Electromagnetic shielding polypropylene composite material and preparation method thereof

Abstract

The invention discloses an electromagnetic shielding polypropylene composite material and a preparation method thereof, the polypropylene composite material comprises the following components by mass: 95-97 parts of polypropylene resin, 0.5-1 part of MOFs-carbon material composition, 3-5 parts of a compatilizer, and 1 part of a processing aid; wherein the MOFs-carbon material composition is prepared from a coupling agent, a double-walled carbon nanotube, graphene oxide and an MOFs material. The polypropylene composite material is endowed with a relatively high electromagnetic shielding effect by adding a micro-content of MOFs-carbon material composition, and relatively high mechanical properties are maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material modification, and specifically relates to an electromagnetic shielding polypropylene composite material and a preparation method thereof. Background Art

[0002] Polypropylene (PP) has the advantages of low density, easy processing, excellent mechanical properties, etc., and has been widely used in the automotive industry, household appliances and machinery fields. For the automotive industry, polypropylene is mainly used in automotive interior and exterior parts, such as interior parts like instrument panels, door panels and pillars, and exterior parts like bumpers, fenders, and deflectors. With the rapid development of electronics and information technology, the demand for conductive materials is becoming more and more urgent. Conductive materials have a wide range of applications in the fields of anti-static and electromagnetic shielding. With the rise of intelligent driving control in the automotive field, the on-vehicle radar brackets and housings urgently need to meet the shielding effect above 77 GHz, and polypropylene composite materials need to meet the electromagnetic shielding requirements. To achieve the electromagnetic shielding effect of polypropylene composite materials is to improve the conductivity of polypropylene materials. In order to improve the conductivity of polypropylene materials, many studies have been carried out. Adding conductive fillers (graphene, conductive carbon black or carbon nanotubes) to polypropylene is one of the main methods to improve the conductive performance of polypropylene materials at present. However, the addition of conductive fillers will cause agglomeration, resulting in a decrease in the mechanical properties of the material. Therefore, there is an urgent need to develop a composite material with good mechanical properties and electromagnetic shielding effect. Summary of the Invention

[0003] In view of this, the present invention provides an electromagnetic shielding polypropylene composite material and a preparation method thereof to solve the problems raised in the above background art. By adding a micro-content of MOFs-carbon material composition, the polypropylene composite material is given a high electromagnetic shielding effect and maintains high mechanical properties.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] In a first aspect, the present invention discloses an electromagnetic shielding polypropylene composite material, which includes, by mass: 95-97 parts of polypropylene resin, 0.5-1 part of MOFs-carbon material composition, 3-5 parts of compatibilizer, and 1 part of processing aid; wherein, the MOFs-carbon material composition is composed of a coupling agent, double-walled carbon nanotubes, graphene oxide and MOFs material.

[0006] As a further scheme of the present invention: the mass ratio of the coupling agent, double-walled carbon nanotubes, graphene oxide and MOFs material is 1:(10-20):(40-60):(30-50).

[0007] As a further solution of the present invention: The MOFs material is in-situ grown and synthesized on double-walled carbon nanotubes and graphene oxide, and forms a coating on the double-walled carbon nanotubes and graphene oxide.

[0008] As a further solution of the present invention: The MOFs-carbon material is prepared from a zirconium source, p-benzoic acid, a reaction solvent, and 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene.

[0009] As a further solution of the present invention: The mass ratio of the zirconium source, p-benzoic acid, the reaction solvent, and 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene is (2-5):(50-60):(160-200):1.

[0010] As a further solution of the present invention: The zirconium source is ZrOCl 2 ·8H 2 O or ZrCl 4 ;

[0011] As a further solution of the present invention: The reaction solvent is N,N-dimethylformamide.

[0012] As a further solution of the present invention: The preparation steps of the MOFs-carbon material composition are as follows:

[0013] Add the zirconium source and p-benzoic acid into the reaction solvent, then add double-walled carbon nanotubes and graphene oxide and stir evenly, and then add 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene and shake well to obtain the MOFs material;

[0014] Add a coupling agent to the MOFs material, mix evenly, transfer it to a sealed container and heat it to 110-120°C, keep it for 24-48 hours, and after separation and drying, the MOFs-carbon material composition is obtained.

[0015] As a further solution of the present invention: The polypropylene resin is industrial conventional polypropylene;

[0016] As a further solution of the present invention: The processing aid is at least one of an antioxidant, a co-antioxidant, a light absorber, or a light stabilizer;

[0017] As a further solution of the present invention: The compatibilizer is maleic anhydride grafted polypropylene.

