Electromagnetic wave shielding thermoplastic composition

Abstract

The present invention relates to an electromagnetic wave shielding thermoplastic composition comprising 0.1 to 50 wt% graphene, 0.1 to 25 wt% additional carbon-based conductive material, and 10 to 90 wt% polymer matrix. The weight ratio (wt / wt) of graphene to the carbon-based conductive material is 3:1 to 1:1, and the additional carbon-based conductive material is crystalline or semi-crystalline. The present invention also relates to an electromagnetic wave shielding thermoplastic granule, thermoplastic powder, thermoplastic film, thermoplastic sheet, or thermoplastic paste 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 compounds can be processed as part of the manufacture of shielding components such as cables or housings. [Background technology]

[0002] Man-made and naturally occurring sources of electromagnetic interference (EMI) can cause temporary disruptions, data loss, and failures of electronic devices, equipment, and systems. These issues pose many challenges and are of critical importance to the automotive, aerospace, defense, and medical industries.

[0003] Due to the rapidly increasing density of electronic devices, EMI increases exponentially, which can degrade device performance and adjacent systems, as well as adversely affect the human body. Miniaturization exacerbates the EMI problem because mutual interference between device components or chip elements can cause localized interference effects. This has prompted the development of appropriate countermeasures to suppress (or eliminate) the effects of EMI.

[0004] Existing shielding methods that address these issues use brittle, inflexible, and heavy systems, as well as rigid housings, meshes, and foils made from heavy and expensive metals such as silver, copper, stainless steel, aluminum, and nickel.

[0005] Metals are the most widely used EMI shielding materials due to their high electrical conductivity. However, they suffer from issues such as high reflectivity, corrosion susceptibility, weight gain, high carbon footprint, and economical processing costs. Due to these issues, polymer-based blends and composites have attracted significant attention due to their unique combinations of electrical, thermal, dielectric, magnetic, and / or mechanical properties that are useful for efficient electromagnetic shielding response.

[0006] Multilayer graphene-based materials have attracted considerable attention due to their unique properties. In recent years, numerous attempts have been made to exploit the attractive and promising properties of graphene-based nanocomposites, especially for electrical and electromagnetic shielding applications. This high-aspect-ratio, highly conductive material offers a suitable solution for high EMI shielding, as well as applications in cables, integrated electronics, sensors, batteries, transistors, capacitors, etc.

[0007] Graphene-based structures have been the subject of much research, as their excellent electrical properties allow for a small skin depth, leading to efficient attenuation of electromagnetic fields due to absorption losses within the shielding material. Furthermore, due to its mechanical properties, graphene is considered a promising candidate material for EMI shielding, as it allows for the fabrication of flexible and lightweight systems (C. Acquarelli, Rinaldi, Tamburrano, G. De Bellis, GDAloia, MSSarto, pp. 488-493, 2014).

[0008] In summary, compared to traditional metal shields, graphene itself is more efficient, lightweight, and flexible, making it potentially suitable 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] U.S. Patent No. 1,107,1241 discloses an electromagnetic wave shielding material using graphene, an electromagnetic wave shielding film containing graphene, and an electronic device or electrical device containing the electromagnetic wave shielding material or film. More specifically, this document discloses shielding of electromagnetic waves in a wide frequency band from about 2 GHz to about 18 GHz using graphene produced by, for example, chemical vapor deposition.

[0010] WO 2014 / 061048 relates to the formulation and preparation of graphite- or graphene-based nanostructured materials, in particular graphene nanoplatelets with controlled morphology and electrical properties, and the use of such GNPs as fillers with variable concentrations for the preparation of polymer matrix nanocomposites with controlled complex permittivity properties. More specifically, the document discloses the use of such nanocomposites to produce sheets or coatings with shielding and / or radar-absorbing properties at radio frequencies (X-band and Ku-band, 8-18 GHz).

[0011] The document US Pat. No. 9,174,413 includes a description of an electromagnetic interference shielding structure and method for shielding an object from electromagnetic radiation at frequencies above 1 megahertz, which involves providing a highly doped graphene sheet around the object to be shielded.

