UV-curable thermally conductive dielectric coatings

Abstract

A UV-curable liquid coating composition sprayable on a substrate thereby forming a thin, pin-hole free, thermally conductive dielectric coating having a combination of improved dielectric strength along with improved thermal conductivity. The liquid coating compositions comprise organic resin, e.g. polyester resin, radical reactive diluent, thermally conductive filler, photoinitiator, adhesion promoter, and at least one additive selected from dispersing agent, de-aerator, defoamer, anti-foaming agent, antioxidant, pigment, organic solvent, and rheology modifier. Also provided are methods of producing the compositions, UV-curable and cured coatings, and substrates comprising UV-curable or cured thermally conductive dielectric coating layers are provided.

Description

[0001]UV-Curable Thermally Conductive Dielectric Coatings TECHNICAL FIELD [0001.] The present invention relates to a UV-curable liquid coating composition useful in depositing a thermally conductive dielectric coating on a substrate, intermediates comprising a substrate having a layer of UV-curable, optionally dried, coating composition deposited thereon, an adherent layer of thermally conductive dielectric cured coating composition on a substrate, coated substrates and methods of producing the compositions, coatings, coating layers and coated substrates. BACKGROUND [0002.] Electrical components are often electrically insulated by application of high dielectric strength materials. While dielectric materials provide electrical insulation, they often do not facilitate heat dissipation and may be heat insulating. Faster heat dissipation from battery operation is highly desirable in many electrical components, particularly for vehicle OEMs to improve driving range of battery powered vehicles and longevity of battery packs. The usual electrical battery insulation in such vehicles is mainly through applying powder coats, heat curable coatings or using plastic insulating wraps or films; none of these electrical insulation means adequately address heat dissipation needs and rapid low temperature production requirements. Powder coats have the downside of requiring high temperatures for curing, e.g.175-205 °C for 10-15 min. plus ramp time for the part to reach cure temperature. (approx.30 min.); heat curable coatings share these drawbacks. Powder coats are in general thick and take multiple coats to ensure pinhole-free films. Powder coats, therefore, have additional downsides of undesirably increasing weight and high thermal impedance. Plastic wraps require complex handling and processing or installation and have unpredictable long term reliability and risk of delamination. [0003.] Conventional powder coats and UV-curable coating options in the market have no enhanced thermal conductivity due at least in part to high coating thickness or multiple coats to ensure needed dielectric protection such that they do not meet the increasing demand for efficient thermal dissipation. Conventional UV-curable materials may also be subject to undesirable shrinkage upon cure leaving areas of reduced dielectric insulation which affects reliability. In general, these options do not facilitate heat dissipation, which is critical to rechargeable batteries which generate heat during charge and discharge. Availability of battery powered vehicles and the like, has increased the need for high dielectric strength and high thermal dissipation materials that are low weight. Thus, there is a need for thin dielectric coating with high dielectric strength along with high thermal conductivity or low thermal resistance that are amenable to production line conditions of no-bake, higher speed cure for these and other uses. [0004.] It is also desirable to develop dielectric coatings that resist conducting electricity but conduct heat to facilitate heat dissipation, particularly for battery cooling systems, prismatic cells, cold plates, power inverters, busbars and chargers. It is also desirable to develop improved dielectric coatings that provide good electrical insulation at low film thicknesses for weight reduction, which are applied by less complex processes and use less time and energy. Therefore, there is a need for a thermally conductive dielectric coating that can be applied defect-free at thinner coating thicknesses than previously available for use in vehicles, the thermally conductive coating having a combination of improved dielectric strength along with improved thermal conductivity or low thermal resistance. SUMMARY [0005.] This invention is directed to UV-curable liquid coating compositions, with reduced VOC content, preferably VOC-free, useful in depositing thermally conductive dielectric coatings that are light- curable in seconds depending on the UV energy applied. Formulations of the VOC-free, UV-curable coating compositions typically comprise at least one of a monomer, oligomer or resin having one or more polymerizable groups capable of undergoing reactions when exposed to UV irradiation; a radical reactive diluent also having one or more polymerizable groups for reactions under UV irradiation, thermally conductive filler, a photoinitiator, and optionally adhesion promoter, dispersing agent and / or other additives. The curing process of as-applied liquid coating compositions can be divided into two steps. First, under UV irradiation, a photoinitiator produces free radicals or reactive cations. Second, the free radicals or reactive cations induce the polymerization of the monomer / oligomer / resins and radical reactive diluents having the polymerizable functional groups, for example unsaturated bonds or epoxy groups. One advantage of the UV-curable coatings according to the invention is that most or all components in the formulations can participate in the curing reaction and become part of the solid film directly or indirectly, resulting in reduced or zero volatile organic compounds (VOC) emission during curing. As used herein, “VOC”is defined under 40 CFR 51.100 as any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions. [0006.] The UV curable coating curing rate is faster, and the energy consumption is less than powder coating. Unlike conventional plastic insulating films, the UV-curable liquid coating compositions disclosed herein can be conveniently spray applied by conventional techniques over all surfaces, such as battery cell cans and complex cooling plates, or alternatively the coating can be applied onto specific portions of a substrate surface by any number of printing or masking methods known in the art. The UV- curable liquid coating compositions described herein have a desirable viscosity such that they are capable of forming thin coatings free of voids on the coated surface. The UV-curable liquid coating compositions may further provide good coverage on edges of the substrates, which is an improvement over some sprayed coatings that have poor edge coverage or shrink upon cure reducing edge coverage. The cured polymeric coatings, having both high dielectric strength and high thermal conductivity as further described herein, are highly advantageous as electrical insulation in battery pack operation where efficient heat dissipation is critical to battery safety and longevity. In addition, the cured polymeric coating can provide further protection against corrosion and abrasion to the battery packs where water condensation and constant vibration are common during vehicle operation. The UV-curable liquid coating compositions, and cured polymeric thermally conductive dielectric coating layers on a substrate and coated substrates according to aspects of the invention solve one or more of the above described disadvantages or needs, and exhibit high dielectric strength, thermal dissipation and good electrical insulation, as further described herein. [0007.] Various embodiments of the UV-curable liquid coating composition may comprise or consist essentially of or consist of: (a) organic monomer, oligomer or resin having one or more polymerizable functional groups for reactions under UV irradiation, e.g. C═C double bonds, epoxy groups and the like, preferably comprising unsaturated polyester resin; (b) an organic radical reactive diluent, different from (a), having one or more polymerizable functional groups for reactions under UV irradiation, as described herein; (c) at least one thermally conductive filler; (d) at least one photoinitiator, and desirably at least one additive selected from adhesion promoter, de-aerator, defoamer, anti-foaming agent and dispersing agent. As used herein, anti-foam agents prevent foam formation while defoamers reduce existing foam. Optionally, such compositions may also contain other additives such as coupling agents, organic solvent, accelerator, rheology modifier optionally surface modified (also referred to herein as a thixotropic agent), , pigments and dyes, plasticizers, flexibilizers, flame retardants, impact modifiers / toughening agents, fillers different from (c), flow control agents, inhibitors, antioxidants, non- reactive diluents, extenders or other adjuvants. In certain Embodiments, the UV-curable liquid coating composition is free of volatile organic compounds (VOC). Embodiments of the invention are described throughout this disclosure, including: [0008.] Embodiment 1. A UV-curable liquid coating composition comprising: (a) at least one UV-curable a monomer, oligomer or resin having one or more polymerizable groups for reactions under UV irradiation, desirably present in an amount in a range of from 9% to 95%, preferably 10% to 50%; (b) at least one functional or di-functional radical reactive diluent, different from (a), and comprising one or more polymerizable groups for reactions under UV irradiation, desirably present in an amount in a range of from 10% to 95%, desirably 15% to 80%, preferably 25% to 50%; (c) at least one thermally conductive filler, desirably present in an amount in a range of from1% to 70%, preferably 5% to 60%, more preferably 10% to 50%; (d) at least one photoinitiator desirably present in an amount in a range of from 0.1% to 7.0%, desirably 0.75% to 5.0%, (e) at least one adhesion promoter, and (f) optionally a dispersing agent, wherein (a) is selected from unsaturated polyester monomers, oligomers, resins and combinations thereof, preferably vinyl esters, more preferably epoxy vinyl esters, such as epoxy acrylate esters and epoxy methacrylate esters, and combinations thereof. [0009.] The UV-curable liquid coating composition of Embodiment 1 may further comprise at least one additive preferably selected from the group consisting of, organic solvent, accelerator, rheology modifier that optionally may be surface modified (also referred to herein as a thixotropic agent), de- aerator, defoamer, coupling agents, anti-foaming agent, pigments and dyes, plasticizers, flexibilizers, flame retardants, impact modifiers / toughening agents, additional filler different from (c ), flow control agents, inhibitors, antioxidants, non-reactive diluents, extenders or other adjuvants. In certain Aspects of this Embodiment, the UV-curable liquid composition is free of formaldehyde. [00010.] Embodiment 2. The UV-curable liquid coating composition of Embodiment 1 further characterized in that said components are or comprise, all given in wt.%: (a) at least one unsaturated polyester resin, preferably epoxy vinyl ester resin, such as epoxy acrylate esters and epoxy methacrylate esters, and combinations thereof, desirably present in a range of from 9% to 95%, preferably 10%-to 50%, more preferably 11% to 35%; (b) at least one radical reactive diluent, desirably present in a range of from 10% to 95%, preferably 15% to 80%, more preferably 25% to 50%; (c) at least one thermally conductive filler such as boron nitride, alumina, aluminum trihydrate, and combinations thereof, desirably present in a range of from 1.0% to70% or 5% to 60%, preferably 10% to 50%; (d) at least one photoinitiator, desirably present in a range of from 0.1% to 5%, preferably 1% to 4%, more preferably 1.5% to 3.5%; (e) at least one adhesion promoter, desirably present in a range of from 0.1% to 10%, preferably 0.5 to 8.0%, more preferably 0.75 to 6.0%, most preferably 1.0% to 5.0%; and optionally (f) at least one dispersing agent, in a range of 0.0% to, in increasing order of preference, 7.0%, 6.0%, 5.0%, 4.0%, 3.0%, or from 0.1% to 2.0%; desirably present in amounts of 0.25%-1.5%, preferably 0.5% to 1.25%; (g) a de-aerator, a defoamer, an anti-foaming agent, or combination of two or more thereof, desirably each present in a range of from 0% to 2.0%; (h) at least one organic solvent, desirably present in a range of from 0% to 20%; (i) at least one additive selected from a rheology modifier, a flexibilizer, and a plasticizer, each desirably present in a range of from 0% to 5%; wherein the wt.% of each component is relative to the total weight of the composition and the total amount of the components does not exceed 100 wt.%. [00011.] Embodiment 3. The UV-curable liquid coating composition according to any one of the above-disclosed Embodiments, wherein (a) the at least one unsaturated polyester resins, epoxy vinyl ester resins, such as epoxy acrylate esters and epoxy methacrylate esters, and combinations thereof, is present in a range of from 9% to 95%, 10 wt.% to 15 wt.%, from 15 wt.% to 20 wt.%, from 20 wt.% to 25 wt.%, from 25 wt.% to 30 wt.%, from 30 wt.% to 35 wt.%, from 35 wt.% to 40 wt.%, from 40 wt.% to 45 wt.%, from 45 wt.% to 50 wt.%, from 50 wt.% to 55 wt.%, from 55 wt.% to 60 wt.% from 60 wt.% to 65 wt.%, from 65 wt.% to 70 wt.%, from 70 wt.% to 75 wt.%, from 75 wt.% to 80 wt.%, from 80 wt.% to 85 wt.%, from 85% to 90%; from 90% to 95%, or any combination of two or more of the foregoing ranges, for example from 25 wt.% to 50 wt.%, or any of the foregoing values, relative to the total weight of the composition. [00012.] Embodiment 4. The UV-curable liquid coating composition according to any one of the above-disclosed Embodiments, wherein (b) the at least one radical reactive diluent, is present in a range of from 10 wt.% to 15 wt.%, from 15 wt.% to 20 wt.%, from 20 wt.% to 25 wt.%, from 25 wt.% to 30 wt.%, from 30 wt.% to 35 wt.%, from 35 wt.% to 40 wt.%, from 40 wt.% to 45 wt.%, from 45 wt.% to 50 wt.%, from 50 wt.% to 55 wt.%, from 55 wt.% to 60 wt.% from 60 wt.% to 65 wt.%, from 65 wt.% to 70 wt.%, from 70 wt.% to 75 wt.%, from 75 wt.% to 80 wt.%, from 80 wt.% to 85 wt.%, from 85% to 90%; from 90% to 95%, or any combination of two or more of the foregoing ranges, for example from 25 wt.% to 50 wt.%, or any of the foregoing values, relative to the total weight of the composition. [00013.] Embodiment 5. The UV-curable liquid coating composition according to any one of the above-disclosed Embodiments, wherein (c) the at least one thermally conductive filler, preferably comprising boron nitride filler, is present in a range of from 5 wt.% to 10%, from 10 wt.% to 15 wt.%, from 15 wt.% to 20 wt.%, from 20 wt.% to 25 wt.%, from 25 wt.% to 30 wt.%, from 30 wt.% to 35 wt.%, from 35 wt.% to 40 wt.%, from 40 wt.% to 45 wt.%, from 45 wt.% to 50 wt.%, from 50 wt.% to 55 wt.