.

[0011] In one or more embodiments of the present invention, the functionalized graphene is graphene containing DOPO (diphenyloxy phosphate) groups, the DOPO grafting rate of the functionalized graphene (GO-DOPO) is about 30-40%, and the phosphorus content is about 3.5-4.5wt%. By introducing the DOPO group into the graphene surface, not only the flame retardancy of the graphene is improved, but also its dispersibility in the polycarbonate matrix is ​​significantly improved, so that it can provide effective thermal conductivity and flame retardancy at a low addition amount, and the DOPO grafting rate and phosphorus content within this range have better effects.

[0012] In one or more embodiments of the present invention, the diameter of the multi-walled carbon nanotube is 5-20 nm, preferably 8-15 nm, and the length of the multi-walled carbon nanotube is preferably 0.1-10 μm, preferably 1-7 μm.

[0013] In one or more embodiments of the present invention, the polycarbonate has a molecular weight of 20,000 to 30,000 g / mol, a glass transition temperature (Tg) of 145 to 155° C., and a melt flow index of 8 to 15 g / 10 min at 300° C. and 1.2 kg.

[0014] In one or more embodiments of the present invention, the compatibilizer is ABS-g-MAH (ABS grafted maleic anhydride compatibilizer) and / or PS-g-MAH (polystyrene grafted maleic anhydride compatibilizer).

[0015] In one or more embodiments of the present invention, the elastomer is methyl methacrylate-butadiene-styrene terpolymer (MBS) and / or styrene-acrylonitrile copolymer (SAN). It is found through verification that the addition of such elastomers can not only effectively enhance the flexibility of the matrix, but also improve the impact resistance and elongation at break of the material, thereby improving the mechanical properties of the composite material.

[0016] In one or more embodiments of the present invention, the methyl methacrylate-butadiene-styrene terpolymer (MBS) preferably has a styrene content of 30-50%, and a glass transition temperature (Tg) of -40°C to -20°C.

[0017] In one or more embodiments of the present invention, the styrene content of the styrene-acrylonitrile copolymer (SAN) is preferably 65-85%, and the glass transition temperature (Tg) is 100-120°C.

[0018] In one or more embodiments of the present invention, the flame retardant is the halogen-free flame retardant EFTOP EF-42 and / or the halogen-free phosphorus-based flame retardant DOPO and its derivatives.

[0019] In one or more embodiments of the present invention, the antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant, and the antioxidant preferably includes antioxidant 1010 and antioxidant 168, wherein the antioxidant 1010 is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and the antioxidant 168 is tris[2.4-di-tert-butylphenyl]phosphite.

[0020] In one or more embodiments of the present invention, the anti-drip agent is selected from at least one of polytetrafluoroethylene (PTFE), aramid fiber, and polystyrene fiber.

[0021] In one or more embodiments of the present invention, the release agent is pentaerythritol stearate and / or stearamide.

[0022] On the other hand, the present invention provides a method for preparing the above-mentioned polycarbonate material containing functionalized graphene, comprising the following steps:

[0023] 1) Pretreatment: dispersing the functionalized graphene and multi-walled carbon nanotubes into a dispersion liquid by ultrasonication, and then vacuum drying the dispersion liquid to obtain pretreated functionalized graphene and multi-walled carbon nanotubes;

[0024] Preferably, the functionalized graphene and multi-walled carbon nanotubes are ultrasonically dispersed in a small amount of ethanol for 30 to 40 minutes to form a dispersion; or

[0025] Drying the dispersion in a vacuum oven at 70 to 80° C. for 8 to 12 hours;

[0026] 2) Premixing: taking appropriate amounts of polycarbonate, elastomer and compatibilizer, adding part of the polycarbonate and the taken polycarbonate, elastomer and compatibilizer into a high-speed mixer for preliminary dispersion by mixing, then adding appropriate amounts of antioxidant, anti-dripping agent and release agent, and continuing to mix to obtain a mixture A; then mixing the remaining part of the polycarbonate with the functionalized graphene and multi-walled carbon nanotubes treated in step 1) at a ratio of 1:20 to obtain a mixture B; and mixing part of the appropriate amount of polycarbonate with the flame retardant at a ratio of 1:20 to obtain a mixture C;

[0027] Preferably, appropriate amounts of polycarbonate, elastomer and compatibilizer are added to a high-speed mixer and mixed at a speed of 500 to 800 rpm for 2 to 3 minutes to perform preliminary mixing and dispersion; or

[0028] Then, an appropriate amount of antioxidant, anti-dripping agent and release agent are added, and the mixture is mixed at a speed of 600 to 1000 rpm for 5 to 10 minutes to obtain a mixture A;

[0029] 3) Melt blending and extrusion: Mixture A, mixture B and mixture C are sequentially put into a twin-screw extruder for melt blending and extrusion to obtain.

