Electromagnetic wave shielding thermoplastic composition

Abstract

The present disclosure relates to an electromagnetic wave shielding thermoplastic composition comprising: 0.1 wt.% to 50 wt.% of graphene; from 0.1 wt.% to 25 wt.% of another carbon-based conductive material; from 10 wt.% to 90 wt.% of a polymer matrix; wherein the weight ratio (wt / wt) of the graphene to the carbon-based conductive material is 3: 1 to 1: 1; wherein the other carbon-based conductive material is crystalline or semi-crystalline. The present disclosure also relates to an electromagnetic wave shielding thermoplastic particle, a thermoplastic powder, a thermoplastic film, a thermoplastic sheet, or a thermoplastic slurry comprising the composition.

Description

Technical Field

[0001] The present disclosure relates to conductive polymers. More specifically, the present disclosure includes highly conductive graphene-filled polymers for radio frequency interference (RFI) and electromagnetic interference (EMI) shielding. The compound can be processed as part of the manufacture of shielding components such as cables or enclosures. Background Art

[0002] Artificial and natural electromagnetic interference (EMI) sources can cause transient disturbances, data loss, and failures of electronic devices, equipment, and systems. These problems pose many challenges and are critical to the automotive, aerospace, defense, and medical industries.

[0003] Due to the exponential density growth of electronic products, EMI has increased significantly, which may reduce device performance and adjacent systems and even have an adverse impact on human health. Miniaturization further exacerbates the EMI problem because the mutual interference between device components or chip elements may produce local interference effects. This has prompted the development of appropriate countermeasures to suppress (or eliminate) the EMI effect.

[0004] Existing shielding methods to address these problems use brittle, inflexible, and heavy systems, as well as rigid enclosures, meshes, and foils made of heavy and expensive metals such as silver, copper, stainless steel, aluminum, and nickel.

[0005] Metals, due to their high electrical conductivity, are by far the most commonly used EMI shielding materials. However, they have problems such as high reflectivity, susceptibility to corrosion, weight loss, high carbon footprint, and uneconomical processing. Considering this, polymer-based blends and composites have attracted great attention due to the unique combination of electrical, thermal, dielectric, magnetic, and / or mechanical properties that can be used for effective electromagnetic shielding response.

[0006] Materials based on multilayer graphene have received extensive attention due to their unique properties. Recently, there have been multiple attempts to utilize the fascinating and promising properties of graphene-based nanocomposites, especially for electrical and electromagnetic shielding applications. The use of such high aspect ratio and electrically conductive materials provides suitable solutions for high EMI shielding and applications in cables, integrated electronics, sensors, batteries, transistors, and capacitors, etc.

[0007] Graphene-based structures have become the focus of numerous studies because their excellent electrical properties result in a shallow skin depth, enabling effective attenuation of the electromagnetic field through absorption losses within the shielding material. Additionally, due to its mechanical properties, graphene is considered a promising candidate for EMI shielding (C. Acquarelli, a Rinaldi, a Tamburrano, G. De Bellis, a G. D. Aloia, and M. S. Sarto, pp. 488 - 493, 2014) as it allows for the production of flexible and lightweight systems.

[0008] In summary, compared to traditional metallic shielding, graphene itself is more efficient, lighter, and more flexible, thus having the potential for commercial applications (J. Liang, Y. Wang, Y. Huang, Y. Ma, Z. Liu, and J. Cai, vol. 47, no. 3, pp. 922 - 925, 2008).

[0009] Document US11071241 B2 discloses an electromagnetic wave shielding material using graphene, an electromagnetic wave shielding film including graphene, and an electronic or electrical device including the electromagnetic wave shielding material or film. More specifically, this document discloses the use of graphene produced, for example, by chemical vapor deposition for electromagnetic wave shielding in a wide frequency band from about 2 GHz to about 18 GHz.