[0012] CN104845361 describes highly conductive thermoplastics reinforced with a combination of chopped carbon fibers and nano-highly conductive carbon black / graphene. The document discloses a complex two-step treatment of the short carbon fiber surface before use: (1) plasma cleaning to remove organic contaminants and non-carbon oxides from the surface, and (2) chemical and physical etching to ensure the presence of carboxyl, carbonyl, and hydroxyl reactive groups.

[0013] Chinese Patent Publication No. 101072493 relates to a type of polyvinyl resin film. More specifically, it relates to a polyethylene film for broadband electromagnetic wave shielding and its preparation method. This document discloses a mixture of metal fibers and metal conductive powder. More specifically, the metal fibers are a mixture of polycrystalline iron fibers and stainless steel fibers, while the metal conductive powder includes nickel powder, copper powder, iron powder, or aluminum powder. It also relates to other mixtures of metal fibers and carbon fibers. The metal fibers are polycrystalline iron fibers or stainless steel fibers, and the carbon fibers are nicarbazin fibers or nickel-plated graphite fibers.

[0014] Chinese Patent Publication No. 1772798 discloses a type of conductive plastic and its processing method and apparatus. The conductive plastic includes conductive fibers, a thermoplastic, and a machining aid. The conductive fibers are arranged in a uniform 3D network structure with multiple junctions, resulting in high conductivity, high antistatic and electromagnetic shielding effects, and low surface and volume resistivity. It can be injection molded, extruded, and molded like common plastics. Furthermore, this publication also covers the use of multiple compositions or mixtures of steel fibers, carbon fibers, metallized carbon fibers, metallized glass fibers, metallized boron fibers, and metallized silicon carbide fibers.

[0015] The document China Patent No. 105694427 discloses a graphene-based composite material for electromagnetic shielding. By uniformly coating reduced graphene oxide on the surface of a foam sponge skeleton, a composite with an electrically conductive isotropic skeleton is realized. An electromagnetic shielding effect of over 40 dB can be achieved at a thickness of 1.5 mm. At the same time, the material exhibits excellent flexibility and elasticity, being able to withstand a compressive deformation of up to 80%. Furthermore, the document reports that the density is only 0.05 g / cm. 3 The material has a specific shielding effect of up to 800dBcm 3 / g.

[0016] Graphene-based composites can be used in industrial processes, can be produced in large quantities at low cost, and are characterized by versatility, efficiency, and low density.

[0017] The present disclosure provides a lightweight solution with electromagnetic shielding and high conductivity.

[0018] These facts are disclosed to explain the technical problem addressed by the present disclosure. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] U.S. Patent No. 1,107,1241 [Patent Document 2] International Publication No. 2014 / 061048 [Patent Document 3] U.S. Patent No. 9,174,413 [Patent Document 4] Chinese Patent Application Publication No. 104845361 [Patent Document 5] Chinese Patent Application Publication No. 101072493 [Patent Document 6] Chinese Patent Application Publication No. 1772798 [Patent Document 7] Chinese Patent No. 105694427 [Non-patent literature]

[0020] [Non-Patent Document 1] C. Acquarelli, Rinaldi, Tamburrano, G. De Bellis, GDAloia, MSSarto, pp.488-493, 2014 [Non-patent document 2] J. Liang, Y. Wang, Y. Huang, Y. Ma, Z. Liu, and J. Cai, vol.47, no.3, pp.922-925, 2008 Summary of the Invention [Problem to be solved by the invention]

[0021] The present disclosure relates to graphene-based composite compositions for RFI and EMI. Additionally, the present disclosure also provides customized electrical conductivity and radio wave attenuation levels. [Means for solving the problem]

[0022] The compounds of the present disclosure are Up to 75% weight reduction by replacing heavy metal shielding, Excellent electrical conductivity with a planar electrical resistivity of 0.1 to 500 ohms / sq. Over 20dB attenuation in the radio and microwave frequency range from 3KHz to 30GHz, an attenuation of more than 50 dB in the microwave frequency range of 30 GHz to 300 GHz, preferably 60 GHz to 90 GHz; It has the advantage of:

[0023] The composite compositions can be applied as radio frequency interference and electromagnetic interference (RFI and EMI) shielding parts in industrial equipment, electronic components, medical devices, communication devices, office devices, military devices, automotive components, aerospace devices, EMI / RFI shielding enclosures, automotive cables, solar panels, consumer electronics, mobile and flexible electronics, wearable electronics, board level shielding, patches, and the like.

