PBT-Carbon Fiber Composite for Microwave Shielding

Abstract

Disclosed is a composite comprising about 50 wt.% to about 99 wt.% thermoplastic resin comprising a polyester; and about 0.1 wt.% to about 15 wt.% carbon fiber filler, the carbon fibers having a bulk density of at least 500 g / l and a volume electrical resistivity of less than 2,000 μΩ·cm, and individual filaments having a diameter to length ratio of at least 300, wherein a 3.175 mm thick molded sample of the composite was observed to have a diameter of 7.0 mm or less according to the free space method. a composite that exhibits less than 15% transmission of incident microwave radiation when measured at frequencies from 5 GHz to 110 GHz, a 3.175 mm thick molded sample of said composite exhibits a percent reflected power measured in transmission mode of at least 15% when observed according to a free space method and measured at frequencies from 75 GHz to 110 GHz, and wherein the combined weight percentage of all components does not exceed 100 wt.%, with all weight percentages being based on the total weight of said composite.

Description

Technical Field

[0001] The present disclosure relates to a material exhibiting microwave shielding properties, and more particularly, to a material exhibiting microwave shielding properties for automotive radar sensor applications.

Background Art

[0002] In the automotive industry, the adoption of electronic radar sensors is increasing to provide driving assistance using functions such as inter-vehicle distance control devices, parking / lane change assist, reverse warning devices, blind spot detection functions, collision avoidance functions, and many other functions. To ensure the proper operation of these sensors, these devices must be protected from possible spurious electromagnetic radiation sources. Microwave radiation is the frequency from about 1 gigahertz (GHz) (wavelength of about 300 millimeters, mm) to 300 GHz (wavelength of about 1 mm), and is the most common source of electromagnetic energy used in the operation of automotive radar sensors. Metals (e.g., aluminum, stainless steel, etc.), metal fillers such as aluminum flakes, stainless steel fibers, and polymer composite materials containing silver-coated polyamide fibers, metallized coating agents, intrinsically conductive polymers (e.g., polyacetylene, polypyrrole, polythiophene, and polyaniline, etc.), silicon carbide, ferrites (iron(III) oxide Fe2O3 + Ni / Zn / Cd / Co oxides), and carbonyl iron are some of the materials used to shield automotive radar sensors from harmful microwave electromagnetic radiation.

[0003] Metals are the most common materials for microwave (MW) shielding, but they are heavy and expensive. Also, metals require complex processing to be formed into final parts. Polymers or carbon composites are typically preferred because they are low density, low cost, easy to mold, and easy to manufacture into large quantities of molded parts. Additionally, carbon fillers may be used in the composite to capture microwave radiation on the housing wall, thereby protecting the electronic sensor within the cavity. Aspects of the present disclosure address these and other needs.

Summary of the Invention

Means for Solving the Problems

[0004] Aspects of the present disclosure relate to a composite comprising a thermoplastic resin of about 50 wt.% to about 99 wt.%, comprising polyester; and a carbon fiber filler of about 0.1 wt.% to about 15 wt.% having a bulk density of at least 500 grams per liter (g / l) and an electrical conductivity of at least 7×10 3 Siemens / meter (S / m). This composite may exhibit less than 3% transmission of microwave radiation when observed according to the free space method and measured at frequencies from 75 to 110 GHz, and may exhibit higher reflection of microwave radiation than a reference composition comprising the same amount of carbon powder filler instead of the carbon fiber filler when observed according to the free space method and measured at frequencies from 18 to 26.5 GHz and from 75 to 110 GHz. A molded sample of the composite exhibits at least 40% of the percent reflected power measured in the transmission mode when observed at frequencies from about 75 GHz to 110 GHz according to the free space method. The weight percent values for all components combined do not exceed 100 wt.%, and all weight percent values are based on the total weight of the composite.

Brief Description of the Drawings

[0005]

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Mode for Carrying Out the Invention

[0006] The present disclosure relates to microwave shielding composite materials. Electronic radar sensors are used in the automotive industry to assist drivers in various operations including vehicle distance control, lane change assistance, self-parking, blind spot detection functions, etc. These sensors must be protected from electromagnetic interference that can impair their normal operation. Metals, such as aluminum and stainless steel, are commonly used as microwave shielding materials, but they are heavy, expensive, and require complex processing to form into final parts. Polymer / carbon composites may be desirable as a lower density and lower cost alternative material. Polymer / carbon composites can also be more easily molded and are manufactured into large quantities of molded parts. The carbon filler in the composite may isolate microwave radiation within the walls of the housing to protect the electronic sensors within the cavity.

[0007] Accordingly, a moderate electrical conductivity, and relatively large dielectric and magnetic losses are some of the characteristics required of materials used for microwave shielding. Metals are the most common materials for microwave (MW) shielding, but they are heavy, expensive, and require complex processing. The shielding effectiveness (SE) of a material describes the ability of the material to reduce the electromagnetic field in its surroundings by blocking the electromagnetic field using a barrier or shield made of a conductive material and / or a magnetic material. In these cases, the shielding can be affected by either absorbing or reflecting some or all of the electromagnetic radiation incident on the material to be protected. The ability of the shielding material to shield this harmful radiation generally depends on the frequency (or wavelength) of the incident radiation and the thickness of the protective layer. Also, the shielding is expected to vary depending on the electrical conductivity and / or dielectric properties of the material.

[0008] The present disclosure describes thermoplastic-based carbon fiber fillers with high modulus and high elastic modulus that maintain a constant shape during molding. These materials are rigid and have a high elastic modulus that maintains a specific shape when molded, and can be used as internal or external components for capturing electromagnetic radiation in automotive sensor applications. The polymer-based composite comprises carbon fibers as a microwave shielding filler. Depending on the aspect ratio of the carbon fiber filler, different MW shielding characteristics may be imparted compared to carbon powder or particulate fillers.

[0009] Prior to the disclosure and description of these compounds, compositions, articles, systems, devices, and / or methods, it is to be understood that they are not limited to specific synthetic methods or specific reagents, unless otherwise specified, and can therefore be various. It is also to be understood that the terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting. Various combinations of the components of the present disclosure, for example, combinations of components derived from dependent claims that depend on the same independent claim, are included in the present disclosure.

[0010] Furthermore, unless otherwise stated, it is to be understood that no method described herein is ever intended to be construed as requiring that its steps be performed in a specific order. Thus, when a method claim does not actually recite an order to follow its steps, or when the steps are not specifically and separately recited in the claims or the specification as being limited to a particular order, no order is intended to be inferred in any way. This applies to any possible basis for implicit interpretation, including logical matters regarding the sequence of steps or the flow of operations; the plain meaning derived from the grammatical construction or punctuation; and the number or type of embodiments described herein. Composite

[0011] Aspects of the present disclosure relate to composites comprising a thermoplastic polymer component (including polyesters) and a carbon fiber filler. The thermoplastic polymer component may include any suitable thermoplastic polymer. Examples include, but are not limited to, polycarbonate, polyetherimide, liquid crystal polymer, polyamide, polyimide, polyester, copolymers thereof, blends thereof, or combinations thereof. In certain examples, the polymer component is a polyalkylene terephthalate.

[0012] Molded plate-like bodies formed from the disclosed composites may be suitable as external or internal components of electrical devices used for microwave absorption, reflection, or shielding applications. According to experiments, plate-like bodies molded from the materials of the present disclosure can transmit less than about 3% of microwave radiation at frequencies from about 75 GHz to about 110 GHz. The molded plate-like bodies may have a thickness of from 1 millimeter (mm) to about 5 mm. In various examples, the molded plate-like bodies may have a thickness of 0.125 inches (3.175 mm). The injection-molded plate-like bodies used to measure the microwave absorption and reflection characteristics of the compositions of the present disclosure were sized 6 inches × 8 inches × 1 / 8 inch.

[0013] In various aspects, the present disclosure provides composite materials useful for manufacturing enclosures that can isolate electronic sensors from harmful microwave electromagnetic energy. These materials have been evaluated for dielectric properties, such as reflection, transmission, and shielding effectiveness, especially at frequencies from about 10 GHz to 120 GHz. Further disclosed herein are radar sensor components (plates, enclosures, covers, etc.) manufactured from these materials, and articles (sensors, cameras, electronic control units (ECUs)) manufactured from these components.

[0014] In a further aspect, the composite may comprise a thermoplastic polymer component (including polyester) and a carbon fiber filler. The composite may comprise from about 50 wt.% to about 99 wt.% of a thermoplastic resin comprising polyester and from about 0.1 wt.% to about 15 wt.% of a carbon fiber filler. The carbon fibers may have a bulk density of at least 300 g / l and an electrical resistivity of less than about 2,000 microohm-centimeters (μΩ·cm), with individual filaments having a length of 5 - 10 mm and a length-to-diameter ratio of at least 300. The disclosed composite may exhibit less than 3% transmission of microwave radiation when observed according to the free space method and measured at a frequency of 75 to 110 GHz. The disclosed composition exhibits high reflection and low transmission of microwave radiation, particularly in the W band. For example, a molded sample of the composite may exhibit at least 45% percent reflected power measured in the transmission mode when observed at a frequency of about 75 GHz to 120 GHz according to the free space method.