[0010] Document WO 2014 / 061048 A2 relates to the formulation and production of nanostructured materials based on graphite or graphene, in particular graphene nanoplatelets with controlled morphology and electrical properties, and the use of said GNPs as fillers at variable concentrations for the production of polymer matrix nanocomposites with controlled complex dielectric constant properties. More specifically, this document discloses the manufacture of thin sheets or coatings with shielding and / or radar absorption properties at radio frequencies (X and Ku bands, 8 - 18 GHz) through the use of said nanocomposites.

[0011] Document US 9174413 B2 includes a description of an electromagnetic interference shielding structure and a method for shielding an object from electromagnetic radiation with a frequency greater than 1 MHz, and it includes providing highly doped graphene sheets around the object to be shielded.

[0012] Document CN 104845361 A describes a highly conductive thermoplastic plastic synergistically reinforced by short carbon fibers and nano - high - conductive carbon black / graphene. This document discloses a complex two - step treatment of the surface of short - cut carbon fibers before use: 1) plasma cleaning to remove surface organic contaminants and non - carbon oxide compounds; and 2) chemical and physical etching to ensure the presence of carboxyl, carbonyl, and hydroxyl reactive groups.

[0013] Document CN 101072493 A relates to a polyethylene resin film. More specifically, it relates to a polyethylene film for shielding broadband electromagnetic waves and a method for preparing the same. This document discloses a mixture of metal fibers and metal conductive powders. More specifically, the metal fibers are a mixture of polycrystalline iron fibers and stainless steel fibers, and the metal conductive powders include nickel powder, copper powder, iron powder or aluminum powder. In addition, it also relates to other mixtures of metal fibers and carbon fibers. The metal fibers are polycrystalline iron fibers or stainless steel fibers; the carbon fibers are nicarbazin fibers or nickel-plated graphite fibers.

[0014] Document CN 1772798 A discloses a conductive plastic and its processing methods and equipment. The conductive plastic includes conductive fibers, thermoplastic plastics and processing aids. The conductive fibers are uniformly arranged into a three-dimensional network structure with multiple connection points, and the conductive plastic has high electrical conductivity, high antistatic effect and electromagnetic shielding effect, and low surface resistance and volume resistivity, and can be injection-molded, extruded and molded like ordinary plastics. In addition, this document also includes the uses of several compositions or mixtures such as steel fibers, carbon fibers, metallized carbon fibers, metallized glass fibers, metallized boron fibers and metallized silicon carbide fibers.

[0015] Document CN 105694427 B discloses a graphene-based composite material for electromagnetic shielding. Reduced graphene oxide is uniformly coated on the surface of the foam sponge skeleton to form a composite material with a conductive isotropic skeleton. An electromagnetic shielding effectiveness higher than 40 dB is generated at a thickness of 1.5 mm. At the same time, this material can withstand a compression deformation of up to 80%, showing good flexibility and elasticity. In addition, this document relates to a material with a density of only 0.05 g / cm 3 and provides a specific shielding effectiveness of up to 800 dB cm 3 / g.

[0016] The graphene-based composite material can be used in industrial methods, can be prepared in large quantities at low cost, and has the characteristics of versatility, high efficiency and low density.

[0017] The present disclosure proposes a lighter solution for electromagnetic shielding and having high electrical conductivity.

[0018] These facts are disclosed to illustrate the technical problems solved by the present disclosure. Summary of the Invention

[0019] General Description

[0020] The present disclosure relates to a graphene-based compound composition for RFI and EMI. In addition, the present disclosure also provides customized electrical conductivity and wave attenuation levels.

[0021] The compounds of the present disclosure include the following advantages:

[0022] Weight reduction of up to 75% through replacement of heavy metal shielding;

[0023] Excellent conductivity, with a sheet resistance of 0.1 to 500 Ohm / sq;

[0024] Attenuation greater than 20 dB in the radio and microwave frequency range from 3 kHz to 30 GHz;

[0025] In the microwave frequency range from 30 GHz to 300 GHz, preferably from 60 GHz to 90 GHz, the attenuation is greater than 50 dB.