[0024] It also discloses a composition comprising a compound having a polymer matrix, which may contain additives, and a conductive carbon-based filler comprising at least graphene platelets. The graphene-based compound is compatible with large-scale production systems and can be further processed by extrusion, injection molding, thermoforming, or rotational molding.

[0025] The present disclosure provides: 0.1 to 50 wt % graphene as a first carbon-based conductive material; 0.1 to 25 wt. % of a further carbon-based conductive material; 10 to 90 wt. % of a polymer matrix; The weight ratio (wt / wt) of graphene to the further carbon-based conductive material is in the range of 3:1 to 1:1; It relates to an electromagnetic wave shielding thermoplastic composition (by weight in terms of final composition).

[0026] In an embodiment for better results, the weight ratio (wt / wt) of graphene to other carbon-based conductive materials is 2.5:1 to 2:1, preferably 2:1. Notably, because the carbon-based conductive materials have very small particle sizes and different aspect ratios (round vs. flake, respectively) compared to graphene particles, this weight ratio facilitates particle dispersion in low-shear and high-shear processes, achieving particle percolation, which is a key condition for obtaining optimal electrical conductivity.

[0027] In one embodiment, the graphene is functionalized with ferromagnetic particles, particularly where up to 75% by weight of the graphene is functionalized with ferromagnetic particles, and the weight ratio of graphene to ferromagnetic particles is between 2:1 and 1:2. In one embodiment, the ferromagnetic particles are iron oxide compounds, particularly where up to 50% by weight of the graphene is functionalized with iron oxide, and the weight ratio of graphene to iron oxide is between 2:1 and 1:2.

[0028] In one embodiment, the composition further comprises ferromagnetic particles as filler, in particular the composition comprises up to 20% by weight of an additive containing ferromagnetic particles, in particular up to 20% by weight of ferromagnetic particles.

[0029] In one embodiment, the composition further comprises an additive selected from plasticizers, compatibilizers, dispersants, antioxidants, and the like, and combinations thereof.

[0030] In one embodiment, the additional carbon-based conductive material is crystalline or semi-crystalline.

[0031] In one embodiment, the further carbon-based conductive material is nanostructured.

[0032] In one embodiment, the additional carbon-based conductive material is a material comprising carbon-based particles, preferably a plurality of carbon-based particles having a particle size of less than 25 nm, capable of forming chain-like aggregates of particles each 1 to 100 micrometers in length, as measured, for example, by scanning electron microscopy and using ImageJ software to measure the maximum visible size of each particle.

[0033] In one embodiment, the lateral size of the graphene is 0.5 to 30 μm.

[0034] Measurement of the lateral size of graphene can be performed by various methods, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), etc. In this disclosure, the lateral size of graphene was measured according to ISO / TS 21356-1:2021.

[0035] In one embodiment, the graphene is in the form of platelets or nanoplatelets with D10, D50, and D90 particle sizes of less than 2, 5, and 15 μm, respectively, as measured, for example, by collecting multiple images with more than 150 individual particles by scanning electron microscopy and measuring the maximum visible size of each particle using ImageJ software. In particular, the graphene is in the form of platelets or nanoplatelets with an average particle lateral size of 3.2±1.6 μm, as measured by imaging 4698 individual particles with a scanning electron microscope and measuring first the length and then the width (perpendicular to the length measurement) for each particle using ImageJ software, according to the procedures of ISO / TS 21356-1:2021. Graphene size measurements can be performed by various methods, such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In the present disclosure, the lateral size of graphene was measured according to ISO / TS 21356-1:2021.

[0036] In one embodiment, the lateral size of the graphene particles is in the range of 1.5 to 5 μm, preferably 1.6 to 4.5 μm, more preferably 2 to 3.2 μm, as measured by scanning electron microscopy.

[0037] Graphene size refers to the overall dimensions or extent of the graphene structure in three-dimensional space, including the length, width, and thickness (or height) of the graphene material.

[0038] The lateral size of graphene, on the other hand, refers to the two-dimensional dimensions of a graphene sheet or layer.