%, from 55 wt.% to 60 wt.%, from 60 wt.% to 65 wt.%, from 65 wt.% to 70 wt.%, or any combination of two or more of the foregoing ranges, for example from 15 wt.% to 55 wt.% or 10 wt.% to 30 wt.%, or any of the foregoing values, relative to the total weight of the composition. [00014.] Embodiment 6 The UV-curable liquid coating composition according to any one of the above-disclosed Embodiments, wherein (d) the at least one photoinitiator, is present in a range of from 0.1 wt.% to 0.2 wt.%, from 0.2 wt.% to 0.3 wt.%, from 0.3 wt.% to 0.4 wt.%, from 0.4 wt.% to 0.5 wt.%, from 0.5 wt.% to 0.6 wt.%, from 0.6% to 0.7 wt.%, from 0.7 wt.% to 0.8 wt.%, from 0.8 wt.% to 0.9 wt.%, from 0.9 wt.% to 1.0 wt.%, from 1.0 wt.% to 1.1 wt.%, from 1.1 wt.% to 1.2 wt.%, from 1.2 wt.% to 1.3 wt.%, from 1.3 wt.% to 1.4 wt.%, from 1.4 wt.% to 1.5 wt.%, from 1.5 wt.% to 1.6 wt.%, from 1.6% to 1.7 wt.%, from 1.7 wt.% to 1.8 wt.%, from 1.8 wt.% to 1.9 wt.%, from 1.9 wt.% to 2 wt.%, from 2 wt.% to 2.1 wt.%, from 2.1 to 2.2 wt.%, from 2.2 wt.% to 2.3 wt.%, from 2.3 wt.% to 2.4 wt.%, from 2.4 wt.% to 2.5 wt.%, from 2.5 wt.% to 2.6 wt.%, from 2.6% to 2.7 wt.%, from 2.7 wt.% to 2.8 wt.%, from 2.8 wt.% to 2.9 wt.%, from 2.9 wt.% to 3 wt.%, from 3 wt.% to 3.1 wt.%, from 3.1 wt.% to 3.2 wt.%, from 3.2 wt.% to 3.3 wt.%, from 3.3 wt.% to 3.4 wt.%, from 3.4 wt.% to 3.5 wt.%, from 3.5 wt.% to 3.6 wt.%, from 3.6% to 3.7 wt.%, from 3.7 wt.% to 3.8 wt.%, from 3.8 wt.% to 3.9 wt.%, from 3.9 wt.% to 4 wt.%, from 4.0 wt.% to 4.1 wt.%, from 4.1 wt.% to 4.2 wt.%, from 4.2 wt.% to 4.3 wt.%, from 4.3 wt.% to 4.4 wt.%, from 4.4 wt.% to 4.5 wt.%, from 4.5 wt.% to 4.6 wt.%, from 4.6% to 4.7 wt.%, from 4.7 wt.% to 4.8 wt.%, from 4.8 wt.% to 4.9 wt.%, from 4.9 wt.% to 5 wt.%, or any combination of two or more of the foregoing ranges, for example from 0.1% to 5%, 1% to 4%, 1.5% to 3.5%, 0.3 wt.% to 0.7 wt.%, or any of the foregoing values, relative to the total weight of the composition. [00015.] Embodiment 7. The UV-curable liquid coating composition according to any one of the above-disclosed Embodiments, wherein (e) the at least one adhesion promoter, is present in a range of from 0.1 wt.% to 0.2 wt.%, 0.2 wt.% to 0.3 wt.%, from 0.3 wt.% to 0.4 wt.%, from 0.4 wt.% to 0.5 wt.%, from 0.5 wt.% to 0.6 wt.%, from 0.6% to 0.7 wt.%, from 0.7 wt.% to 0.8 wt.%, from 0.8 wt.% to 0.9 wt.%, from 0.9 wt.% to 1.0 wt.%, from 1.0 wt.% to 1.1 wt.%, from 1.1 wt.% to 1.2 wt.%, from 1.2 wt.% to 1.3 wt.%, from 1.3 wt.% to 1.4 wt.%, from 1.4 wt.% to 1.5 wt.%, from 1.5 wt.% to 1.6 wt.%, from 1.6% to 1.7 wt.%, from 1.7 wt.% to 1.8 wt.%, from 1.8 wt.% to 1.9 wt.%, from 1.9 wt.% to 2 wt.%, from 2 wt.% to 2.1 wt.%, from 2.1 to 2.2 wt.%, from 2.2 wt.% to 2.3 wt.%, from 2.3 wt.% to 2.4 wt.%, from 2.4 wt.% to 2.5 wt.%, from 2.5 wt.% to 2.6 wt.%, from 2.6% to 2.7 wt.%, from 2.7 wt.% to 2.8 wt.%, from 2.8 wt.% to 2.9 wt.%, from 2.9 wt.% to 3 wt.%, from 3 wt.% to 3.1 wt.%, from 3.1 wt.% to 3.2 wt.%, from 3.2 wt.% to 3.3 wt.%, from 3.3 wt.% to 3.4 wt.%, from 3.4 wt.% to 3.5 wt.%, from 3.5 wt.% to 3.6 wt.%, from 3.6% to 3.7 wt.%, from 3.7 wt.% to 3.8 wt.%, from 3.8 wt.% to 3.9 wt.%, from 3.9 wt.% to 4 wt.%, from 4.0 wt.% to 4.1 wt.%, from 4.1 wt.% to 4.2 wt.%, from 4.2 wt.% to 4.3 wt.%, from 4.3 wt.% to 4.4 wt.%, from 4.4 wt.% to 4.5 wt.%, from 4.5 wt.% to 4.6 wt.%, from 4.6% to 4.7 wt.%, from 4.7 wt.% to 4.8 wt.%, from 4.8 wt.% to 4.9 wt.%, from 4.9 wt.% to 5 wt.%, from 5.0 wt.% to 5.1 wt.%, from 5.1 wt.% to 5.2 wt.%, from 5.2 wt.% to 5.3 wt.%, from 5.3 wt.% to 5.4 wt.%, from 5.4 wt.% to 5.5 wt.%, from 5.5 wt.% to 5.6 wt.%, from 5.6% to 5.7 wt.%, from 5.7 wt.% to 5.8 wt.%, from 5.8 wt.% to 5.9 wt.%, from 5.9 wt.% to 6 wt.%, from 6 wt.% to 6.1 wt.%, from 6.1 to 6.2 wt.%, from 6.2 wt.% to 6.3 wt.%, from 6.3 wt.% to 6.4 wt.%, from 6.4 wt.% to 6.5 wt.%, from 6.5 wt.% to 6.6 wt.%, from 6.6% to 6.7 wt.%, from 6.7 wt.% to 6.8 wt.%, from 6.8 wt.% to 6.9 wt.%, from 6.9 wt.% to 7 wt.%, from 7 wt.% to 7.1 wt.%, from 7.1 wt.% to 7.2 wt.%, from 7.2 wt.% to 7.3 wt.%, from 7.3 wt.% to 7.4 wt.%, from 7.4 wt.% to 7.5 wt.%, from 7.5 wt.% to 7.6 wt.%, from 7.6% to 7.7 wt.%, from 7.7 wt.% to 7.8 wt.%, from 7.8 wt.% to 7.9 wt.%, from 7.9 wt.% to 8 wt.%, from 8.0 wt.% to 8.1 wt.%, from 8.1 wt.% to 8.2 wt.%, from 8.2 wt.% to 8.3 wt.%, from 8.3 wt.% to 8.4 wt.%, from 8.4 wt.% to 8.5 wt.%, from 8.5 wt.% to 8.6 wt.%, from 8.6% to 8.7 wt.%, from 8.7 wt.% to 8.8 wt.%, from 8.8 wt.% to 8.9 wt.%, from 8.9 wt.% to 9 wt.%, or any combination of two or more of the foregoing ranges, for example from 0.3 wt.% to 0.7 wt.%, _0.1% to 9%, 0.5 to 8.0%, 1.0% to 6.0%, or any of the foregoing values, relative to the total weight of the composition. [00016.] Embodiment 8. The UV-curable liquid coating composition according to any one of the above-disclosed Embodiments, wherein (f) the at least one dispersing agent is present in a range of from 0.1 wt.% to 0.2 wt.%, from 0.2 wt.% to 0.25wt.%, from 0.25 wt. % to 0.3 wt.%, from 0.3 wt.% to 0.35wt.%, from 0.35 wt. % to 0.4 wt.%, from 0.4 wt.% to 0.45wt.%, from 0.45 wt. % to 0.5 wt.%, from 0.5 wt.% to 0.55wt.%, from 0.55 wt. % to 0.6 wt.%, from 0.6% to 0.65wt.%, from o.65 wt. % to 0.7 wt.%, from 0.7 wt.% to 0.75wt.%, from 0.75 wt. % to 0.8 wt.%, from 0.8 wt.% to 0.85wt.%, from 0.85 wt. % to 0.9 wt.%, from 0.9 wt.% to 1.0 wt.%, from 1.0 wt.% to 1.1 wt.% to 1.2 wt.%, from 1.2 wt.% to 1.25wt.%, from 1.25 wt. % to 1.3 wt.%, from 1.3 wt.% to 1.4 wt.%, from 1.4 wt.% to 1.5 wt.%, from 1.5 wt.% to 1.6 wt.%, from 1.6% to 1.7 wt.%, from 1.7 wt.% to 1.8 wt.%, from 1.8 wt.% to 1.9 wt.%, from 1.9 wt.% to 2.0 wt.% or any combination of two or more of the foregoing ranges, for example from 0.1% to 2.0%; 0.3 wt.% to 0.8 wt.%, 0.25%-1.5%, 0.5% to 1.25%;or any of the foregoing values, relative to the total weight of the composition. [00017.] Embodiment 9. The UV-curable liquid UV-curable coating composition according to any one of the above-disclosed Embodiments, wherein (g) the de-aerator, the defoamer, the anti-foaming agent, or a combination thereof is present are each present in a range of from 0.1 wt.% to 0.2 wt.%, 0.2 wt.% to 0.3 wt.%, from 0.3 wt.% to 0.4 wt.%, from 0.4 wt.% to 0.5 wt.%, from 0.5 wt.% to 0.6 wt.%, from 0.6% to 0.7 wt.%, from 0.7 wt.% to 0.8 wt.%, from 0.8 wt.% to 0.9 wt.%, from 0.9 wt.% to 1.0 wt.%, from 1.0 wt.% to 1.1 wt.%, from 1.1 wt.% to 1.2 wt.%, from 1.2 wt.% to 1.3 wt.%, 1.3 wt.% to 1.4 wt.%, from 1.4 wt.% to 1.5 wt.%, from 1.5 wt.% to 1.6 wt.%, from 1.6 wt.% to 1.7 wt.%, from 1.7 wt.% to 1.8 wt.%, from 1.8 wt.% to 1.9 wt.%, from 1.9 wt.% to 2.0 wt.% or any combination of two or more of the foregoing ranges, for example from 0% to 2.0%; from 0.3 wt.% to 0.7 wt.%, or any of the foregoing values, relative to the total weight of the composition. [00018.] Embodiment 9. The UV-curable liquid coating composition according to any one of the above-disclosed Embodiments, wherein (h) the at least one organic solvent, is present in a range of from 0.5 to 1 wt.%, from 1 wt.% to 2 wt.%, from 2 wt.% to 3 wt.%, from 3 wt.% to 4 wt.%, from 4 wt.% to 5 wt.%, from 5 wt.% to 6 wt.%, from 6% to 7 wt.%, from 7 wt.% to 8 wt.%, from 8 wt.% to 9 wt.%, from 9 wt.% to 10 wt.%, from 10 wt.% to 11 wt.%, from 11 wt.% to 12 wt.%, from 12 wt.% to 13 wt.%, 13 wt.% to 14 wt.%, from 14 wt.% to 15 wt.%, from 15 wt.% to 16 wt.%, from 16 wt.% to 17 wt.%, from 17 wt.% to 18 wt.%, from 18 wt.% to 19 wt.%, from 19 wt.% to 20 wt.%, or any combination of two or more of the foregoing ranges, for example from 0.5 wt.% to 1.2 wt.%, or any of the foregoing values, relative to the total weight of the composition.. [00019.] Embodiment 10. The UV-curable liquid coating composition according to any one of the above-disclosed Embodiments, wherein (i) the at least one additive selected from a rheology modifier, a flexibilizer, and a plasticizer is present in an amount ranging from 0.1 wt.% to 0.2 wt.%, 0.2 wt.% to 0.3 wt.%, from 0.3 wt.% to 0.4 wt.%, from 0.4 wt.% to 0.5 wt.%, from 0.5 wt.% to 0.6 wt.%, from 0.6% to 0.7 wt.%, from 0.7 wt.% to 0.8 wt.%, from 0.8 wt.% to 0.9 wt.%, from 0.9 wt.% to 1.0 wt.%, from 1.0 wt.% to 1.1 wt.%, from 1.1 wt.% to 1.2 wt.%, from 1.2 wt.% to 1.3 wt.%, 1.3 wt.% to 1.4 wt.%, from 1.4 wt.% to 1.5 wt.%, from 1.5 wt.% to 1.6 wt.%, from 1.6 wt.% to 1.7 wt.%, from 1.7 wt.% to 1.8 wt.%, from 1.8 wt.% to 1.9 wt.%, from 1.9 wt.% to 2.0 wt.% from 2.1 wt.% to 2.2 wt.%, from 2.2 wt.% to 2.3 wt.%, 2.3 wt.% to 2.4 wt.%, from 2.4 wt.% to 2.5 wt.%, from 2.5 wt.% to 2.6 wt.%, from 2.6 wt.% to 2.7 wt.%, from 2.7 wt.% to 2.8 wt.%, from 2.8 wt.% to 2.9 wt.%, from 2.9 wt.% to 3.0 wt.% from 3.1 wt.% to 3.2 wt.%, from 3.2 wt.% to 3.3 wt.%, 3.3 wt.% to 3.4 wt.%, from 3.4 wt.% to 3.5 wt.%, from 3.5 wt.% to 3.6 wt.%, from 3.6 wt.% to 3.7 wt.%, from 3.7 wt.% to 3.8 wt.%, from 3.8 wt.% to 3.9 wt.%, from 3.9 wt.% to 4.0 wt.%, from 4.0 wt.% to 4.1 wt. %, 4.1 wt.% to 4.2 wt.%, from 4.2 wt.% to 4.3 wt.%, 4.3 wt.% to 4.4 wt.%, from 4.4 wt.% to 4.5 wt.%, from 4.5 wt.% to 4.6 wt.%, from 4.6 wt.% to 4.7 wt.%, from 4.7 wt.% to 4.8 wt.%, from 4.8 wt.% to 4.9 wt.%, from 4.9 wt.% to 5.0 wt.% or any combination of two or more of the foregoing ranges, for example from 0.3 wt.% to 0.7 wt.%, or any of the foregoing values, relative to the total weight of the composition. [00020.] Embodiment 11. The UV-curable liquid coating composition of Embodiment 10, wherein the at least one additive comprises the rheology modifier present according to any one of the above- disclosed Embodiments in a range of from 0.05% to 5%. [00021.] For a variety of reasons, it is preferred that UV-curable liquid coating compositions, uncured layers of as-deposited coating compositions, optionally dried; and cured thermally conductive dielectric coatings disclosed herein may be made in the absence of certain ingredients, i.e. be free of certain materials, whether added or generated in situ, other than minor amounts of contaminants; or may be substantially free from certain ingredients used for similar purposes in the prior art. Specifically, it is increasingly preferred in the order given, independently for each preferably minimized ingredient listed below, that at least some embodiments according to the invention contain no more than 1.0, 0.5, 0.35, 0.10, 0.08, 0.04, 0.02, 0.01, 0.001, or 0.0002 percent, more preferably said numerical values in grams per liter, more preferably said numerical values in ppm, of each of the following constituents: free Bisphenol A, halogenated epoxy resins, nonylphenol, toluene, xylene, copper, gold, silver, oxidizing agents such as peroxides and peroxyacids, permanganate, perchlorate, chlorate, chlorite, hypochlorite, perborate, hexavalent chromium, trivalent chromium, sulfuric acid and sulfate, nitric acid and nitrate ions; as well as formaldehyde, formamide, hydroxylamines, cyanides, cyanates; dissolved or soluble boron species, e.g. borax, borate; strontium; and / or free halogen ions, e.g., fluoride, chloride, bromide or iodide. In some embodiments, solid particles of a polymer / boron nitride composite, such as thermoset polymer / BN particles and / or thermoplastic polymer / BN particles are absent from the coating composition or concentration is minimized to no more than 1.0, 0.5, 0.35, 0.10, 0.08, 0.04, 0.02, 0.01, 0.001, or 0.0002 percent, more preferably said numerical values in grams per liter, more preferably said numerical values in ppm. [00022.] As used herein, "dielectric coating" refers to a coating that is electrically insulating. As will be described in further detail herein, the dielectric coating of embodiments of the present invention remains electrically insulating, i.e. conducts little, preferably no electricity, at a dielectric withstand voltage of greater than 2.0 kV, desirably greater than 3.0 kV, preferably greater than 4.0 kV, most preferably greater than 5 kV, as measured by a HypotMAX 7720 or an Ikonix 3865 and in accordance with ASTM D 149-09 Hipot test. Dielectric withstand strength is calculated based upon the thickness of the sample and the dielectric withstand voltage. [00023.] As used herein, the term "polymer" refers to oligomers (having more than in increasing order of preference 3, 4 or 5 monomer units or MW of at least 500, 1000, 5000 but less than 10,000 Daltons, typically between 4 and 10 repeating units, homopolymers (e.g., prepared from a single monomer species), copolymers (e.g., prepared from at least two monomer species), terpolymers, graft polymers and the like. The term "resin" as used herein refers to polymers having functional groups capable of further reactions, for example cross-linking, esterification, condensation and / or addition reactions. Further, the term "crosslinker" refers to a molecule comprising two or more functional groups reactive with polymer functional groups, and capable of linking two or more polymer molecules through chemical bonds. As used herein the term “radical reactive diluent” will be understood by the skilled person as a diluent that is reactive with radicals generated when components, such as the photoinitiator, in the composition are exposed to UV light. [00024.] The transitional terms “comprising,” “consisting essentially of,” and “consisting of” are intended to connote their generally accepted meanings in the patent lexicon; for those embodiments provided in terms of “consisting essentially of,” the basic and novel characteristic(s) is the facile operability of the methods or compositions / systems to provide compositions as exhibiting the claimed functional features using only those components listed. [00025.] When a list is presented, unless stated otherwise, it is to be understood that each individual element of that list, and every combination of that list, is a separate embodiment. For example, a list of embodiments presented as “A, B, or C” is to be interpreted as including the embodiments, “A,” “B,” “C,” “A or B,” “A or C,” “B or C,” or “A, B, or C,” as separate embodiments. [00026.] Unless otherwise specified, compositional percentages are in terms of weight percent, relative to the weight of the material or composition. Molecular weight is given in number average molecular weight. [00027.] It is to be appreciated that certain features of the disclosure which are, for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. That is, unless obviously incompatible or specifically excluded, each individual embodiment is deemed to be combinable with any other embodiment(s) and such a combination is another embodiment. Conversely, various features of the disclosure that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any sub-combination. Finally, while an embodiment may be described as part of a series of steps or part of a more general structure, each said step may also be considered an independent embodiment, combinable with others. [00028.] Other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term "about". BRIEF DESCRIPTION OF THE DRAWINGS [00029.] FIG.1 shows Scanning Electron Microscope (SEM) image of cross-section of a corner of an aluminum battery cell container coated according to the invention, showing the metal of the container, a cured thermally conductive dielectric coating adhered thereto and indicators of measured