[0026] The compound composition can be used as a radio frequency interference and electromagnetic interference (RFI&EMI) shielding part for industrial equipment, electronic components, medical equipment, communication equipment, office equipment, military equipment, automotive components, aerospace equipment, EMI / RFI shielding enclosures, automotive cables, solar panels, consumer electronics, mobile and flexible electronics, wearable electronics, board-level shields, and patches.

[0027] Also disclosed is a composition comprising a compound having a polymer matrix, which composition may contain additives and conductive carbon-based fillers (at least comprising graphene sheets). The graphene-based compound is compatible with large-scale production systems and can be further processed by extrusion, injection molding, thermoforming, or rotational molding.

[0028] The present disclosure relates to an electromagnetic wave shielding thermoplastic composition (weights are related to the final composition), comprising:

[0029] 0.1 wt.% to 50 wt.% of graphene as a first carbon-based conductive material;

[0030] 0.1 wt.% to 25 wt.% of another carbon-based conductive material;

[0031] 10 wt.% to 90 wt.% of a polymer matrix;

[0032] Wherein the weight ratio (wt / wt) of graphene to another carbon-based conductive material is from 3:1 to 1:1.

[0033] In an embodiment, for better results, the weight ratio (wt / wt) of graphene to another carbon-based conductive material is from 2.5:1 to 2:1, preferably 2:1. Significantly, the carbon-based conductive material has a very small particle size and a different aspect ratio compared to graphene particles (circular and flake-shaped respectively), so the present weight ratio promotes the dispersion of these particles during low-shear and high-shear processes and allows for particle percolation, which is an important condition for achieving optimal conductivity.

[0034] In an embodiment, the graphene is graphene functionalized with ferromagnetic particles, in particular at most 75 wt.% of the graphene is functionalized with ferromagnetic particles, and the weight ratio of graphene to ferromagnetic particles is from 2:1 to 1:2. In an embodiment, the ferromagnetic particles are iron oxide compounds. In particular, at most 50 wt.% of the graphene is functionalized with iron oxide, and the weight ratio of graphene to iron oxide is from 2:1 to 1:2.

[0035] In an embodiment, the composition further comprises ferromagnetic particles as fillers, in particular the composition comprises at most 20 wt.% of an additive containing ferromagnetic particles, in particular at most 20 wt.% of ferromagnetic particles.

[0036] In an embodiment, the composition further comprises additives selected from the following: plasticizers, compatibilizers, dispersants, antioxidants, etc. and combinations thereof.

[0037] In an embodiment, the other carbon-based conductive material is crystalline or semi-crystalline.

[0038] In an embodiment, the other carbon-based conductive material is nanostructured.

[0039] In an embodiment, the other carbon-based conductive material is a material comprising carbon-based particles (preferably a plurality of carbon-based particles with a particle size below 25 nm), which may respectively form chain-like particle aggregates with a length from 1 micron to 100 microns, as measured, for example, by scanning electron microscopy and measuring the maximum visible size of each particle using ImageJ software.

[0040] In an embodiment, the lateral size of the graphene is from 0.5 μm to 30 μm.

[0041] The measurement of the lateral size of graphene can be carried out in various ways, namely scanning electron microscopy (SEM), transmission electron microscopy (TEM), etc.; in the present disclosure, the lateral size of graphene is measured according to ISO / TS21356-1:2021.

[0042] In an embodiment, the graphene is in the form of flakes or nanosheets, with D10, D50, and D90 particle sizes less than 2 μm, 5 μm, and 15 μm, respectively, which is measured, for example, by collecting multiple images of more than 150 individual particles using a scanning electron microscope and measuring the maximum visible size of each particle using ImageJ software. In particular, the graphene is in the form of flakes or nanosheets, with an average particle lateral size of 3.2 ± 1.6 μm, which is measured by imaging 4698 individual particles using a scanning electron microscope according to the procedure of ISO / TS21356-1:2021 and first measuring the length of each particle and then measuring the width of each particle (measured perpendicular to the length) using ImageJ software. The measurement of the graphene size can be carried out in various ways, namely scanning electron microscopy (SEM), transmission electron microscopy (TEM), etc.; in the present disclosure, the graphene lateral size is measured according to ISO / TS21356-1:2021.

