WO2016106398A1 - Formulations d'émail et de vernis de fil thermoconducteur - Google Patents

Formulations d'émail et de vernis de fil thermoconducteur Download PDF

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Publication number
WO2016106398A1
WO2016106398A1 PCT/US2015/067538 US2015067538W WO2016106398A1 WO 2016106398 A1 WO2016106398 A1 WO 2016106398A1 US 2015067538 W US2015067538 W US 2015067538W WO 2016106398 A1 WO2016106398 A1 WO 2016106398A1
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WIPO (PCT)
Prior art keywords
boron nitride
weight
enamel
insulated wire
less
Prior art date
Application number
PCT/US2015/067538
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English (en)
Inventor
Rohit Bhosale
Chandrashekar Raman
Original Assignee
Momentive Performance Materials Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Momentive Performance Materials Inc. filed Critical Momentive Performance Materials Inc.
Publication of WO2016106398A1 publication Critical patent/WO2016106398A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
    • C03C8/24—Fusion seal compositions being frit compositions having non-frit additions, i.e. for use as seals between dissimilar materials, e.g. glass and metal; Glass solders
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/32—Non-oxide glass compositions, e.g. binary or ternary halides, sulfides or nitrides of germanium, selenium or tellurium
    • C03C3/328—Nitride glasses
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/24—Electrically-conducting paints
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/61—Additives non-macromolecular inorganic
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/38—Boron-containing compounds
    • C08K2003/382—Boron-containing compounds and nitrogen
    • C08K2003/385—Binary compounds of nitrogen with boron

Definitions

  • the present technology relates to novel enamel and/or varnish formulations that are thermally conductive and/or electrically insulating.
  • the present technology also relates to enamel and/or varnish formulations having enhanced dielectric strength and other dielectric properties.
  • Copper or aluminum wires are extensively used in a wide range of electrical equipment or electronic components such as electric motors, transformers, generators, inductors, electromagnets, etc.
  • the conductor wires are often coated with a thin layer of electrical insulation, commonly known as enamel, to prevent short circuits between the conductors.
  • enamel a thin layer of electrical insulation, commonly known as enamel, to prevent short circuits between the conductors.
  • resin chemistries are used in enamel depending on the desired operating temperature such as epoxies, polyurethanes, polyesters, polyamides, polyamide-imides, and polyimides.
  • These enamels may be either thermoplastic or thermoset resins.
  • the enamel layer may be a single resin layer, or could consist of multiple, concentric layers.
  • the varnish may be typically be an epoxy resin, but may also be selected from other suitable chemistries such as polyurethanes, polyesters, polyamides, polyamide-imides, and polyimides.
  • the present technology provides, in one aspect, a thermally conductive enamel and varnish formulations.
  • the enamel or varnish formulation may include inorganic additive or filler materials that are electrically insulating.
  • the present technology provides a thermally conductive enamel or varnish formulation that is capable of dissipating heat to maintain acceptable operating temperatures for electrical and electronic components.
  • the formulations disclosed herein may be used as an enamel or a varnish depending on the desired outcome.
  • the terms enamel and varnish may be used interchangeably.
  • the enamel formulations have enhanced dielectric strength.
  • the dielectric strength of the enamel formulation may be enhanced by the addition of various fillers to the enamel resin.
  • the dielectric constant of the enamel formulation may be tuned to meet a certain impedance requirement depending on the thickness of the enamel layer and the frequency of the electrical field in the conductor.
  • the enamel formulation comprises boron nitride (BN).
  • the enamel formulation may also include an additional metal oxide and/or a mineral additive.
  • the formulation comprises at least about 3% BN by weight, or at least about 5% BN by weight, or at least about 10 % BN by weight, or at least about 20% BN by weight, or at least 30% BN by weight, or at least 40% BN by weight, or at least about 50% BN by weight, or even up to about 80% BN by weight.
  • the enamel formulation has an in-plane thermal conductivity of at least 0.5 W/mK, or at least 0.8 W/mK, or at least 1.0 W/mK, or at least 2.0 W/mK, or at least 5 W/mK, or even up to 10 W/mK.
  • the enamel formulation has a through-plane thermal conductivity of at least 0.5 W/mK, or at least 0.8 W/mK, or at least 1.0 W/mK, or at least 2.0 W/mK, or at least 5 W/mK, or even up to 10 W/mK.