[0015] Further disclosed are parts of an automotive radar sensor, such as a plate, a housing, or a cover, etc., which are injection molded from a material comprising a polymer and a carbon filler, and the injection molded parts have a specific design, an average thickness, a microwave shielding efficiency, an absorption bandwidth, and a specific surface resistivity and volume resistivity. Still another aspect of the present disclosure is an article, such as a radar sensor, a camera, an electronic control unit (ECU), etc., which comprises an injection molded part made from a radar shielding material, and such an injection molded part has at least two openings that allow transmission of microwave radiation between a transmitting antenna and a receiving antenna disposed on a printed circuit board of the sensor. Automotive radar sensors for lane change assistance, self-parking, blind spot detection functions, and collision avoidance typically operate at a frequency of 24 GHz, and those for adaptive cruise control operate at a frequency of 77 GHz. Thus, the composites of the present disclosure have been observed in the K band including the frequency of 24 GHz and in the W band including the frequency of 77 GHz. Thermoplastic resin

[0016] In various aspects, the composite can comprise a thermoplastic resin or a thermosetting resin. The thermoplastic resin can comprise polypropylene, polyethylene, ethylene copolymers, polyamides, polycarbonates, polyesters, polyoxymethylene (POM), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polycyclohexylene dimethylene terephthalate (PCT), liquid crystal polymers (LCP), polyphenylene sulfide (PPS), polyphenylene ether (PPE), polyphenylene oxide-polystyrene blends, polystyrene, impact-modified polystyrene, acrylonitrile-butadiene-styrene (ABS) terpolymers, acrylic polymers, polyetherimide (PEI), polyurethanes, polyetheretherketone (PEEK), polylactic acid (PLA)-based polymers, polyethersulfone (PES), and combinations thereof. The thermoplastic resin can also comprise thermoplastic elastomers such as polyamide and polyester-based elastomers. The base substrate can also comprise blends of the above resins and / or other types of combinations. In various aspects, the composite can also comprise a thermosetting polymer. Suitable thermosetting resins can include phenolic resins, urea resins, melamine-formaldehyde resins, urea-formaldehyde lattices, xylene resins, diallyl phthalate resins, epoxy resins, aniline resins, furan resins, polyurethanes, or combinations thereof, and the like.

[0017] In various aspects of the present disclosure, the thermoplastic resin can comprise a polyester. For example, the thermoplastic resin can comprise a polyalkylene ester (polyester), such as a polyalkylene terephthalate polymer.

[0018] The polyesters are represented by the following formula (A):

[0019] [Chemical Formula] It has a repeating unit, in which T is a residue derived from terephthalic acid or its chemical equivalent, and D is a residue derived from the polymerization of ethylene glycol, butylene diol, specifically 1,4-butanediol, or its chemical equivalent. Chemical equivalents of the diacid include dialkyl esters such as dimethyl esters, diaryl esters, anhydrides, salts, acid chlorides, acid bromides, and the like. Chemical equivalents of ethylene glycol and butylene diol include esters such as dialkyl esters, diaryl esters, and the like. In addition to the units derived from terephthalic acid or its chemical equivalent, and ethylene glycol or butylene diol, specifically 1,4-butanediol or its chemical equivalent, other T and / or D units can be present in the polyester, provided that the type or amount of such units does not significantly adversely affect the desired properties of the thermoplastic composition. Poly(alkylene arylates) can be considered to have a polyester structure according to formula (A), where T comprises a group derived from aromatic dicarboxylates, cycloaliphatic dicarboxylic acids, or derivatives thereof.

[0020] Examples of particularly useful T groups include, but are not limited to, 1,2-, 1,3-, and 1,4-phenylene; 1,4- and 1,5-naphthylene; cis- or trans-1,4-cyclohexylene; and the like. Specifically, when T is 1,4-phenylene, the poly(alkylene arylate) is a poly(alkylene terephthalate). In addition, for poly(alkylene arylates), particularly useful alkylene groups D include, for example, ethylene, 1,4-butylene, and bis-(alkylene disubstituted cyclohexane) containing cis- and / or trans-1,4-(cyclohexylene) dimethylene.

[0021] Examples of polyalkylene terephthalates include polyethylene terephthalate (PET), poly(1,4-butylene terephthalate) (PBT), and poly(propylene terephthalate) (PPT). Also useful are poly(alkylene naphthoates), such as poly(ethylene naphthalate) (PEN), and poly(butylene naphthalate) (PBN). A useful poly(cycloalkylene diester) is poly(cyclohexane dimethylene terephthalate) (PCT). Combinations containing at least one of the aforementioned polyesters may also be used.

[0022] Copolymers containing alkylene terephthalate repeating ester units having other ester groups may also be useful. Useful ester units can include different alkylene terephthalate units, and these units can be present in the polymer chain either as individual units or as blocks of poly(alkylene terephthalates). Specific examples of such copolymers include poly(cyclohexane dimethylene terephthalate)-co-poly(ethylene terephthalate), etc. When the polymer contains 50 mol% or more of poly(ethylene terephthalate), it is abbreviated as PETG, and when the polymer contains 50 mol% or more of poly(1,4-cyclohexane dimethylene terephthalate), it is abbreviated as PCTG. Poly(cycloalkylene diesters) can be considered to also include poly(alkylene cyclohexane dicarboxylates). Among these, a specific example is the poly(1,4-cyclohexane dimethanol-1,4-cyclohexane dicarboxylate) (PCCD) having repeating units of formula (B):

[0023]

Chemical formula

[0024] In another aspect, the composite can further comprise poly(1,4 - butylene terephthalate), i.e., "PBT" resin. PBT can be obtained by polymerizing a glycol component consisting of at least 70 mol%, preferably at least 80 mol% of tetramethylene glycol, and an acid or ester component consisting of at least 70 mol%, preferably at least 80 mol% of terephthalic acid and / or its polyester - forming derivative. Examples of commercially available PBT include those available under the trade names VALOX(™) 315, VALOX(™) 195, and VALOX(™) 176 from SABIC(™), which have an intrinsic viscosity of from 0.1 deciliter / gram (dl / g) to about 2.0 dl / g (or from 0.1 dl / g to 2 dl / g) as measured in a 60:40 phenol / tetrachloroethane mixture or a similar solvent at 23 degrees to 30 degrees Celsius (°C). In one aspect, the PBT resin has an intrinsic viscosity of from 0.1 dl / g to 1.4 dl / g (or about 0.1 dl / g to about 1.4 dl / g), specifically from 0.4 dl / g to 1.4 dl / g (or about 0.4 dl / g to about 1.4 dl / g).

[0025] In a further aspect, the composite may further comprise a polycarbonate-polysiloxane copolymer or a poly(carbonate-siloxane) copolymer. Non-limiting examples of poly(carbonate-siloxane) copolymers may include various copolymers available from SABIC (trademark). In one aspect, the poly(carbonate-siloxane) copolymer may have a total siloxane content between 1 wt.% and 45 wt.%, based on the total weight of the poly(carbonate-siloxane) copolymer. As an example, the poly(carbonate-siloxane) copolymer may have a polysiloxane content of 6 weight percent, based on the total weight of the poly(carbonate-siloxane) copolymer. In various aspects, the 6 weight percent polysiloxane block copolymer may have a weight average molecular weight (M w ) of from about 23,000 to 24,000 Daltons, using gel permeation chromatography with a bisphenol A polycarbonate absolute molecular weight standard. In certain aspects, the 6 weight percent siloxane polysiloxane-polycarbonate copolymer has a melt flow rate of about 10 cm at 300 °C / 1.2 kg 3 / 10 may have a melt volume flow rate (MVR) (e.g., see C9030T, a copolymer with a 6 wt% polysiloxane content available as the “transparent” EXL C9030T resin polymer from SABIC Innovative Plastics). In a further example, the poly(carbonate-siloxane) copolymer may comprise 20 wt% polysiloxane based on the total weight of the poly(carbonate-siloxane) copolymer. Suitable poly(carbonate-siloxane) copolymers may comprise a bisphenol A polysiloxane-polycarbonate copolymer end-capped with para-cumylphenol (PCP) and having a 20% polysiloxane content (see C9030P commercially available as “opaque” EXL C9030P from SABIC™). In various embodiments, the weight average molecular weight of the 20% polysiloxane block copolymer is tested according to polycarbonate standards using gel permeation chromatography (GPC) on a cross-linked styrene-divinylbenzene column and calibrated against a polycarbonate reference using a UV-VIS detector set at 264 nm on a 1 mg / ml sample eluted at a flow rate of about 1.0 ml / min and may be from about 29,900 daltons to about 31,000 daltons. Further, the 20% polysiloxane block copolymer may have an MVR at 300 °C / 1.2 kg of 7 cm 3 / 10 and may exhibit a siloxane domain sized in the range from about 5 μm to about 20 μm. The poly(carbonate-siloxane) copolymer may be present in the composite in an amount such that it has a total siloxane content between 1 wt.% and 15 wt.% based on the total weight of the composite.

[0026] As described herein, the composition may comprise from about 40 wt.% to about 99 wt.% polyalkylene polymer. In further examples, the composition may comprise from about 50 wt.% to about 99 wt.%, or from about 40 wt.% to about 99 wt.%, or from about 55 wt.% to about 99 wt.%, or from about 60 wt.% to about 99 wt.%, or from about 70 wt.% to about 99 wt.%, or from about 40 wt.% to about 99 wt.%, or from about 55 wt.% to about 99 wt.%, or from about 60 wt.% to about 95 wt.%, or from about 75 wt.% to about 99 wt.% polyalkylene polymer.

[0027] Certain embodiments of the composition comprise from about 50 wt.% to about 99 wt.%, or from about 40 wt.% to about 99 wt.%, or from about 55 wt.% to about 99 wt.%, or from about 60 wt.% to about 99 wt.%, or from about 70 wt.% to about 99 wt.%, or from about 40 wt.% to about 99 wt.%, or from about 55 wt.% to about 99 wt.%, or from about 60 wt.% to about 99 wt.%, or from about 75 wt.% to about 99 wt.% thermoplastic resin. In various embodiments, the composite comprises a blend of thermoplastic resins, such as a blend of suitable polyester resins. Carbon fiber filler

[0028] In various aspects, the composite comprises a carbon fiber filler. Various types of conductive carbon fibers may be used in the composition. Carbon fibers are generally classified according to their diameter, morphology, and degree of graphitization (the morphology and degree of graphitization are related to each other). These characteristics are currently determined by the method used in the synthesis of carbon fibers. Further, the carbon fiber filler or composite may not contain, or may substantially not contain, carbon nanotubes, carbon platelets, or carbon powder or fine particles.

