Light-curable composition and assembly

Abstract

Provided is a light-curable composition that includes one or more monofunctional (meth)acrylate monomers with at least one monomer having a homopolymer glass transition temperature of from 0°C to 200°C; a crosslinker selected from multifunctional oligomeric (meth)acrylates, aliphatic urethane (meth)acrylates, aromatic urethane (meth)acrylates, polyester (meth)acrylates, and epoxy (meth)acrylates; one or more adhesion promoters selected from glycidyl (meth)acrylate, 2-hydroxyethyl(meth)acrylate acid phosphate, phosphonate ester-containing (meth)acrylic monomer, phosphate ester-containing (meth)acrylic monomer, silane, and (meth)acrylic acid; a photoinitiator; a flame retardant; and one or more fillers comprising hollow fillers, refractory fillers comprising kaolin, intumescent fillers, or mixtures thereof. The cured composition can function as an electrical insulator in battery assemblies, while protecting components from hot particles and gases in case of thermal runaway events.

Description

PA103346W003LIGHT-CURABLE COMPOSITION AND ASSEMBLYField of the Invention

[0001] The present disclosure relates to light-curable compositions that can be useful in production of battery assemblies.Background

[0002] Electric vehicle (EV) batteries generally use cylindrical or prismatic cells enclosed in a rigid outer container. These can be stacked to form battery modules that can harness the power of large numbers of electrolytic cells. In the event of a short circuit, overcharging, or other cell stress, it is possible for a thermal runaway event to occur where a lithium-ion battery becomes overheated. When this occurs, individual cells of a battery assembly can release high-temperature gases and particles that can propagate to the rest of the vehicle or to neighboring cells.

[0003] To protect the vehicle and the passengers from fire propagation there is a need for special solutions that withstand prolonged exposure to very high temperatures (typically over 1200°C) and erosion from hot particles discharged from the damaged cell. Often these barriers need to thermally insulate the lid from the hot gases to avoid the burning or melting of the lid material (in case the lid is made from polymers or aluminum), or e-coat burning on the opposite side of the lid (in the case of e- coated steel lids). Absent adequate protection, there is a risk of fires propagating into cabin areas of the vehicle.Summary:

[0004] In conventional battery assemblies, relatively thick mica sheets have been used to protect lids and / or venting channels from hot gases and particles. The primary components of mica include silicon dioxide (SiCE), aluminum oxide (AI2O3), potassium oxide (I O), magnesium oxide (MgO), iron oxide (Fe2O3), and water. Mica sheets can be rather rigid, which complicates their application to surfaces. Other drawbacks include the high cost of thick mica sheets, and the need to affix these sheets to assembly structures by adhesives.

[0005] Provided herein are light curable barrier coatings that can be applied via spraying, coating, extrusion, or dipping to battery assembly components and that cure rapidly within a few seconds under actinic radiation. These light-cured coatings are based on acrylic chemistry and surprisingly withstand the very harsh conditions of thermal runaway events. These coatings are easy to apply and can be coated on surfaces with unusual shapes and angles. Advantageously, these barrier coatings also electrically insulate assembly components and prevent arcing and shorts during a thermal runaway event. In other applications, these coatings can be applied to battery housing substrates and all components therein.

[0006] Provided is a one-part composition that can be used in coating various electric conductive parts such as busbars, cell housings or battery lids used in electric vehicle batteries. The coating can act as an electrical insulator, while protecting components from hot particles and gases in case of thermal runawayevents. The key advantage of this composition is that it allows for unlimited open time, separating the dispensing step from the curing step, which reduces cycle times and allows for greater flexibility in the manufacturing process.

[0007] In a first aspect, a light-curable composition is provided. The light-curable composition comprises: one or more monofimctional (meth)acrylate monomers with at least one monomer having a homopolymer glass transition temperature of from 0°C to 200°C; a crosslinker selected from multifunctional oligomeric (meth)acrylates, aliphatic urethane (meth)acrylates, aromatic urethane (meth)acrylates, polyester (meth)acrylates, and epoxy (meth)acrylates; one or more adhesion promoters selected from glycidyl (meth)acrylate, 2-hydroxyethyl(meth)acrylate acid phosphate, phosphonate ester- containing (meth)acrylic monomer, phosphate ester-containing (meth)acrylic monomer, silane, and (meth)acrylic acid; a photoinitiator; a flame retardant; and one or more fillers comprising hollow fillers, refractory fillers comprising kaolin, intumescent fillers, or mixtures thereof.