  • the enamel formulation has a dielectric strength of at least 10 KV/mm, or at least 20 KV/mm, or at least 30 KV/mm, or at least 50 KV/mm, or even up to 100 KV/mm.
  • the enamel formulation has a dielectric constant of
  • the dielectric constant is 3, or 4, or 6, or 10, or 50, or even up to 500.
  • FIG. 1 is a cross-sectional view of a wire coated with an enamel formulation according to the invention.
  • the current invention discloses various novel enamel and/or varnish compositions.
  • the enamel and/or varnish compositions are thermally conductive formulations.
  • the varnish may comprise the same formulation as the enamel composition or may comprise a different formulation from the enamel composition.
  • the enamel composition comprises a resin matrix and a filler disposed in the resin matrix.
  • Thermally conductive formulations of resin systems may be produced by adding inorganic additives or filler materials to the resin matrix. Because electrical insulation properties may be important, potential additives may also be electrically insulating.
  • an enameled wire 10 comprises a wire/conductor 20 and an enamel coating 30 disposed about the wire/conductor 20.
  • the resin material is generally not limited and may include any material suitable for an enamel as desired for a particular purpose or intended application.
  • materials suitable for the enamel resin include, but are not limited to, a polyvinyl formal, a polyester, a polyurethane, a polyamide, a polyimide, a polyamideimide, a polyepoxide, a polyesterimide, and combinations of two or more thereof.
  • the enamel composition further comprises a filler.
  • the enamel composition comprises a thermally conductive filler.
  • the thermally conductive filler may also exhibit good electrical insulation properties, particularly for applications where the enamel composition will be used to coat electrically conductive materials.
  • suitable fillers include, but are not limited to boron nitride, silica, glass fibers, a metal oxide such as, zinc oxide, magnesium oxide, beryllium oxide, titanium oxide, zirconium oxide, yttrium oxide, etc., calcium carbonate, talc, mica, wollastonite, clays, exfoliated clays, aluminum silicate, alumina, aluminum nitride, graphite, metallic powders, e.g., aluminum, copper, bronze, brass, etc., or a combination of two or more thereof.
  • the enamel coating 30 may include a silica, alumina, magnesium oxide, zinc oxide, yttria, zirconia, or a combination of two or more thereof
  • the enamel formulation 30 may include silica.
  • more complex materials such as metal oxides with more than one cation such as barium titanate, calcium titanate, lead titanate, strontium titanate, barium strontium titanate (BST), barium zirconate, or materials such silicates, oxynitrides, perovskites, chalcogenides, or a combination of two or more thereof.
  • BST barium strontium titanate
  • barium zirconate or materials such silicates, oxynitrides, perovskites, chalcogenides, or a combination of two or more thereof.
  • doped versions of these materials that demonstrate superior properties may also be considered.
  • BST doped with various rare earth oxides or heavy metal oxides may have very high dielectric constants.
  • nitride materials such as boron nitride (BN), aluminum nitride, and/or silicon nitride may be used.
  • the enamel formulation may further comprise various mineral fillers such as talc, mica, vermiculite, clay, kaolin, wollastonite, bentonite, montmorillonite, aluminum silicates, or a combination of two or more thereof.
  • mineral fillers such as talc, mica, vermiculite, clay, kaolin, wollastonite, bentonite, montmorillonite, aluminum silicates, or a combination of two or more thereof.
  • the materials mentioned above may be used in particulate form or agglomerated form, or as short fibers, or longer fibers, or as flakes of controlled average size and/or controlled size distributions or with controlled aspect ratio for fibers and flakes.
  • the enamel formulation comprises BN.
  • BN has high thermal conductivity (> 300 W/mK), high dielectric strength (> 50 KV/mm), low dielectric constant (approximately 4.1 @ 1 MHz), and very low loss tangent ( ⁇ 0.0002 @ 1 MHz).
  • the "in- plane” thermal conductivity is defined to be along the length of the conductor, and the "through-plane” thermal conductivity, also known as the through-thickness thermal conductivity, is in the thickness direction of the article. It is possible that the thermal conductivity of such formulations may be anisotropic, i.e., the in-plane and through-plane conductivities may not be equal.