[0029] In certain aspects, the carbon fiber filler comprises a coating agent or sizing agent. Suitable coating agents may comprise polymers such as polyurethane or polyamide. As a specific example, the carbon fiber may have a coating agent or sizing agent of polyurethane. The amount or the content of the sizing agent may vary. The sizing agent may be up to 10% based on the weight of the fiber. For example, the carbon fiber may comprise a sizing agent of 2% to 8%, or 3% to 6%. In a specific example, the carbon fiber may have a polyurethane sizing agent of 2.7%.

[0030] The carbon fiber filler may have a specific bulk density. In one example, the carbon fiber filler may exhibit a bulk density of at least 100 grams per liter (g / l), at least 200 g / l, at least 250 g / l, at least 300 g / l, or at least 400 g / l, or at least 500 g / l, or at least 600 g / l.

[0031] In a further aspect, the carbon fibers may have a specific length. The carbon fibers may have a length of at least 3 mm, at least 4 mm, or at least 5 mm. In certain aspects, the carbon fibers may have a length from about 5 mm to about 10 mm. For example, the carbon fibers may have a length of at least 6 mm. The individual filaments of a given carbon fiber may be grouped into a fiber bundle. The individual carbon fiber filaments may have a diameter of about 7 micrometers (μm). The individual filaments may be grouped into a fiber bundle having a diameter of 1 - 2 mm.

[0032] The carbon fiber filler may have a specific conductivity. For example, the conductivity of the carbon fiber filler may be 9·10 3 S / m. The carbon fiber filler may exhibit an electrical resistivity of less than about 2,000 μΩ·cm. Certain carbon fiber fillers may be of the HTC493 type commercially available as Tenax - J HT C493 from Teijin / Toho America Inc., Tenax (trademark).

[0033] In some aspects, the composition can comprise from about 0.01 wt.% to about 15 wt.% carbon fiber filler, based on the total weight of the polymer composition. The ratio of the thermoplastic resin to the carbon filler can be from about 10,000:1 to about 5:1, 1000:1 to about 5:1, 100:1 to about 5:1, 1000:1 to about 3:1, 32:1 to about 5:1, or about 24:1 to about 6:1. In a further aspect, the composition may contain from about 4 wt.% to about 8 wt.%, or from about 0.1 wt.% to about 6 wt.%, or from about 0.1 wt.% to about 10 wt.%, or from about 1 wt.% to about 8 wt.%, or from about 0.5 wt.% to about 7 wt.% carbon fiber filler, or from about 1 wt.% to about 12 wt.% carbon - based filler, or from about 2 wt.% to about 10 wt.% carbon fiber filler. Additive

[0034] The disclosed thermoplastic composition can comprise one or more additives conventionally used in the manufacture of molded thermoplastic parts, provided that any optional additives do not adversely affect the desired properties of the resulting composition. Mixtures of optional additives can also be used. Such additives can be incorporated at a suitable point during the mixing of the components to form the composite mixture. Exemplary additives include, but are not limited to, ultraviolet agents, ultraviolet stabilizers, heat stabilizers, antistatic agents, antimicrobial agents, drip inhibitors, radiation stabilizers, pigments, dyes, fibers, fillers, plasticizers, fibers, flame retardants, antioxidants, lubricants, wood, glass, and metal, and combinations thereof. According to certain embodiments, the polymer composition may maintain mechanical and dielectric properties even when using high levels of fillers (e.g., greater than 30 wt.% based on the total weight of the polymer composition).

[0035] The composites disclosed herein can comprise one or more additional fillers. The fillers can be selected to impart additional impact strength and / or to provide additional properties based on the final selected properties of the polymer composition. In some embodiments, the fillers can comprise inorganic materials that can include, but are not limited to, clay, titanium oxide, asbestos fibers, silicates and silica powders, boron powder, calcium carbonates, talc, kaolin, sulfides, barium compounds, metals and metal oxides, wollastonite, glass spheres, glass fibers, flaky fillers, fibrous fillers, natural fillers and reinforcing agents, and organic fibrous fillers for reinforcement. In certain embodiments, the composite may comprise a glass fiber filler. For example, the composite may comprise from about 0.01 wt.% to about 25 wt.%, from about 10 wt.% to about 25 wt.%, from about 15 wt.% to about 25 wt.% glass fiber filler based on the total weight of the composite. In further embodiments, the composite may not contain or may substantially not contain a glass filler.

[0036] Suitable fillers or reinforcing agents include, for example, ummo, clay, feldspar, quartz, silica, perlite, tripoli, diatomaceous earth, aluminum silicate (mullite), synthetic calcium silicate, fused silica, fumed silica, sand, boron nitride powder, boron silicate powder, calcium sulfate, calcium carbonates (such as chalk, limestone, marble, and synthetic precipitated calcium carbonates), talc (including fibrous, modular, acicular, and lamellar talc), wollastonite, hollow or solid glass spheres, silicate spheres, cenospheres, aluminosilicates or (armospheres), kaolin, silicon carbide, alumina, boron carbide, iron, nickel, or copper whiskers, continuous and chopped carbon or glass fibers, molybdenum disulfide, zinc sulfide, barium titanate, barium ferrite, barium sulfate, barite, titanium dioxide, aluminum oxide, magnesium oxide, particulate or fibrous aluminum, bronze, zinc, copper, or nickel, glass flakes, flake-shaped silicon carbide, flake-shaped aluminum diboride, flake-shaped aluminum, steel flakes, natural fillers such as wood flour, fibrous cellulose, cotton, sisal, jute, starch, lignin, ground nut shells, or rice husk fillers, reinforcing organic fibrous fillers such as poly(ether ketone), polyimide, polybenzoxazole, poly(phenylene sulfide), polyesters, polyethylene, aromatic polyamides, aromatic polyimides, polyetherimides, polytetrafluoroethylene, and poly(vinyl alcohol), and combinations comprising at least one of the aforementioned fillers or reinforcing agents. The fillers and reinforcing agents may be coated or surface-treated with, for example, silane to improve their adhesion and dispersibility in the polymer matrix. The fillers can generally be used in an amount of 1 to 200 parts by weight based on 100 parts by weight of the total composition.

[0037] In some embodiments, the thermoplastic composition may include a synergist. In various examples, the filler may serve as a flame retardant synergist. A synergist, when added to a flame retardant composition, promotes an improvement in flame retardant properties over a comparative composition containing the same components in the same amounts except for the synergist. Examples of mineral fillers that may serve as synergists include wollastonite, talc, calcium carbonate, dolomite, wollastonite, barium sulfate, silica, kaolin, feldspar, barite, or the like, or combinations comprising at least one of the foregoing mineral fillers. Metal synergists, such as antimony oxide, can also be used with flame retardants. In one example, the synergist may comprise magnesium hydroxide and phosphoric acid. The mineral filler may have an average particle size of from about 0.1 to about 20 μm, specifically from about 0.5 to about 10 μm, more specifically from about 1 to about 3 μm.

[0038] The thermoplastic composition can be made to contain an antioxidant. The antioxidant can contain either a primary antioxidant or a secondary antioxidant. For example, the antioxidant includes organic phosphites such as tris(nonylphenyl) phosphite, tris(2,4-di-t-butylphenyl) phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, or the like; alkylated monophenols or polyphenols; alkylation reaction products of polyphenols and dienes such as tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane; butylation reaction products of para-cresol or dicyclopentadiene; alkylated hydroquinones; hydroxylated thiodiphenyl ethers; alkylidene bisphenols; benzyl compounds; esters of beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid and monohydric or polyhydric alcohols; esters of beta-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionic acid and monohydric or polyhydric alcohols; esters of thioalkyl or thioaryl compounds such as distearyl thiodipropionate, dilauryl thiodipropionate, ditridecyl thiodipropionate, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], or the like; amides such as beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid, or the like, or combinations containing at least one of the aforementioned antioxidants. The antioxidant can generally be used in an amount of 0.01 to 0.5 parts by weight based on 100 parts by weight of the total composition excluding the filler.

[0039] In various embodiments, the thermoplastic composition can comprise a release agent. Exemplary release agents can include, for example, metal stearates, stearyl stearate, pentaerythritol pentastearate, beeswax, montan wax, paraffin wax, or the like, or combinations comprising at least one of the foregoing release agents. The release agent is generally used in an amount of about 0.1 to about 1.0 parts by weight, based on 100 parts by weight of the total composition excluding the filler.

[0040] In one embodiment, the thermoplastic composition can comprise a heat stabilizer. By way of example, heat stabilizers can include, for example, organic phosphites such as triphenyl phosphite, tris-(2,6-dimethylphenyl) phosphite, tris-(mixture of mono- and di-nonylphenyl) phosphite, or the like; phosphonates such as dimethyl benzene phosphonate, or the like; phosphates such as trimethyl phosphate, or the like, or combinations comprising at least one of the foregoing heat stabilizers. The heat stabilizer can generally be used in an amount of from 0.01 to 0.5 parts by weight, based on 100 parts by weight of the total composition excluding the filler.

[0041] In a further aspect, a light stabilizer can be present in the thermoplastic composition. Exemplary light stabilizers can include, for example, benzotriazoles such as 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)-benzotriazole, and 2-hydroxy-4-n-octoxybenzophenone, or the like, or a combination including at least one of the aforementioned light stabilizers. The light stabilizer can generally be used in an amount of about 0.1 to about 1.0 parts by weight, based on 100 parts by weight of the total composition excluding the filler. The thermoplastic composition can also include a plasticizer. For example, plasticizers can include phthalic acid esters such as dioctyl-4,5-epoxy-hexahydrophthalate, tris-(octoxycarbonylethyl) isocyanurate, tristearin, epoxidized soybean oil, or the like, or a combination including at least one of the aforementioned plasticizers. The plasticizer is generally used in an amount of about 0.5 to about 3.0 parts by weight, based on 100 parts by weight of the total composition excluding any filler material.