[0008] In a second aspect, a battery assembly is provided comprising: an electrically-conductive substrate, optionally comprising a metal lid, busbar, or cell housing; and the provided composition disposed thereon.

[0009] In a third aspect, a method of making a battery assembly comprising an assembly surface is provided, the method comprising: applying the provided composition onto the assembly surface; and curing the light-curable composition using actinic radiation to form a protective coating that extends over the assembly surface.

[0010] The provided compositions and methods provide an efficient, cost-effective solution for batteries in electric vehicles and potentially many other applications, improving safety and performance. Compared with two-part compositions, the provided compositions and methods enable curing times of a few seconds in comparison to several minutes to hours. This greatly reduces production cycle times during the assembly of the battery or eliminates the need to store the assembly components for extended periods of time for curing or reaching an appropriate handling strength. After the composition is cured, assembly components can be directly moved to the next production or mounting step, enabling battery production lines to use less space and less energy.Brief Description of the Drawings

[0011] FIG. 1 is an isometric view of a battery cell assembly incorporating a light-curable composition according to an exemplary embodiment.

[0012] FIG. 2 is an isometric view of a battery housing assembly incorporating a light-curable composition according to an exemplary embodiment.

[0013] FIG. 3 is an isometric view of a battery lid assembly incorporating a light-curable composition according to an exemplary embodiment.

[0014] FIG. 4 is an isometric view of a busbar assembly incorporating a light-curable composition according to an exemplary embodiment.

[0015] FIG. 5 is an isometric view of an electrical cable assembly incorporating a light-curable composition according to an exemplary embodiment.

[0016] FIGS. 6 and 7 are schematic views showing two different methods of coating and curing the light-curable composition.

[0017] Repeated use of reference characters in the specification and drawings is intended to represent the same or analogous features or elements of the disclosure. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the disclosure. The figures may not be drawn to scale.DEFINITIONS

[0018] As used herein:“allyl” refers to a functional group having the formula CH2=CH-CH2-.“ambient conditions” means at 21 °C and 101.3 kilopascals.“ambient temperature” means 21°C.“curable” refers to a composition that can be cured.“cure,” or “polymerize,” refers to a process of reacting monomeric, oligomeric, and / or polymeric molecules together in a chemical reaction to form polymer chains or three-dimensional networks.“halogen” refers to a halogen atom or one or more halogen atoms, including chlorine, bromine, iodine, and fluorine atoms or fluoro, chloro, bromo, or iodo substituents.“(meth)acrylate group” refers to a functional group that is either an acrylate group of the formula CH2=CH-C(O)O- or a methacrylate group of the formula CH2=C(CH3)-C(O)O-.“molecular weight” refers to weight average molecular weight, unless otherwise indicated.“oligomer,” or ’’oligomeric,” refers to a molecule that comprises at least two repeat units and that has a molecular weight less than its entanglement molecular weight; such a molecule, unlike a polymer, exhibits a significant change in properties upon the removal or addition of a single repeat unit.“weight average molecular weight” is a parameter reflecting the weight fraction of individual polymer chains in a polymer sample and measured using known gel permeation chromatography (GPC) techniques.Detailed Description

[0019] As used herein, the terms “preferred” and “preferably” refer to embodiments described herein that can afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the invention.

[0020] As used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a” or “the” component may include one or more of the components and equivalents thereof known to those skilled inthe art. Further, the term “and / or” means one or all of the listed elements or a combination of any two or more of the listed elements.