[0043] In an embodiment, the lateral size range of the graphene particles is from 1.5 μm to 5 μm; preferably from 1.6 μm to 4.5 μm; more preferably from 2 μm to 3.2 μm, which is measured by a scanning electron microscope.

[0044] The graphene size refers to the overall size or range of the graphene structure in three-dimensional space. It includes the length, width, and thickness (or height) of the graphene material.

[0045] On the other hand, the graphene lateral size specifically refers to the two-dimensional size of the graphene sheet or layer.

[0046] In an embodiment, another carbon-based conductive material is selected from the following list: natural and synthetic graphite, carbon black, carbon nanotubes, carbon fibers, carbon nano onions, graphene oxide, carbon nanospheres, fullerenes, or mixtures thereof.

[0047] In an embodiment, for better results, another carbon-based conductive material is carbon black. Carbon black consists of smaller round particles, which can fill the spaces between the graphene nanoparticles, promoting more contact sites between the two materials, which in turn leads to proper electroosmotic flow of the EMI shielding performance. The typical particle size of carbon black varies between 13 nm and 50 nm, or less than 25 nm.

[0048] In an embodiment, the amount of graphene is 1 wt.% to 30 wt.%, more preferably 5 wt.% to 20 wt.%.

[0049] In an embodiment, the amount of another carbon-based conductive material is 0.1 wt.% to 25 wt.%, preferably 0.3 wt.% to 20 wt.%, more preferably 0.5 wt.% to 15 wt.%, still more preferably 1 wt.% to 15 wt.%, and even more preferably 2 wt.% to 15 wt.%.

[0050] In an embodiment, the amount of carbon black is 0.1 wt.% to 25 wt.%, preferably 0.3 wt.% to 20 wt.%, more preferably 0.5 wt.% to 15 wt.%, still more preferably 1 wt.% to 15 wt.%, and even more preferably 2 wt.% to 15 wt.%.

[0051] In an embodiment, the polymer matrix is selected from the following list: polyvinyl chloride, polyamide, polybutylene terephthalate, cross-linked polyethylene, fluorinated ethylene propylene, polyethylene, polypropylene, polystyrene, acrylonitrile butadiene styrene, polylactic acid, polytetrafluoroethylene, polyethylene terephthalate, polymethyl methacrylate, thermoplastic elastomer, thermoplastic polyurethane, polychlorotrifluoroethylene, polyacrylonitrile, polycarbonate, polydimethylsiloxane, polyethersulfone, polysulfone, polyetheretherketone, polyphenylene sulfide, polyamideimide, and polyetherimide, or a mixture thereof.

[0052] In an embodiment, the polymer is polyvinyl chloride or polyamide or polybutylene terephthalate. Graphene and another carbon-based conductive material can be dispersed in these polar polymers because polar oxygen-containing functional groups prevent their re-stacking, thereby enhancing their conductive properties.

[0053] In an embodiment, the polymer matrix is polypropylene, polyvinyl chloride, or polyamide, or polybutylene terephthalate, or acrylonitrile-butadiene-styrene, or polyethylene.

[0054] In an embodiment, for better results, if the polymer matrix is polypropylene, the weight ratio (wt / wt) of graphene to another carbon-based conductive material is 1:2; if it is polyvinyl chloride, the weight ratio (wt / wt) of graphene to another carbon-based conductive material is 2:1; if it is polyamide, the weight ratio (wt / wt) of graphene to another carbon-based conductive material is 2:1; if it is polybutylene terephthalate, the weight ratio (wt / wt) of graphene to another carbon-based conductive material is 2:1; if it is acrylonitrile-butadiene-styrene, the weight ratio (wt / wt) of graphene to another carbon-based conductive material is 2:1; if it is polyethylene, the weight ratio (wt / wt) of graphene to another carbon-based conductive material is 1:1.

[0055] In an embodiment, the composition further comprises an additive.