[0042] UV absorbers can also be present in the disclosed thermoplastic compositions. Exemplary UV absorbers include, for example, hydroxybenzophenones; hydroxybenzotriazoles; hydroxybenzotriazines; cyanoacrylates; oxanilides; benzoxazinones; 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)-phenol (CYASORB™ 5411); 2-hydroxy-4-n-octyloxybenzophenone (CYASORB™ 531); 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)-phenol (CYASORB™ 1164); 2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one) (CYASORB™ UV-3638); 1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenylacryloyl)oxy]methyl]propane (UVINUL™ 3030); 2,2'-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one); 1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenylacryloyl)oxy]methyl]propane; titanium oxide, cerium oxide, zinc oxide, etc., all of which are nanosize inorganic materials with a particle size of less than 100 nanometers; or the like, or a combination containing at least one of the aforementioned UV absorbers. The UV absorber is generally used in an amount of 0.01 to 3.0 parts by weight based on 100 parts by weight of the total composition excluding any fillers.

[0043] The thermoplastic composition can further include a lubricant. As an example, the lubricant can be, for example, fatty acid esters such as alkyl stearyl esters, such as methyl stearate, or the like; in a suitable solvent, a mixture of methyl stearate and hydrophilic and hydrophobic surfactants including polyethylene glycol polymers, polypropylene glycol polymers, and copolymers thereof, for example, a mixture of methyl stearate and a polyethylene - polypropylene glycol copolymer; or a combination including at least one of the aforementioned lubricants. The lubricant can generally be used in an amount of about 0.1 to about 5 parts by weight based on 100 parts by weight of the total composition excluding any fillers.

[0044] Dripping inhibitors, such as fibril - forming or non - fibril - forming fluoropolymers such as polytetrafluoroethylene (PTFE), can also be used in the composition. The dripping inhibitor can be encapsulated by a hard copolymer, such as styrene - acrylonitrile copolymer (SAN). PTFE encapsulated in SAN is known as TSAN. In one example, TSAN can be made to contain 50 wt.% PTFE and 50 wt.% SAN based on the total weight of the encapsulated fluoropolymer. SAN can be made to contain, for example, 75 wt.% styrene and 25 wt.% acrylonitrile based on the total weight of the copolymer. The dripping inhibitor, such as TSAN, can be used in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the total composition excluding any fillers.

[0045] As an example, the disclosed composition can comprise an impact modifier. The impact modifier can be a chemically reactive impact modifier. By definition, a chemically reactive impact modifier can have at least one reactive group such that when the impact modifier is added to the polymer composition, the impact properties of the composition (represented by the value of the Izod impact strength) are improved. In some examples, the chemically reactive impact modifier can be an ethylene copolymer having reactive functional groups selected from, but not limited to, anhydride, carboxyl, hydroxyl, and epoxy. In a further aspect of the present disclosure, the composition can comprise a rubbery impact modifier. The rubbery impact modifier can be a polymeric material whose shape and size are substantially recoverable at room temperature after the removal of force. However, the rubbery impact modifier typically desirably has a glass transition temperature below 0 °C. In certain aspects, the glass transition temperature (T g ) can be less than -5 °C, less than -10 °C, less than -15 °C, and typically less than -30 °C for T g to obtain better performance. Representative rubbery impact modifiers can include, for example, functionalized polyolefin ethylene-acrylate terpolymers such as ethylene-acrylic acid esters-maleic anhydride (MAH), or glycidyl methacrylate (GMA). The functionalized rubbery polymer can optionally contain repeating units within the backbone derived from monomer-containing anhydride groups such as maleic anhydride. In another scenario, the functionalized rubbery polymer can contain anhydride moieties grafted onto the polymer in a post-polymerization step. Impact modifiers can include ethylene-ethyl acrylate copolymers, polybutylene tere / phthalate-co-polyoxybutylene, or ethylene-methyl acrylate-glycidyl methacrylate copolymers, or combinations thereof. Properties and Articles

[0046] In certain embodiments, the disclosed composites may exhibit more desirable microwave shielding properties as compared to substantially similar reference compositions that comprise carbon powder and do not have the disclosed carbon fiber filler. For example, a composition containing the same mixture of polybutylene terephthalate but containing the same amount of carbon fiber (as a weight percentage) compared to a reference formulation that contains carbon black powder (but not a carbon fiber filler) as the conductive filler exhibits the following properties: - Higher reflection of microwave radiation in the K band (18 - 26.5 GHz) and the W band (75 - 110 GHz); - Lower transmission of microwave radiation in the K band (18 - 26.5 GHz) and the W band (75 - 110 GHz); - Higher range of shielding effectiveness (SE) of microwave radiation in the K band (18 - 26.5 GHz), 5 - 80 dB vs. 2 - 25 dB, and the W band (75 - 110 GHz), 45 - 120 dB vs. 5 - 55 dB; - Nearly completely opaque microwave performance (less than about 3% transmission) at the higher frequency W band (75 - 110 GHz) for all compositions investigated; - Nearly completely opaque microwave performance (less than about 3% transmission) at the lower frequency K band (18 - 26.5 GHz) for formulations containing 4 wt% or more of carbon fiber exhibit.

[0047] A plate-like body molded from the disclosed composite may exhibit specific microwave shielding properties. For example, a molded plate-like body with a thickness of about 0.125 inches (3.175 mm) may reflect at least 45% of the incident microwave radiation at frequencies from about 75 GHz to 110 GHz and at least 30% of the incident microwave radiation at frequencies from about 18 GHz to 26.5 GHz. Further, Compositions EX1 to 5 containing carbon fibers were found to reflect more microwave radiation than Compositions CE-1 to CE-5 containing carbon powder for all frequencies examined in the K band and W band and for the same filling amounts of carbon powder and carbon fibers (FIGS. 5 to 14). Examples EX-3, EX-4, and EX-5 showed percent reflections higher than about 70% in the K band (18 - 26.5 GHz) and higher than about 65% in the W band (75 - 110 GHz). It was also found that none of the Comparative Example Compositions CE-1 to CE-5 produced reflections higher than about 45% in the K band (18 - 26.5 GHz) and higher than about 40% in the W band (75 - 110 GHz). Such performance may be seen for molded plate-like bodies with thicknesses between 1 mm and 5 mm. A plate-like body molded from the disclosed composite may exhibit specific attenuation properties.

[0048] The 3.175 mm thick molded sample of this composite was found to exhibit higher reflection of microwave radiation than a reference composition comprising the same amount of carbon powder filler instead of the carbon fiber filler when observed according to the free space method and measured at frequencies from 18 to 26.5 GHz and from 75 to 110 GHz.

[0049] Composites further comprising PBT and poly(carbonate - siloxane) copolymers exhibit further properties. These formulations generally achieved significant performance with lower carbon fiber filler contents. The percent absorption power measured in transmission mode at the W - band (75 - 110 GHz) was less than 55% of the incident radiation for compositions having only polyester and a high carbon fiber loading, while this value was higher than 55% for compositions characterized by a low carbon fiber content but containing poly(carbonate - siloxane) copolymers. Composites containing poly(carbonate - siloxane) copolymers with a carbon fiber filler present in an amount from 0.15 wt.% to 2 wt.% may exhibit at least 70% of the percent absorption power measured in transmission mode at 77 GHz. These composites also exhibited at least 500 J / m of unnotched Izod impact strength at - 30 °C and at least 45 J / m of notched Izod impact strength at - 30 °C when measured according to ASTM D256.

[0050] Thus, the disclosed composites may be used to optimize the balance between microwave absorption and microwave reflection to achieve a desired shielding effectiveness (a combination of both absorption - based shielding and reflection - based shielding). The polymer / filler ratios of the disclosed materials may be manipulated to modify the electromagnetic response of those materials.

[0051] In the automotive industry, electromagnetic shielding properties have been utilized to protect electronic radar sensors from electromagnetic interference that could impair their normal operation. Metals (aluminum, stainless steel) are the most common materials for microwave (MW) shielding, but they are heavy, expensive, and require complex processing to be formed into final parts. Carbon fillers capture or deflect MW radiation within the housing wall that protects the electronic sensor within the cavity. Polymer-carbon composites can protect radar sensors located within the housing, for example, when used in a housing under the hood of a car, by preventing electromagnetic radiation of external origin from degrading the electronic performance of the sensor. Also, carbon-containing elastomers such as silicone, polyurethane, and nitrile rubber, among others, can be used as high-loss protection blankets that attenuate the resonant frequencies generated by the normal operation of the sensors within the cavity. Relatively high dielectric constant and electrical conductivity, and large dielectric and magnetic losses are some of the characteristics required of materials used for microwave shielding. The present disclosure provides PBT-carbon fiber composites that can be used to protect radar sensors from harmful electromagnetic interference. The polymer / filler ratio of these composites can be manipulated to adjust the relative amounts of microwave absorption and reflection to maximize the shielding effectiveness of these materials.