[0021] It is noted that the term “comprises,” and variations thereof do not have a limiting meaning where these terms appear in the accompanying description. Moreover, “a,” “an,” “the,” “at least one,” and “one or more” are used interchangeably herein. Relative terms such as left, right, forward, rearward, top, bottom, side, upper, lower, horizontal, vertical, and the like may be used herein and, if so, are from the perspective observed in the particular drawing. These terms are used only to simplify the description, however, and not to limit the scope of the invention in any way.

[0022] Reference throughout this specification to “one embodiment,” “certain embodiments,” “one or more embodiments” or “an embodiment” means that a particular feature, structure, material, or characteristic described relating to the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases such as “in one or more embodiments,” “in certain embodiments,” “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment of the invention.Light-curable Compositions

[0023] Provided are one-part, light-curable compositions capable of being deployed in protective coating solutions for electric vehicle batteries. In various embodiments, the composition includes one or more monofiinctional (meth)acrylate monomers; a crosslinker that is distinct from the one or more (meth)acrylate monomers, one or more adhesion promoters that is distinct from the one or more (meth)acrylate monomers and the crosslinker, a photoinitiator; and a flame retardant. In preferred embodiments, the composition further includes one or more fillers. Each of the foregoing components shall be examined below.

[0024] The one or more (meth)acrylate monomers are part of a base resin of the overall composition. Such monomers can include any useful acrylate or methacrylate that contain at least one ethylenically unsaturated bond and are capable of undergoing free radical polymerization. In preferred embodiments, the one or more monofunctional (meth)acrylate monomers include at least one monomer having a homopolymer glass transition temperature of from 0°C to 200°C, or in some embodiments, less than, equal to, or greater than 0°C, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200°C.

[0025] Examples of useful ethylenically unsaturated compounds include acrylic acid esters, methacrylic acid esters, hydroxy-functional acrylic acid esters, hydroxy-functional methacrylic acid esters, and combinations thereof. Such free radically polymerizable compounds include mono-, di- or poly-(meth)acrylates (i.e., acrylates and methacrylates) such as, methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-hexyl (meth)acrylate, stearyl (meth)acrylate, cycloaliphatic (meth)acrylates such as, tertiobutyl cyclohexyl acrylate, 3,3,5 trimethyl cyclohexanol acrylate, tricyclododecanemethanol acrylate, menthol (meth)acrylate, isobomyl (meth)acrylate, allyl (meth)acrylate, glycerol tri(meth)acrylate, ethyleneglycol di(meth)acrylate, diethyleneglycoldi(meth)acrylate, triethyleneglycol di(meth)acrylate, 1,3-propanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1,2,4-butanetriol tri(meth)acrylate, 1,4-cyclohexanediol di(meth)acrylate, pentaerythritol tetra(meth)acrylate, sorbitol hex(meth)acrylate, tetrahydrofurfuryl (meth)acrylate, bis [ 1 -(2-acryloxy)] -p-ethoxyphenyldimethylmethane, bis [ 1 -(3 -acryloxy-2 -hydroxy)] -p- propoxyphenyldimethylmethane, ethoxylated bisphenolA di(meth)acrylate, and trishydroxyethyl- isocyanurate tri(meth)acrylate; (meth)acrylamides (i.e., acrylamides and methacrylamides) such as (meth)acrylamide, methylene bis-(meth)acrylamide, and diacetone (meth)acrylamide; urethane (meth)acrylates; the bis-(meth)acrylates of polyethylene glycols; and vinyl compounds such as styrene, diallyl phthalate, divinyl succinate, divinyl adipate and divinyl phthalate. Other suitable free radically polymerizable compounds include siloxane -functional (meth)acrylates.

[0026] In various embodiments, the provided composition can contain one or more one monofunctional (meth)acrylate monomers. Preferred monofunctional (meth)acrylic monomers include cycloaliphatic (meth)acrylates such as, tertiobutyl cyclohexyl acrylate, 3,3,5 trimethyl cyclohexanol acrylate, tricyclododecanemethanol acrylate, menthol (meth)acrylate, isobomyl (meth)acrylate, and mixtures thereof.