thickness of the cured coating showing complete coating of substrate corners with no gaps and retention of more than 2 / 3-layer thickness compared to maximum thickness shown. [00030.] FIG.2 shows Scanning Electron Microscope (SEM) image of cross-section of a corner of an aluminum battery cell container coated according to the invention, showing the metal of the container, a cured thermally conductive dielectric coating adhered thereto and indicators of measured thickness of the cured coating showing complete coating of substrate corners with no gaps and retention of more than 3 / 4-layer thickness compared to maximum coating thickness shown. DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS [00031.] The present disclosure may be understood more readily by reference to the following description taken in connection with the accompanying Summary, Figures and Examples, all of which form a part of this disclosure. For purposes of the following detailed description, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. [00032.] The invention as described herein provides improved dielectric coatings that facilitate heat dissipation, particularly for vehicle battery systems, and provide good electrical insulation at low film thicknesses for weight reduction. Deposition methods for the dielectric coatings are also better suited to mass production lines, being applied by less complex processes and using less time and energy. Embodiments of the invention are described below. Certain embodiments set forth in this disclosure include UV-curable liquid coating compositions comprising: (a) at least one polyester resin, (b) at least one radical reactive diluent, (c) at least one thermally conductive filler; (d) at least one photoinitiator , (e) at least one adhesion promotor , and (f) at least one dispersing agent, wherein the at least one polyester resin may comprise, consist essentially of or consist of unsaturated polyester resins, preferably epoxy vinyl ester resins, such as epoxy acrylate esters and epoxy methacrylate esters, and combinations thereof. [00033.] In certain embodiments, the UV-curable liquid coating compositions comprise components as further described herein: (a) at least one unsaturated polyester resin, preferably epoxy vinyl ester resin, such as epoxy acrylate esters and epoxy methacrylate esters, and combinations thereof, desirably present in a range of from 9% to 95%, preferably 10%-to 50%, more preferably 11% to 35%; (b) at least one radical reactive diluent, desirably present in a range of from 10% to 95%, preferably 15% to 80%, more preferably 25% to 50%; (c) at least one thermally conductive filler such as boron nitride, alumina, aluminum trihydrate, and combinations thereof, desirably present in a range of from 1.0% to70% or 5% to 60%, preferably 10% to 50%; (d) at least one photoinitiator, desirably present in a range of from 0.1% to 5%, preferably 1% to 4%, more preferably 1.5% to 3.5%; (e) at least one adhesion promoter, desirably present in a range of from 0.1% to 10%, preferably 0.5 to 8.0%, more preferably 1.0% to 6.0%; and optionally (f) at least one dispersing agent, in a range of 0.0% to, in increasing order of preference, 7.0%, 6.0%, 5.0%, 4.0%, 3.0%, or from 0.1% to 2.0%; desirably present in amounts of 0.25%-1.5%, preferably 0.5% to 1.25%; (g) a de-aerator, a defoamer, an anti-foaming agent, or combination of two or more thereof, desirably each present in a range of from 0% to 2.0%; (h) at least one organic solvent, desirably present in a range of from 0.5% to 20%; (i) at least one additive selected from a rheology modifier, a flexibilizer, and a plasticizer, each desirably present in a range of from 0% to 5%; wherein the wt.% of each component is relative to the total weight of the composition and the total amount of the components does not exceed 100 wt.%. Polyester resins [00034.] In general, a variety of polyester resins, preferably having one, two or more sites of unsaturation, are suitable as (a) polyester resins for the compositions of this invention. Non limiting examples include unsaturated polyester resins, epoxy vinyl ester resins, such as epoxy acrylate esters and epoxy methacrylate esters and the like. These resins have one or more sites of ethylenic unsaturation, preferably having at least about two C=C functional groups per molecule, and may have other functional groups. Polyester oligomers and monomers having similar functionality may also be used. [00035.] Representative unsaturated polyester resins are described in U.S. Pat. Nos.4,742,121; 5,567,767; 5,571,863; 5,688,867; 5,777,053; 5,874,503 and 6,063,864 and in PCT Published Application Nos. WO94107674 A1, WO00123495 A1 and WO 031101918D , incorporated herein by reference. [00036.] The polyester resin may be prepared from the condensation of one or more carboxylic acids (such as mono, di- or poly-functional unsaturated or saturated carboxylic acids) or their derivatives (such as acid anhydrides, C, alkyl esters, etc.) with one or more alcohols (including mono-functional, di- functional and poly-functional alcohols). The carboxylic acid or derivative reactant may for example be a mixture of an unsaturated carboxylic acid or derivative and a saturated carboxylic acid or derivative. [00037.] The unsaturated carboxylic acids or their derivatives may for example have about 3 to about 12, about 3 to about 8, or about 4 to about 6 carbon atoms. Representative unsaturated carboxylic acids and their derivatives include maleic acid, fumaric acid, chloromaleic acid, itaconic acid, citraconic acid, methylene glutaric acid, mesaconic acid, acrylic acid, methacrylic acid, and esters or anhydrides thereof. Desirably unsaturated carboxylic acids and their derivatives include maleic, fumaric acids. fumaric esters and anhydrides thereof. An unsaturated carboxylic acid or its derivative may for example be present in an amount from about 20 to about 90 mole percent, about 35 to about 75 mole percent, or about 50 to about 65 mole percent of total carboxylic acids or acid derivatives used to make the unsaturated polyester resin. [00038.] The saturated carboxylic acids and their derivatives may for example have from about 8 to about 18, about 8 to about 15, or about 8 to about 12 carbon atoms. Representative saturated carboxylic acids and their derivatives may be aromatic, aliphatic or a combination thereof, and include succinic acid, glutaric acid, d-methylglutaric acid, adipic acid, sebacic acid, pimelic acid, phthalic anhydride, o-phthalic acid, isophthalic acid, terephthalic acid, dihydrophthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid or anhydride, tetrachlorophthalic acid, chlorendic acid or anhydride, dodecanedicarboxylic acids, nadic anhydride, cis-5-norbomene- 2,3-dicarboxylic acid or anhydride, dimethyl-2,6-naphthenic dicarboxylate, dimethyl-2,6-naphthenic dicarboxylic acid, naphthenic dicarboxylic acid or anhydride and 1,4-cyclohexane dicarboxylic acid. Other representative carboxylic acids include ethylhexanoic acid, propionic acid, benzene-1,2,4-tricarboxylic acid, benzoic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4,5- benzenetetracarboxylic acid and anhydrides thereof. Representative aromatic saturated carboxylic acids include o-phthalic acid, isophthalic acid and their derivatives. Representative aliphatic saturated carboxylic acids include 1,4-cyclohexane dicarboxylic acid, hexahydrophthalic acid, adipic acid and their derivatives. The saturated carboxylic acids or their derivatives may for example be present in an amount from about 10 to about 80 mole percent, about 25 to about 65 mole percent, or about 35 to about 50 mole percent of total carboxylic acids or acid derivatives used to make the unsaturated polyester resin. Also, an aromatic carboxylic acid may for example be present in an amount from 0 to 100 percent, from 0 to about 50 percent, or from 0 to about 25 percent of the saturated carboxylic acids or acid derivatives used to make the unsaturated polyester resin, and an aliphatic carboxylic acid may for example be present in an amount from 0 to 100 percent, from about 50 to 100 percent, or from about 75 to 100 percent of the saturated carboxylic acids or acid derivatives used to make the unsaturated polyester resin. [00039.] Representative alcohols for use in making the unsaturated polyester resins include alkanediols and oxaalkanediols such as ethylene glycol, 1,2-propylene glycol, propane-3-diol, 1,3- butylene glycol, butene-1,4-diol, hexane-1,6-diol, diethylene glycol, triethylene glycol, polyethylene glycol, cyclohexane-1,2-diol, 2,2-bis-(p-hydroxycyclohexy1)-propane, 5-norbornene-2,2-dimethylol, 2,3- norbornene diol, cyclohexane dimethanol, and the like. Alcohols having a neo-structure such as 1,2- propanediol, 2-methyl 1,3-propanediol, 2,2-dimethyl heptanediol, 2,2- dimethyl octanediol, 2,2-dimethyl- 1,3-propanediol (aka, neopentyl glycol), pentaerythritol, dipentaerythritol, tripentaerythritol, trimethylol propane, di-trimethylol propane, 2,2,4-trimethyl-l,3-pentanediol,2 -butyl-2-ethyl-1,3-propanediol, 3- hydroxy-2,2-dimethylpropyl3-hydroxy-2,2-dimetphyrolpanate, and the like may be preferred. Monofunctional alcohols may also be used to prepare the unsaturated polyester resin. Representative monofunctional alcohols include benzyl alcohol, cyclohexanol, 2-ethylhexyl alcohol, 2-cyclohexyl ethanol, 2,2-dimethyl-1-propanol and lauryl alcohol. Where a monofunctional alcohol is used, the amount present may a non-zero amount less than about 10 mole percent, or less than about 5 mole percent of the total alcohols used to make the unsaturated polyester resin. [00040.] The unsaturated polyester resin may be prepared by esterification techniques catalysts (e.g., esterification or transesterification catalysts) that will be familiar to those skilled in the art. The esterification process is typically carried out until the polyester attains an acid number corresponding to the desired molecular weight. For example, the final acid number may be from about 7 to about 30, the number average molecular weight (Mn) may be from about 800 to about 3600, and the weight average molecular weight (Mw) may be from about 1,300 to about 11,000. The acid number may be reduced by increasing the reaction temperature, carrying out the reaction for a longer period of time, or by adding an acid neutralizer as will be familiar to those skilled in the art. [00041.] The unsaturated polyester resin may also be formed by reacting an oligoester, i.e. an ester oligomer chain containing a small number of repeating ester units, having a weight average molecular weight of about 200 to about 4000 with a diisocyanate and a hydroxyalkyl(meth)acrylate to provide a urethane acrylate having terminal vinyl groups, as described in WO2006091446A1. The urethane acrylate resin may be used as is, or in a mixture with another unsaturated polyester resin such as an aliphatic or aromatic unsaturated polyester resin. [00042.] In certain embodiments, unsaturated polyester resins are reacted with radical reactive diluent, such as styrene monomers, using a free radical photoinitiator. The double bonds on the polyester as well as the pendent double bond on the styrene diluent provide pathways for both chain extension and crosslinking. [00043.] Epoxy vinyl esters useful in the invention are typically derived from an epoxy resin where the oxirane group has been reacted to generate a functional group having a pendant double bond. Desirably, the modification of the epoxy resin is achieved through the reaction of the oxirane group with alpha-beta unsaturation, for example an acrylate, thereby producing an acrylic (double bond) end group. For example, a bisphenol A may be reacted with methacrylic acid to form an epoxy methacrylate ester. Examples of suitable epoxy resins include bisphenol A epoxy, cycloaliphatic epoxy, epoxy novolac, and epoxy cresol novolac. [00044.] Typically, the vinyl ester resin composition may be prepared by dissolving the vinyl ester in a suitable compatible diluent to facilitate handling, cure and to provide excellent mechanical properties. Such compatible diluents may include, for instance, styrene, chlorostyrene, vinyl toluene, α-methyl styrene, diallyl phthalate, triallyl cyanurate, acrylate and methacrylate esters, for example Bisphenol A epoxy diacrylate and trimethylpropane triacrylate, and divinyl benzene. Styrene and mono-, di- and tri- (meth)acrylate esters are preferred compatible diluent. The resin, however, may also be dissolved in a non-reactive diluent, such as, for instance, acetone where low application viscosity is required but where properties obtainable only with the neat resin are desired. [00045.] The vinyl ester resins of the present invention may be prepared by an addition reaction between ethylenically unsaturated monocarboxylic acids and epoxy resins, which comprise multiple oxirane groups reactive with the acid as well as an R group that does not participate in the reaction. The R group may be selected from, for instance, alkylene, cycloalkylene, arylene, arylalkylene, oxyarylene, oxyarylalkylene and cycloalkylene esters. Processes for preparing vinyl ester resins useful in the present invention include those disclosed in U.S. Pat. No.3,256,226 to Fekete et al.; No.3,317,465 to Doyle et al.; No.3,345,401 to May; No.3,373,221 to May; No.3,377,406 to Newey; and No.3,432,478 to May.; No.3,548,030 to Jernigan; No.3,564,074 to Swisher et al.; No.3,634,542 to Dowd et al.; and No. 3,637,618 to May, incorporated herein by reference. Generally, the vinyl ester resins of the present invention are prepared using suitable catalysts, such as for instance, tertiary amines, phosphines, alkalis or -onium salts. Suitable components of several vinyl ester resins may include but are not limited to Bisphenol A epoxy, novolac epoxy and the like reacted with unsaturated acids such as acrylic and methacrylic acid and derivatives thereof. [00046.] Increased variety of vinyl ester resins may be obtained by selecting the unsaturated monomer diluents, as described below, which can be combined with and copolymerized with the vinyl ester resin. Preferred vinyl ester resins useful in the present invention are the bisphenol-A (BPA)-epoxy based vinyl ester resins. These resins may be employed in the resin compositions of the present invention either with or without a reactive diluent, for example a co-reactive monomer such as styrene. [00047.] The BPA-epoxy based vinyl ester resins provide handling properties similar to ambient temperature cure polyester systems but upon cure exhibit excellent physical properties similar to cured epoxy systems, thus combining the desired properties of these two different thermosetting resins into a single resin system. [00048.] Polyester resins may be co-cured with radical reactive diluent, such as styrene monomer, using a free radical photoinitiator. The double bonds on the polyester backbone as well as the pendent double bond on the styrene monomer provide pathways for both chain extension and crosslinking. Radical reactive diluent [00049.] Desirably, one or more radical reactive diluents may be used to reduce composition viscosity and may at least partially replace solvent. Generally, a