[0030] In one or more embodiments of the present invention, the speed of the twin-screw machine is 300-500 rpm. The screw speed is set to 300-500 rpm to ensure that the material is fully plasticized during the extrusion process. After extrusion, cooling and granulation are performed to finally obtain a thermally conductive flame-retardant polycarbonate material containing special graphene.

[0031] In one or more embodiments of the present invention, the twin-screw extruder needs to be equipped with at least two side feeding ports, and the two side feeding ports are respectively located in the sixth zone and the seventh zone, wherein the mixed material A is added from the main feeding port, the mixed material B is added from the side feeding port of the sixth zone, and the mixed material C is added from the side feeding port of the seventh zone;

[0032] In one or more embodiments of the present invention, the temperature zones of the twin-screw extruder are set as follows:

[0033] The feeding zone (zone 1) is 230-240°C, the middle zone (zones 2 to 5) is 240-260°C, zone 6 is 240-250°C, zone 7 is 230-240°C, zone 8 to zone 10 is 240-260°C, and the die zone is 250-260°C. In the twin-screw extrusion step, the full plasticization of the ingredients and the uniform distribution of the filler are achieved through reasonable temperature zone settings. This process method significantly improves the thermal conductivity, flame retardancy and toughness of the composite material, solves the problem of increased brittleness of the material after the addition of fillers in the traditional method, and provides an innovative solution for the preparation of thermally conductive flame-retardant polycarbonate.

[0034] In one or more embodiments of the present invention, the functionalized graphene is prepared by a method comprising the following steps:

[0035] (1) adding an appropriate amount of graphite powder and potassium permanganate to a mixed solution of sulfuric acid and phosphoric acid, stirring for reaction, to obtain a reaction solution, preferably stirring at 50° C. for 12 hours; then pouring the reaction solution into ice water, stirring, and then adding hydrogen peroxide to obtain a mixture, and then cooling, filtering, and drying the mixture to obtain graphene.

[0036] (2) dispersing the graphene in TMF solvent and ultrasonically dispersing to obtain a graphene dispersion; then adding thionyl chloride (SOCl2) to the graphene dispersion and reflux at 65°C for 12 hours, a black precipitate - chlorinated graphene gradually appears at the bottom, and then washing the precipitate with THF by centrifugation several times to remove excess thionyl chloride;

[0037] (3) dispersing the chlorinated graphene in chlorobenzene (PhCl) and subjecting it to ultrasonic treatment; then dissolving DOPO in PhCl to obtain a DOPD solution; then slowly adding the chlorinated graphene dispersion to the DOPD solution, then heating to 85°C and stirring and refluxing for 12h, then centrifugally separating and vacuum drying to obtain GO-DOPO. The specific preparation steps are as follows:

[0038]

[0039] In another aspect, the present invention further provides a use of the above-mentioned polycarbonate material containing functionalized graphene in the preparation of optical components, electronic components or automotive parts.

[0040] In yet another aspect, the present invention further provides an optical element, an electronic element or an automobile component, which is made of the above-mentioned polycarbonate material containing functionalized graphene.

[0041] Compared with the prior art, the polycarbonate material containing functionalized graphene of the present invention has the following advantages:

[0042] 1. In view of the shortcomings of existing polycarbonate materials in thermal conductivity and flame retardancy, functionalized graphene and multi-walled carbon nanotubes (MWCNTs) are introduced into the polycarbonate matrix to form an efficient thermal conductivity and flame retardant composite system. Functionalized graphene can be closely combined with the polycarbonate matrix to form an effective thermal conductivity path, thereby significantly improving the thermal conductivity efficiency of the material, and functionalized graphene can form a dense carbonized layer during the combustion process, which can effectively enhance the flame retardancy; compared with traditional metal fiber fillers, the combination of functionalized graphene and multi-walled carbon nanotubes improves thermal conductivity, flame retardancy and mechanical properties while maintaining the lightweight and good processability of the material. In addition, multi-walled carbon nanotubes form thermal conductive channels in the polycarbonate matrix through their high thermal conductivity and network structure, which can effectively improve the thermal conductivity and mechanical properties of polycarbonate materials, and reduce the droplet phenomenon during the flame retardant process, further improving the flame retardant effect of the material. The combination of the two can not only improve the thermal conductivity, but also achieve multiple optimizations of flame retardancy, thermal conductivity, mechanical properties and lightweight at a lower filler addition amount through synergistic effects.