[0027] The one or more monofunctional (meth)acrylate monomers can be present in an amount of from 5 percent to 50 percent, from 10 percent to 45 percent, from 20 percent to 40 percent, or in some embodiments, less than, equal to, or greater than 1 percent, 2, 5, 7, 10, 15, 20, 25, 30, 35, 40, 45, or 50 percent by weight, relative to the overall weight of the composition.

[0028] The composition further includes at least one crosslinker. These monomers are multifunctional and generally include at least two, three, or even more ethylenically unsaturated (e.g., free radically) polymerizable groups, such as (meth)acrylate groups. In preferred embodiments, the crosslinker is selected from multifunctional oligomeric (meth)acrylates, aliphatic urethane (meth)acrylates, aromatic urethane (meth)acrylates, polyester (meth)acrylates, and epoxy (meth)acrylates. Mixtures of the foregoing are also possible.

[0029] Examples of suitable crosslinking monomers with two ethylenically unsaturated (e.g. free radically) polymerizable groups include 1,2-ethanediol diacrylate, 1,3-propanediol diacrylate, 1,9- nonanediol diacrylate, 1,12-dodecanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, butylene glycol diacrylate, bisphenol A diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, tripropylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, polyethylene / polypropylene copolymer diacrylate, polybutadiene diacrylate, neopentylglycol hydroxypivalate diacrylate modified caprolactone, and dimethacrylates of any of the foregoing diacrylates, and combinations thereof.

[0030] Examples of crosslinking monomers with three or four ethylenically unsaturated (e.g. free radically) polymerizable groups include trimethylolpropane triacrylate (e.g., commercially available under the trade designation TMPTA-N from Cytec Industries, Inc., Smyrna, GA and under the trade designation SR-351 from Sartomer, Exton, PA), pentaerythritol triacrylate (e.g., commercially available under the trade designation SR-444 from Sartomer), tris(2-hydroxyethylisocyanurate) triacrylate (e.g.,commercially available under the trade designation SR-368 from Sartomer), a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (e.g., commercially available from Cytec Industries, Inc., under the trade designation PETIA with an approximately 1 : 1 ratio of tetraacrylate to triacrylate and under the trade designation PETA-K with an approximately 3 : 1 ratio of tetraacrylate to triacrylate), pentaerythritol tetraacrylate (e.g., commercially available under the trade designation SR-295 from Sartomer), di -trimethylolpropane tetraacrylate (e.g., commercially available under the trade designation SR-355 from Sartomer), and ethoxylated pentaerythritol tetraacrylate (e.g., commercially available under the trade designation SR-494 from Sartomer). Examples of suitable with five (meth)acryloyl groups includes dipentaerythritol pentaacrylate (e.g., commercially available under the trade designation SR-399 from Sartomer).

[0031] Higher functionality meth(acrylates) include tri-, tetra- or pentafunctional monomeric or oligomeric aliphatic, cycloaliphatic, or aromatic acrylates or methacrylates.

[0032] Examples of suitable aliphatic tri-, tetra- and pentafimctional (meth)acrylates include triacrylates and trimethacrylates of hexane-2,4,6-triol; glycerol or 1,1,1 -trimethylolpropane; ethoxylated or propoxylated glycerol or 1,1,1 -trimethylolpropane; and the hydroxyl-containing tri(meth)acrylates which are obtained by reacting triepoxide compounds, for example the triglycidyl ethers of said triols, with (meth)acrylic acid. It is also possible to use, for example, pentaerythritol tetraacrylate, bistrimethylolpropane tetraacrylate, pentaerythritol monohydroxytriacrylate or -methacrylate, or dipentaerythritol monohydroxypentaacrylate or -methacrylate. In some embodiments, tri(meth)acrylates comprise 1,1 -trimethylolpropane triacrylate or methacrylate, ethoxylated or propoxylated 1,1,1- trimethylolpropanetriacrylate or methacrylate, ethoxylated or propoxylated glycerol triacrylate, pentaerythritol monohydroxy triacrylate or methacrylate, or tris(2 -hydroxy ethyl) isocyanurate triacrylate. Further examples of suitable aromatic tri(meth)acrylates are the reaction products of triglycidyl ethers of trihydroxy benzene and phenol or cresol novolaks containing three hydroxyl groups, with (meth)acrylic acid.