  • the enamel has an in-plane thermal conductivity of at least about 0.5 W/mK, or at least about 0.8 W/mK, or at least about 1.0 W/mK, or at least about 2.0 W/mK, or at least about 5 W/mK, or even up to about 10 W/mK.
  • the enamel has an in-plane thermal conductivity in the range of at least about 0.5 W/mK to at least about 0.8 W/mK; at least about 0.5 W/mK to at least about 1.0 W/mK; at least about 0.5 W/mK to at least about 2.0 W/mK; at least about 0.5 W/mK to at least about 5.0 W/mK; at least about 0.5 W/mK to at least about 10.0 W/mK; or at least about 0.5 W/mK to at least about 20W/mK.
  • the enamel has an in-plane thermal conductivity in the range of at least about at least about 0.8 W/mK to at least about 1.0 W/mK; at least about 0.8 W/mK to at least about 2.0 W/mK; at least about 0.8 W/mK to at least about 5.0 W/mK; at least about 0.8 W/mK to at least about 10.0 W/mK; or at least about 0.8 W/mK to at least about 20 W/mK.
  • the enamel has an in-plane thermal conductivity in the range of at least about 1.0 W/mK to at least about 2.0 W/mK; at least about 1.0 W/mK to at least about 5.0 W/mK; at least about 1.0 W/mK to at least about 10.0 W/mK; or at least about 1.0 W/mK to at least about 20 W/mK.
  • the enamel 10 has a through-plane thermal conductivity of at least about 0.5 W/mK, or at least about 0.8 W/mK, or at least about 1.0 W/mK, or at least about 2.0 W/mK, or at least about 5 W/mK, or even up to about 10 W/mK.
  • the enamel has an through-plane thermal conductivity in the range of at least about 0.5 W/mK to at least about 0.8 W/mK; at least about 0.5 W/mK to at least about 1.0 W/mK; at least about 0.5 W/mK to at least about 2.0 W/mK; at least about 0.5 W/mK to at least about 5.0 W/mK; at least about 0.5 W/mK to at least about 10.0 W/mK.
  • the enamel has an through-plane thermal conductivity in the range of at least about at least about 0.8 W/mK to at least about 1.0 W/mK; at least about 0.8 W/mK to at least about 2.0 W/mK; at least about 0.8 W/mK to at least about 5.0 W/mK; at least about 0.8 W/mK to at least about 10.0 W/mK.
  • the enamel has an through-plane thermal conductivity in the range of at least about 1.0 W/mK to at least about 2.0 W/mK; at least about 1.0 W/mK to at least about 5.0 W/mK; at least about 1.0 W/mK to at least about 10.0 W/mK.
  • the total weight loading of fillers in the composition is at least about 3% by weight, or at least about 10 % by weight, or at least about 20% by weight, or at least about 50% by weight, or even up to about 90% by weight.
  • the total weight loading of fillers in the composition is in the range of at least about 3% by weight to at least about 10% by weight; at least about 3% by weight to at least about 20% by weight; at least about 3% by weight to at least about 50% by weight; or at least about 3% by weight to at least about 90% by weight.
  • the total weight loading of fillers in the composition is in the range of at least about 10% by weight to at least about 20% by weight; at least about 10% by weight to at least about 50% by weight; or at least about 10% by weight to at least about 90% by weight.
  • the total weight loading of fillers in the composition is in the range of at least about 20% by weight to at least about 50% by weight or at least about 20% by weight to at least about 90% by weight.
  • the enamel formulation comprises boron nitride.
  • boron nitride materials include boron nitride platelets, boron nitride agglomerates, or a mixture thereof.
  • the average particle size of the boron nitride may be about 3 microns, or about 10 microns, or about 25 microns or about 50 microns, or about 100 microns or about 150 microns, or even up to about 400 microns.
  • the fundamental crystal size of the boron nitride may be about 0.1 microns, or about 0.5 microns, or about 2 microns, or about 10 microns, or even up to about 50 microns.
  • the surface area of the boron nitride may be less than 50 m 2 /g, or less than 20 m 2 /g, or less than 10 m 2 /g, or less than 5 m 2 /g, or less than 2 m 2 /g, or even less than 1 m 2 /g.