[0043] 2. The addition of compatibilizers and elastomers not only enhances the interfacial compatibility of functionalized graphene, multi-walled carbon nanotubes and polycarbonate, but also significantly improves the toughness and elongation at break of the composite material, effectively improving the mechanical properties of the material and avoiding the brittleness problem that may be caused by high thermal conductivity fillers.

[0044] 3. The addition of thermally conductive fillers usually affects the flexibility of the material, and in the application of thermally conductive flame retardant materials, maintaining good toughness is crucial to the overall performance and durability of the application. The inventors used the synergistic effect of flame retardants and anti-dripping agents to achieve flame retardancy of polycarbonate materials while significantly improving the stability of molten droplets and preventing the material from dripping under high temperature conditions, making it more suitable for applications with high safety requirements.

[0045] Specifically, by introducing appropriate flame retardants, the flame propagation can be effectively suppressed and the flame retardancy level can be improved, thereby improving the safety of the material. In addition, in order to reduce the molten droplet phenomenon that may occur when the material burns, the addition of an anti-dripping agent can significantly suppress the generation of molten droplets, which helps to improve the overall flame retardant effect, especially in critical applications. It can reduce the risk of secondary combustion. The addition of antioxidants can provide good antioxidant protection for the material during processing and use, extend the service life of the composite material, and avoid performance degradation caused by thermal oxidation degradation.

[0046] The method for preparing the polycarbonate material containing functionalized graphene of the present invention has the following advantages:

[0047] 1. A specific pretreatment and step-by-step mixing method is used to achieve uniform dispersion of functionalized graphene and multi-walled carbon nanotubes in a polycarbonate (PC) matrix, so that the prepared composite material has excellent thermal conductivity and meets the V-0 flame retardant grade, significantly improving the safety and application reliability of the material.

[0048] 2. Ultrasonic dispersion and vacuum drying of functionalized graphene and multi-walled carbon nanotubes improve the dispersion effect of fillers and avoid agglomeration problems. Then, materials are added in sections to make the dispersion of polycarbonate, elastomer and compatibilizer more uniform, effectively improving the processing performance and fluidity of the materials.

[0049] 3. Through advanced processing technologies such as twin-screw extrusion, efficient and uniform filler dispersion can be achieved, further improving the thermal conductivity and flame retardant effect of the material. PC composite materials using twin-screw extrusion have improved thermal conductivity while still maintaining good fluidity and molding performance. They are suitable for various processing methods such as injection molding and extrusion, and can be well used in the fields of electronics, electrical, and automobiles, expanding their application prospects. DETAILED DESCRIPTION

[0050] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0051] Unless otherwise specified, the reagents and materials herein can be purchased from conventional channels.

[0052] Unless otherwise specified, all preparations and tests herein took place at 25°C.

[0053] Unless otherwise specified, “GO” in this article refers to “graphene”.

[0054] Unless otherwise specified, "DOPO" herein refers to "diphenyloxyphosphate".

[0055] Unless otherwise specified, “GO-DOPO” herein refers to “functionalized graphene”, i.e., “graphene containing diphenyloxy phosphate groups”.

[0056] Unless otherwise specified, all preparations and tests herein took place at 25°C.

[0057] As used herein, "includes," "comprising," "including," "containing," "having," or other variations thereof are intended to encompass non-exclusive inclusions, and no distinction is made between these terms. The term "comprising" means that other steps and ingredients that do not affect the end result may be added. The term "comprising" also includes the terms "consisting of" and "consisting essentially of." The composite materials and methods / processes of the present invention may comprise, consist of, and consist essentially of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein.

[0058] Example 1. Preparation of functionalized graphene

[0059] 1) Add appropriate amount of graphite powder and potassium permanganate to a mixed solution of sulfuric acid and phosphoric acid and stir at 50°C for 12 hours. After the reaction is completed, pour the solution into ice water, stir and add hydrogen peroxide. After the mixture is cooled to 25°C, filter the solution, wash the residue with deionized water and ethanol, and dry to obtain graphene (Graphite Oxide, GO).