[0052] Radar shielding materials are mainly commercially available in the form of flexible sheets or blankets based on elastomers, liquid paints, and closed-cell polymer foams. The present disclosure provides carbon fiber-filled materials using thermoplastics that are rigid and maintain a certain shape during molding, and these materials can be used as internal or external components that reflect electromagnetic radiation in automotive sensor applications. Disclosed herein are carbon fiber-filled materials using thermoplastics that can be used as internal or external components that capture electromagnetic radiation in automotive sensor applications. Since the disclosed compositions include thermoplastic resins rather than elastomeric resins, they may exhibit a higher modulus of elasticity than equivalent elastomeric resins. A further aspect of the present disclosure includes components (especially plates, housings, covers) of automotive radar sensors molded from materials comprising a polymer and a carbon fiber filler, and these molded components have specific designs, average thicknesses, microwave shielding efficiencies, absorption bandwidths, shielding effectiveness, and attenuation.

[0053] Yet another embodiment of the present disclosure is an article (especially a radar sensor, a camera, an ECU) comprising a molded component made from a radar shielding material, and such a molded component has at least two openings that allow the transmission of microwave radiation between a transmitting antenna and a receiving antenna located within the printed circuit board of the sensor. In various aspects, the present disclosure relates to an article comprising the compositions herein. The compositions can be molded into articles of useful shapes by various means for forming articles such as injection molding, extrusion molding, rotational molding, blow molding, and thermoforming. The compositions may be useful in the manufacture of articles that require materials having good fluidity, good impact strength, and good dielectric properties. In various aspects, the compositions may also be useful for conductive purposes.

[0054] The advantageous properties of the compositions disclosed herein can be suitable for a range of applications. Method for manufacturing the composite

[0055] Aspects of the present disclosure further relate to methods of manufacturing composites that include a thermoplastic polymer component. In many aspects, the compositions can be prepared according to various methods. The compositions of the present disclosure can be blended, compounded, or otherwise combined with the foregoing components by various methods involving intimate admixture of the materials with any additional additives desired in the formulation. Since melt mixing equipment is available in commercial polymer processing facilities, melt forming methods can be used. In various further aspects, the equipment used in such melt forming methods can include, but is not limited to, co-rotating and counter-rotating extruders, single screw extruders, co-kneaders, disc-pack processors, and various other types of extrusion devices. In a further aspect, the extruder is a twin screw extruder. In various further aspects, the composition can be processed in an extruder at a temperature of from about 180°C to about 350°C, particularly from 250°C to 300°C.

[0056] The method may further comprise processing the composite to provide a sheet-like body of a desired thickness. The sheet-like body can be extrusion molded, injection molded, compression molded, or injection compression molded and can have a thickness between about 0.5 mm and 6 mm. Other processes such as, but not limited to, laminating, co-extrusion, thermoforming, or hot pressing may also be applicable to thin thermoplastic films. In such aspects, additional layers of other materials (e.g., other thermoplastic polymer layers, metal layers, etc.) may be combined with the composite. Various combinations of the components of the present disclosure, such as combinations of components derived from dependent claims that depend on the same independent claim, are encompassed by the present disclosure. Definitions

[0057] Also, it is to be understood that the terms used in this specification are for the purpose of describing particular embodiments only and are not intended to be limiting. As used in this specification and the claims, the term "comprising" can include embodiments "consisting of" and "consisting essentially of". Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art. In this specification and the appended claims, reference will be made to a plurality of terms as defined herein.

[0058] As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a thermoplastic polymer component" includes mixtures of two or more thermoplastic polymer components. As used in this specification, the term "combination" includes blends, mixtures, alloys, reaction products, and the like.

[0059] In one aspect, "substantially free of" can be less than about 0.5 weight percent (wt.%). In another aspect, substantially free of can be less than about 0.1 wt.%. In another aspect, substantially free of can be less than about 0.01 wt.%. In yet another aspect, substantially free of can be less than about 100 ppm. In yet another aspect, substantially free of can refer to an amount below a detectable level even if present. For example, a carbon fiber filler or composite may be free of or substantially free of carbon nanotubes, carbon platelets, or carbon powder.

[0060] As used herein, the shielding effectiveness of a material is the result of its reflection, absorption, and internal reflection losses. In the most common definition, the shielding effectiveness (SE) of a material describes the ability of a material to reduce a field by blocking the electromagnetic field around that material using a barrier or shield made of a conductive material and / or a magnetic material. In such cases, shielding can be done by either absorbing or reflecting some or all of the electromagnetic radiation incident on the material to be protected. The ability of the shielding material to block this harmful radiation typically depends on the frequency (or wavelength) of the incident radiation, the thickness of the protective layer, and is expected to vary with the electrical conductivity and / or dielectric properties of the material. See M. H. Al-Saleh, W. H. Saadeh, U. Sundararaj, “EMI shielding effectiveness of carbon based nanostructured polymeric materials: A comparative study,” CARBON 60, PP. 146-156, 2013. This is given by the following equation: SE T (dB)=SE A +SE R +SE M which is expressed as.

[0061] When the shielding efficiency is > 10 dB, the shielding effectiveness due to multiple reflections SE M is usually negligible. Thus, the total shielding effectiveness is: SE T (dB)=SE A +SE R , which simplifies to, where SE A and SE R are calculated directly as follows from S-parameter measurements using a vector network analyzer:

[0062]

Equation

[0063] In the above formula, S 11 is the scattering parameter for reflection, and S 21 is the scattering parameter for transmission. A shielding effectiveness of less than 20 dB is considered the minimum, and an SE above 35 dB is required for most applications.

[0064] In this specification, a range can be expressed as from one value (the first value) to another value (the second value). When such a range is expressed, the range includes, in some embodiments, one or both of the first and second values. Similarly, when a value is expressed as an approximation, it will be understood that the use of the antecedent "about" forms another embodiment for a particular value. Further, it will be understood that each endpoint of a range is effective both in relation to the other endpoint and independently of the other endpoint. It is also understood that multiple values are disclosed herein, and each value is disclosed herein as "about" that value in addition to the particular value itself. For example, if the value "10" is disclosed, then about "10" is also disclosed. It is also understood that each unit between two particular units is also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0065] As used herein, the terms “about” and “or about” mean that the quantity or value in question can be the specified value, approximately the specified value, or substantially the same as the specified value. As used herein, unless otherwise indicated or inferred, the value is generally understood to be within a variation of ±10% of the stated nominal value. This term is intended to convey that equivalent results or effects recited in the claims are facilitated by such similar values. That is, amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but can be approximate and / or can be larger or smaller as desired, reflecting tolerances, conversion factors, rounding, measurement errors, and the like, and other factors known to those of skill in the art. Generally, an amount, size, formulation, parameter, or other quantity or characteristic is “about” or “approximate,” whether or not expressly so designated. When “about” is used prior to a quantitative value, the parameter is also understood to include the specific quantitative value itself, unless specifically defined otherwise. As used herein, the terms “optional” or “optionally” mean that the subsequent recited event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not. For example, the phrase “optional additional step” means that the additional step can or cannot be included, and that the description includes both methods that include the additional step and methods that do not include the additional step.

[0066] Disclosed are not only the ingredients used to prepare the compositions of the present disclosure, but also the compositions themselves as used within the scope of the methods disclosed herein. These and other materials are disclosed herein, and although combinations, subsets, interactions, groups, etc. of these materials are disclosed, it is understood that each of these various individual and collective combinations and permutations of the compounds is specifically contemplated and described herein, even if specific reference to them cannot be explicitly disclosed. For example, if certain compounds are disclosed, considered, and numerous modified forms that can be made to the multiple molecules containing those compounds are considered, then specifically contemplated, unless otherwise indicated, are each and every combination and permutation of that compound and the possible modified forms. Thus, if not only the set of molecules A, B, and C is disclosed, but also the set of molecules D, E, and F is disclosed, and the combination molecule A-D, which is an example of a combination molecule, is disclosed, then each of the combinations A-E, A-F, B-D, B-E, B-F, C-D, C-E, and C-F is considered to be disclosed, even if each is not individually recited. Similarly, any subset or combination of these is also considered to be disclosed. Thus, for example, the subgroups A-E, B-F, C-E are considered to be disclosed. This concept applies to all aspects of this application, including but not limited to the steps in the methods of making and using the compositions of the present disclosure. Thus, if there are various additional steps that can be performed, it is understood that each of these additional steps can be performed using any particular aspect or combination of aspects of the methods of the present disclosure.

[0067] In this specification and the appended claims, where the parts by weight of a particular component or ingredient in a composition or article are referred to, it indicates the weight relationship, expressed in parts by weight, between that component or ingredient and the other components or ingredients in the composition or article. Thus, in a compound containing 2 parts by weight of component X and 5 parts by weight of component Y, X and Y are present in a weight ratio of 2:5 and are present in such a ratio regardless of whether additional components are contained in the compound.

[0068] The weight percent of a component is based on the total weight of the formulation or composition in which the component is included, unless specifically stated to the contrary.

[0069] The terms "residue" and "structural unit" as used with respect to the components of a polymer are synonymous throughout this specification.

[0070] As used herein, the terms "weight percent," "wt%," and "wt.%," can be used interchangeably and, unless otherwise specified, indicate the weight percent of a given component based on the total weight of the composition. Thus, unless otherwise specified, all wt% values are based on the total weight of the composition. It is desirable to understand that the sum of the wt% values of all components in the disclosed composition or formulation is equal to 100.

[0071] Unless otherwise stated to the contrary in this specification, all test standards are the latest standards in effect at the time of this application. Each of the materials disclosed herein is commercially available and / or the method of its manufacture is known to those skilled in the art. It is understood that the compositions disclosed herein have specific functions. What is disclosed herein are the specific structural requirements for performing the disclosed functions, and it is understood that there are various structures that can perform the same function associated with the disclosed structure and that these structures typically achieve the same results. Aspects of the present disclosure

[0072] The present disclosure relates to, and includes, at least the following aspects.