[0018] In a second aspect, the present invention discloses a preparation method of the electromagnetic shielding polypropylene composite material as described above, including the following steps:

[0019] Mix the polypropylene resin, the MOFs-carbon material composition, the compatibilizer, and the processing aid evenly to obtain a mixture;

[0020] Put the mixture into the main feeding port of a parallel twin-screw extruder, and after melting and extrusion granulation, a high thermal conductivity polypropylene composite material can be obtained.

[0021] As a further solution of the present invention: the barrel temperature of the parallel twin-screw extruder is 160°C - 230°C, the head temperature is 220°C, the screw speed is 500 r / min, the melt pressure is 1.0 MPa, and the vacuum degree is less than -0.06 MPa.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] An electromagnetic shielding polypropylene composite material prepared by the present invention can be recycled and reused, meeting the development requirements of green and circular materials. The graphene oxide used has a two-dimensional structure, and the double-walled carbon nanotubes have a one-dimensional structure, both of which have very high electrical conductivity. Generally, the electrical conductivity of electromagnetic shielding materials plays a positive role in attenuating the energy of electromagnetic waves. The present invention uses double-walled carbon nanotubes with a one-dimensional structure and graphene oxide with a two-dimensional structure to jointly form a network structure under the framework of the MOFs porous structure, thereby playing a significant role in attenuating the energy of electromagnetic waves.

[0024] An electromagnetic shielding polypropylene composite material prepared by the present invention uses MOFs materials to grow in-situ on the double-walled carbon nanotubes and graphene oxide bodies, enabling the MOFs materials to play a fixing role in connecting the double-walled carbon nanotubes and graphene oxide, and forming countless tiny network structures centered on graphene oxide.

[0025] An electromagnetic shielding polypropylene composite material prepared by the present invention adds a small amount of silane coupling agent during the growth process of the MOFs-carbon material composition. The hydroxyl groups formed by the hydrolysis of the silane coupling agent can undergo a chemical grafting reaction with terephthalic acid in the MOFs materials, thereby endowing the MOFs-carbon material composition with good compatibility with polypropylene and achieving better dispersion during the melt blending process.

[0026] An electromagnetic shielding polypropylene composite material prepared by the present invention, in which the porous MOFs-carbon material composition with a three-dimensional structure forms an electromagnetic shielding point independently in the composite material, and after melt blending, further constructs an electromagnetic shielding network with a lattice structure, ultimately endowing the composite material with excellent electromagnetic shielding performance. Specific embodiments

[0027] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention.

[0029] The specific information of the raw materials used in the following examples and comparative examples is as follows:

[0030] Polypropylene homopolymer (PP-H), grade 012, density 0.9 g / cm 3 , melt index 1.2 g / 10 min (temperature 230 °C, load 2.16 Kg), Shandong Wusheng Natural Gas Chemical Co., Ltd.

[0031] Graphene oxide, thickness 0.55 - 1.2 nm, diameter 0.5 - 3 μm, number of layers 1 - 5 layers, manufactured by Zhongke Leiming (Beijing) Technology Co., Ltd.

[0032] Double-walled carbon nanotubes, tube diameter 10 - 20 nm, length 10 - 30 μm, manufactured by Beijing Decodaojin Technology Co., Ltd.

[0033] Silane coupling agent KH550, purchased from Nanjing Xiangfei Chemical Research Institute.

[0034] Maleic anhydride grafted polypropylene, grade Saudi Basel 350K, grafting rate 0.7 - 0.9%, manufactured by Dongguan Shenghao Plastic Raw Materials Co., Ltd.

[0035] The processing aids include a primary antioxidant, a secondary antioxidant, a light absorber, and a light stabilizer, which are mixed in a mass ratio of 1:1:1:1. The primary antioxidant has the grade Irganox565 and is manufactured by BASF, Germany. The secondary antioxidant has the grade AN168 and the manufacturer is Qingdao Dedate Chemical Group. The light absorber has the grade Chiguard5050 and is manufactured by Qitai Co., Ltd. The light stabilizer has the grade LA-52 and is manufactured by Adeka (China) Investment Co., Ltd.

[0036] All materials are commercially available conventional and commonly used products.

[0037] It can be understood that the above raw material reagents are only examples of some specific embodiments of the present invention to make the technical solutions of the present invention clearer, and do not represent that the present invention can only use the above reagents. Specifically, it shall be subject to the scope in the claims. In addition, the "parts" mentioned in the examples and comparative examples refer to parts by weight unless otherwise specified.

[0038] Any range described in the present invention includes the end values and any numerical value between the end values, as well as any sub-range formed by any numerical value between the end values or the end values.