[0060] 2) Graphene was dispersed in TMF solvent and then ultrasonicated for 1 hour to obtain a graphene dispersion. Sulfoxide chloride (SOCl2) was then added to the graphene dispersion and refluxed at 65°C for 12 hours. A black precipitate (acylation graphene) gradually appeared at the bottom. The precipitate was then washed with THF by centrifugation several times to remove excess thionoxide chloride.

[0061] 3) Disperse the chlorinated graphene in chlorobenzene (PhCl) and treat with ultrasound for 1 hour. Dissolve DOPO in PhCl in a 50°C oil bath. Slowly add the chlorinated graphene dispersion to the DOPD solution, then heat to 85°C and stir under reflux for 12 hours. The final product, functionalized graphene (GO-DOPO), is obtained by centrifugation and vacuum drying, with a DOPO grafting rate of about 30-40% and a phosphorus content of 3.5-4.5wt%.

[0062] The specific reaction process is as follows:

[0063]

[0064] Example 2-4. Preparation of polycarbonate material containing functionalized graphene

[0065] 1. An appropriate amount of the functionalized graphene and multi-walled carbon nanotubes prepared in Example 1 were ultrasonically dispersed in a small amount of ethanol for 30-40 minutes to form a uniform dispersion, and then the dispersed functionalized graphene and multi-walled carbon nanotubes were dried in a vacuum oven at 70-80° C. for 8-12 hours to remove the residual solvent.

[0066] 2. Take an appropriate amount of polycarbonate, elastomer and compatibilizer, add the taken part of the polycarbonate, the taken elastomer and compatibilizer into a high-speed mixer, and mix at a speed of 500-800rpm for 2-3 minutes to ensure preliminary uniform dispersion. Subsequently, add antioxidant, anti-drip agent and release agent, and continue to mix at a speed of 600-1000rpm for 5-10 minutes to obtain mixture A. At the same time, the remaining part of the polycarbonate taken is mixed with the functionalized graphene and multi-walled carbon nanotubes treated in step (a) at a ratio of 1:20 to obtain mixture B; an appropriate amount of polycarbonate is mixed with a flame retardant at a ratio of 1:20 to obtain mixture C.

[0067] 3. Add the mixture A, mixture B and mixture C into the twin-screw extruder in turn for melt blending and extrusion. The extruder needs to be equipped with at least two side feed ports, and the feed ports on both sides are located in the sixth zone and the seventh zone respectively. Mixture A is added from the main feed port, mixture B is added from the side feed port of the sixth zone, and mixture C is added from the side feed port of the seventh zone. The temperature zones of the extruder are set as follows: feeding zone (zone 1): 230-240°C, middle zone (zones 2 to 5): 240-260°C, zone 6: 240-250°C, zone 7: 230-240°C, zone 8 to zone 10: 240-260°C, head zone: 250-260°C. The screw speed is set to 300-500rpm to ensure that the material is fully plasticized during the extrusion process. After extrusion, it is cooled and granulated to finally obtain a thermally conductive flame-retardant polycarbonate material containing special graphene.

[0068] The polycarbonate materials containing functionalized graphene of Examples 2-4 were prepared according to the above reaction process. The composition, content and experimental conditions of each raw material in Examples 1-3 are shown in Table 1-2:

[0069] Table 1. Composition and content of each raw material in Examples 2-4

[0070]

[0071]

[0072] Table 2. Experimental conditions in each reaction step of Examples 2-4

[0073]

[0074]

[0075] According to the above conditions, a polycarbonate material containing functionalized graphene was prepared and tested. The properties of the polycarbonate material containing functionalized graphene obtained in Examples 2-4 are shown in Table 3 below, wherein: the density was tested according to GB / T1033.1-2008; the melting point was tested according to GB / T 19466.3-2004; the yield strength, tensile modulus and elongation at break were tested according to the provisions of GB / T1040.2-2006, and the test speed was 50 mm / min; the notched impact strength was tested according to the provisions of GB / T1843-2006, and the test temperature was 23° C.; the thermal conductivity was tested using the transient hot wire method according to GB / T1029-2008; the flame retardant performance test: conducted according to GB / T2408-2008, and the sample size was 125*13*1.6 mm.