  • the aspect ratio of the fundamental crystals of the boron nitride may be at least 5, or at least 10, or at least 20, or at least 50, or at least 100, or at least 300, or at least 600, or even up to 1000.
  • the enamel coating comprises boron nitride having an average particle size in a range of about 1 microns to about 50 microns, about 2 microns to about 30 microns, or about 3 microns to about 25 microns.
  • the varnish comprises boron nitride having an average particle size in a range of about 10 microns to about 150 microns, about 25 microns to about 100 microns, or about 30 microns to about 75 microns. It may be desirable to include a varnish comprising boron nitride having a larger average particle size as compared to the average particle size of the enamel coating.
  • the enamel formulation comprises boron nitride and an additional metal oxide or a mineral additive.
  • the formulation comprises at least about 3% BN by weight, or at least about 10 % BN by weight, or at least about 20% BN by weight, or at least about 50% BN by weight, or even up to about 80% BN by weight.
  • the total weight loading of BN in the composition is in the range of at least about 3% BN by weight to at least about 10% BN by weight; at least about 3% BN by weight to at least about 20% BN by weight; at least about 3% BN by weight to at least about 50% BN by weight; or at least about 3% BN by weight to at least about 80% BN by weight.
  • the total weight loading of fillers in the composition is in the range of at least about 10% by weight to at least about 20% by weight; at least about 10% by weight to at least about 50% by weight; or at least about 10% by weight to at least about 80% by weight.
  • the total weight loading of fillers in the composition is in the range of at least about 20% by weight to at least about 50% by weight or at least about 20% by weight to at least about 80% by weight.
  • the enamel formulation comprises BN flakes or platelets.
  • the average BN platelet size may be in the range of about 0.1 microns to about 100 microns, about 0.5 microns to about 50 microns, about 1 to about 25 microns, or about 2 to about 20 microns.
  • the average BN platelet size may be about 0.1 microns, or about 0.5 microns, or about 2 microns, or about 10 microns, or about 50 microns, or even up to about 100 microns.
  • the surface area of the BN platelets may be less than 50 m 2 /g, or less than 20 m 2 /g, or less than 10 m 2 /g, or less than 6 m 2 /g, or less than 3 m 2 /g, or even less than 1 m 2 /g.
  • the graphitization index, a measure of the extent of crystallinity of the BN crystals may be less than 8, or less than 4, or less than 2, or less than 1.5, or less than 1.2, or possibly even less than 1.0.
  • the enamel formulation comprises exfoliated or delaminated BN platelets or flakes.
  • the BN flakes or platelets may have an average aspect ratio (defined as ratio of crystal diameter to crystal thickness) of at least 5, or at least 10, or at least 20, or at least 50, or at least 100, or at least 300, or at least 600, or even up to 1000.
  • the BN flakes or platelets may have an average aspect ratio in the range of about 10 to about 1000; about 10 to about 600; about 10 to about 300; about 20 to about 1000; about 20 to about 600; about 20 to about 300; about 50 to about 1000; about 50 to about 600; about 50 to about 300.
  • the crystal thickness may be estimated by calculations from the surface area and the average aspect ratio may be calculated using the measured average particle size of the BN platelets.
  • the particle size may be measured using suitable methods such as laser light diffraction or sedimentation analysis.
  • the enamel formulation comprises agglomerate grades of BN.
  • Use of BN agglomerates may eliminate the anisotropy in BN crystals.
  • BN agglomerate particles are aggregates of smaller BN crystal platelets. For example, it is possible to make a 60 micron agglomerate of about 6 micron fundamental crystals (e.g., Momentive's PTX60 BN powder grade), or a 150 micron agglomerate of about 8 micron crystals (e.g., Momentive's PT350 BN powder grade).
  • the porosity of BN agglomerates is defined as the void fraction within the agglomerate. In one embodiment, the porosity within the BN agglomerate may be less than about 80%, or less than about 50%, or less than about 35%, or less than about 20%, or less than about 10%.
  • the enamel formulation contains an additive to treat the surface of the fillers used in the formulation.
  • the additive may be a silane.
  • suitable silanes include, but are not limited to, an alkacryloxy silane, a vinyl silane, a chloro silane, a mercapto silane, a blocked mercapto silane, or a combination of two or more thereof.