[0073] Aspect 1A. A composite comprising: a thermoplastic resin of about 50 wt.% to about 99 wt.% comprising polyester; and a carbon fiber filler of about 0.1 wt.% to about 15 wt.%, wherein the carbon fiber has a bulk density of at least 500 g / l and a volume electrical resistivity of less than 2,000 μΩ·cm, and individual filaments have a diameter-to-length ratio of at least 300, and wherein a 3.175 mm thick molded sample of the composite exhibits less than 15% transmission of incident microwave radiation when observed according to the free space method and measured at frequencies from 75 GHz to 110 GHz, and the 3.175 mm thick molded sample of the composite exhibits at least 15% of the percent reflected power measured in the transmission mode when observed according to the free space method and measured at frequencies from 75 GHz to 110 GHz, and the weight percent values combined for all components do not exceed 100 wt.%, and the total weight percent values are based on the total weight of the composite.

[0074] Aspect 1B. A composite consisting essentially of: a thermoplastic resin of about 50 wt.% to about 99 wt.% comprising polyester; and a carbon fiber filler of about 0.1 wt.% to about 15 wt.%, wherein the carbon fiber has a bulk density of at least 500 g / l and a volume electrical resistivity of less than 2,000 μΩ·cm, and individual filaments have a diameter-to-length ratio of at least 300, and wherein a 3.175 mm thick molded sample of the composite exhibits less than 15% transmission of incident microwave radiation when observed according to the free space method and measured at frequencies from 75 GHz to 110 GHz, and the 3.175 mm thick molded sample of the composite exhibits at least 15% of the percent reflected power measured in the transmission mode when observed according to the free space method and measured at frequencies from 75 GHz to 110 GHz, and the weight percent values combined for all components do not exceed 100 wt.%, and the total weight percent values are based on the total weight of the composite.

[0075] Aspect 2. The composite according to any one of Aspects 1A to 1B, wherein the polyester comprises a polyalkylene terephthalate polymer.

[0076] Aspect 3. The composite according to any one of Aspects 1A to 2, wherein the polyester comprises polybutylene terephthalate.

[0077] Aspect 4. The composite according to any one of Aspects 1A to 3, wherein a 3.175 - mm thick molded plate - like body comprising the composite transmits less than about 5% of the incident microwave radiation at frequencies from 75 GHz to 110 GHz.

[0078] Aspect 5. The composite according to any one of Aspects 1A to 4, wherein a 3.175 - mm thick molded sample of the composite exhibits a total shielding effectiveness between 40 dB and 120 dB when measured according to the free - space method at frequencies from 75 GHz to 110 GHz.

[0079] Aspect 6. The composite according to any one of Aspects 1A to 5, wherein a 3.175 - mm thick molded sample of the composite exhibits a total shielding effectiveness greater than that of a reference composition comprising the same amount of carbon powder filler instead of a carbon fiber filler, when measured according to the free - space method at frequencies from 75 GHz to 110 GHz.

[0080] Aspect 7. The composite according to any one of Aspects 1A to 5, wherein a 3.175 - mm thick molded sample of the composite exhibits a higher reflection of microwave radiation than a reference composition comprising the same amount of carbon powder filler instead of a carbon fiber filler, when observed according to the free - space method at frequencies from 18 to 26.5 GHz and measured at frequencies from 75 to 110 GHz.

[0081] Aspect 8. The composite according to any one of Aspects 1A to 7, wherein the individual filaments of the carbon fiber filler are 5 to 10 mm in length.

[0082] Aspect 9. The composite according to any one of Aspects 1A to 7, wherein the individual filaments of the carbon fiber filler have a diameter-to-length ratio of at least 500.

[0083] Aspect 10. The composite according to any one of Aspects 1A to 7, wherein the carbon fiber filler has an aspect ratio greater than 300:1.

[0084] Aspect 11. The composite according to any one of Aspects 1A to 7, wherein the carbon fiber filler has an aspect ratio greater than 200:1.

[0085] Aspect 12. The composite according to any one of Aspects 1A to 7, wherein the carbon fiber filler has an aspect ratio greater than 50:1.

[0086] Aspect 13. The composite according to any one of Aspects 1A to 12, wherein the carbon fiber filler is not a carbon nanotube, a carbon platelet, or carbon powder.

[0087] Aspect 14. The composite according to any one of Aspects 1A to 12, which does not contain or substantially does not contain carbon nanotubes, carbon platelets, or carbon powder.

[0088] Aspect 15. The thermoplastic resin further comprises a poly(carbonate-siloxane) copolymer, the carbon fiber filler is present in an amount of 0.15 wt.% to 2 wt.%, and when a 3.175 mm molded sample of the composite is observed according to the free space method and measured at a frequency of 75 to 110 GHz, it exhibits at least 55% percent absorption power measured in the transmission mode of incident microwave radiation. The composite according to any one of Aspects 1A to 14.

[0089] Aspect 16. The composite according to aspect 15, wherein when the thermoplastic resin is measured according to ASTM D256, it exhibits a notched Izod impact strength of at least 500 J / m at -30°C and a notched Izod impact strength of at least 45 J / m at -30°C.

[0090] Aspect 17. The composite according to aspect 15, wherein when the thermoplastic resin is measured according to ASTM D256, it exhibits a notched Izod impact strength of at least 600 J / m at 23°C and a notched Izod impact strength of at least 60 J / m at 23°C.

[0091] Aspect 18. The composite according to any one of aspects 15 to 17, wherein the carbon fiber-based filler is present in an amount between about 0.12 wt.% and about 0.98 wt.%, and when observed at a frequency of 77 GHz, it exhibits at least 70% of the percent absorbed power measured in transmission mode.

[0092] Aspect 19. The composite according to any one of aspects 15 to 18, wherein the thermoplastic resin further comprises a poly(carbonate-siloxane) copolymer having a siloxane content of at least 5 wt.% based on the total weight of the poly(carbonate-siloxane) copolymer, and the composite has a total siloxane content between 1 wt.% and 15 wt.% based on the total weight of the composite.

[0093] Aspect 20. An article that is an automotive radar sensor for electromagnetic radiation and comprises the composite according to any one of aspects 1A to 19.

Examples

[0094] The following examples are presented to provide those skilled in the art with a complete disclosure and description of how the compounds, compositions, articles, devices, and / or methods claimed herein are made and evaluated, are intended to be purely exemplary, and are not intended to limit the disclosure. Although efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperatures, etc.), it is desirable to account for some error and deviation. Unless otherwise indicated, parts are parts by weight, temperature is in °C or ambient temperature, and pressure is at or near atmospheric pressure. Unless otherwise indicated, percentages referred to in connection with compositions are by wt%.

[0095] There are numerous variations and combinations of mixing conditions, such as component concentrations, extruder design, feed rates, screw speeds, temperature, pressure, and other mixing ranges and conditions that can be used to optimize the purity and yield of the product obtained from the described processes. Optimizing such process conditions would require only reasonable and routine experimentation. Example I Comparison of PBT Resins Containing Carbon Powder or Carbon Fiber Microwave Shielding Fillers

[0096] Various composite samples were prepared. The comparative formulations are shown in Table 1. The comparative samples contained a blend of polyethylene terephthalate Valox™ 195 and Valox™ 315 in a ratio equal to 1.408 (Valox™ 195 / Valox™ 315), and further contained carbon black powder (the carbon black powder is Ensaco™ 360 G), and were designated as CE-1 to CE-5. Table 1. Comparative Formulations

[0097]

Table 1

[0098] Samples EX-1 to EX-5 of the present invention are shown in Table 2 below and are a combination of a blend of polybutylene terephthalate resin and a carbon fiber filler. The carbon fiber filler is TENAX J HT C493 6mm chopped fiber. As in the case of the comparative formulation, the (Valox (trademark) 195 / Valox (trademark) 315) ratio of the formulation of the present invention is also equal to 1.408. Table 2. Formulation of the present invention

[0099]

Table 2

[0100] Composite samples were prepared on a co-rotating intermeshing twin-screw extruder with a diameter of 40 mm. In this case, the components of different formulations were added to the extruder, melted and mixed, and for the comparative formulation, it was extruded from the extruder through a 5-hole die plate, and for the formulation of the present invention, it was extruded from the extruder through a 6-hole die plate. The extruder was operated at a screw speed of 200 rpm for most formulations, and at a rate of 29 - 45 Kg / h (0.029 - 0.045 tons / h) for the comparative formulation and 68 Kg / h (0.068 tons / h) for the formulation of the present invention. The extruder torque was maintained between about 35% and about 65% of the maximum torque. The extruder barrel temperature was maintained between about 185 - 200 °C (upstream, near the feed throat of the extruder) and about 250 °C (downstream, near the die plate of the extruder). The die plate temperature was maintained at about 250 °C, and the temperature of the melt exiting the extruder was measured at about 275 °C.

[0101] Scattering parameter S for reflection in the K band 11 and scattering parameter S for transmission 21 (both measured and calculated) were observed. S at 0 dB 11 is a perfect reflector (metal plate, e.g., stainless steel, aluminum, etc., with no reflection loss), while S at 0 dB 21It should be noted that it is a perfect transparent body (such as air, without transmission loss). Figures 1A and 1B respectively show the scattering parameters of CE-1 and EX-1 in the K band (18 - 26.5 GHz). As shown, in the K band, since EX-1 shows less reflection loss than CE-1 and CE-1 shows less transmission loss than EX-1, it is suggested that in this frequency range, EX-1 is a better microwave reflector while CE-1 is a better microwave transmitter.