[0056] In an embodiment, the amount of the additive is 0.1 wt.% to 25 wt.%, and the additive is preferably selected from a plasticizer, a dispersant, an antioxidant, or a combination thereof. For better results, the additive is a plasticizer and its amount is 0.1 wt.% to 25 wt.%. The amount of the plasticizer is determined according to the polymer matrix used and the desired final flexibility. The higher the amount of the plasticizer, the more flexible the resulting material.

[0057] In an embodiment, the plasticizer is selected from the following list: phthalate ester, trimellitate ester, aliphatic dibasic acid ester, benzoate ester, polyester, citrate ester, epoxidized soybean oil, epoxidized linseed oil (ELO), castor oil, palm oil, starch, sugar, phosphate ester, chlorinated paraffin, alkyl sulfonate ester, or a mixture thereof, preferably trimellitate ester.

[0058] In an embodiment, the composition further comprises ferromagnetic particles, particularly up to 20 wt.% of ferromagnetic particles.

[0059] In an embodiment, the composition is in liquid form; or solid form. Preferably, the liquid is in-situ polymerization, and the solid is compounding and masterbatch. Preferably, the composition is in the form of granules, powders or pellets.

[0060] In an embodiment, an incident electromagnetic wave having a wide frequency band from 1 kHz to 30 GHz is shielded with an efficiency higher than 20 dB.

[0061] In an embodiment, an incident electromagnetic wave having a wide frequency band from 30 GHz to 300 GHz is shielded with an efficiency higher than 50 dB.

[0062] In an embodiment, a planar slab of the composition with a thickness of at least 1 mm ensures a shielding efficiency higher than 20 dB and 50 dB for frequencies from 1 kHz to 30 GHz and from 30 GHz to 300 GHz, respectively.

[0063] In an embodiment, a planar slab of the composition with a thickness of at least 3 mm ensures a shielding efficiency higher than 40 dB and 85 dB for frequencies in the ranges from 1 kHz to 30 GHz and from 30 GHz to 300 GHz, respectively.

[0064] The present disclosure also relates to an electromagnetic wave shielding thermoplastic granule, thermoplastic powder, thermoplastic film, thermoplastic sheet or thermoplastic slurry, which comprises the composition disclosed in the foregoing embodiments.

[0065] The present disclosure also relates to the use of the composition as an electromagnetic wave shield, wherein the composition comprises:

[0066] 0.1 wt.% to 50 wt.% of graphene as the first carbon-based conductive material;

[0067] 0.1 wt.% to 25 wt.% of another carbon-based conductive material;

[0068] 10 wt.% to 90 wt.% of a polymer matrix;

[0069] wherein the weight ratio (wt / wt) of graphene to the other carbon-based conductive material ranges from 3:1 to 1:0.5; preferably from 3:1 to 1:1. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] The following drawings provide illustrations of preferred embodiments of the present disclosure and should not be considered as limiting the scope of the invention.

[0071] Figure 1 : A graphical representation of an embodiment of the EMI shielding performance of a 1 mm thick flat plate at low frequencies from 1 kHz to 3.5 GHz.

[0072] Figure 2 : A graphical representation of an embodiment of the EMI shielding performance of a 1 mm thick flat plate at high frequencies preferably from 60 GHz to 90 GHz.

[0073] Figure 3 : A graphical representation of an embodiment of the EMI shielding performance of a 3 mm thick slab at low frequencies from 1 kHz to 3.5 GHz.

[0074] Figure 4 : A graphical representation of an embodiment of the EMI shielding performance of a 3 mm thick sample at high frequencies preferably from 60 GHz to 90 GHz.

[0075] Figure 5 : A graphical representation of the results of scanning electron microscope images of the surface (upper left and upper right) and cross-section (lower left and lower right) of this specification, in which it can be seen how the carbon-based material (carbon black) and graphene nanoparticles achieve an agglomerate-free and non-heterogeneous cross-sectional surface at relevant dimensions to provide the required electromagnetic shielding. DETAILED DESCRIPTION

[0076] This specification relates to highly conductive graphene-based polymer compositions suitable for radio frequency interference (RFI) and electromagnetic interference (EMI) shielding applications, wherein in an embodiment, the composition comprises graphene nanosheets blended in a polymer matrix. The composition may also comprise other carbon-based fillers. These highly conductive graphene compounds can be used in a variety of processing methods such as extrusion, injection molding, thermoforming, or rotational molding.