[0039] Preparation Example

[0040] Preparation of Examples 1-5 and Comparative Examples 1-3:

[0041] Weigh each raw material according to the ratio in Table 1 below, place them together in a high-speed mixer and mix for 10 min, then add them to a twin-screw extruder, melt, extrude, pelletize, cool, and dry to obtain an electromagnetic shielding polypropylene composite material. Among them, the barrel temperature is 160 °C in Zone 1, 220 °C in Zone 2, 220 °C in Zone 3, 230 °C in Zone 4, 230 °C in Zone 5, 230 °C in Zone 6, and 220 °C at the die head, the screw speed is 500 r / min, the melt pressure is 1.0 MPa, and the vacuum degree is -0.06 MPa.

[0042] Among them, the MOFs-carbon material composition is prepared according to the following method: Dissolve 0.3 parts of ZrOCl 2 ·8H 2 O and 5 parts of terephthalic acid are fully dissolved in 18 parts of N,N-dimethylformamide, then add 0.78 parts of KH550, 7.8 parts of carbon nanotubes, and 46.8 parts of graphene oxide and stir evenly. Subsequently, add 0.1 part of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene, ultrasonically vibrate for 5 min, transfer to a reaction kettle, heat to 120 °C and keep for 24 h. After the reaction, centrifuge at 8000 r / min, wash by centrifugation at 8000 r / min using N,N-dimethylformamide. The precipitate is soaked in 50 mL of acetone for 12 h, then centrifuged at 8000 r / min, and kept in a vacuum drying oven at 120 °C for 12 h to obtain the MOFs-carbon material composition 1.

[0043] Preparation of Comparative Example 4

[0044] Weigh each raw material according to the ratio in Table 1 below, place them together in a high-speed mixer and mix for 10 min, then add them to a twin-screw extruder, melt, extrude, pelletize, cool, and dry to obtain an electromagnetic shielding polypropylene composite material. Among them, the barrel temperature is 160 °C in Zone 1, 220 °C in Zone 2, 220 °C in Zone 3, 230 °C in Zone 4, 230 °C in Zone 5, 230 °C in Zone 6, and 220 °C at the die head, the screw speed is 500 r / min, the melt pressure is 1.0 MPa, and the vacuum degree is -0.06 MPa.

[0045] Among them, the MOFs-carbon material composition is prepared according to the following method: Dissolve 0.3 parts of ZrOCl 2 ·8H 20.3 parts of ZrOCl2·8H2O and 5 parts of p-benzoic acid were fully dissolved in 18 parts of N,N-dimethylformamide, then 0.78 parts of KH550, 54.6 parts of graphene oxide were added and stirred evenly. Subsequently, 0.1 part of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene was added, sonicated for 5 min, transferred to a reaction kettle, heated to 120 °C and maintained for 24 h. After the reaction, centrifuged at 8000 r / min, centrifugally washed with N,N-dimethylformamide at 8000 r / min. The precipitate was soaked in 50 mL of acetone for 12 h, then centrifuged at 8000 r / min, and maintained at 120 °C in a vacuum drying oven for 12 h to obtain the MOFs-carbon material composition 2.

[0046] Preparation of Comparative Example 5

[0047] Weigh each raw material according to the ratio in Table 1 below, place them together in a high-speed mixer and mix for 10 min, then add them to a twin-screw extruder, melt, extrude, granulate, cool, and dry to obtain an electromagnetic shielding polypropylene composite material. Among them, the barrel temperature is 160 °C in zone 1, 220 °C in zone 2, 220 °C in zone 3, 230 °C in zone 4, 230 °C in zone 5, 230 °C in zone 6, 220 °C at the die head, the screw speed is 500 r / min, the melt pressure is 1.0 MPa, and the vacuum degree is -0.06 MPa.

[0048] Among them, the MOFs-carbon material composition was prepared according to the following method: 0.3 parts of ZrOCl2·8H2O and 5 parts of p-benzoic acid were fully dissolved in 18 parts of N,N-dimethylformamide, then 0.78 parts of KH550, 7.8 parts of carbon nanotubes were added and stirred evenly. Subsequently, 0.1 part of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene was added, sonicated for 5 min, transferred to a reaction kettle, heated to 120 °C and maintained for 24 h. After the reaction, centrifuged at 8000 r / min, centrifugally washed with N,N-dimethylformamide at 8000 r / min. The precipitate was soaked in 50 mL of acetone for 12 h, then centrifuged at 8000 r / min, and maintained at 120 °C in a vacuum drying oven for 12 h to obtain the MOFs-carbon material composition 3.

[0049] Table 1 Formulation Table of an Electromagnetic Shielding Polypropylene Composite Material

[0050]

[0051] Test Example

[0052] The polypropylene composite materials prepared in Examples 1-5 and Comparative Examples 1-5 were respectively put into an injection molding machine (barrel temperature 220 °C, mold temperature 60 °C) to be melted, and standard specimens were respectively prepared; then performance tests were carried out. The test items and results are shown in Table 2.