radical reactive diluent copolymerizes with the above-described resin during cure and is incorporated into the coating. The one or more radical reactive diluents may be monofunctional, multifunctional or a mixture thereof. Monofunctional diluents may be selected to increase cured coating ductility while multifunctional diluents can be selected to increase cross-link density of the cured coating. In some embodiments, the radical reactive diluents are preferably one or more radical reactive diluents capable of participating in a radical polymerization reaction, non-limiting examples are compounds with ethylenic unsaturation. Representative examples include substituted and unsubstituted styrene, methyl methacrylate (MMA), and; mono-, di-, and poly- functional esters of unsaturated monofunctional acids (such as acrylic acid and methacrylic acid) with alcohols or polyols having from 1 to about 18 carbon atoms; and mono-, di-, and poly-functional esters of unsaturated monofunctional alcohols with carboxylic acids or their derivatives having from 1 to about 18 carbon atoms. Other suitable radical reactive diluents include, for example, acrylates, methacrylates, phthalates such as diallyl phthalate; triallylcyanurates; vinyl ethers; and the like. [00050.] Representative acrylates and methacrylates include isobornyl acrylate (IBOA), isobornyl methacrylate (IBOMA), butanediol dimethacrylate, tripropylene glycol diacrylate (TPGDA); , ethylene dimethacrylate (EGDMA), polyethylene glycol dimethacrylate (PEGDMA), polypropylene glycol dimethacrylate (PPGDMA), trimethylolpropane triacrylate (TMPTA), trimethylol propane trimethacrylate (TMPTMA), tetramethylol propane trimethacrylate, dipropylene glycol dimethacrylate, dipropylene glycol diacrylate (DPGDA), Methyl 2-((allyloxy)methyl)acrylate) monomer, 1,4-Cyclohexane dimethanol divinyl ether (CHDM-di), monofunctional cyclic acrylates, such as aromatic polyether acrylate, isodecyl acrylate, isodecyl methacrylate, 1,3-butylene glycol dimethacrylate, 2-hydroxy ethyl methacrylate (2- HEMA), 1,6 hexane diol dimethacrylate (HDODMA), triethylene glycol dimethacrylate (TEGDMA), acetoacetoxyethyl methacrylate (AAEM) and the acrylate counterparts thereof. Isobornyl species are preferred and generally are present in a ratio of (a) to IBOA of about 2.2:1 to about 0.5:1. [00051.] Mixtures of radical reactive diluents may be used. Preferred radical reactive diluents include styrene, methyl methacrylate, TMPTMA, vinyltoluene, para-tertiary-butylstyrene, para- methylstyrene, EGDMA, 2-HEMA and mixtures thereof. The total amount of radical reactive diluent may for example represent about 5 to about 60 wt. %, about 15 to about 50 wt. %, or about 25 to about 45 wt. % of the total coating composition. Thermally Conductive Filler [00052.] The thermally conductive filler comprises boron nitride, preferably hexagonal BN (h- BN). The thermally conductive filler may further comprise other particles selected from a variety of materials that afford thermally conductive properties at the loading concentrations described herein. Examples of preferred thermally conductive particle materials include alumina, alumina trihydrate (ATH), aluminum nitride, boron nitride, beryllium oxide, zinc oxide, , magnesium oxide, and combinations thereof. Such particles impart both substantial thermal conductivity and enhance dielectric strength of the coatings of the present invention. In some embodiments, where a plurality of the above thermally conductive fillers are present, the ratio of BN conductive filler to total conductive filler amount may be in a range of 0.1: 1.0 to 0.99:1.0, preferably in a range 0.2:1.0 or 0.89:1. In preferred embodiments a total amount of heat conductive filler is generally in a range of about 5% to about 60% of the total composition. [00053.] Co-fillers such as zirconium dioxide, titanium dioxide, silicon dioxide, silicon nitride or calcium carbonate are less thermally conductive and may be used in the coating composition to replace part of the boron nitride, provided that performance in tests described herein is not unacceptably affected. [00054.] Hexagonal boron nitride (“h-BN”) preferred for use in the invention is an inert, lubricious ceramic material having a platy hexagonal crystalline structure, which is similar to that of graphite, but is more electrically insulating than graphite. In one embodiment, the invention relates to a mixture of at least two different boron nitride materials are selected such that they provide synergistic effects, such as improved viscosity properties. The different boron nitride powder materials are selected from platelet morphology and non-platelet morphology. Non-platelet boron nitride is defined herein as any boron nitride other than platelet boron nitride. For example, non-boron nitride powder materials can include agglomerates of boron nitride that are made up of boron nitride platelets. The agglomerates of boron nitride powder materials can have spherical or irregular shape and vary in size from each other. Other non-platelet boron nitride powder materials include, but are not limited to, for example, partially crystalline boron nitride, amorphous boron nitride, and nano boron nitride powder materials having different properties including but not limited to surface areas, sizes, aspect ratios, densities. According to one embodiment, the two different boron nitride powder materials may be two different spherical agglomerates of boron nitride powder materials having different particle sizes. [00055.] To aid in reactant viscosity control, the thermally conductive ceramic particles may be of a certain particle size distribution and within a controlled aspect ratio range. The particle sieve size may accordingly be between 0.01-100 micrometers. In another embodiment, the thermally conductive ceramic particles may have a mean particle size of 0.01-100 micrometers, or at least 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.75, 1.0, 1.5, 2.0between 1-25 micrometers. The particle aspect ratios for sphere, rod, or plate-shaped particles may preferably be between 1-50, or between 1-10. [00056.] In one embodiment, at least one of the two different BN powder materials comprises crystalline or partially crystalline boron nitride particles made by processes known in the art, in either agglomerate boron nitride or platelet boron nitride forms. These may include spherical BN particles. In a preferred embodiment, the BN powder materials comprise platelets, preferably at least 50%, 60% or 70% platelets. [00057.] On one embodiment, particle size distribution with a D50 may be in a range from about 1, 1.2, 1.4, 1.6, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 micrometers to about 10.0, 9.5, 9.0, 8.5, 8.0, 7.5, 7.0, 6.5 or 6.0 micrometers. In another embodiment, the BN particles had a particle size distribution of D90 in a particle size range of 12 -25, or 14-24, or 16-22 micrometers. Particle size distribution can be measured by laser light scattering, e.g. a Mastersizer 2000, dispersion in ethanol. [00058.] Surface area of the BN platelet powder materials desirably is less than 20 m2 / g and may range in surface area as low as less than 3.0 m2 / g. Preferably, surface area and aspect ratio are selected such that filler does not unduly increase viscosity and particles do not extend beyond the surface of the cured coating layer. Photoinitiator [00059.] The UV-curable liquid coating composition comprises at least one photoinitiator. Photoinitiators enhance the rapidity of the curing process when the UV-curable composition is exposed to electromagnetic radiation, such as actinic radiation, for example ultraviolet (UV) radiation. The photoinitiator included in the UV-curable liquid coating composition as supplied to the end user is activated after deposition of the composition on a substrate surface by exposing the uncured coating composition to UV or other electromagnetic radiation of sufficient intensity for a sufficient time to initiate. [00060.] The initiator or cross-linking agent can be a photoinitiator. Examples of some useful photoinitiators include, but are not limited to, photoinitiators available commercially from Ciba Specialty Chemicals, under the “IRGACURE” and “DAROCUR” trade names, specifically “IRGACURE” 184 (1- hydroxycyclohexyl phenyl ketone), 907 (2-methyl-1-[4-(methylthio)phenyl]-2-morpholino propan-1- one), 369 (2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone), 500 (the combination of 1-hydroxy cyclohexyl phenyl ketone and benzophenone), 651 (2,2-dimethoxy-2-phenyl acetophenone), 1700 (the combination of bis(2,6-dimethoxybenzoyl-2,4,4-trimethyl pentyl) phosphine oxide and 2- hydroxy-2-methyl-1-phenyl-propan-1-one), and 819[bis(2,4,6-trimethyl benzoyl) phenyl phosphine oxide] and “DAROCUR” 1173 (2-hydroxy-2-methyl-1-phenyl-1-propan-1-one) and 4265 (the combination of 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide and 2-hydroxy-2-methyl-1-phenyl- propan-1-one. Of course, combinations of these materials may also be employed herein. [00061.] Other photoinitiators useful herein include alkyl pyruvates, such as methyl, ethyl, propyl, and butyl pyruvates, and aryl pyruvates, such as phenyl, benzyl, and appropriately substituted derivatives thereof. Photoinitiators particularly well-suited for use herein include ultraviolet photoinitiators, such as 2,2-dimethoxy-2-phenyl acetophenone (e.g., “IRGACURE” 651), and 2-hydroxy-2-methyl-1-phenyl-1- propane (e.g., “DAROCUR” 1173), bis(2,4,6-trimethyl benzoyl) phenyl phosphine oxide (e.g., “IRGACURE” 819), and the photoinitiator combination of bis(2,6-dimethoxybenzoyl-2,4,4- trimethylpentyl) phosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one (e.g., “IRGACURE” 1700), as well as the photoinitiator bis (η5-2,4-cyclopentadien-1-yl)-bis[2,6-difluoro-3-(1H-pyrrol-1- yl)phenyl]titanium (e.g., “IRGACURE” 784DC). Useful actinic radiation includes ultraviolet light, which may or may not be supplemented with other energy sources. [00062.] Desirably, the actinic radiation used to cure the UV-curable liquid coating composition has a wavelength from about 200 nm to about 400 nm. Useful UV includes, but is not limited to, UVA (about 320 nm to about 400 nm), UVB (about 290 nm to about 320 nm), UVC (about 220 nm to about 290 nm) and combinations thereof. Useful light supplemental to the UV light may be visible light includes, but is not limited to, violet, indigo, blue, green light, and combinations thereof. Such useful visible lights may have a wavelength from about 450 nm to about 550 nm. Photoinitiators can be employed in concentrations effective to initiate curing of the UV-curable liquid coating composition at a desired exposure to actinic radiation and typically in concentrations of about 0.01% to about 10% by weight of composition. Adhesion Promoter [00063.] An optional component of adhesion promoter may be included in the compositions of the invention to improve binding to metal substrates, e.g. cross-hatch adhesion performance, and resistance to humidity. Organosilanes compounds may be used to promote adhesion , improve the strength and provide enhanced resistance to humid conditions. Other well-known adhesion promoters include organotitanates, zinc di(meth)acrylate, organozinc oligomers, organic chromium and zirconium complexes. If present, the adhesion promoter may comprise one or more adhesion promoting chemistries, as described below, and a total amount of the adhesion promoter component may be in a range of at least about 0.1, 0.3, 0.5, 0.75, 1.0, 1.5, 2, 2.5,3, 3.5, 4, or 4.5 wt.% and not more than about 10, 9, 8, 7, 6 or 5 wt.%, at least for economic reasons. In one embodiment, where the adhesion promoter is silane have functional groups similar to those of the UV resin, more promoter may be used and incorporated into the coating. [00064.] In some embodiments, adhesion promoters are used and may comprise silanes, such as epoxy, vinyl / acrylate / methacrylate functionalized silanes, desirably a methacryl functionalized silane, such as Dynasylan products and some polyester based products, such as TEGO Addbond products both commercially available from Evonik Operations GmbH; as well as organo-phosphoric acids, such as HEMA-phosphates. Examples of organozinc oligomers include organozinc acrylates, such as di(meth)acrylate based-oligomer, e.g. polyester zinc acrylate oligomer and urethane zinc acrylate oligomer. [00065.] Examples of the silane adhesion promoters include, but are not limited to, aminosilanes such as γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N- (aminoethyl)-Y- aminopropyltrimethoxysilane, N- (aminoethyl)-Y-aminopropyltrimethyl dimethoxysilane, and N-phenyl- Y-aminopropyltrimethoxysilane; epoxysilane such as -(3,4-epoxycyclohexyl)- ethyltrimethoxysilane, γ- glycidoxypropyltrimethoxy silane, and γ- glycidoxypropyltriethoxysilane; vinylsilane such as vinyl tris( - methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, and γ- methacryloxypropyltrimethoxysilane; hexamethyldisilazane; and γ-mercaptopropyltrimethoxysilane. [00066.] Examples of the titanate adhesion promoters include, but are not limited to, tetraisopropoxy titanium, tetra-n-butoxy titanium, butyl titanate dimer, tetrastearyl titanate, titanium acetylacetonate, titanium lactate, tetraoctyleneglycol titanate, titanium lactate, and tetra stearoxy titanium. Wetting and Dispersing Agent [00067.] Compositions of the invention preferably comprise wetting and dispersing agent (also referred to herein as “dispersing agent”), added to reduce agglomeration and settling of inorganic fillers in the coating composition, in particular BN and silica fillers. In some embodiments, a ratio of total amount of heat conductive filler to total amount of dispersant can be in a range of about 70:1 to 15:1, preferably about 60:1 to 20:1. [00068.] An important performance criterion for the wetting and dispersing agent (f) is that it inhibits the thickening effect of inorganic fillers in the coating composition. Excessive thickening of the coating composition before it is applied to a substrate can negatively affect sprayability, cured coating surface roughness, and cause air retention voids in the coating. The wetting and dispersing agent (f) is a component which comprises one or more groups X with affinity to the filler and therefore can bind to the filler surface covalently, ionically, and / or by physisorption. The wetting dispersing agent also causes stabilization of the filler particles and to prevent agglomeration, which leads otherwise to the sedimentation of the solids and hence a non-homogenous product. Responsible for this stabilization in general are one or more groups Y in the wetting and dispersing agent (f) which ensure compatibility with the surrounding medium. [00069.] Suitable wetting and dispersing agents (f) used are preferably wetting and dispersing agents (f) of relatively high molecular mass, more particularly polymeric wetting and dispersing agents (f). Suitable functional polymers preferably possess a number-average molecular mass (Mn) of at least 400 g / mol, preferably at least 800 g / mol, more preferably at least 2000 g / mol. The maximum molecular weight Mn is usefully 100000 g / mol, preferably 50000 g / mol, and more preferably 25000 g / mol. The number-average molecular weights can be determined by gel permeation chromatography against a polystyrene standard. [00070.] The wetting and dispersing agent (f) used in accordance with the invention more particularly can be selected from linear or branched polymers and copolymers having compatibility with the surrounding medium and functional groups and / or groups with filler affinity. Examples of wetting and dispersing agents include alkylammonium salts of polymers and copolymers, polymers and copolymers having acidic groups, comb and block copolymers, such as block copolymers having, in particular, basic groups with filler affinity, optionally modified acrylate block copolymers, optionally modified polyurethanes, optionally modified and / or optionally salified polyamines, epoxide-amine adducts, phosphoric esters, especially those of polyethers, polyesters, and polyether-esters, basic or acidic ethoxylates such as alkoxylated monoamines or polyamines or acidic 1,2-dicarboxylic anhydride monoesters of alkoxylated monoalcohols, reaction products of unsaturated fatty acids with maleic anhydride and / or mono-, di-, and polyamines; as well as amino alcohols, and unsaturated 1,2-dicarboxylic acids and their anhydrides and their salts and reaction products with alcohols and / or amines; polymers and copolymers with fatty acid residues, optionally modified polyacrylates, such as transesterified polyacrylates, optionally modified polyesters, such as acid-functional and / or amino-functional polyesters, polyphosphates, and also mixtures of the foregoing. [00071.] Polymeric wetting and dispersing agents (f) based on polyisocyanates may be prepared by addition reaction of monohydroxy compounds, diisocyanate-functional compounds, and compounds having a tertiary amino group onto the existing NCO groups of polyisocyanates containing isocyanurate, biuret, urethane and / or allophanate groups. Amine based wetting and dispersing agents (f) which are obtainable by making an amine salt (salification) of an amine-functional compound with an acid may be used. [00072.] The following groups of wetting and dispersing agents (f) display particularly good effect in the compositions of the invention: (a)reaction products of unsaturated fatty acids with maleic anhydride and / or mono-, di-, and polyamines, amino alcohols, and (b) unsaturated 1,2-dicarboxylic acids and their anhydrides and their salts and reaction products with alcohols and / or amines, unsaturated polyamine amides and salts thereof and lower molecular weight acidic polyesters. [00073.] Wetting and dispersing agents (f) of these kinds are available as commercial products from, for example, BYK-Chemie from Wesel, under the trade names BYK-220 S, BYK-P 9908, BYK- 9076, BYK-9077, BYK-P 104, BYK-P 104 S, BYK-P 105, BYK-W 9010, BYK-W 920, BYK-W 935, BYK-W 940, BYK-W 960, BYK-W 965, BYK-W 966, BYK-W 975, BYK-W 980, BYK-W 990, BYK- W 995, BYK-W 996, as well as trade name groups BYKUMEN, BYKJET, LACTIMON, ANTI-TERRA and DISPERBYK. Where the desire is for a low content of volatile organic compounds, especially of organic solvents, the aforementioned commercial products are desirably used as solvent-free active substances and preferably free of volatile constituents. Organic Solvent [00074.] An optional component of added organic solvent may be used to reduce viscosity of the coating composition. The added solvent, such as butyl acetate or acetone, is distinguished from incidental solvents included in raw materials and incorporated into coating composition with the raw materials. Examples of incidental solvents included with raw materials include mineral spirits, naphtha and the like. As used herein, solvent refers to chemicals that are removed during manufacture and not incorporated into the final product (other than trace amounts). Rheology Modifier [00075.] An optional component of rheology modifier may be used to control the viscosity characteristics and the body and hold-up characteristics of vinyl ester resins by imparting thixotropy to the vinyl ester resin composition. Suitable examples include modified and unmodified pyrogenic (fumed) amorphous silica or synthetic amorphous silica, desirably the silica may be basic or hydrophobically modified silica. In one embodiment the rheology modifier may be produced by combining at least one unsaturated polyester resin with at least one fumed silica. Desirably the rheology modifier is selected from those having one or more of the following attributes: a BET surface area of from 150 to 210 m2 / g; a SiO2 content of greater than or equal to 98.5wt.%; and an NaO content of less than or equal to 0.5 wt.%. Rheology modifiers of these kinds are available as commercial products, for example, Cab-O-Sil M-5 (a fumed silica product manufactured by Cabot Corporation) and Aerosil® brand commercially available from Evonik Operations GmbH. Flexibilizer [00076.] An optional component of flexibilizer may be included in embodiments of the invention. Suitable examples of flexibilizer include methylmethacrylate-butadiene-styrene (MBS) and similar rubbers, one example being Clearstrength XT-100 commercially available from Arkema Inc.; polysulfide resins, such as Thioplast resins commercially available from Nouryon Chemicals LLC . Plasticizer [00077.] Optional plasticizers may be used in certain embodiments of the invention to increase flexibility and toughness of the cured dielectric coating. Increased toughness of the dielectric coating may reduce crazing and contribute to longer battery life, particularly in batteries used in moving vehicles. Examples of optional plasticizer include phthalates, benzoates, dibenzoates, phthalate esters, naphthalene sulfonate, trimellitates, adipates, sebacates, maleates, sulfonamides, organophosphates and polybutene. De-aerator [00078.] Another component that may be present is one or more air release agents, so-called de- aerator. Air release agents may assist the UV-curable liquid coating composition to release air before full cure thereby reducing entrapping of air and thereby causing weakness or porosity. Typical air release agents include silicone or non-silicone materials including a solutions of polyalkylene ether and / or polyolefin in petroleum distillate, silicone de-aerators, acrylic polymers, hydrophobic solids, vegetable oil-based, and mineral oil based paraffin waxes. Commercially available air release agents include BYK- 066, BYK-077, BYK-500, BYK-501, BYK- 515, and BYK-555 de-aerators (from BYK-Chemie USA, Inc.). When used, the air release agent amount may for example be up to about 1.5 wt. %, up to about 1 wt. %, or from about 0.1 to about 0.5 wt. % of the UV-curable liquid coating composition. Accelerator [00079.] Another optional component that may be present is one or more accelerators. Representative accelerators for use in the UV-curable liquid coating compositions are electron donating species that help in the activation of a photoinitiator or catalyst and facilitate or speed curing of the UV- curable liquid coating composition at relatively low temperatures, e.g., at temperatures of about 0 to about 30 °C. Representative accelerators include metal compounds (e.g., cobalt, manganese, potassium, iron, vanadium, copper, and aluminum salts of organic acids); amines (e.g., dimethylaniline, diethylaniline, phenyl diethanolamine, dimethyl paratoluidine, and 2-aminopyridine); Lewis acids (e.g., boron fluoride dihydrate and ferric chloride); bases (e.g., tetramethyl ammonium hydroxide); quaternary ammonium salts (e.g., trimethyl benzyl ammonium chloride and tetrakismethylol phosphonium chloride); sulfur compounds (e.g., dodecyl mercaptan and 2-mercaptoethanol); dimethyl acetoacetamide; ethyl acetoacetate; methyl acetoacetate and mixtures thereof. For example, cobalt salts of organic acids may be used to facilitate the low temperature decomposition of peroxide catalysts and cure of the disclosed UV- curable liquid coating compositions. Preferred accelerators include metal salts of organic acids, as disclosed above, in particular cobalt alkyloate salts, such as cobalt 2 – ethylhexanoate cobalt octanoate, potassium octanoate, dimethyl acetoacetamide, ethyl acetoacetate, methyl acetoacetate and mixtures thereof. The accelerators typically are used in an amount of about 0.05 to about 3 wt. %, or about 0.05 to about 2 wt. % of the UV-curable liquid coating composition. Inhibitor [00080.] Another optional component that may be present is an inhibitor. One or more inhibitors help prolong or maintain shelf life for the uncured UV-curable liquid coating compositions by inhibiting premature polymerization. Suitable inhibitors may include free-radical inhibitors and / or scavengers such as quinones (e.g., hydroquinone (HQ), toluhydroquinone (THQ), mono-tertiarybutyl hydroquinone (MTBHQ), di tertiary-butyl hydroquinone (DTBHQ), napthaquinone (NQ), and monomethyl ether hydroquinone (MEHQ)), butylated hydroxy toluene (BHT), tertiary butyl catechol (TBC), and the like. The inhibitor may for example be present in an amount of from about 0.01 to about 0.5 wt. %, from about 0.01 to about 0.3 wt. % or from about 0.01 to about 0.1 wt. % of the UV-curable liquid coating composition. Filler or Extender [00081.] In addition to the thermally conductive fillers of component (c), additional fillers different from (c), as described in the following paragraphs can also be used, provided that they do not extinguish or reduce the cured coating’s thermal conductivity to 0.20 W / mK or less and / or reduce the cured coating’s dielectric withstand voltage to less than 2.0 kV. The UV-curable liquid coatings may optionally comprise at least one other extender filler such as clay, ground limestone, mica, talc, barium sulfate, precipitated silica, silica different from the rheology modifier and the like. Said extender fillers may also contribute to impart thixotropy to the UV-curable liquid coatings of the invention. Although UV-curable liquid coating compositions of the invention comprising a rheology modifier as disclosed herein can be produced in the absence of additional extender fillers without a decrease in their performance, it is nevertheless possible to add such additional fillers, if desired. These amounts of such fillers are not limited, although they are typically added in amounts of from about 0 to about 40 wt. % of the UV-curable liquid coating composition. [00082.] In some embodiments wherein the UV cured coatings of the invention may be in contact with moisture or aqueous materials in the use environment, the UV-curable liquid coating compositions, preferably contain no more than 1.0, 0.5, 0.35, 0.10, 0.08, 0.04, 0.02, 0.01, 0.001, or 0.0002 percent, more preferably said numerical values in grams per liter, more preferably said numerical values in ppm, or are free of extender filler susceptible to chemical or physical reaction with moisture or aqueous materials, e.g. swelling, dissolution or hydration and the like. In this manner, the cured coating will not exhibit blushing, delamination or failure after long-term contact with moisture or aqueous materials. Typical extender fillers in that case include chopped or milled fiberglass, talc, silicone dioxide, titanium dioxide, wollastonite, mica, clay, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, magnesium sulfate and barium sulfate. While small amounts of water-susceptible extender filler may be tolerated, preferably no more than about 2 wt. %, and more preferably no more than about 1 wt. %, including no more than 0.8, 0.5, 0.3 and 0.1 wt. % water-susceptible extender filler is employed in the UV-curable liquid coating composition. Other Additives [00083.] As described above the UV-curable liquid coating composition may contain a number of other optional additives such as a coupling agents, anti-foaming agent, pigments and dyes, plasticizers, flame retardants, chelate modified epoxy resin, auxiliary impact modifiers / toughening agents, flow control agents, antioxidants, non-reactive diluents, extenders or other adjuvants. [00084.] The UV-curable liquid coating composition of the invention can comprise additional secondary thermally conductive fillers. Examples of the secondary thermally conductive fillers include， aluminum nitride (AlN)， magnesium oxide (MgO)， zinc oxide (ZnO)， silicon nitride (Si3N4)， aluminum powder and graphite. When the UV-curable liquid coating composition comprises secondary thermally conductive fillers， the content of the secondary thermally conductive fillers may be 0 wt.％ but may be a non-zero amount of 1.0 wt.％ or more， more preferably 5.0 wt.％ or more based on the UV-curable liquid coating composition. The content of the further thermally conductive fillers is 20 wt.％ or less， preferably 15 wt.% or less， more preferably 10 wt.％ or less based on the UV-curable liquid coating composition, provided that this secondary material does not interfere with desired dielectric or heat conducting benefits of the invention. [00085.] Examples of flame retardant include antimony oxides， halocarbon， halogenated ester, halogenated ether， brominated flame retardant agent， and halogen free compounds such as organophosphorus compounds， organonitrogen compounds， and intumescent flame retardants. [00086.] Examples of antioxidant include sodium sulfite， sodium pyrosulfite， sodium hydrogen sulfite， sodium thiosulfate and dibutyl phenol, particularly sterically hindered substituted phenols, e.g. pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate). [00087.] Examples of UV stabilizer include benzophenones， benzotriazoles， substituted acrylates， aryl esters and some compounds containing nickel or cobalt salts. [00088.] Examples of coupling agent include silane coupling agent， titanate coupling agent， zirconium coupling agent， magnesium coupling agent and tin coupling agent. [00089.] Examples of pigment or dye include sulfate， silicate， borate， molybdate， phosphate， vanadate， cyanate， sulfide， azo pigment， phthalocyanine pigment， anthraquinone， indigo， quinacridone and dioxazine dyes. [00090.] Various embodiments of the invention are described throughout this disclosure. In each of the embodiments described herein, the UV-curable liquid coating composition is preferably a two-part coating composition where the two-parts are mixed together a sufficient time period before application or optionally are mixed together in a spray nozzle during or immediately prior to application. Preparation of two-part compositions is a conventional method of keeping reactive components of a composition from reacting prematurely. Customarily, Part A comprises resins and other components reactive with the photoinitiator as well as suitable carriers, additives and adjuvants; and Part B comprises the photoinitiator and any carriers or additives suitable for packaging with the photoinitiator. It will be understood by those of skill in the art that the embodiments listing all components together describe both the Part A & B mixture as well as the two-part composition comprising Part A and Part B prior to their combination. This disclosure may also encompass one-part compositions, which provide at least some benefits of the invention, where reaction of combined components is prevented or slowed by known means, such as reversable blocking of the photoinitiator and / or reactants. Methods [00091.] Methods of depositing a layer of UV-curable coating composition may include spraying, printing, dipping and similar processes. The UV-curable liquid coating composition may, for example, be applied by conventional techniques over all article surfaces such that the part, e.g. a vehicle part or component, a cooling device and the like, is fully enveloped, by for example dipping or spraying, with spray-application being preferred for this use. Alternatively, the UV-curable liquid coating composition can be applied onto specific portions of the part by any number of masking or printing methods known in the art. In some embodiments, the UV-curable liquid coating composition desirably has viscosity suitable for spraying and / or printing, as well as zero solvent present or optionally low solvent content, which contributes to depositing thin coatings, free of voids providing good substrate edge coverage by an uncured layer of as-deposited coating composition. The low solvent content may be, for example, in increasing order of preference, less than 50, 40, 30, 20, 15, 10, 8, 6, 4, 2 or 1 wt.