[0033] Other examples of crosslinkers are (meth)acrylic functional oligomers and generally include at least two, three, or even more ethylenically unsaturated (e.g., free radically) polymerizable groups, such as (meth)acrylate groups. These (meth)acrylic functional oligomers can be aliphatic urethane (meth)acrylates, aromatic urethane (meth)acrylates, polyester (meth)acrylates, epoxy (meth)acrylates.

[0034] Multifunctional urethane (meth)acrylate crosslinkers are commercially available from Sartomer, Colombes France, under the trade designation CN9002, CN9012, CN9200, CN9213LV, CN9215, CN9245, CN9276, CN9301B80, CN963B80, CN964A85, CN965, CN966H90, CN9800, CN981, CN991, CN996, CN9196, CN970D60, CN9761 or CN992.

[0035] Multifunctional urethane (meth)acrylate crosslinkers are commercially available from Allnex, Frankfurt, Germany, under the trade designation EBECRYL. For instance, these can include EBECRYL 225, 230, 231, 242, 244, 246, 250, and 264.

[0036] Multifunctional polyester (meth)acrylate crosslinkers are commercially available from Sartomer, Colombes France under the trade designations SARBIO 7201, SARBIO 7202, CN203,CN2035, CN2295EU, CN2303EU, CN2505, CN2560, CN2565, CN2608A, CN2634, CN2917, CN704, CN736, CN790, CN890 and SB400.

[0037] Multifunctional polyester (meth)acrylate crosslinkers are commercially available from Allnex, Frankfurt, Germany under the trade designation EBECRYL. For instance, these include EBECRYL 571, 657, 809, 810, 812, and 838.

[0038] Multifunctional epoxy (meth)acrylate crosslinkers are commercially available from Sartomer, Colombes France, under the trade designation SARBIO 7107, CN104, CN112D60, CN113D70, CN 122A80, CN 131BEU, CN 132, and CN2003EU. Other multifunctional epoxy (meth)acrylate crosslinkers are commercially available from Allnex, Frankfurt, Germany, under the trade designation EBECRYL. For instance, these include EBECRYL 605, 608, 3200, 3411, 3415, 3418, 3503, 3600, and 3700.

[0039] The crosslinker(s) can be present in an amount of from 2.5 percent to 70 percent, or in some embodiments, less than, equal to, or greater than 2 percent, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 12, 15, 17, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, or 70 percent by weight, relative to the overall weight of the composition.

[0040] The provided compositions further include one or more adhesion promoters, which are reactive compounds that improve the adhesive bond between the light-curable composition and a substrate. The adhesion promoter is commonly a relatively low molecular weight compound that contains at least one functional group reactive with the other reactive groups present in the reactive composition. Examples of suitable reactive groups include (meth)acrylate groups (co-reactive with free radically polymerizable groups) and epoxy groups (co-reactive with hydroxyl groups). These low molecular weight compounds can have number average molecular weights of less than 1,000 g / mol, or even less than 500 g / mol.Examples of suitable reactive adhesion promoters include the cycloaliphatic difunctional epoxy EPONEX brand 1510 commercially available from Momentive Specialty Chemicals, Columbus, Ohio.Additionally, hydroxyl-functional (meth)acrylate compounds and silane -functional (meth)acrylates can also be used as reactive adhesion promoters.

[0041] Particularly useful adhesion promoters include glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate acid phosphate, phosphonate ester-containing (meth)acrylic monomer, phosphate ester- containing (meth)acrylic monomer, silane, (meth)acrylic acid, and combinations thereof.

[0042] In a preferred embodiment, the adhesion promoter is a silane and is present in an amount of from 0.25 percent to 10 percent, or in some embodiments, less than, equal to, or greater than 0.25 percent, 0.5, 0.75, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, or 10 percent by weight, relative to the overall weight of the composition.