[0077] The present disclosure relates to an electromagnetic wave shielding thermoplastic composition, comprising: 0.1 wt.% to 50 wt.% of graphene; 0.1 wt.% to 25 wt.% of another carbon-based conductive material; 10 wt.% to 90 wt.% of a polymer matrix; wherein the weight ratio (wt / wt) of graphene to the carbon-based conductive material is 3:1 to 1:1 (preferably 3:1 to 2:1); and wherein the another carbon-based conductive material is crystalline or semi-crystalline. The present disclosure also relates to an electromagnetic wave shielding thermoplastic granule, thermoplastic powder, thermoplastic film, thermoplastic sheet or thermoplastic slurry comprising the composition.

[0078] In an embodiment, the present disclosure can shield electromagnetic waves with an efficiency higher than 20 dB in a wide frequency band of 1 kHz to 30 GHz (preferably 30 MHz to 30 GHz) using a thickness of 1 mm.

[0079] In another embodiment, the present disclosure can shield electromagnetic waves with an efficiency higher than 50 dB in a wide frequency band of 30 GHz to 300 GHz using a thickness of 1 mm.

[0080] The preferred embodiments of the present specification will be described in detail with reference to the accompanying drawings. However, they are not intended to limit the scope of the present application.

[0081] In an embodiment, the present disclosure relates to a compound composition comprising graphene nanosheets for shielding electromagnetic interference in the frequency range of 1 kHz to 300 GHz.

[0082] In an embodiment, the composition is a graphene-based compound composition for EMI shielding, comprising:

[0083] 0.1 wt.% to 50 wt.%, preferably 1 wt.% to 30 wt.%; more preferably 5 wt.% to 20 wt.% of graphene nanosheets;

[0084] 0.1 wt.% to 25 wt.%, preferably 0.5 to 15 wt.% of other carbon-based materials for RFI and EMI shielding;

[0085] a polymer matrix in which the particles are melt-blended and dispersed, the particles being a mixture of graphene nanosheets and carbon-based materials, and the amount of the polymer matrix being 10 wt.% to 90 wt.%; and

[0086] 0.1 wt.% to 25 wt.% of optional additives, preferably the additive is a plasticizer.

[0087] In an embodiment, the weight ratio (wt / wt) of graphene to another carbon-based conductive material is 3:1 to 1:1, preferably 2.5:1 to 2:1, more preferably 2:1.

[0088] In one embodiment, another carbon-based conductive material is selected from the following list: natural and synthetic graphite, carbon black, carbon nanotubes, carbon fibers, carbon nano-onions, graphene oxide, or carbon nanospheres, fullerenes, or mixtures thereof. Preferably, the carbon-based material is carbon black.

[0089] In one embodiment, the polymer matrix is selected from the following list, but not limited to: polyvinyl chloride (PVC), polyamide (PA), polybutylene terephthalate (PBT), crosslinked polyethylene (XLPE), fluorinated ethylene propylene (FEP), polyethylene (PE), polypropylene (PP), polystyrene (PS), acrylonitrile-butadiene-styrene (ABS), polylactic acid (PLA), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), thermoplastic elastomer (TPE), thermoplastic polyurethane (TPU), polychlorotrifluoroethylene (PCTFE), polyacrylonitrile (PAN), polycarbonate (PC), polydimethylsiloxane (PDMS), polyethersulfone (PES), polysulfone (PSU), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyamideimide (PAI) and polyetherimide (PEI), or mixtures thereof.

[0090] In one embodiment, the plasticizer is selected from the following list: phthalates, aliphatic dibasic acid esters, benzoates, polyesters, citrates, epoxidized soybean oil (ESBO), epoxidized linseed oil (ELO), castor oil, palm oil, starch, sugar, phosphate esters, chlorinated paraffins, alkyl sulfonates, and more preferably trimellitates, or mixtures thereof.