  • the additive may also include a siloxane, polysiloxane, silazane, silicone hydride, polyhedral silsesquioxane or modified polyhedral silsesquioxane, another organometallic such as zirconate, aluminate, titanate, fatty acid derivative such as sorbitol monostearate (sorbitan), non-ionic surfactant, or a combination of two of more thereof.
  • a siloxane polysiloxane, silazane, silicone hydride, polyhedral silsesquioxane or modified polyhedral silsesquioxane, another organometallic such as zirconate, aluminate, titanate, fatty acid derivative such as sorbitol monostearate (sorbitan), non-ionic surfactant, or a combination of two of more thereof.
  • the surface treatment additive may be used at loadings as low as 0.01% by weight, or up to 0.1% by weight, or up to 1% by weight, or up to 5% by weight of the filler. In one embodiment the surface treatment additive may be used at loadings up to about 10% by weight of the filler.
  • the surface treatment additive may be used at loadings in the range of about 0.01% by weight to about 0.1% by weight; about 0.01% by weight to about 1% by weight; 0.01% by weight to about 5% by weight, or 0.01% by weight to about 10% by weight.
  • the surface treatment additive may be used at loadings in the range of about 0.1% by weight to about 1% by weight or about 0.1% by weight to about 5% by weight; or 0.1% by weight to about 10% by weight.
  • the fillers are treated with the chosen additive prior to addition to the enamel resin.
  • the surface treatment step may include an optional heat treatment or humidity treatment, i.e. exposed to higher temperature and/or higher humidity, after the addition of the surface treatment additive to the filler or blend of fillers.
  • the chosen additive and the fillers are added simultaneously to the enamel resin formulation.
  • the enamel formulations have enhanced dielectric strength.
  • the dielectric strength of the enamel formulation may be enhanced by the addition of various fillers to the enamel resin.
  • the enamel formulation has a dielectric strength of at least 10 KV/mm, or at least 20 KV/mm, or at least 30 KV/mm, or at least 50 KV/mm, or even up to 100 KV/mm.
  • the total weight loading of fillers in the composition is at least about 3% by weight, or at least about 10 % by weight, or at least about 20% by weight, or at least about 50% by weight, or even up to about 90% by weight.
  • the total weight loading of fillers in the composition is in the range of at least about 3% by weight to at least about 10% by weight; at least about 3% by weight to at least about 20% by weight; at least about 3% by weight to at least about 50% by weight; or at least about 3% by weight to at least about 90% by weight.
  • the total weight loading of fillers in the composition is in the range of at least about 10% by weight to at least about 20% by weight; at least about 10% by weight to at least about 50% by weight; or at least about 10% by weight to at least about 90% by weight.
  • the total weight loading of fillers in the composition is in the range of at least about 20% by weight to at least about 50% by weight or at least about 20% by weight to at least about 90% by weight.
  • the enamel formulation comprises boron nitride.
  • the enamel formulation comprises boron nitride flakes/platelets, or boron nitride agglomerates, or a combination of both.
  • the boron nitride platelets in the enamel formulation have an aspect ratio of at least 5, or at least 10, or at least 20, or at least 50, or at least 100, or at least 300, or at least 600, or even up to 1000.
  • the formulation comprises at least about 3% BN by weight, or at least about 10 % BN by weight, or at least about 20% BN by weight, or at least about 50% BN by weight, or even up to about 80% BN by weight.
  • the total weight loading of BN in the composition is in the range of at least about 3% BN by weight to at least about 10% BN by weight; at least about 3% BN by weight to at least about 20% BN by weight; at least about 3% BN by weight to at least about 50% BN by weight; or at least about 3%
  • the total weight loading of fillers in the composition is in the range of at least about 10% by weight to at least about 20% by weight; at least about 10% by weight to at least about 50% by weight; or at least about 10% by weight to at least about 80% by weight.
  • the total weight loading of fillers in the composition is in the range of at least about 20% by weight to at least about 50% by weight or at least about 20% by weight to at least about 80% by weight.
  • the enamel formulation comprises BN flakes or platelets.
  • the formulation comprises exfoliated or delaminated boron nitride.
  • the average BN platelet size may be 0.1 microns, or 0.5 microns, or 2 microns, or 10 microns, or 50 microns, or even up to 100 microns.