[0039] In one embodiment, the additional carbon-based conductive material is selected from natural and synthetic graphite, carbon black, carbon nanotubes, carbon fibers, carbon nano-onions, graphene oxide, carbon nanospheres, fullerenes, or mixtures thereof.

[0040] In one embodiment, for better results, an additional carbon-based conductive material is carbon black. Carbon black is composed of smaller, rounded particles that can fill the spaces between graphene nanoparticles, promoting a greater number of contact sites between the two materials and resulting in electrical percolation suitable for EMI shielding performance. Typical particle sizes of carbon black are 13-50 nm, or less than 25 nm.

[0041] In one embodiment, the amount of graphene is 1 to 30 wt %, more preferably 5 to 20 wt %.

[0042] In one embodiment, the amount of the additional carbon-based conductive material is 0.1 to 25% by weight, preferably 0.3 to 20% by weight, more preferably 0.5 to 15% by weight, even more preferably 1 to 15% by weight, and even more preferably 2 to 15% by weight.

[0043] In one embodiment, the amount of carbon black is 0.1 to 25% by weight, preferably 0.3 to 20% by weight, more preferably 0.5 to 15% by weight, more preferably 1 to 15% by weight, more preferably 2 to 15% by weight.

[0044] In one embodiment, the polymer matrix is ​​selected from 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 elastomers, thermoplastic polyurethanes, polychlorotrifluoroethylene, polyacrylonitrile, polycarbonate, polydimethylsiloxane, polyethersulfone, polysulfone, polyetheretherketone, polyphenylene sulfide, polyamideimide, and polyetherimide, or mixtures thereof.

[0045] In one embodiment, the polymer is polyvinyl chloride, polyamide, or polybutylene terephthalate. Graphene and additional carbon-based conductive materials can be dispersed in these polar polymers, with the polar oxygen-containing functional groups preventing their re-stacking, thereby improving conductivity.

[0046] In one embodiment, the polymer matrix is ​​polypropylene, polyvinyl chloride, polyamide, polybutylene terephthalate, acrylonitrile butadiene styrene, or polyethylene.

[0047] In one embodiment, to achieve better results, when the polymer matrix is ​​polypropylene, the weight ratio (wt / wt) of graphene to the additional carbon-based conductive material is 1:2; when the polymer matrix is ​​polyvinyl chloride, the weight ratio (wt / wt) of graphene to the additional carbon-based conductive material is 2:1; when the polymer matrix is ​​polyamide, the weight ratio (wt / wt) of graphene to the additional carbon-based conductive material is 2:1; when the polymer matrix is ​​polybutylene terephthalate, the weight ratio (wt / wt) of graphene to the additional carbon-based conductive material is 2:1; when the polymer matrix is ​​acrylonitrile butadiene styrene, the weight ratio (wt / wt) of graphene to the additional carbon-based conductive material is 2:1; and when the polymer matrix is ​​polyethylene, the weight ratio (wt / wt) of graphene to the additional carbon-based conductive material is 1:1.

[0048] In one embodiment, the composition further comprises an additive.

[0049] In one embodiment, the amount of additive is 0.1 to 25% by weight, preferably selected from plasticizers, dispersants, antioxidants, or combinations thereof. For better results, the additive is a plasticizer, and the amount is 0.1 to 25% by weight. The amount of plasticizer is determined depending on the polymer matrix used and the final flexibility desired. The higher the amount of plasticizer, the more flexible the material will be.

[0050] In one embodiment, the plasticizer is selected from phthalates, trimellitates, aliphatic dibasic esters, benzoates, polyesters, citrates, epoxidized soybean oil, epoxidized linseed oil (ELO), castor oil, palm oil, starch, sugars, phosphates, chlorinated paraffins, alkyl sulfonates, or mixtures thereof, preferably trimellitates.

[0051] In one embodiment, the composition further comprises ferromagnetic particles, in particular up to 20% by weight of ferromagnetic particles.

[0052] In one embodiment, the composition is in liquid or solid form. Preferably, the liquid is in situ polymerization, and the solid is compounding and masterbatch. Preferably, the composition is in particle, powder, or granular form.