[0076] Table 3. Properties of polycarbonate materials containing functionalized graphene obtained in Examples 2-4

[0077]

[0078] As can be seen from Table 3 above, the polycarbonate materials containing functionalized graphene obtained in Examples 2-4 have excellent comprehensive properties, exhibit excellent thermal conductivity, ensure that heat is effectively conducted in applications, and improve the heat dissipation performance of electronic and electrical equipment. The flame retardant properties of the material meet the expected requirements and can effectively prevent fire hazards. The material has a high tensile modulus, good yield strength and impact resistance, ensuring that the mechanical strength adapts to complex application environments, and extending the service life of the material in structural components and high-stress areas. In addition, the low density and stable molding properties of the material also ensure lightweight design requirements and meet the high standards of modern high-performance electronics and automotive industries.

[0079] Example 5-7. Preparation of polycarbonate material containing functionalized graphene

[0080] Polycarbonate materials containing functionalized graphene were prepared according to the same experimental conditions as in Examples 2-4, except that the composition and content of each raw material in each example were as shown in Table 4 below.

[0081] Table 4. Composition and content of each raw material in Examples 5-7

[0082]

[0083]

[0084] According to the component compositions of each weight percentage of Examples 5-7, a thermally conductive flame-retardant polycarbonate material was prepared according to the above preparation method, and was tested by the same method as in Table 3 above. The properties of the polycarbonate material containing functionalized graphene obtained in Examples 5-7 are shown in Table 5 below.

[0085] Table 5. Properties of polycarbonate materials containing functionalized graphene obtained in Examples 5-7

[0086]

[0087] As can be seen from Table 5 above, the polycarbonate materials containing functionalized graphene obtained in Examples 5-7 have excellent comprehensive properties. The materials exhibit excellent thermal conductivity, ensuring that heat is effectively conducted in applications and improving the heat dissipation performance of electronic and electrical equipment. The flame retardant properties of the materials meet the expected requirements and can effectively prevent fire hazards. The materials have high tensile modulus, good yield strength and impact resistance, ensuring that the mechanical strength adapts to complex application environments and extending the service life of the materials in structural components and high stress areas. In addition, the low density and stable molding properties of the materials also ensure lightweight design requirements and meet the high standards of modern high-performance electronics and automotive industries.

[0088] Example 8-9. Preparation of polycarbonate material containing functionalized graphene

[0089] The polycarbonate material containing functionalized graphene was prepared under the same experimental conditions as in the above-mentioned Examples 2-3, except that the composition and proportion of each raw material in each Example were as shown in the following Table 6.

[0090] Table 6. Composition and content of each raw material in Examples 8-9

[0091]

[0092] According to the weight percentage of the components in Examples 8-9, a thermally conductive flame-retardant polycarbonate material was prepared according to the above preparation method, and tested by the same method as in Table 3. The properties of the polycarbonate material containing functionalized graphene obtained in Examples 8-9 are shown in Table 7 below.

[0093] Table 7. Properties of polycarbonate materials containing functionalized graphene obtained in Examples 8-9

[0094]

[0095] The results show that the polycarbonate material containing functionalized graphene obtained in Examples 8-9 has excellent comprehensive properties. The material exhibits excellent thermal conductivity, ensuring that heat is effectively conducted in applications and improving the heat dissipation performance of electronic and electrical equipment. The flame retardant properties of the material meet the expected requirements and can effectively prevent fire hazards. The material has a high tensile modulus, good yield strength and impact resistance, ensuring that the mechanical strength adapts to complex application environments and extending the service life of the material in structural components and high-stress areas. In addition, the low density and stable molding properties of the material also ensure lightweight design requirements and meet the high standards of modern high-performance electronics and automotive industries.

[0096] In summary, experiments show that the polycarbonate material containing functionalized graphene of the present invention, by adjusting each component in a suitable ratio, adds functionalized graphene and multi-walled carbon nanotubes to form an efficient heat-conducting and flame-retardant composite system, constitutes an effective heat-conducting path, thereby significantly improving the thermal conductivity efficiency of the material, and the functionalized graphene can form a dense carbonized layer during the combustion process, which can effectively enhance the flame retardancy; the lightweight and good processability of the material are also maintained. And by adding compatibilizers and elastomers, not only the interfacial compatibility of functionalized graphene, multi-walled carbon nanotubes and polycarbonate is enhanced, but also the toughness and elongation at break of the composite material are significantly improved, the mechanical properties of the material are effectively improved, and the brittleness problem that may be caused by high thermal conductive fillers is avoided. And by utilizing the synergistic effect of flame retardants and anti-dripping agents, while achieving the flame retardancy of polycarbonate materials, the droplet stability is significantly improved, and the dripping phenomenon of the material under high temperature conditions is prevented, making it more suitable for applications with high safety requirements.