[0043] Alternatively, the adhesive promoter can be a glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate acid phosphate, phosphonate ester-containing (meth)acrylic monomer, phosphate ester- containing (meth)acrylic monomer, silane, (meth)acrylic acid, or combination thereof, and present in an amount of from 0.5 percent to 20 percent, or in some embodiments, less than, equal to, or greater than 0.5percent, 0.75, 1, 1.5, 2, 2.5, 3, 4, 5, 7, 10, 12, 15, 17, or 20 percent by weight, relative to the overall weight of the composition.

[0044] The provided compositions also include at least one photoinitiator used to cure the composition. Photoinitiators of interest are capable of polymerizing free radically photopolymerizable compositions upon exposure to actinic radiation. Such compounds can include binary and tertiary systems. Typical tertiary photoinitiators include an iodonium salt, a photosensitizer, and an electron donor compound as described in U.S. Patent No. 5,545,676 (Palazzotto et al.). Iodonium salts include diaryl iodonium salts, e.g., diphenyliodonium chloride, diphenyliodonium hexafluorophosphate, and diphenyliodonium tetrafluoroboarate. Some preferred photosensitizers may include monoketones and diketones (e.g., alpha diketones) that absorb some light within a range of about 300 nm to about 800 nm (preferably, about 400 nm to about 500 nm) such as camphorquinone, benzil, furil, 3, 3,6,6- tetramethylcyclohexanedione, phenanthraquinone and other cyclic alpha diketones. Preferred electron donor compounds include substituted amines, e.g., ethyl 4-(N,N-dimethylamino)benzoate.

[0045] Other suitable photoinitiators for polymerizing free radically photopolymerizable compositions include the class of phosphine oxides that typically have a functional wavelength range of about 380 nm to about 1200 nm. Certain phosphine oxide free radical initiators with a functional wavelength range of about 380 nm to about 450 nm include acyl and bisacyl phosphine oxides. Preferred photoinitiators can initiate free radical polymerization of the composition when exposed to actinic radiation having a wavelength of from 365 nm to 450 nm.

[0046] Commercially available phosphine oxide photoinitiators capable of free-radical initiation when irradiated at wavelength ranges of 365 nm to 450 nm include bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide (IRGACURE 819, Ciba Specialty Chemicals, Tarrytown, N.Y.), bis(2,6- dimethoxybenzoyl)-(2,4,4-trimethylpentyl)phosphine oxide (CGI 403, Ciba Specialty Chemicals), a 25:75 mixture, by weight, of bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphine oxide and 2- hydroxy-2-methyl-l-phenylpropan-l-one (IRGACURE 1700, Ciba Specialty Chemicals), a 1: 1 mixture, by weight, of bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide and 2-hydroxy-2-methyl-l- phenylpropane-l-one (DAROCUR 4265, Ciba Specialty Chemicals), and ethyl 2,4,6- trimethylbenzylphenyl phosphinate (EUCIRIN LR8893X, BASF Corp., Charlotte, N.C.).

[0047] Other suitable photoinitiators capable of free-radical initiation when irradiated at wavelength ranges of 365 nm to 450 nm include, for example, 2,2-dimethoxy-l,2-diphenylethan-l-one (OMNIRAD 651), sold by IGM Resins B.V., Waalwijk, Netherlands, or 2 -hydroxy-2 -methyl- 1 -phenylpropanone (OMNIRAD 1173 obtained from IGM Resins), or oligo[2-hydroxy-2-methyl-l-[4- (1- methylvinyl)phenyl] propanone] obtained from IGM Resins under the trade designation ESACURE KIP 150, and difunctional alpha-hydroxy ketones obtained from IGM Resins under the trade designations ESACURE ONE and ESACURE KIP 160 (2-hydroxy-l-[4-[4-(2-hydroxy-2-methylpropionyl)phenoxy] phenyl] -2 -methylpropanone). A difunctional alpha-hydroxy ketone refers to a compound that includes two alpha-hydroxy ketone groups. A multifunctional alpha-hydroxy ketone refers to a compound that includes two or more alpha-hydroxy ketone groups.