%, more preferably the recited numerical values in grams / liter or mg / liter. [00092.] After optionally drying or solvent flash off, the uncured layer may be cured or may be transported and / or made part of an assembly followed by curing. The cured, preferably cross-linked composition, thereby forms a thermally conductive dielectric layer, typically in the form of a coating adhered to a substrate. [00093.] Preferred curing methods comprise actinic radiation, e.g. UV, as described in herein. The UV curing may be used alone or may be combined with application of heat, to for example raise the temperature, flash-off solvent, or other known means. [00094.] The UV-curable liquid coating compositions, applied and cured as described herein, produced cured thin coatings free of voids having good coverage on substrate edges and providing good overall electrical insulation. The cured coatings may have thicknesses in a range of about 1.75, 2.0, 2.5 up to about 3.0, 3.5, 4 mils (meaning thousandths of an inch), i.e. about 40, 50, 65 up to about 75, 90 or 100 micrometers (also referred to herein as” μm” and “micron”). In comparison, cured UV and powder coatings require thicknesses of more than 5 mils (> 127μm) up to more than 10 mils (>254 μm) to provide void-free cured coatings, coverage of substrate edges with necessary coating thicknesses and no bare spots to achieve electrical insulation. Substrates comprising cured coatings according to the invention desirably show no visible edge effect, such as greater thickness at edges or picture frame effects, even at the lower coating thicknesses described above; these defects are commonly present in comparative coatings. [00095.] The cured dielectric coatings according to aspects of the invention, provide both rapid thermal dissipation and good electrical insulation with high dielectric strength. [00096.] The cured dielectric coatings are useful in applications where heat dissipation and electrical insulation are required. The cured dielectric coatings find use in high energy density power generation or storage where significant heat can be generated during operation, such as in battery packs in cars or aircraft. The cured dielectric coatings, having both high dielectric strength and high thermal conductivity, are advantageous as electrical insulation in battery pack operation where efficient heat dissipation is critical to battery safety and longevity. [00097.] The cured dielectric coating is also capable of providing additional protection against corrosion and abrasion during vehicle operation where environmental factors, e.g. water condensation, pollutants, vibration and the like, can damage underlying substrates. [00098.] UV curing of the as-applied coating composition, may be augmented or supplemented by optional additional steps, for example the coated article can be air dried, heat cured at relatively low temperatures, for example in a range of 10°C to 100°C, preferably at least in increasing order of preference 15, 20 or 25°C and not more than in increasing order of preference 100, 90, 80, 70, 65, 60, 50, 40, 30°C , or various combinations of curing steps together with UV curing. [00099.] Benefits of using the coating compositions of embodiments of the invention to form thermally conductive, dielectric coatings may include, but are not limited to: • Easy preparation of the coating composition using standard or low shear mixing instead of high shear missing; reducing or eliminating complex filler milling steps; simple application using, for example spray or print techniques; and optional shipping and handling of uncured coated substrates; • Single layer deposition provides thin coating with good edge coverage, in preferred embodiments avoiding multiple deposition steps; • Efficient fast cure times ranging from about 2-200 seconds for curing via UV, desirably in a low time range of 2, 4, 6, 8, 10, 12, 15, 20, 25, 30, 40, 50 or 60 seconds and no more than 200, 150, 120, 90, 80, 75, 70, 68, 66, 65, 64, 63, 62 seconds • Cured dielectric coating provides greater than 2.0, 3.0, 3.5, 4.0, 4.5 or 5.0 kV electrical insulation and reduced heat retention; • Cured dielectric coatings exhibit high thermal conductivity and / or low thermal resistance as measured according to ASTM D5470 such that the cured coatings aid in heat dissipation. In some embodiments, cured dielectric coatings of the invention exhibit thermal conductivity of in increasing order of preference greater than about 0.25, 0.30, 0.35, 0.40, 0.45, 0.50 or 0.55 Watts per meter-Kelvin (W / mK), which is significantly better than powder coats at 0.20 W / mK. Void testing: [000100.] Electrical insulative testing of a cured coating to reveal coating voids, which may include bare edges, pinholes and low thickness areas on substrates may be performed by “Hipot testing”, derived from the term High Potential Test. In Hipot testing, a high voltage is directly applied to a part having a cured coating under test. The test voltage is usually much higher than the ordinary operating voltage of the part in order to stress the dielectric properties of the coating under test. The test is designed to detect current leakage due to insulative cured coating defects, such as pin holes, cracks, voids and even low coating weight areas. Breakdown in the insulative coating results in current flowing across the test points of the Hipot tester, i.e. current leakage. Hipot testing of cured coatings according to the invention showed no voids, even around corners and edges of substrates coated which shows that edges are equally protected. Electrical insulating Testing [000101.] Electrical insulation performance is confirmed as being “good”, that is permitting no flow of current through the test specimen using a high voltage test (“Hipot Test”) which detects flow of current upon application of a selected voltage for a specific time period. The “dielectric withstand voltage” being a voltage which a dielectric material (insulator) will withstand without current passing through the insulator, i.e. the greatest voltage at which little or no current flows (Passing test result). Desirably, electrical insulation properties of the cured dielectric coating according to the invention may exhibit a dielectric withstand voltage, in increasing order of preference, of greater than about 2.0, 2.5, 3.0, 3.5, 4.0, 4.2, 4.4, 4.5, 4.6, 4.7.4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4 or 5.5 kV as measured in accordance with ASTM D 149-09 Hipot test. Alternatively, the dielectric withstand voltage may be increased in a stepwise fashion and the amount of current that the test sample permits to flow (also referred to as current leakage) recorded in microAmps (µA). Unaged cured coating layers according to the invention typically limit current leakage at 3.5kV and 5.0kv to as low as zero µA up to about 5.0. µA Dielectric Strength Testing [000102.] Dielectric Strength is a measure of the electrical strength of a material as an insulator. Dielectric strength is defined as the maximum voltage required to produce a dielectric breakdown through the material and is expressed as Volts per unit thickness. Breakdown is typically exhibited as an electrical burn-through puncture of the sample or insulator decomposition. A higher dielectric strength represents a better quality of insulator. The measurement enables performance comparisons between different materials used at different coating thicknesses. Desirably, the cured dielectric coating may exhibit a dielectric strength of, in increasing order of preference, greater than about 80, 90, 100, 120, 130, 140, 150 or 160 kV / mm thickness (e.g. approximately 1.5, 2, 2.5, 3.0, 3.5 or 4.0 kV / mil thickness). [000103.] Throughout this text, it is recognized that the descriptions refer to compositions and methods of making and using said compositions. That is, where the disclosure describes or claims a feature or embodiment associated with a composition or a method of making or using a composition, it is appreciated that such a description or claim is intended to extend these features or embodiment to embodiments in each of these contexts (i.e., compositions, methods of making, and methods of using). [000104.] The following examples are intended to complement, rather than displace or supersede, the previous descriptions. EXAMPLES [000105.] The following Examples provide experimental methods used to make and test liquid coating compositions for depositing a thermally conductive dielectric coating on a substrate, their uncured properties & cured properties and performance. While each example disclosed in the specification is considered to provide specific individual embodiments of compositions, methods of preparation and use, none of the Examples is to be considered limiting of the more general embodiments described herein. [000106.] In the following examples, efforts have been made to ensure accuracy with respect to numbers used (e.g., amounts, temperature, etc.), but some experimental error and deviation should be accounted for. Unless indicated otherwise, temperature is in degrees C, ambient being about 22 °C, and pressure is at or near atmospheric. No high shear mixing was required unless stated otherwise, below. Testing Methods: [000107.] Unless otherwise stated herein, liquid coating compositions of the examples were spray applied onto commercially available metal test panels and cured as described below. The cured dielectric coatings adhered to the metal test panels, dielectric coated test panels were tested according to the following standard test methods: • Dielectric withstanding voltage strength / HiPot test: ASTM D149-09 • Thermal conductivity: ASTM D5470 • Thermal resistance: ASTM D5470 • Adhesion / cross-hatch: ASTM D3359 Example 1 Boron Nitride only [000108.] The ingredients listed in Table 1 were added into a mixing vessel in sequence. The mixture was mixed at 600 RPM for 4 hours, and then transferred to a HVLP Spray gun. A group of commercially available aluminum 3003 alloy panels, free of contaminants, were isopropyl alcohol ( IPA) solvent wiped, allowed to air dry and then spray coated to 3 mils thickness. The panels were passed through an UV conveyor oven equipped with H+ bulb, which provided total spectral emissions covering a wide range of wavelengths (about 200 to 450 nm) and cured the coatings on the panels. [000109.] Some of the panels with a cured coating were tested for dielectric withstanding voltage strength / HiPot test and withstood 4.3 kV for 1 second with 0.2 µA leakage current. Other panels having a cured coating thereon scored 5 when tested for crosshatch adhesion according to ASTM D3359. The panels were aged in a Thermotron Chamber at 85 °C and 85% relative humidity for 500 hours, and then tested again and withstood 4.3kV DC and maintained crosshatch adhesion of 5. Table 1 Component Reagent Amount in wt.% Radical reactive diluents Isobornyl acrylate monofunctional monomer 16.24 TPGDA - Tripropylene glycol diacrylate; difunctional 24.36 with a branched alkyl polyether backbone UV resin Modified bisphenol A epoxy diacrylate oligomer; 32.48 Viscosity, 60°C, 3500 mPa.s Photoinitiators Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide 1.62 1-hydroxycyclohexyl-phenyl ketone 1.62 Additives Wetting / Dispersing agent 0.81 De-aerator 0.41 Pigment Vossen Blau 750 LS 0.26 Filler Boron Nitride platelet (D90: 12-25 µm) 18.96 Adhesion promoters Methacrylfunctional silane 1.62 Multifunctional aminosilane 1.62 Example 2 Boron Nitride only – Different resin makeup [000110.] The ingredients listed in Table 2 were added into a mixing vessel in sequence and the UV-curable liquid composition was prepared, applied, cured and tested according to the procedure recited above for Example 1, unless specified otherwise. The cured coatings of 3 mils thickness withstood 4.3 kV for 1 second with 0.2 µA leakage current and had crosshatch adhesion of 5 according to ASTM D3359. The panels were kept in a Thermotron Chamber at 85 oC and 85% relative humidity for 500 hours, and then tested again and withstood 4.3kV DC and maintained crosshatch adhesion of 5. Table 2 Component Reagent Amount in wt.% Radical reactive diluents Isobornyl acrylate monofunctional monomer 16.24 DPGDA dipropylene glycol diacrylate, difunctional 24.36 UV resin Modified bisphenol A epoxy diacrylate oligomer, 32.48 Viscosity, 60°C, 1200 mPa.s Photoinitiators Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide 1.62 2-Hydroxy-2-methylpropiophenone 1.62 Additives Wetting / Dispersing Agent 0.81 De-Aerator 0.41 Pigment Vossen Blau 750 LS 0.26 Filler Boron Nitride platelet (D90: 12-25 µm) 18.96 Adhesion promoters Methacrylfunctional silane 1.62 Multifunctional aminosilane 1.62 Example 3 ATH only [000111.] The ingredients listed in Table 3 were added into a mixing vessel in sequence and the UV-curable liquid composition was prepared, applied, cured and tested according to the procedure recited above for Example 1, unless specified otherwise. The cured coatings had a thickness of 2.4 mils and withstood 4.3 kV for 1 second with 0.6 µA leakage current and had crosshatch adhesion of 5 according to ASTM D3359. Table 3 Component Reagent Amount in wt.% Radical reactive diluents Isobornyl acrylate monofunctional 14.38 DPGDA dipropylene glycol diacrylate, difunctional 21.54 UV resins Modified bisphenol A epoxy diacrylate oligomer, Viscosity, 28.75 60°C, 3500 mPa.s Photoinitiators Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide 1.09 1-hydroxycyclohexyl-phenyl ketone 1.09 Additives Wetting and Dispersing Agent 0.54 Defoamer 0.21 Pigment Vossen Blau 750 LS 0.54 Filler Aluminum trihydrate (ATH) - median particle size approx.1µm 30.18 Adhesion promoter Multifunctional aminosilane 1.68 Example 4 Boron Nitride and ATH – Ratio 2 / 7 Table 4 Component Reagent Amount in wt.