[0097] In addition, it is also found through experiments that, in the case of containing the following weight percentages of the components: 61-66% of polycarbonate, 6-10% of functionalized graphene, 3-6% of multi-walled carbon nanotubes, 3-8% of flame retardant, 10-17% of elastomer, 2-4% of compatibilizer, 0.5-2.0% of antioxidant, 0.5-2.0% of anti-dripping agent and 0.5-2.0% of release agent, the polycarbonate material containing functionalized graphene of the present invention has better thermal conductivity and tensile strength.

[0098] Comparative Examples 1-5

[0099] The polycarbonate material was prepared under the same experimental conditions as in Example 2, except that the composition and content of each raw material in each example were as shown in Table 8 below.

[0100] Table 8. Raw materials and contents of each component in Comparative Examples 1-5

[0101]

[0102] According to the component compositions of each weight percentage of Comparative Examples 1-5, a thermally conductive flame-retardant polycarbonate material was prepared according to the above preparation method, and was tested by the same method as in Table 3 above. The properties of the polycarbonate materials containing functionalized graphene obtained in Comparative Examples 1-5 are shown in Table 9 below.

[0103] Table 9. Properties of polycarbonate materials obtained in Comparative Examples 1-5

[0104]

[0105] As can be seen from Tables 8-9 above, compared with Example 2, no functionalized graphene and multi-walled carbon nanotubes were added in Comparative Example 1, and it can be found that the thermal conductivity and flame retardancy of the material decreased significantly. At the same time, the yield strength and impact strength of the material also decreased significantly. No functionalized graphene was added in Comparative Example 2, and it can be found that the thermal conductivity and flame retardancy of the material decreased significantly. There were no multi-walled carbon nanotubes in Comparative Example 3, and it can be found that the thermal conductivity of the material decreased slightly. It shows that functionalized graphene and multi-walled carbon nanotube filling play an important role in the thermal conductivity and flame retardancy of the material. At the same time, the strength, rigidity and impact resistance of the material are improved, the tensile properties of the material are increased, and the durability of the material under stress is extended. No elastomer was added in Comparative Example 4, indicating that the addition of elastomer significantly improved the elongation at break and impact strength of the material, making it more suitable for application scenarios requiring high toughness and impact resistance, such as automobiles, electronic and electrical components. At the same time, thermal conductivity is also improved, indicating that the presence of elastomer helps the uniform distribution of fillers in the matrix. No compatibilizer was added in Comparative Example 5, indicating that the addition of the compatibilizer effectively improved the dispersibility of the functionalized graphene and carbon nanotubes in the polycarbonate matrix, and greatly improved the mechanical properties and thermal conductivity of the material.

[0106] In summary, the polycarbonate material containing functionalized graphene of the present invention:

[0107] 1. In view of the shortcomings of existing polycarbonate materials in thermal conductivity and flame retardancy, functionalized graphene and multi-walled carbon nanotubes (MWCNTs) are introduced into the polycarbonate matrix to form an efficient thermal conductivity and flame retardant composite system. Functionalized graphene can be closely combined with the polycarbonate matrix to form an effective thermal conductivity path, thereby significantly improving the thermal conductivity efficiency of the material, and functionalized graphene can form a dense carbonized layer during the combustion process, which can effectively enhance the flame retardancy; compared with traditional metal fiber fillers, the combination of functionalized graphene and multi-walled carbon nanotubes improves thermal conductivity, flame retardancy and mechanical properties while maintaining the lightweight and good processability of the material. In addition, multi-walled carbon nanotubes form thermal conductive channels in the polycarbonate matrix through their high thermal conductivity and network structure, which can effectively improve the thermal conductivity and mechanical properties of polycarbonate materials, and reduce the droplet phenomenon during the flame retardant process, further improving the flame retardant effect of the material. The combination of the two can not only improve the thermal conductivity, but also achieve multiple optimizations of flame retardancy, thermal conductivity, mechanical properties and lightweight at a lower filler addition amount through synergistic effects.

[0108] 2. The addition of compatibilizers and elastomers not only enhances the interfacial compatibility of functionalized graphene, multi-walled carbon nanotubes and polycarbonate, but also significantly improves the toughness and elongation at break of the composite material, effectively improving the mechanical properties of the material and avoiding the brittleness problem that may be caused by high thermal conductivity fillers.