  • the surface area of the BN platelets may be less than 50 m 2 /g, or less than 20 m 2 /g, or less than 10 m 2 /g, or less than 6 m 2 /g, or less than 3 m 2 /g, or even less than 1 m 2 /g.
  • the enamel formulation comprises boron nitride agglomerates.
  • the average particle size of the agglomerate may be 3 microns, or 10 microns, or 50 microns, or 150 microns, or even up to 400 microns.
  • the fundamental crystal size of these agglomerates may be 0.1 microns, or 0.5 microns, or 2 microns, or 10 microns, or even up to 50 microns.
  • the surface area of the BN agglomerates may be less than 50 m 2 /g, or less than 20 m 2 /g, or less than 10 m 2 /g, or less than 5 m 2 /g, or less than 2 m 2 /g, or even less than 1 m 2 /g.
  • the aspect ratio of the fundamental crystals of these agglomerates may be at least 5, or at least 10, or at least 20, or at least 50, or at least 100, or at least 300, or at least 600, or even up to 1000.
  • the porosity within the BN agglomerate may be less than 10%, or less than 20%, or less than 35%, or less than 50%, or even up to 80%.
  • the enamel formulation comprises BN and an additional filler with a flake or platelet or platelet-like morphology.
  • the additional platelet filler may be mica, or talc, or clay, or bentonite, or a combination of two or more thereof.
  • the additional platelet filler may be exfoliated or delaminated.
  • the dielectric constant of the enamel formulation may be tuned.
  • the dielectric constant of the enamel formulation may need to be tuned to meet a particular application's need.
  • AC alternating current
  • the impedance from enamel layer depends on the dielectric constant of the formulations and the frequency of the electrical field in the conductor.
  • the dielectric constant of the insulation may need to be adjusted to tune the impedance to a desired range for a particular application for optimal performance.
  • Methods for adjusting the dielectric constant include, but are not limited to, adjusting the amount and/or type of filler, adjusting the frequency of the electric field in the conductor, introducing voids of air or nitrogen into the enamel formulation, or a combination of two or more thereof.
  • the dielectric constant of a material depends on the frequency of the electric field applied. The embodiments mentioned below are based on properties at a frequency of 1 MHz, but other frequencies may be used as well. [0082] In one embodiment, the enamel formulation has a dielectric constant of
  • the dielectric constant is 3, or 4, or 6, or 10, or 50, or even up to 500.
  • the enamel formulation comprises boron nitride.
  • the enamel formulation comprises boron nitride and an additional metal oxide.
  • These may be materials such as, but not limited to, barium titanate, or strontium titanate, or doped versions of these material.
  • BN has a dielectric constant around 4.0 (3.9 - 4.2) at 1 MHz. Under static electric fields, the dielectric constant of BN is approximately 5 - 7. Like thermal conductivity, the dielectric constant of BN is also anisotropic. This is a fairly low dielectric constant compared some other filler materials. For example, alumina has a dielectric constant of 9 - 9.5. In contrast, some titanates have very high dielectric constants such as strontium titanate (approximately 300); or BST doped with lanthanum oxide and/or antimony oxide may have a dielectric constant as high as 6000.
  • the formulation comprises at least 3% BN by weight, or at least 10 % BN by weight, or at least 20% BN by weight, or at least 50% BN by weight, or even up to 80% BN by weight.
  • the total weight loading of fillers in the composition is at least 3% by weight, or at least 10 % by weight, or at least 20% by weight, or at least 50% by weight, or even up to 90% by weight.
  • the enamel formulation comprises BN flakes or platelets.
  • the average BN platelet size may be 0.1 microns, or 0.5 microns, or 2 microns, or 10 microns, or 50 microns, or even up to 100 microns.
  • the surface area of the BN platelets may be less than 50 m 2 /g, or less than 20 m 2 /g, or less than 10 m 2 /g, or less than 6 m 2 /g, or less than 3 m 2 /g, or even less than 1 m 2 /g.
  • the graphitization index, a measure of the extent of crystallinity of the BN crystals may be less 8, or less than 4, or less than 2, or less than 1.5, or less than 1.2 or possibly even less than 1.0.
  • the enamel formulation comprises exfoliated or delaminated BN platelets or flakes.