[0053] In one embodiment, incident electromagnetic waves having a wide frequency band from 1 kHz to 30 GHz are shielded with an effectiveness of over 20 dB.

[0054] In one embodiment, incident electromagnetic waves having a wide frequency band from 30 GHZ to 300 GHZ are shielded with an effectiveness of over 50 dB.

[0055] In one embodiment, a planar slab of the composition having a thickness of at least 1 mm ensures a shielding effectiveness of greater than 20 dB and 50 dB for frequencies between 1 kHz and 30 GHz and between 30 GHz and 300 GHz, respectively.

[0056] In one embodiment, a planar slab of the composition having a thickness of at least 3 mm ensures a shielding effectiveness of greater than 40 dB and 85 dB for frequencies ranging from 1 kHz to 30 GHz and from 30 GHz to 300 GHz, respectively.

[0057] The present disclosure also relates to an electromagnetic wave shielding thermoplastic granule, thermoplastic powder, thermoplastic film, thermoplastic sheet or thermoplastic paste comprising the composition according to the above embodiments.

[0058] The present disclosure also relates to the use of the composition as an electromagnetic wave shield, the composition comprising: 0.1 to 50 wt % graphene as a first carbon-based conductive material; 0.1 to 25 wt. % of a further carbon-based conductive material; 10 to 90 wt. % of a polymer matrix; The weight ratio (wt / wt) of graphene to the further carbon-based conductive material is in the range of 3:1 to 1:0.5, preferably 3:1 to 1:1.

[0059] The accompanying drawings provide preferred embodiments for illustrating the present disclosure and should not be considered as limiting the scope of the present invention. [Brief explanation of the drawings]

[0060] [Figure 1] 1 is a graphical representation of an embodiment showing the EMI shielding performance of a 1 mm thick planar slab at low frequencies from 1 kHz to 3.5 GHz. [Figure 2] 1 is a graphical representation of an embodiment showing the EMI shielding performance of a 1 mm thick planar slab at high frequencies, preferably between 60 GHz and 90 GHz. [Figure 3] 1 is a graphical representation of an embodiment showing the EMI shielding performance of a 3 mm thick slab at low frequencies from 1 kHz to 3.5 GHz. [Figure 4] 1 is a graphical representation of an embodiment showing the EMI shielding performance of a 3 millimeter thick sample at high frequencies, preferably 60 GHz to 90 GHz. [Figure 5] 1 is a graphical representation of the results of surface (top left and top right figures) and cross-sectional (bottom left and bottom right) scanning electron microscope images herein, showing how carbon-based materials (carbon black) and graphene nanoparticles achieve a non-heterogeneous cross-sectional surface free of agglomerates at relevant dimensions to provide the desired electromagnetic shielding. DETAILED DESCRIPTION OF THE INVENTION

[0061] The present invention relates to highly conductive graphene-based polymer compositions suitable for radio frequency shielding (RFI) and electromagnetic interference shielding (EMI) applications. In one embodiment, the compositions comprise graphene nanoplatelets blended within a polymer matrix. The compositions may further comprise other carbon-based fillers. These highly conductive graphene compounds can be used in multiple processing methods, including extrusion, injection molding, thermoforming, or rotational molding.

[0062] The present disclosure provides a carbon-based conductive material comprising 0.1 to 50 wt. % graphene as a first carbon-based conductive material; 0.1 to 25 wt. % of a further carbon-based conductive material; 10 to 90 wt. % of a polymer matrix; The present invention relates to an electromagnetic wave shielding thermoplastic composition, in which the weight ratio (wt / wt) of graphene to the additional carbon-based conductive material is in the range of 3:1 to 1:1 (preferably 3:1 to 2:1), and the additional carbon-based conductive material is crystalline or semi-crystalline. The present invention also relates to an electromagnetic wave shielding thermoplastic granule, thermoplastic powder, thermoplastic film, thermoplastic sheet, or thermoplastic paste comprising the composition.

[0063] In one embodiment, the present invention can shield electromagnetic waves with an effectiveness of over 20 dB in a wide frequency band from 1 kHz to 30 GHZ, preferably from 30 MHZ to 30 GHZ, using a thickness of 1 mm.