[0109] 3. The addition of thermally conductive fillers usually affects the flexibility of the material, and in the application of thermally conductive flame retardant materials, maintaining good toughness is crucial to the overall performance and durability of the application. The inventors used the synergistic effect of flame retardants and anti-dripping agents to achieve flame retardancy of polycarbonate materials while significantly improving the stability of molten droplets and preventing the material from dripping under high temperature conditions, making it more suitable for applications with high safety requirements.

[0110] In addition, the preparation method of the polycarbonate material containing functionalized graphene adopts a specific pretreatment and step-by-step mixing method to achieve uniform dispersion of functionalized graphene and multi-walled carbon nanotubes in a polycarbonate (PC) matrix, so that the prepared composite material has excellent thermal conductivity and meets the V-0 flame retardant grade, significantly improving the safety and application reliability of the material; by ultrasonically dispersing and vacuum drying the functionalized graphene and multi-walled carbon nanotubes, the dispersion effect of the filler is improved and the agglomeration problem is avoided. Then, the materials are added in sections to make the dispersion of polycarbonate, elastomer and compatibilizer more uniform, effectively improving the processing performance and fluidity of the material; through advanced processing technologies such as twin-screw extrusion, efficient and uniform filler dispersion can be achieved, further improving the thermal conductivity and flame retardant effect of the material. The PC composite material using twin-screw extrusion has improved thermal conductivity while still maintaining good fluidity and molding performance. It is suitable for various processing methods such as injection molding and extrusion. It can be well used in the fields of electronics, electrical, and automobiles, expanding its application prospects.

[0111] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0112] In addition, it should be understood that although this specification is described according to implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form the technology in this field.

Claims

1. A polycarbonate material containing functionalized graphene, the polycarbonate material containing the following components in percentage by weight: 55-75% polycarbonate, 5-10% functionalized graphene, 3-7% multi-walled carbon nanotubes, 3-8% flame retardant, 10-20% elastomer, 2-5% compatibilizer, 0.5-2% antioxidant, 0.5-2% anti-dripping agent and 0.5-2.0% release agent.

2. The polycarbonate material containing functionalized graphene according to claim 1, characterized in that: The polycarbonate material contains the following components in percentage by weight: 61-66% of polycarbonate, 6-10% of functionalized graphene, 3-6% of multi-walled carbon nanotubes, 3-8% of flame retardant, 10-17% of elastomer, 2-4% of compatibilizer, 0.2-2.0% of antioxidant, 0.5-2.0% of anti-dripping agent and 0.5-2.0% of release agent.

3. The polycarbonate material containing functionalized graphene according to claim 1 or 2, characterized in that: The functionalized graphene is graphene containing DOPO (diphenyloxy phosphate) groups, the DOPO grafting rate of the functionalized graphene (GO-DOPO) is about 30-40%, and the phosphorus content is about 3.5-4.5wt%; Preferably, the diameter of the multi-walled carbon nanotube is 5 to 20 nm, preferably 8 to 15 nm, and the length of the multi-walled carbon nanotube is preferably 0.1 to 10 μm, preferably 1 to 7 μm.

4. The polycarbonate material containing functionalized graphene according to any one of claims 1 to 3, characterized in that: The polycarbonate has a molecular weight of 20,000 to 30,000 g / mol, a glass transition temperature (Tg) of 145 to 155° C., and a melt flow index of 8 to 15 g / 10 min at 300° C. and 1.2 kg; Preferably, the compatibilizer is ABS-g-MAH and / or PS-g-MAH.

5. The polycarbonate material containing functionalized graphene according to any one of claims 1 to 4, characterized in that: The elastomer is methyl methacrylate-butadiene-styrene terpolymer (MBS) and / or styrene-acrylonitrile copolymer (SAN); Preferably, the methyl methacrylate-butadiene-styrene terpolymer (MBS) has a styrene content of 30 to 50% and a glass transition temperature (Tg) of -40°C to -20°C; or The styrene content of the styrene-acrylonitrile copolymer (SAN) is preferably 65-85%, and the glass transition temperature (Tg) is 100-120°C.

6. The polycarbonate material containing functionalized graphene according to any one of claims 1 to 5, characterized in that: The flame retardant is a halogen-free flame retardant EFTOP EF-42 and / or a halogen-free phosphorus flame retardant DOPO and its derivatives; Preferably, the antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant, and the antioxidant preferably includes antioxidant 1010 and antioxidant 168, wherein the antioxidant 1010 is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and the antioxidant 168 is tris[2,4-di-tert-butylphenyl]phosphite.