  • the BN flakes or platelets may have an average aspect ratio (defined as ratio of crystal diameter to crystal thickness) of at least 5, or at least 10, or at least 20, or at least 50, or at least 100, or at least 300, or at least 600, or even up to 1000.
  • the aspect ratio may be estimated by calculations from the surface area and the measured particle size of the BN platelets.
  • the enamel formulation comprises agglomerate grades of BN.
  • BN agglomerate particles are aggregates of smaller BN crystal platelets.
  • the enamel formulation comprises boron nitride agglomerates.
  • the average particle size of the agglomerate may be 3 microns, or 10 microns, or 50 microns, or 150 microns, or even up to 400 microns.
  • the fundamental crystal size of these agglomerates may be 0.1 microns, or 0.5 microns, or 2 microns, or 10 microns, or even up to 50 microns.
  • the surface area of the BN agglomerates may be less than 50 m 2 /g, or less than 20 m 2 /g, or less than 10 m 2 /g, or less than 5 m 2 /g, or less than 2 m 2 /g, or even less than 1 m 2 /g.
  • the aspect ratio of the BN agglomerates may be less than 10, or less than 5, or less than 2, or preferably less than 1.5.
  • the aspect ratio of the fundamental crystals that make up these agglomerates may be at least 5, or at least 10, or at least 20, or at least 50, or at least 100, or at least 300, or at least 600, or even up to 1000.
  • the porosity of BN agglomerates is defined as the void fraction within the agglomerate. In one embodiment, the porosity within the BN agglomerate may be less than about 50%, or less than about 35%, or less than about 20%, or less than about 10%. In one embodiment, the porosity with the BN agglomerate may be up to about 80%.
  • the enamel formulation has at least 3% (by volume) porosity.
  • the porosity may be 10%, or 20% or even up to 50%. However, excessive porosity may reduce dielectric strength.

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Wood Science & Technology (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Inorganic Chemistry (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

La présente invention concerne une composition d'émail qui est thermoconductrice, électriquement isolante, ou les deux. La présente invention concerne une composition d'émail qui a une résistance diélectrique élevée. De plus, la présente invention concerne une composition d'émail selon laquelle la constante diélectrique est accordée pour satisfaire une certaine exigence d'impédance en fonction de l'épaisseur de couche d'émail et de la fréquence du champ électrique du conducteur.
PCT/US2015/067538 2014-12-23 2015-12-22 Formulations d'émail et de vernis de fil thermoconducteur WO2016106398A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US201462096119P 2014-12-23 2014-12-23
US62/096,119 2014-12-23
US201562102777P 2015-01-13 2015-01-13
US62/102,777 2015-01-13

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019018457A1 (fr) * 2017-07-19 2019-01-24 Sabic Global Technologies B.V. Charge électriquement isolante et thermoconductrice pour fils bobinés
WO2019173660A1 (fr) * 2018-03-09 2019-09-12 Engi-Mat Co. Matériaux diélectriques composites thermoconducteurs

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020142161A1 (en) * 1999-12-10 2002-10-03 Cynthia Grimes Magnet wire having enamel with a boron nitride filler
WO2008039279A1 (fr) * 2006-09-28 2008-04-03 Siemens Energy, Inc. Formes morphologiques de matières de charge pour l'isolation électrique
US20080122310A1 (en) * 2004-02-02 2008-05-29 Alstom Technology Ltd Method for producing a conductor bar of transposed stranded conductors

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020142161A1 (en) * 1999-12-10 2002-10-03 Cynthia Grimes Magnet wire having enamel with a boron nitride filler
US20080122310A1 (en) * 2004-02-02 2008-05-29 Alstom Technology Ltd Method for producing a conductor bar of transposed stranded conductors
WO2008039279A1 (fr) * 2006-09-28 2008-04-03 Siemens Energy, Inc. Formes morphologiques de matières de charge pour l'isolation électrique

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019018457A1 (fr) * 2017-07-19 2019-01-24 Sabic Global Technologies B.V. Charge électriquement isolante et thermoconductrice pour fils bobinés
CN110998751A (zh) * 2017-07-19 2020-04-10 沙特基础工业全球技术公司 用于卷曲电线的导热、电绝缘填料
WO2019173660A1 (fr) * 2018-03-09 2019-09-12 Engi-Mat Co. Matériaux diélectriques composites thermoconducteurs

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