% Radical reactive diluents Isobornyl acrylate monofunctional 14.38 DPGDA dipropylene glycol diacrylate 21.54 UV resin Modified bisphenol A epoxy diacrylate oligomer; Viscosity, 28.75 60°C, 3500 mPa.s Photoinitiators Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide 1.09 1-hydroxycyclohexyl-phenyl ketone 1.09 Additives Wetting / Dispersing Agent 0.54 Defoamer 0.21 Pigment Vossen Blau 750 LS 0.54 Filler Aluminum trihydrate (ATH) - median particle size 1 micron 23.47 Boron Nitride platelet (D90: 12-25 µm) 6.71 Adhesion promoters Multifunctional aminosilane 1.68 [000112.] The ingredients listed in Table 4 were added into a mixing vessel in sequence and the UV-curable liquid composition was prepared, applied, cured and tested according to the procedure recited above for Example 1, unless specified otherwise. The cured coatings had a thickness of 2.7 mils, withstood 4.3 kV for 1 second with 0.4 µA leakage current and had crosshatch adhesion of 5 according to ASTM D3359. Example 5 Boron Nitride and ATH – Ratio 1 / 8 MO1791-58 [000113.] The ingredients listed in Table 5 were added into a mixing vessel in sequence and the UV-curable liquid composition was prepared, applied, cured and tested according to the procedure recited above for Example 1, unless specified otherwise. The cured coatings had a thickness of 2.5 mils, withstood 4.3 kV for 1 second with 0.6 µA leakage current and had crosshatch adhesion of 5 according to ASTM D3359. Table 5 Component Reagent Amount in wt.% Radical reactive diluents Isobornyl acrylate monofunctional radical reactive diluent 14.38 DPGDA dipropylene glycol diacrylate radical reactive 21.54 diluent UV resin Modified bisphenol A epoxy diacrylate oligomer; Viscosity, 28.75 60°C, 3500 mPa.s Photoinitiators Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide 1.09 1-hydroxycyclohexyl-phenyl ketone 1.09 Additives Wetting / Dispersing Agent 0.54 Defoamer 0.21 Pigment Vossen Blau 750 LS 0.54 Filler Aluminum trihydrate (ATH) - median particle size 1 µm 26.82 Boron Nitride platelet (D90: 12-25 µm) 3.36 Adhesion promoter Multifunctional aminosilane 1.68 Example 6 Boron Nitride and ATH – Ratio 2 / 7 with Additional Diluent [000114.] The ingredients listed in Table 6 were added into a mixing vessel in sequence. The mixture was mixed at 600 RPM for 4 hours, and then transferred to a HVLP Spray gun and applied on a group of aluminum 3003 alloy panels prepared according to Example 1 procedure. The coated panels were cured and tested according to the procedure recited above for Example 1, unless specified otherwise. The cured coatings had a thickness of 2.7 mils, withstood 4.3 kV for 1 second with 0.7 µA leakage current and had crosshatch adhesion of 5 according to ASTM D3359. Table 6 Component Reagent Amount in wt.% Radical reactive diluents Isobornyl acrylate monofunctional 13.07 Methyl 2-((allyloxy)methyl)acrylate) monomer 5.94 DPGDA dipropylene glycol diacrylate 19.65 UV resin Modified bisphenol A epoxy diacrylate oligomer; 26.22 Viscosity, 60°C, 3500 mPa.s Photoinitiators Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide 0.99 1-hydroxycyclohexyl-phenyl ketone 0.99 Additives Wetting / Dispersing Agent 0.79 De-Aerator 0.40 Pigment Vossen Blau 750 LS 0.25 Fillers Aluminum trihydrate (ATH) - median particle size 1 µm 22.18 Boron Nitride platelet (D90: 12-25 µm) 6.34 Adhesion promoters Multifunctional aminosilane 1.58 Methacrylfunctional silane 1.58 Example 7 Boron Nitride and ATH – Ratio 2 / 7 and Additional Diluent [000115.] The ingredients listed in Table 7 were added into a mixing vessel in sequence and the UV-curable liquid composition was prepared, applied, cured and tested according to the procedure recited above for Example 1, unless specified otherwise. The cured coatings had a thickness of 3.5 mils withstood 4.3 kV for 1 second with 0.6 µA leakage current and had crosshatch adhesion of 5 according to ASTM D3359. Table 7 Component Reagent Amount in wt.% Radical reactive diluents Isobornyl acrylate monofunctional monomer 12.45 1,4-Cyclohexane dimethanol divinyl ether (CHDM-di) 6.25 monomer DPGDA dipropylene glycol diacrylate 18.70 UV resin Modified bisphenol A epoxy diacrylate oligomer; Viscosity, 24.99 60°C, 3500 mPa.s Photoinitiators Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide 1.25 1-hydroxycyclohexyl-phenyl ketone 1.25 Additives Wetting / Dispersing Agent 0.87 De-Aerator 0.42 Pigment Vossen Blau 750 LS 0.50 Fillers Aluminum trihydrate (ATH) - median particle size 1 µm 23.32 Boron Nitride platelet (D90: 12-25 µm) 6.67 Adhesion promoters Multifunctional aminosilane 1.67 Methacrylfunctional silane 1.67 Example 850% ATH –Additional Diluent Table 8 Component Reagent Amount in wt.% Radical reactive diluents Isobornyl acrylate monofunctional monomer 29 TMPTMA - Trimethylolpropane trimethacrylate 1.5 UV resin Trifunctional, aromatic polyether urethane methacrylate 15 oligomer, Viscosity, 60°C, 1450 mPa.s Photoinitiators 1-hydroxycyclohexyl-phenyl ketone 1.5 Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide 1.5 Filler Aluminum trihydrate (ATH) - median particle size 1 µm 50 Adhesion promoter Zinc Dimethacrylate 1 [000116.] The ingredients listed in Table 8 were added into a mixing vessel in sequence. The mixture was mixed at 2000 RPM for 8 minutes, and then applied on a group of aluminum 3003 alloy panels using a draw down bar. The panels were prepped, cured and tested according to the procedure recited above for Example 1, unless specified otherwise. The cured coatings had a thickness of 2.4 mils, withstood 4.3 kV for 1 second and had crosshatch adhesion of 5 according to ASTM D3359. Example 950% ATH –Additional Diluent [000117.] The ingredients listed in Table 9 were added into a mixing vessel in sequence and the UV-curable liquid composition was prepared, applied, cured and tested according to the procedure recited above for Example 8, unless specified otherwise. The cured coatings had a thickness of 2.4 mils withstood 4.3 kV for 1 second and had crosshatch adhesion of 5 according to ASTM D3359. Table 9 Component Reagent Amount in wt.% Radical reactive diluents Isobornyl acrylate monofunctional radical reactive diluent 20 TMPTMA-Trimethylolpropane trimethacrylate 1.5 Mono functional cyclic acrylate 10 UV resin Trifunctional, aromatic polyether urethane methacrylate 11 oligomer, Viscosity, 60°C, 1450 mPa.s Photoinitiators 1-hydroxycyclohexyl-phenyl ketone 1.5 Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide 1.5 Additives Wetting / Dispersing Agent 1 De-Aerator 0.5 Pigment Vossen Blau 750 LS 0.20 Filler Aluminum trihydrate (ATH) - median particle size approx. 50 1 µm Antioxidant Antioxidant 1010 (CAS 6683-19-8)* 1 Adhesion promoter Vinyltrimethoxy silane 1 * Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) Example 10 Boron nitride 10% and 40% ATH –Additional Diluent [000118.] The ingredients listed in Table 10 were added into a mixing vessel in sequence and the UV-curable liquid composition was prepared, applied, cured and tested according to the procedure recited above for Example 8, unless specified otherwise. The cured coatings had a thickness of 2.4 mils withstood 4.3 kV for 1 second and had crosshatch adhesion of 5 according to ASTM D3359. Table 10 Component Reagent Amount in wt.% Radical reactive diluents Isobornyl acrylate monofunctional 20 TMPTMA-Trimethylolpropane trimethacrylate 1.5 Mono functional cyclic acrylate 10 UV resin Trifunctional, aromatic polyether urethane methacrylate 11 oligomer, Viscosity, 60°C, 1450 mPa.s Photoinitiators 1-hydroxycyclohexyl-phenyl ketone 1.5 Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide 1.5 Additives Wetting / Dispersing Agent 1 De-Aerator 0.5 Pigment Vossen Blau 750 LS 0.20 Fillers Aluminum trihydrate (ATH) - median particle size approx. 40 1 µm 10 Boron Nitride platelet (D90: 12-25 µm) Antioxidant Antioxidant 1010 1 Adhesion promoter Vinyltrimethoxy silane 1 Example 11 Boron nitride 5% and 45% ATH –Additional Diluent [000119.] The ingredients listed in Table 11 were added into a mixing vessel in sequence and the UV-curable liquid composition was prepared, applied, cured and tested according to the procedure recited above for Example 8, unless specified otherwise. The cured coatings had a thickness of 2.4 mils withstood 4.3 kV for 1 second and had crosshatch adhesion of 5 according to ASTM D3359. Table 11 Component Reagent Amount in wt.% Radical reactive diluents Isobornyl acrylate monofunctional 20 TMPTMA-Trimethylolpropane trimethacrylate 1.5 Mono functional cyclic acrylate 10 UV resin Trifunctional, aromatic polyether urethane methacrylate 11 oligomer, Viscosity, 60°C, 1450 mPa.s Photoinitiators 1-hydroxycyclohexyl-phenyl ketone 1.5 Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide 1.5 Additives Wetting / Dispersing Agent 1 De-Aerator 0.5 Pigment Vossen Blau 750 LS 0.20 Filler Aluminum trihydrate (ATH) - median particle size approx. 45 1 µm 5 Boron Nitride platelet (D90: 12-25 µm) Antioxidant Antioxidant 1010 1 Adhesion promoter Vinyltrimethoxy silane 1 Example 12 Boron nitride 5% and 35% ATH –Additional Diluent [000120.] The ingredients listed in Table 12 were added into a mixing vessel in sequence and the UV-curable liquid composition was prepared, applied, cured and tested according to the procedure recited above for Example 8, unless specified otherwise. The cured coatings had a thickness of 2.4 mils withstood 4.3 kV for 1 second and had crosshatch adhesion of 5 according to ASTM D3359. Table 12 Component Reagent Amount in wt.% Radical reactive diluents Isobornyl acrylate monofunctional 20 TMPTMA-Trimethylolpropane trimethacrylate 1.5 Mono functional cyclic acrylate 10 UV resin Aliphatic urethane acrylate, MW approx.2700, Viscosity, 15 60°C, 21000 mPa.s Photoinitiators 1-hydroxycyclohexyl-phenyl ketone 1.5 Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide 1.5 Additives Wetting / Dispersing Agent 1 De-Aerator 0.5 Pigment Vossen Blau 750 LS 0.20 Filler Aluminum trihydrate (ATH) - median particle size approx.1 35 µm Boron Nitride platelet (D90: 12-25 µm) 5 Antioxidant Antioxidant 1010 1 Adhesion promoters Methacrylfunctional silane 2 Multifunctional aminosilane 3 Example 13 Boron nitride 9.5% and 38% ATH –Additional Diluent [000121.] The ingredients listed in Table 13 were added into a mixing vessel in sequence and the UV-curable liquid composition was prepared, applied, cured and tested according to the procedure recited above for Example 8, unless specified otherwise. The cured coatings had a thickness of 2.4 mils withstood 4.3 kV for 1 second and had crosshatch adhesion of 3 according to ASTM D3359. Table 13 Component Reagent Amount in wt.% Radical reactive Isobornyl acrylate monofunctional 19 diluents TMPTMA-Trimethylolpropane 1.42 trimethacrylate Mono functional cyclic acrylate 9.5 UV resin Aliphatic urethane acrylate, MW approx. 14.27 2700, Viscosity, 60°C, 21000 mPa.s Photoinitiators 1-hydroxycyclohexyl-phenyl ketone 1.43 Bis(2,4,6-trimethylbenzoyl)- 1.43 phenylphosphineoxide Additives Wetting / Dispersing Agent 0.95 De-Aerator 0.47 Pigment Vossen Blau 750 LS 0.09 Filler Aluminum trihydrate (ATH) - median 38 particle size approx.1 µm 9.5 Boron Nitride platelet (D90: 12-25 µm) Antioxidant Antioxidant 1010 0.95 Adhesion promoters Methacrylfunctional silane 1.9 Multifunctional aminosilane 0.95 Example 1450% ATH –Additional Diluent [000122.] The ingredients listed in Table 14 were added into a mixing vessel in sequence and the UV-curable liquid composition was prepared, applied. cured and tested according to the procedure recited above for Example 8, unless specified otherwise. The cured coatings had a thickness of 2.4 mils withstood 4.3 kV for 1 second and had crosshatch adhesion of 5 according to ASTM D3359. Table 14 Component Reagent Amount in wt.% Radical reactive diluents Isobornyl acrylate monofunctional radical reactive diluent 16 TMPTMA-Trimethylolpropane trimethacrylate 1.6 Mono functional cyclic acrylate 10.5 UV resin Aliphatic urethane acrylate, MW approx.2700, Viscosity, 15.5 60°C, 21000 mPa.s Photoinitiators 1-hydroxycyclohexyl-phenyl ketone 1.6 Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide 1.6 Additives Wetting / Dispersing Agent 1.06 De-Aerator 0.5 Filler Aluminum trihydrate (ATH) - median particle size approx.1 50 µm Antioxidant Antioxidant 1010 1.06 Adhesion promoter Zinc Dimethacrylate 1 Example 1550% ATH –Additional Diluent [000123.] The ingredients listed in Table 15 were added into a mixing vessel in sequence and the UV-curable liquid composition was prepared, applied, cured and tested according to the procedure recited above for Example 8, unless specified otherwise. The cured coatings had a thickness of 2.4 mils withstood 4.3 kV for 1 second and had crosshatch adhesion of 5 according to ASTM D3359. Table 15 Component Reagent Amount in wt.% Radical reactive diluents Isobornyl acrylate monofunctional 17.44 TMPTMA- Trimethylolpropane. Trimethacrylate 1.7 Mono functional cyclic acrylate 11.5 UV resin Trifunctional, aromatic polyether urethane methacrylate, 12.5 Viscosity, 60°C, 1450 mPa.s Photoinitiators 1-hydroxycyclohexyl-phenyl ketone 1.7 Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide 1.7 Additives Wetting / Dispersing Agent 1.15 De-Aerator 0.5 Filler Aluminum trihydrate (ATH) - median particle size approx. 50 1 µm Antioxidant Antioxidant 1010 1.15 Adhesion promoter Zinc Dimethacrylate 1 [000124.] Humidity Aged 1,000 hour Panel Testing: Cured coated panels from each of Examples 1- 15 were aged in a Thermotron chamber maintained at 85 °C with 85% relative humidity for 1,000 hrs., which was double the exposure time of the prior tests. After aging, the coated panels were tested for crosshatch adhesion and dielectric withstanding voltage according to the test methods disclosed above, with the following results: [000125.] Summary of Humidity Aged 1,000 hour Coating Performance: All 1,000 hour aged, coated panels maintained crosshatch adhesion and passed the dielectric withstand test at 5000 volts for 2 minutes with leakage current from 0.7 to 2.0 µA. Example 16 [000126.] Fresh coated and UV cured panels according to each of Examples 1-15 were tested for thermal conductivity according to ASTM D5470. All of the panels tested exhibited thermal conductivity of at least 0.25 Watts per meter-Kelvin (W / mK), some exhibited thermal conductivity of at least 0.40 W / mK. [000127.] These results evidenced thermal conductivity increased by at least 25% compared to conventional powder coat performance of 0.2 W / mK which indicated that the cured coatings according to the invention provide improved heat dissipation. [000128.] The above exemplary embodiments show that the inventive coating compositions are useful for in forming void-free, thin coatings with good coverage on substrate edges, and provide both quick thermal dissipation and good electrical insulation with high dielectric strength. Therefore, the cured coatings offer great advantages in applications where high energy density power generation or storage with significant heat being generated during operation such as the battery packs in vehicles, such as cars or aircraft. The coating can provide further protection against battery damage during the vehicle operation were water condensation and constant vibration are common sources of corrosion and abrasion. The coating can be cured with UV light.