7. The polycarbonate material containing functionalized graphene according to any one of claims 1 to 6, characterized in that: The anti-dripping agent is selected from at least one of polytetrafluoroethylene (PTFE), aramid fiber, and polystyrene fiber; Preferably, the release agent is pentaerythritol stearate and / or stearamide.

8. The method for preparing a polycarbonate material containing functionalized graphene according to any one of claims 1 to 7, comprising the following steps: 1) Pretreatment: dispersing the functionalized graphene and multi-walled carbon nanotubes into a dispersion liquid by ultrasonication, and then vacuum drying the dispersion liquid to obtain pretreated functionalized graphene and multi-walled carbon nanotubes; Preferably, the functionalized graphene and multi-walled carbon nanotubes are ultrasonically dispersed in a small amount of ethanol for 30 to 40 minutes to form a dispersion; or Drying the dispersion in a vacuum oven at 70 to 80° C. for 8 to 12 hours; 2) Premixing: taking appropriate amounts of polycarbonate, elastomer and compatibilizer, adding part of the polycarbonate and the taken elastomer and compatibilizer into a high-speed mixer for preliminary dispersion by mixing, then adding appropriate amounts of antioxidant, anti-dripping agent and release agent, and continuing to mix to obtain a mixture A; then mixing the remaining part of the polycarbonate with the functionalized graphene and multi-walled carbon nanotubes treated in step 1) at a ratio of 1:20 to obtain a mixture B; and mixing part of the appropriate amount of polycarbonate with the flame retardant at a ratio of 1:20 to obtain a mixture C; Preferably, appropriate amounts of polycarbonate, elastomer and compatibilizer are added to a high-speed mixer and mixed at a speed of 500 to 800 rpm for 2 to 3 minutes to perform preliminary mixing and dispersion; or Then, an appropriate amount of antioxidant, anti-dripping agent and release agent are added, and the mixture is mixed at a speed of 600 to 1000 rpm for 5 to 10 minutes to obtain a mixture A; 3) Melt blending and extrusion: Mixture A, mixture B and mixture C are sequentially put into a twin-screw extruder for melt blending and extrusion to obtain.

9. The method for preparing a polycarbonate material containing functionalized graphene according to claim 8, characterized in that: The speed of the twin-screw extruder is 300-500 rpm; Preferably, the twin-screw extruder needs to be equipped with at least two side feeding ports, and the feeding ports on both sides are respectively located in the sixth zone and the seventh zone, wherein the mixed material A is added from the main feeding port, the mixed material B is added from the side feeding port of the sixth zone, and the mixed material C is added from the side feeding port of the seventh zone; Further preferably, each temperature zone of the twin-screw extruder is set as follows: The feeding zone (zone 1) is 230-240°C, the middle zone (zones 2 to 5) is 240-260°C, zone 6 is 240-250°C, zone 7 is 230-240°C, zone 8 to zone 10 is 240-260°C, and the head zone is 250-260°C.

10. The method for preparing a polycarbonate material containing functionalized graphene according to claim 8 or 9, characterized in that: The functionalized graphene is prepared by a method comprising the following steps: (1) adding an appropriate amount of graphite powder and potassium permanganate to a mixed solution of sulfuric acid and phosphoric acid, stirring for reaction, to obtain a reaction solution, preferably stirring at 50° C. for 12 hours; then pouring the reaction solution into ice water, stirring, and then adding hydrogen peroxide to obtain a mixture, and then cooling, filtering, and drying the mixture to obtain graphene. (2) dispersing the graphene in TMF solvent and ultrasonically dispersing to obtain a graphene dispersion; then adding thionyl chloride (SOCl2) to the graphene dispersion and reflux at 65°C for 12 hours, a black precipitate - chlorinated graphene gradually appears at the bottom, and then washing the precipitate with THF by centrifugation several times to remove excess thionyl chloride; (3) dispersing the chlorinated graphene in chlorobenzene (PhCl) and subjecting it to ultrasonic treatment; Then, DOPO was dissolved in PhCl to obtain a DOPD solution; then, the acyl chloride graphene dispersion was slowly added to the DOPD solution, and then the temperature was raised to 85° C. and stirred under reflux for 12 h, and then GO-DOPO was obtained by centrifugation and vacuum drying.

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