[0102] Figures 2A and 2B respectively show the scattering parameters of CE-5 and EX-5 in the K band (18 - 26.5 GHz). As shown, in the K band, since EX-5 shows less reflection loss than CE-5 and CE-5 shows less transmission loss than EX-5, it is suggested that in this frequency range, EX-5 is a better microwave reflector while CE-5 is a better microwave transmitter. Figures 3A and 3B respectively show the scattering parameters of CE-1 and EX-1 in the W band (75 - 110 GHz). As shown, in the W band, since EX-1 shows less reflection loss than CE-1 and CE-1 shows less transmission loss than EX-1, it is suggested that in this frequency range, EX-1 is a better microwave reflector while CE-1 is a better microwave transmitter. Also, for CE-1, the value of S 11 is different for each frequency investigated. Figures 4A and 4B respectively show the scattering parameters of CE-5 and EX-5 in the W band (75 - 110 GHz). The scattering parameter S 11 measured for reflection for both CE-5 and EX-5 approaches 0 dB over the observed frequencies, but the S 11 for EX-5 is closer to 0 dB than the S 11 for CE-5, suggesting that EX-5 is a better microwave reflector than CE-5 in this frequency range. Similarly, the S 21Since it is closer to the 0 dB line than EX-5, CE-5 is a better microwave transmission body than EX-5 in the W-band frequency range.

[0103] The percent power in the transmission mode in the K-band (18 - 26.5 GHz) and W-band (75 - 110 GHz) was also observed. Figures 5A and 5B are graphical representations of the percent power in the transmission mode in the K-band for CE-1 and EX-1, respectively. The sum of absorption, reflection, and transmission at each frequency must be 100% of the incident MW radiation. In the transmission mode, due to the presence of a high level of carbon particles dispersed in the polymer, a portion of the transmission through the sample is naturally blocked, and thus, in the same way that a metal plate acts to block transmitted radiation when using measurements in the metal-backed reflection mode, it acts to block any passage of microwave energy from the sample to the receiving antenna. As shown in this figure, when observed in the K-band (18 - 26.5 GHz), the transmittance of the comparative sample CE-1 was approximately 65 - 75%, while the transmittance of the sample EX-1 of the present invention was approximately 5 - 15%. EX-1 also exhibited greater microwave absorption in the transmission mode when observed in the K-band (comparing 15 - 25% in CE-1 to ~35 - 60% in EX-1). Microwave reflection was also higher for EX-1 (approximately 30 - 50%) compared to CE-1 (approximately 0 to 20%) for all frequencies examined in the K-band.

[0104] Figures 6A and 6B each show the percent power in the transmission mode in the K band for CE-2 and EX-2, respectively. Similarly, for EX-2 (about 2%), the transmission is much less compared to the comparative sample CE-2 (about 22% - 45%). Figures 7A and 7B each show the percent power in the transmission mode in the K band for CE-3 and EX-3, respectively. The percent transmission for EX-3 has significantly decreased to about 1% or less, while the percent transmission for CE-3 remains between about 7% and 13%. Also, when the concentration of the carbon filler in both compositions is kept the same, for the comparative sample CE-3, the microwave absorption is higher and the microwave reflection is lower compared to the sample EX-3 of the present invention.

[0105] Figures 8A and 8B are respectively graphs showing the percent power measured in the transmission mode in the K-band (18 - 26.5 GHz) for CE-4 and EX-4. For the sample EX-4 of the present invention having 8 wt.% chopped carbon fibers, the transmission has decreased to almost zero, and thus the sum of absorption and reflection occupies almost 100% of the amount of radiation incident on the sample. While the absorption of the carbon powder sample remains high at about 60% to 67%, the absorption rate of the carbon fiber sample remains at about 25%. These trends are consistent for CE-5 and EX-5, which are respectively shown in Figures 9A and 9B showing the percent power in the transmission mode in the K-band (18 - 26.5 GHz). These trends were also observed at even higher frequencies in the W-band. Figures 10A and 10B respectively show the percent power in the transmission mode in the W-band (75 - 110 GHz) for CE-1 and EX-1. At higher frequencies, the sample EX-1 of the present invention having 2 wt.% chopped carbon fibers has almost 0% transmission, and the absorption and reflection are divided approximately equally at about 50% each. For the sample EX-2 of the present invention shown in Figure 11B (see CE-2 in Figure 11A), the transmittance is also almost 0%. Figures 12A and 12B respectively show the percent power in the transmission mode in the W-band (75 - 110 GHz) for CE-3 and EX-3. As shown by the graph, in the comparative sample CE-3, the microwave absorption is higher compared to the sample EX-3 of the present invention, while for EX-3 with a carbon filler content of 6 wt.% (powder in CE-3 and fiber in EX-3), the microwave reflection is high. Figures 13A and 13B respectively show the percent power in the transmission mode in the W-band (75 - 110 GHz) for CE-4 and EX-4. CE-4 and EX-4 continue to show the previous trend that the microwave absorption rate is higher and the microwave reflectance is lower for the comparative samples than for the samples of the present invention with a carbon filler content of 8 wt.%. It is worth mentioning that for the comparative sample CE-4, the ratio of % absorption / % reflection is about 70 / 30, while for the sample EX-4 of the present invention considering the same carbon filler content, it is also about 70 / 30 for the ratio of % reflection / % absorption.Figures 14A and 14B each show the percent power in transmission mode measured at the W band (75 - 110 GHz) for CE-5 and EX-5. Again, microwave absorption is greater for the comparative sample CE-5 than for the sample EX-5 of the present invention at the same carbon filler content. The microwave transmittance is negligibly small for both samples. Also worth mentioning is that the percent reflected power measured in the W band (75 - 110 GHz) for five compositions of the present invention containing chopped carbon fibers as a microwave trapping filler increased from about 50% in EX-1 (2 wt% filler) to about 60% in EX-2 (4 wt% filler), to about 70% in EX-3 (6 wt% filler), to about 72% in EX-4 (8 wt% filler), and to about 75% in EX-5 (10 wt% filler).

[0106] These values suggest that the disclosed composites can be used to optimize the relative amounts of microwave absorption and reflection of the composition in a given frequency range. The polymer / filler ratio of the disclosed materials may be manipulated to modify the electromagnetic response of those materials. For example, when testing these resins in the K band, the microwave transmission may be modified between 15% and nearly 0%, and the microwave reflection may be modified between 30% and 75%. The polymer / carbon fiber filler ratio directly affects the value of the ratio of reflection to absorption of microwave energy in the high-frequency W band, ranging from 50% / 50% in EX-1 (2 wt.% carbon fiber loading) to 75% / 25% in EX-5 (10 wt% carbon fiber loading).

[0107] Shielding effectiveness describes the combined effect of microwave absorption and reflection of a material. Figures 15A and 15B are graphs showing the total shielding effectiveness in the K band (18 - 26.5 GHz) for CE-1 to CE-5 and EX-1 to EX-5, respectively. Figure 15A shows that when observed in the K band, the total shielding effectiveness of the comparative compositions CE-1 to CE-5 varied from about 2 dB to about 25 dB. Similarly, Figure 15B shows that when observed in the K band, the total shielding effectiveness of the compositions EX-1 to EX-5 of the present invention varied from about 5 dB to about 80 dB. Figures 16A and 16B show the total shielding effectiveness in the W band (75 - 110 GHz) for CE-1 to CE-5 and EX-1 to EX-5, respectively. As shown by these graphs, the shielding effectiveness of the comparative compositions CE-1 to CE-5 varied between about 5 dB and 55 dB, while the shielding effectiveness of the compositions EX-1 to EX-5 of the present invention varied between about 50 dB and 110 dB. As these results show, shielding effectiveness is a combination of the amount of microwave radiation absorbed or reflected by the material, and is much higher in the compositions of the present invention compared to the comparative compositions when considering the same amount of carbon filler, powder, or fiber in the formulations. From these results, it was shown that this appears to be the case for both of the two frequency ranges investigated, the K band (18 - 26.5 GHz) and the W band (75 - 110 GHz).

[0108] The percent absorption power in the transmission mode observed at the K-band (18 - 26.5 GHz) for CE-1 to CE-5 and EX-1 to EX-5 is shown in FIGS. 17A and 17B, respectively. These results indicate that in the compositions of the present invention of the present disclosure, % absorption values in the K-band between about 20% and 60% can be expected. FIGS. 18A and 18B show the percent absorption power in the transmission mode observed at the W-band (75 - 110 GHz) for comparative formulations CE-1 to CE-5 and formulations EX-1 to EX-5 of the present invention, respectively. These results indicate that in the compositions of the present invention of the present disclosure, % absorption values in the W-band between about 25% and 50% can be expected.

[0109] The above results indicate that materials that reflect MW radiation more highly are produced from carbon fibers as compared to materials comprising carbon powder of the same loading. Materials comprising carbon powder were more MW absorptive. This is particularly true at the W-band, since EX-1 to EX-5 absorb about 20 - 60% of the incident MW radiation while CE-1 to CE-5 absorb about 50 - 80%. These differences are even more pronounced when comparing compositions containing the same amount of carbon filler (powder vs. fiber). See FIGS. 18A and 18B. The % absorption ranges for CE-1 to CE-5 and EX-1 to EX-5 were similar at the K-band. Again, a relatively large difference in percent absorption power was observed when comparing compositions containing the same amount of carbon filler (powder vs. fiber). See FIGS. 17A and 17B. Without being bound by any particular theory, the carbon powder-based comparative compositions thus appear to shield MW radiation mainly by absorption, while the carbon fiber-based compositions of the present invention shield MW radiation mainly by reflection.

[0110] The values of the absorbed power, reflected power, and transmitted power measured for the composites of the present disclosure were observed in accordance with the free space method. The free space method consists of a vector network analyzer connected to two antennas (a transmitting antenna and a receiving antenna) that focus microwave energy at or through a slab of material. This method can be carried out in transmission mode (where all three energy transfer modes of transmission, absorption, and reflection are possible), or in metal-backed reflection mode (where only absorption and reflection are possible, and transmission is suppressed by placing a metal plate between the sample and the receiving antenna). This method is non-contact and is particularly effective at millimeter wave frequencies. The samples were evaluated in transmission mode as shown in Figure 19.