[0091] In an embodiment, the amount of the plasticizer is 0.1 wt.% to 25 wt.%.

[0092] In an embodiment, the graphene contains an oxygen content of less than 5 atomic%, which can simultaneously achieve good conductivity and dispersibility of its particles in a polar polymer system. This will improve the overall shielding effectiveness. In an embodiment, the thickness of the graphene particles is 1 nm to 50 nm.

[0093] In an embodiment, the electromagnetic wave shielding thermoplastic composition is placed in the form of a flat plate, and the sheet resistance is preferably adjusted to 0.1 ohm / sq to 500 ohm / sq in order to achieve electroosmotic flow according to the polymer matrix in use, thereby achieving a balance between the polymer matrix and conductivity.

[0094] In one embodiment, the volume resistivity of the composition is 1×10 -5 to 2×10 -3 ohm·cm.

[0095] In an embodiment, the composition is processed by extrusion, injection molding, thermoforming, or rotational molding.

[0096] In an embodiment, the composition is obtained by melt blending / compounding, or melt extrusion, or solvent melt / compounding, or in-situ polymerization of a mixture. Preferably, the composition is obtained by melt blending.

[0097] In an embodiment, Figure 1 The low-frequency attenuation of a 1-mm thick flat plate from 1 kHz to 4.2 GHz is shown, which exhibits good attenuation (>30 dB), mainly due to the high absorption ability (insertion loss) of the incident EM waves.

[0098] In an embodiment, Figure 2 The high-frequency attenuation of a 1-mm thick flat plate from 60 GHz to 90 GHz is shown, which exhibits high attenuation (>50 dB), mainly due to the high absorption ability (insertion loss) of the incident EM waves.

[0099] In an embodiment, Figure 3 The low-frequency attenuation of a 3-mm thick flat plate from 1 kHz to 4.2 GHz is shown, exhibiting good attenuation (>40 dB), mainly due to the high absorption ability (insertion loss) of the incident EM waves.

[0100] In an embodiment, Figure 4 The high-frequency attenuation of a 3-mm thick flat plate from 60 GHz to 90 GHz is shown, exhibiting high attenuation (>85 dB), mainly due to the high absorption ability (insertion loss) of the incident EM waves.

[0101] In an embodiment, Figure 5 Four scanning electron microscope images of the surface (upper left (A) and upper right (B)) and cross-section (lower left (C) and lower right (D)) of the present disclosure are shown. It can be observed that no particle agglomerates are formed and uniform dispersion can be achieved, thus verifying the synergistic effect between graphene sheets and carbon black. Uniform particle dispersion throughout the plate thickness can also be observed from the cross-sectional images (C and D), and most of the graphene sheets are oriented in the same direction.

[0102] The term "comprising" whenever used in this document is intended to mean the presence of the stated features, integers, steps, components, but does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof.

[0103] The present disclosure should not in any way be construed as limited to the described embodiments, and many possibilities of its modification will be foreseen by those of ordinary skill in the art. The above embodiments are combinable.

[0104] The following claims further elaborate specific embodiments of the present disclosure.

Claims

1. An electromagnetic wave shielding thermoplastic composition, comprising: 0.1 wt.% to 50 wt.% of graphene as a first carbon-based conductive material; 0.1 wt.% to 25 wt.% of another carbon-based conductive material; 10 wt.% to 90 wt.% of a polymer matrix; wherein the weight ratio (wt / wt) of graphene to the another carbon-based conductive material ranges from 3:1 to 2:1; wherein the another carbon-based conductive material is crystalline or semi-crystalline.

2. The composition according to the previous claim, wherein the weight ratio (wt / wt) of graphene to the another carbon-based conductive material is from 2.5:1 to 2:

1.

3. The composition according to any one of the preceding claims, wherein the weight ratio (wt / wt) of graphene to the another carbon-based conductive material is 2:

1.