[0053] Table 2

[0054]

[0055] Among them, the tensile strength is tested with reference to the test standard ISO 527, the flexural strength is tested with reference to ISO 178, the notched impact strength of the simply supported beam is tested with reference to ISO 179, and the volume resistivity is tested with reference to IEC60093.

[0056] It can be seen from Table 2 that: in Comparative Example 1, the pure polypropylene itself has a relatively high volume resistivity. In Comparative Example 2, after adding double-walled carbon nanotubes and graphene oxide, the volume resistivity slightly decreases. At the same time, due to the lack of the dispersion effect of the compatibilizer, the graphene oxide and double-walled carbon nanotubes agglomerate, resulting in a slight decrease in the tensile strength and impact strength of the material. In Comparative Example 3, after adding maleic anhydride grafted polypropylene compatibilizer, it helps to disperse the graphene oxide and double-walled carbon nanotubes, forming partial conductive paths, further reducing the volume resistivity, and improving the tensile strength and impact strength of the material. In Examples 1 to 5, the addition of a trace amount of MOFs-carbon material composition significantly reduces the volume resistivity of the material, so that it can be applied to high-performance electromagnetic shielding materials.

[0057] Although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0058] Therefore, the above are only the preferred embodiments of the present application, and are not used to limit the scope of implementation of the present application; that is, all equivalent transformations made according to the scope of the claims of the present application are within the protection scope of the claims of the present application.

Claims

1. An electromagnetic shielding polypropylene composite material, characterized in that: Calculated by weight, it includes: 95-97 parts of polypropylene resin, 0.5-1 parts of MOFs-carbon material composition, 3-5 parts of compatibilizer, and 1 part of processing aid; wherein the MOFs-carbon material composition consists of a coupling agent, double-walled carbon nanotubes, graphene oxide and MOFs material.

2. The electromagnetic shielding polypropylene composite material according to claim 1, characterized in that: The mass ratio of the coupling agent, double-walled carbon nanotubes, graphene oxide and MOFs material is 1:(10-20):(40-60):(30-50).

3. The electromagnetic shielding polypropylene composite material according to claim 1, characterized in that: The MOFs material is in-situ grown and synthesized on double-walled carbon nanotubes and graphene oxide, and forms a coating on the double-walled carbon nanotubes and graphene oxide.

4. The electromagnetic shielding polypropylene composite material according to claim 1, characterized in that: The MOFs-carbon material is prepared from a zirconium source, terephthalic acid, a reaction solvent and 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene.

5. The electromagnetic shielding polypropylene composite material according to claim 4, characterized in that: The mass ratio of the zirconium source, benzoic acid, reaction solvent and 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene is (2-5):(50-60):(160-200):

1.

6. The electromagnetic shielding polypropylene composite material according to claim 1 or 4, characterized in that: The zirconium source is ZrOCl2·8H2O or ZrCl4; and / or, The reaction solvent is N,N-dimethylformamide.

7. The electromagnetic shielding polypropylene composite material according to claim 4, characterized in that: The preparation steps of the MOFs-carbon material composition are: A zirconium source and benzoic acid are added to a reaction solvent, and then double-walled carbon nanotubes and graphene oxide are added and stirred evenly, and then 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene is added and shaken sufficiently to obtain a MOFs material; A coupling agent is added to the MOFs material, mixed evenly, and then transferred to a sealed container and heated to 110-120° C. for 24-48 hours. After separation and drying, a MOFs-carbon material composite is obtained.

8. The electromagnetic shielding polypropylene composite material according to claim 1, characterized in that: The polypropylene resin is industrial conventional polypropylene; and / or, The processing aid is at least one of an antioxidant, an auxiliary antioxidant, a light absorber or a light stabilizer; and / or, The compatibilizer is maleic anhydride grafted polypropylene.

9. The method for preparing the electromagnetic shielding polypropylene composite material according to any one of claims 1 to 8, characterized in that: The following steps are involved: Mixing polypropylene resin, MOFs-carbon material composition, compatibilizer and processing aid to obtain a mixture; The mixture is fed into the main feeding port of a parallel twin-screw extruder, and a high thermal conductivity polypropylene composite material is obtained through melting, extrusion and granulation.

10. The preparation method according to claim 9, characterized in that: The barrel temperature of the parallel twin-screw extruder is 160° C.-230° C., the head temperature is 220° C., the screw speed is 500 r / min, the melt pressure is 1.0 MPa, and the vacuum degree is less than -0.06 MPa.

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