[0064] In another embodiment, the present invention can shield electromagnetic waves with an effectiveness of 50 dB or more in a wide frequency band from 30 GHz to 300 GHz using a thickness of 1 mm.

[0065] Preferred embodiments of the present specification will be described in detail with reference to the drawings, but these embodiments do not limit the scope of the present invention.

[0066] In one embodiment, the present disclosure relates to a composite composition comprising graphene nanoplatelets for shielding electromagnetic interference at frequencies between 1 kHz and 300 GHz.

[0067] In one embodiment, the composition comprises: 0.1 to 50 wt %, preferably 1 to 30 wt %, more preferably 5 to 20 wt % of graphene nanoplatelets; 0.1 to 25 wt. %, preferably 0.5 to 15 wt. %, of other carbon-based materials for RFI and EMI shielding; a polymer matrix in which particles are melt-blended and dispersed, the particles being a mixture of graphene nanoplatelets and carbon-based materials, the amount of the polymer matrix being 10-90 wt%; 0.1 to 25 wt. % of an additional additive, preferably the additive is a plasticizer; A graphene-based composite composition for EMI shielding comprising:

[0068] In one embodiment, the weight ratio (wt / wt) of graphene to the further carbon-based conductive material is from 3:1 to 1:1, preferably from 2.5:1 to 2:1, more preferably 2:1.

[0069] In one embodiment, the further carbon-based conductive material is selected from 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.

[0070] In one embodiment, the polymer matrix is ​​selected from, but is not limited to, polyvinyl chloride (PVC), polyamide (PA), polybutylene terephthalate (PBT), cross-linked polyethylene (XLPE), fluorinated ethylene propylene (FEP), polyethylene (PE), polypropylene (PP), polystyrene (PS), acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), polyethyl ethacrylate (PMMA), thermoplastic elastomers (TPE), thermoplastic polyurethanes (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.

[0071] In one embodiment, the plasticizer is selected from phthalates, aliphatic dibasic esters, benzoates, polyesters, citrates, epoxidized soybean oil (ESBO), epoxidized linseed oil (ELO), castor oil, palm oil, starch, sugars, phosphates, chlorinated paraffins, alkyl sulfonates, more preferably trimellitic acid, or mixtures thereof.

[0072] In one embodiment, the amount of plasticizer is 0.1 to 25% by weight.

[0073] In one embodiment, the graphene contains less than 5 atomic % oxygen, which allows for good electrical conductivity and particle dispersibility in polar polymer systems, improving overall shielding effectiveness. In one embodiment, the graphene particles have a thickness of 1 to 50 nm.

[0074] In one embodiment, the electromagnetic wave shielding thermoplastic composition is placed in the form of a planar slab, and the sheet resistance is adjusted to preferably 0.1 to 500 ohms / sq to achieve electrical percolation depending on the polymer matrix used, thereby achieving a balance between the polymer matrix and electrical conductivity.

[0075] In one embodiment, the composition has a bulk electrical resistivity of 1×10 -5 ~2×10 -3 ohm·cm.

[0076] In one embodiment, the composition is processed by extrusion, injection molding, thermoforming, or rotational molding.

[0077] In one embodiment, the composition is obtained by hot melt mixing / blending, hot melt extrusion, solvent melting / blending, or in situ polymerization mixing. Preferably, the composition is obtained by hot melt mixing.

[0078] In one embodiment, Figure 1 shows the low frequency attenuation from 1 kHz to 4.2 GHz for a 1 mm thick planar slab that exhibits good attenuation (greater than 30 dB) due to its high absorption capability (insertion loss) of incident electromagnetic waves.

[0079] In one embodiment, Figure 2 shows the high frequency attenuation between 60 and 90 GHz for a 1 mm thick planar slab, which exhibits high attenuation (greater than 50 dB) primarily due to its high absorption capability (insertion loss) of the incident EM waves.

[0080] In one embodiment, Figure 3 shows the low frequency attenuation from 1 kHz to 4.2 GHz for a 3 mm thick planar slab that exhibits good attenuation (greater than 40 dB) due to its high absorption capability (insertion loss) of the incident EM waves.

[0081] In one embodiment, Figure 4 shows the high frequency attenuation between 60 and 90 GHz for a 3 mm thick planar slab, which exhibits high attenuation (greater than 85 dB) primarily due to its high absorption capability (insertion loss) of incident EM waves.