4. The composition according to any one of the preceding claims, wherein the another carbon-based conductive material is a material comprising carbon-based particles and / or is nanostructured.

5. The composition according to any one of the preceding claims, wherein the another carbon-based conductive material is selected from the following list: natural and synthetic graphite, carbon black, carbon nanotubes, carbon fibers, carbon nano-onions, graphene oxide, carbon nanospheres, fullerenes, or mixtures thereof.

6. The composition according to the previous claim, wherein the another carbon-based conductive material is carbon black.

7. The composition according to any one of the preceding claims, wherein the lateral size of graphene is from 0.5 μm to 30 μm.

8. The composition according to any one of the preceding claims, wherein graphene is in the form of flakes or nanosheets, and the lateral size of the particles ranges from 1.5 μm to 5 μm; preferably from 1.6 μm to 4.5 μm; more preferably from 2 μm to 3.2 μm.

9. The composition according to any one of the preceding claims, wherein the amount of graphene is from 1 wt.% to 30 wt.%, more preferably from 5 wt.% to 20 wt.%.

10. The composition according to any one of the preceding claims, wherein graphene is functionalized with ferromagnetic particles.

11. The composition according to the previous claim, graphene is functionalized with ferromagnetic particles, and at most 75 wt.% of the graphene is functionalized with ferromagnetic particles.

12. The composition according to any one of claims 10-11 preceding, wherein the ferromagnetic particles are iron oxides.

13. The composition according to any one of the preceding claims, wherein the amount of the another carbon-based conductive material ranges from 0.3 wt.% to 20 wt.%, more preferably from 0.5 wt.% to 15 wt.%, more preferably from 1 wt.% to 15 wt.%, more preferably from 2 wt.% to 15 wt.%.

14. The composition according to any one of the preceding claims, wherein the polymer matrix is selected from the following list: polyvinyl chloride, polyamide, polybutylene terephthalate, crosslinked polyethylene, fluorinated ethylene propylene, polyethylene, polypropylene, polystyrene, acrylonitrile butadiene styrene, polylactic acid, polytetrafluoroethylene, polyethylene terephthalate, polymethyl methacrylate, thermoplastic elastomer, thermoplastic polyurethane, polychlorotrifluoroethylene, polyacrylonitrile, polycarbonate, polydimethylsiloxane, polyethersulfone, polysulfone, polyetheretherketone, polyphenylene sulfide, polyamideimide and polyetherimide, or a mixture thereof.

15. The composition according to any one of the preceding claims, wherein the polymer matrix is polypropylene, polyvinyl chloride, or polyamide, or polybutylene terephthalate, or acrylonitrile butadiene styrene, or polyethylene.

16. The composition according to any one of the preceding claims, the composition further comprising 0.1 wt.% to 25 wt.% of an additive selected from plasticizers, dispersants, antioxidants, or combinations thereof.

17. The composition according to the previous claim, wherein the additive is a plasticizer selected from the following list: phthalates, trimellitates, aliphatic dibasic acid esters, benzoates, polyesters, citrates, epoxidized soybean oil, epoxidized linseed oil (ELO), castor oil, palm oil, starch, sugar, phosphate esters, chlorinated paraffins, alkyl sulfonates, or mixtures thereof, preferably trimellitates.

18. The composition according to any one of the preceding claims, the composition further comprising ferromagnetic particles, particularly comprising up to 20 wt.% of ferromagnetic particles.

19. An electromagnetic wave shielding thermoplastic pellet, thermoplastic powder, thermoplastic film, thermoplastic sheet or thermoplastic slurry comprising the composition according to any one of claims 1-18 above.

20. Use of the composition as an electromagnetic wave shield, wherein the composition comprises: 0.1 wt.% to 50 wt.% of graphene as a first carbon-based conductive material; 0.1 wt.% to 25 wt.% of another carbon-based conductive material; 10 wt.% to 90 wt.% of a polymer matrix; wherein the weight ratio (wt / wt) of graphene to the another carbon-based conductive material ranges from 3:1 to 1:0.5; preferably 3:1 to 1:1.

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