[0111] The electrical surface resistivity and volume resistivity were observed at room temperature for the comparative samples and the samples of the present invention, and measured in accordance with ASTM D257 on molded plate-like bodies measuring 4 inches × 5 inches and 1 / 8 inch thick (10.2 cm × 12.7 cm and 0.32 cm thick) under ambient conditions of a voltage in the range of 10 to 100 V, a relative humidity (RH) of 50%, and 23°C. Table 3 shows the values for different comparative samples CE-1 to CE-5 and samples of the present invention EX-1 to EX-5. Figure 20 represents Table 3 showing the volume electrical resistivity and surface electrical resistivity of CE-1 to CE-5, EX-1, and EX-5 respectively. Figures 21A and 21B are graphical representations of the volume resistivity and surface resistivity for different samples respectively. Example II. Comparison of PBT resins having carbon fibers and further containing poly(carbonate-siloxane)

[0112] To further evaluate the performance of carbon fibers, various composite samples further comprising a poly(carbonate-siloxane) copolymer were prepared. The formulations are represented in Table 4 (shown in Figure 22). All samples included a combination of PBT and PC-siloxane, although the carbon fiber content in comparative sample CE-6 was low (0.1 wt.%). The composite samples were prepared as provided in Example I. Dielectric properties were observed at 77 GHz for samples with a nominal thickness of 3.175 mm (0.125 inches). The values are represented in Table 5 (Figure 23). The complex dielectric constant was also observed at frequencies in the W-band (75 - 110 GHz). The real and imaginary parts of the complex dielectric constant were observed using Teflon as a control or standard. The dielectric performance at frequencies between 75 and 110 GHz for sample CE-6 and EX-6 through EX-9 was observed. Figures 24 and 25 show the real part ε’ and imaginary part ε” of the complex dielectric constant at frequencies from 75 GHz to 110 GHz, respectively. Figure 26 is a graphical representation of the attenuation constant, and it appeared that as the amount of carbon fiber increased, the attenuation constant became more negative. Figure 27 is a graphical representation of the total shielding effectiveness, which increased with increasing carbon fiber content throughout the samples. Figure 28 is a graphical representation of the percent power absorbed in transmission mode with respect to the amount of carbon fiber added to the formulation.

[0113] For the 3.066 mm sample of CE-6, not only the real and imaginary part values of the complex permittivity, but also the values of the reflected, transmitted, and absorbed percent power measured in transmission mode are shown in FIGS. 29 and 30, respectively. For the 3.067 mm sample of EX-6, not only the real and imaginary part values of the complex permittivity, but also the values of the reflected, transmitted, and absorbed percent power measured in transmission mode are shown in FIGS. 31 and 32, respectively. For the 3.037 mm sample of EX-7, not only the real and imaginary part values of the complex permittivity, but also the values of the reflected, transmitted, and absorbed percent power measured in transmission mode are shown in FIGS. 33 and 34, respectively. For the 3.024 mm sample of EX-8, not only the real and imaginary part values of the complex permittivity, but also the values of the reflected, transmitted, and absorbed percent power measured in transmission mode are shown in FIGS. 35 and 36, respectively. For the 3.054 mm sample of EX-9, not only the real and imaginary part values of the complex permittivity, but also the values of the reflected, transmitted, and absorbed percent power measured in transmission mode are shown in FIGS. 37 and 38, respectively. Comparative example CE-6, which has less than 0.2 wt.% carbon fiber in the PBT / PC-siloxane blend, has a much higher transmittance than samples EX-6 to EX-9 of the present invention. Reflection appeared to increase with increasing carbon fiber content from EX-6 to EX-9. At 77 GHz, the percent absorbed power measured in transmission mode is maximum (approximately 71.5%) when the concentration of carbon fiber in the composition is about 0.5 wt.%. FIGS. 39 and 40 graphically show, at 77 GHz, not only the real and imaginary permittivities, but also the percent power in absorption, reflection, and transmission that is transmitted, respectively.

[0114] For CE-6 and EX6-9, additional physical and mechanical properties were also evaluated, those at 23 °C are presented in Tables 6A and 6B (shown in Figures 41 and 42 respectively), and those at 30 °C are presented in Table 7 (shown in Figure 43). Graphical representations of the Izod impact strength at 23 °C and 30 °C according to ASTM D256 are presented in Figures 44 and 45 respectively. The presence of poly(carbonate-siloxane) appeared to improve the impact strength and ductility of the formulations at low temperatures. Table 8 (shown in Figure 46) presents the values of heat deflection HDT, specific gravity, flow rate, and viscosity for CE-6, and EX-6 through EX-9. Table 9 (shown in Figure 47) presents the values of volume resistivity and surface resistivity for CE-6, and EX-6 through EX-9.

[0115] The above is intended to be illustrative and not restrictive. For example, the above embodiments (or one or more aspects thereof) may be used in combination with each other. Other embodiments may be used by those skilled in the art, for example, at the time of considering the above. The abstract is provided to enable the reader to quickly grasp the nature of the technical disclosure. It is also submitted with the understanding that it will not be used to limit the scope or meaning of the claims. Also, in the above mode for carrying out the invention, various features may be grouped together in order to simplify the disclosure. It is desirable that this not be construed as intending that the disclosed features not claimed are essential to any of the claims. Rather, the subject matter of the invention may lie in less than all the features of a particular disclosed embodiment. Accordingly, the following claims are incorporated as examples or embodiments into the mode for carrying out the invention, each claim being independent in itself as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the present disclosure is desirably determined with reference to the appended claims, together with the broadest possible scope of equivalents to which such claims are entitled.

[0116] It will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the scope or spirit of the present disclosure. Other embodiments of the present disclosure will be apparent to those skilled in the art upon consideration of the detailed description and examples of the present disclosure disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the appended claims. The patentable scope of the present disclosure is defined by the claims and can include other examples that are contemplated by those skilled in the art. Such other examples are intended to be included within the scope of the claims if they have structural elements that do not differ from the literal language of the claims or if they include equivalent structural elements that do not differ substantially from the literal language of the claims.

Claims

1. From about 50 wt% to about 99 wt% of a thermoplastic resin comprising a polyester and a poly(carbonate-siloxane) copolymer; From about 0.15 wt% to about 2 wt% of a carbon fiber filler, wherein the carbon fibers have a bulk density of at least 500 g / l and a volume electrical resistivity of less than 2,000 μΩ·cm, and the individual filaments have an aspect ratio of at least 300, the carbon fiber filler; A composite comprising: When a 3.175 mm thick molded sample of the composite is observed according to the free space method and measured at a frequency from 75 to 110 GHz, it exhibits at least 55% percent absorption power measured in the transmission mode of the incident microwave radiation; When a 3.175 mm thick molded sample of the composite is observed according to the free space method and measured at a frequency from 75 GHz to 110 GHz, it exhibits less than 15% transmission of the incident microwave radiation; When a 3.175 mm thick molded sample of the composite is observed according to the free space method and measured at a frequency from 75 GHz to 110 GHz, it exhibits at least 15% of the percent reflection power measured in the transmission mode; A composite in which the weight percentage combined for one of all components does not exceed 100 wt%, and the value of the total weight percentage is based on the total weight of the composite.

2. The composite according to claim 1, wherein the polyester comprises a polyalkylene terephthalate polymer.

3. The composite according to claim 1, wherein the polyester comprises polybutylene terephthalate.

4. The composite according to claim 1, wherein a 3.175 mm thick molded plate-like body comprising the composite transmits less than about 5% of the incident microwave radiation at a frequency from 75 GHz to 110 GHz.

5. The composite according to claim 1, wherein a 3.175 mm thick molded sample of the composite exhibits a total shielding effectiveness greater than that of a reference composition comprising the same amount of carbon powder filler instead of the carbon fiber filler, measured according to the free space method at a frequency from 75 GHz to 110 GHz.

6. The composite, wherein a 3.175 mm thick molded sample of the composite exhibits higher reflection of microwave radiation than a reference composition comprising the same amount of carbon powder filler instead of the carbon fiber filler when observed according to the free space method and measured at frequencies from 18 to 26.5 GHz and from 75 to 110 GHz, as claimed in claim 1. **Claim 7** The composite according to claim 1, wherein the individual filaments of the carbon fiber filler are 5 to 10 mm in length. **Claim 8** The composite according to claim 1, wherein the individual filaments of the carbon fiber filler have a diameter-to-length ratio of at least 500. **Claim 9** The composite according to claim 1, wherein the carbon fiber filler has an aspect ratio greater than 300:

1. **Claim 10** The composite according to claim 1, wherein the carbon fiber filler is not carbon nanotubes, carbon platelets, or carbon powder. **Claim 11** The composite according to claim 1, which does not contain or substantially does not contain carbon nanotubes, carbon platelets, or carbon powder. **Claim 12** The composite according to claim 11, wherein the thermoplastic resin exhibits a notchless Izod impact strength of at least 500 J / m and a notched Izod impact strength of at least 45 J / m at -30 °C when measured according to ASTM D256. **Claim 13** The composite according to claim 11, wherein the thermoplastic resin exhibits a notchless Izod impact strength of at least 600 J / m and a notched Izod impact strength of at least 60 J / m at 23 °C when measured according to ASTM D256. **Claim 14** The composite according to claim 11, wherein the carbon fiber filler exhibits at least 70% of the percent absorbed power measured in transmission mode when observed at a frequency of 77 GHz. **Claim 15** The composite according to claim 1, wherein the poly(carbonate-siloxane) copolymer has a siloxane content of at least 5 wt% based on the total weight of the poly(carbonate-siloxane) copolymer, and the composite has a total siloxane content between 1 wt% and 15 wt% based on the total weight of the composite. **Claim 16** An article comprising the composite according to any one of claims 1 to 15 and being an automotive radar sensor for electromagnetic radiation.

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