Claims

CLAIMS 1. A UV-curable liquid coating composition comprising: (a) at least one UV-curable a monomer, oligomer or resin having one or more polymerizable groups for reactions under UV irradiation; wherein (a) is selected from unsaturated polyester monomers, oligomers, resins and combinations thereof, preferably vinyl esters, more preferably epoxy vinyl esters, optionally comprising epoxy acrylate esters and epoxy methacrylate esters, and combinations thereof (b) at least one radical reactive diluent, different from (a), and comprising one or more polymerizable groups for reactions under UV irradiation, (c) at least one thermally conductive filler, (d) at least one photoinitiator, (e) at least one adhesion promoter, and (f) optionally a dispersing agent.

2. A UV-curable liquid coating composition comprising: (a) at least one UV-curable a monomer, oligomer or resin having one or more polymerizable groups for reactions under UV irradiation, desirably present in an amount in a range of from 9% to 95%, preferably 10% to 50%;wherein (a) is selected from unsaturated polyester monomers, oligomers, resins and combinations thereof, preferably vinyl esters, more preferably epoxy vinyl esters, comprising epoxy acrylate esters and epoxy methacrylate esters, and combinations thereof (b) at least mono-functional or di-functional radical reactive diluent, different from (a), and comprising one or more polymerizable groups for reactions under UV irradiation, desirably present in an amount in a range of from 10% to 95%, desirably 15% to 80%, preferably 25% to 50%; (c) at least one thermally conductive filler, desirably present in an amount in a range of from 1% to 70%, preferably 5% to 60%, more preferably 10% to 50%; (d) at least one photoinitiator, desirably present in a range of from 0.1% to 5%, preferably 1% to 4%, more preferably 1.5% to 3.5%; (e) at least one adhesion promoter, desirably present in a range of from 0.1% to 10%, preferably 0.5 to 8.0%, more preferably 1.0% to 6.0%; and optionally(f) at least one dispersing agent, in a range of 0.0% up to, in increasing order of preference, 7.0%, 6.0%, 5.0%, 4.0%, 3.0%, or from 0.1% to 2.0%; desirably present in amounts of 0.25%-1.5%, preferably 0.5% to 1.25%; (g) a de-aerator, a defoamer, an anti-foaming agent, or combination of two or more thereof, desirably each present in a range of from 0% to 2.0%; (h) at least one organic solvent, desirably present in a range of from 0.0% to 20%; (i) at least one additive selected from a rheology modifier, a flexibilizer, and a plasticizer, each desirably present in a range of from 0% to 5% wherein the wt.% of each component is relative to the total weight of the composition and the total amount of the components does not exceed 100 wt.%.

3. The UV-curable liquid coating composition of Claim 1 or 2, wherein (a) the at least one unsaturated polyester resins, epoxy vinyl ester resins, such as epoxy acrylate esters and epoxy methacrylate esters, and combinations thereof, is present in a range of from 10 wt.% to 95%, relative to the total weight of the composition.

4. The UV-curable liquid coating composition of Claim 1 or 2, wherein (b) the at least one radical reactive diluent, is present in a range of from 10 wt.% to 95%, relative to the total weight of the composition.

5. The UV-curable liquid coating composition of Claim 1 or 2, wherein (c) the at least one thermally conductive filler, preferably comprising boron nitride filler, is present in a range of from 5 wt.% to 60 wt.%, relative to the total weight of the composition.

6. The UV-curable liquid coating composition of Claim 1 or 2, wherein (d) the at least one photoinitiator, is present in a range of from 0.5 wt.% to 4 wt.%, relative to the total weight of the composition.

7. The UV-curable liquid coating composition of Claim 1 or 2, wherein (e) the at least one adhesion promoter is present in a range of from 0.5 to 8.0%.

8. The liquid epoxy adhesive composition of Claim 1 or 2, wherein (f) the at least one dispersing agent, is contained in the composition in an amount ranging from 0.1% to 7.0% relative to the total weight of the composition.

9. The UV-curable liquid coating composition of Claim 1 or 2, wherein (g) is present as the de- aerator, the defoamer or combination thereof, present in a range of from 0.1% to 2.0%; relative to the total weight of the composition.

10. The UV-curable liquid coating composition of Claim 1 or 2, wherein (h) the at least one organic solvent, is present in a range of from 1 wt.% to 20%, relative to the total weight of the composition.

11. The UV-curable liquid coating composition of Claim 1 or 2, wherein (i) the at least one additive, is present in an amount ranging from in a range of from 0.1 wt.% to 5.0 wt.%, relative to the total weight of the composition.

12. The UV-curable liquid coating composition of Claim 1 or 2, wherein the at least one additive comprises the rheology modifier present in a range of from 0.1% to 5%, relative to the total weight of the composition.

13. The UV-curable liquid coating composition of Claim 1 or 2, wherein the at least one flexibilizer, is present in a range of from 0.1% to 5%, relative to the total weight of the composition.

14. The UV-curable liquid coating composition of Claim 1 or 2, wherein the at least one plasticizer; is present in a range of from 0.1% to 5.0%, relative to the total weight of the composition.

15. An intermediate article of manufacture comprising a substrate surface, preferably a metal surface; and deposited thereon an uncured layer of the UV-curable liquid coating composition of Claim 1 or 2, optionally dried on the substrate surface, having a thickness of about 40 to about 100 micrometers.

16. An article of manufacture comprising a substrate surface, preferably a metal surface; and deposited on the surface an adherent, UV-cured layer of the UV-curable liquid coating composition of Claim 1 or 2.

17. A method of making a dielectric coating exhibiting a thermal conductivity comprising steps of: obtaining a substrate comprising a metal surface, cleaning and optionally deoxidizing the metal surface; applying the UV-curable liquid coating composition according to claim 1 to the metal surface thereby forming an uncured layer and exposing the uncured layer to UV radiation for a time sufficient to form a cured dielectric coating of about 40 to about 100 micrometers thickness, said cured coating exhibits a dielectric strength of greater than about 80 kV / mm of cured coating thickness and exhibits a thermal conductivity, as measured according to ASTM D5470, of at least 0.25 Watts per meter-Kelvin (W / mK).

18. The method of claim 17, wherein the UV radiation cure times range from about 2-200 seconds.

19. An article of manufacture comprising a substrate surface, preferably a metal surface; and deposited on the surface an adherent, UV-cured layer comprising radical polymerization reaction products of unsaturated polyester monomers, oligomers, resins and combinations thereof; at least one radical reactive diluent, different from (a), and at least one adhesion promoter wherein the cured layer is electrically insulating and thermally conductive such that the cured layer exhibits a dielectric strength of greater than about 80 kV / mm of cured coating thickness and exhibits thermally conductivity, as measured according to ASTM D5470, of greater than about 0.25 Watts per meter-Kelvin (W / mK).

20. The article of manufacture of claim 19 wherein the electrically insulating and thermally conductive cured layer on the substrate surface exhibited crosshatch adhesion of “5”, when tested according to ASTM D3359.

21. The article of manufacture of claim 20 wherein the electrically insulating and thermally conductive cured layer on the substrate surface exhibited crosshatch adhesion of “5”, when tested according to ASTM D3359 after being aged in a Thermotron Chamber at 85 °C and 85% relative humidity for 500 hours.

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