[0082] In one embodiment, Figure 5 shows four scanning electron microscope images of the surface (top left (A) and top right (B)) and cross-section (bottom left (C) and bottom right (D)) of the present disclosure. It can be observed that no particle agglomerates are formed and a uniform dispersion can be achieved, demonstrating the synergistic effect of graphene platelets and carbon black. From the cross-sectional images (C and D), a uniform particle dispersion is observed throughout the thickness of the slab, with the graphene platelets oriented in approximately the same direction.

[0083] The term "comprising" as used in this document is intended to indicate the presence of stated features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0084] The present disclosure is not limited to the described embodiments, and those skilled in the art will envision many possible variations of the present invention. The above embodiments can be combined.

[0085] The accompanying claims further define particular embodiments of the present disclosure.

Claims

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

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

1.

3. 3. The composition of claim 1, wherein the weight ratio (wt / wt) of the graphene to the further carbon-based conductive material is 2:

1.

4. 4. The composition of claim 1, wherein the further carbon-based conductive material is a material comprising carbon-based particles and / or is nanostructured.

5. 5. The composition of claim 1, wherein the further carbon-based conductive material is selected from natural and synthetic graphite, carbon black, carbon nanotubes, carbon fibers, carbon nano-onions, graphene oxide, carbon nanospheres, fullerenes, or mixtures thereof.

6. The composition of claim 5 , wherein the additional carbon-based conductive material is carbon black.

7. The composition of any one of claims 1 to 6, wherein the graphene has a lateral size of 0.5 to 30 μm.

8. 8. The composition according to claim 1, wherein the graphene is in the form of platelets or nanoplatelets with a lateral size of 1.5 to 5 μm, preferably 1.6 to 4.5 μm, and more preferably 2 to 3.2 μm.

9. 9. The composition according to any one of claims 1 to 8, wherein the amount of graphene is from 1 to 30 wt%, more preferably from 5 to 20 wt%.

10. 10. The composition of claim 1, wherein the graphene is functionalized with ferromagnetic particles.

11. 11. The composition of claim 10, wherein up to 75% by weight of the graphene is functionalized with ferromagnetic particles.

12. 12. The composition of claim 10 or 11, wherein the ferromagnetic particles are iron oxide.

13. 13. The composition of any one of claims 1 to 12, wherein the amount of the further carbon-based conductive material is in the range of 0.3 to 20 wt%, more preferably 0.5 to 15 wt%, even more preferably 1 to 15 wt%, even more preferably 2 to 15 wt%.

14. 14. The composition of any one of claims 1 to 13, wherein the polymer matrix is ​​selected from 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 elastomers, thermoplastic polyurethanes, polychlorotrifluoroethylene, polyacrylonitrile, polycarbonate, polydimethylsiloxane, polyethersulfone, polysulfone, polyetheretherketone, polyphenylene sulfide, polyamideimide, and polyetherimide, or mixtures thereof.

15. 15. The composition of any one of claims 1 to 14, wherein the polymer matrix is ​​polypropylene, polyvinyl chloride, or polyamide, or polybutylene terephthalate, or acrylonitrile butadiene styrene, or polyethylene.

16. 16. The composition of any one of claims 1 to 15, further comprising 0.1 to 25 wt% of an additive selected from a plasticizer, a dispersant, an antioxidant, or a combination thereof.

17. 17. The composition of claim 16, wherein the additive is a plasticizer selected from phthalates, trimellitates, aliphatic dibasic acid esters, benzoates, polyesters, citrates, epoxidized soybean oil, epoxidized linseed oil (ELO), castor oil, palm oil, starch, sugars, phosphates, chlorinated paraffins, alkyl sulfonates, or mixtures thereof, preferably trimellitate.

18. 18. The composition according to any one of claims 1 to 17, further comprising ferromagnetic particles, in particular up to 20% by weight of ferromagnetic particles.

19. 19. An electromagnetic wave shielding thermoplastic granule, thermoplastic powder, thermoplastic film, thermoplastic sheet or thermoplastic paste comprising the composition of any one of claims 1 to 18.

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

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