[0048] It is often beneficial to pair a photoinitiator with curing light source that enables a depth of cure sufficient to cure the composition fully when used to a fill a cavity or space within an assembly. For certain applications, the provided composition advantageously provide a depth of cure of at least 5 millimeters, or in some embodiments, less than, equal to, or greater than 0.5 millimeters, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 millimeters when exposed to actinic radiation having a monomodal wavelength distribution centered at 450 nm under ambient conditions.

[0049] The photoinitiator can be present in any amount sufficient to provide the desired rate of cure. For a photoinitiator, this amount will be dependent in part on the light source, the thickness of the composition to be exposed to actinic radiation, and the extinction coefficient of the photoinitiator. Commonly, the photoinitiator is present in an amount of from 0.01 percent to 5 percent, or in some embodiments, less than, equal to, or greater than 0.01, 0.02, 0.05, 0.07, 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 percent, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 12, 15, 17, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, or 70 relative to the overall weight of the composition.

[0050] The composition can also contain one or more flame retardants to render the cured composition non-flammable. Incorporation of a flame -retardant assists in preventing a thermal runaway event in an EV battery from starting a fire that could potentially endanger vehicle occupants. Useful flame retardants include aluminum hydroxide (Al(0H)3), which releases water vapor upon heating, effectively cooling the matrix material and suppressing the flame. Another option is magnesium hydroxide (Mg(OH)2), which operates similarly to aluminum hydroxide. Additionally, antimony trioxide (Sb2O3) is commonly used as a synergist with other flame retardants, improving their effectiveness. Other useful flame retardants include other metal hydroxides, borate, huntite, hydromagnesite, carbonate, talc, halogenated flame retardants, non-halogenated flame-retardants such as phosphorus-based flame retardants, expandable graphite, clay, and combinations thereof.

[0051] Aluminum hydroxide and magnesium hydroxide are commercially available from Martinswerk-Huber Minerals, Germany, under the trade designations MARTINAL, HYDRAL, HYMOD, MOLDX, MAGNIFIN, ZEROGEN and VERTEX.

[0052] Other suitable non-halogenated flame retardants are for instance commercially available from Clariant, Germany. Phosphorous-based flame retardants using ammonium polyphosphates are available from Clariant Germany and sold under the trade designation EXOLIT AP, EXOLIT AP422, EXOLIT AP462, EXOLIT AP740, EXOLIT AP750, EXOLIT AP765, and EXOLIT AP766. Another phosphorus- based flame retardant is red phosphorus commercially available from Clariant under the trade designation EXOLIT RP, EXOLIT RP 607 and Red Phosphorus HB801. Another class of phosphorus based flame retardants is based on organo phosphorus compounds. These organo phosphorous compounds are commercially available from Clariant, Germany under the trade designations EXOLIT OP, EXOLIT OP 930, EXOLIT OP 1230, EXOLIT OP 550, and EXOLIT OP 560.

[0053] Other non-halogenated flame retardants are available from Lanxess, Germany under the trade designation Amgard, Disflamoll, Levagard or Reofos; from Buddenheim, Germany under the trade designation BUDIT.

[0054] In a preferred embodiment, the cured composition provides a VO flame retardancy rating. A VO rating is demonstrated when a given material is ignited in a vertical position and burning stops within 10 seconds after the ignition source is removed. According to another test, the provided compositions can be capable of providing thermal protection when subjected to a 1100°C torch flame for more than 5 seconds, more than 10 seconds, or even more than 20 seconds.

[0055] Particle size can be an important consideration in incorporating a flame retardant. Generally, smaller particle sizes ranging from 1 to 10 micrometers are preferred as they provide better dispersion and surface area for flame suppression. However, larger particle sizes can be used in certain applications where improved mechanical properties are desired. In various embodiments, the median particle size can be from less than, equal to, or greater than 1 micrometer, 2, 3, 4, 5, 6, 7, 8, 9, or 10 micrometers.

[0056] The flame retardant can be present in an amount of from 15 percent to 70 percent, or in some embodiments, less than, equal to, or greater than 15 percent, 17, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, or 70 percent by weight, relative to the overall weight of the composition.

[0057] The provided compositions can also include one or more suitable fillers that are distinct from the foregoing flame retardants. Useful fillers include hollow fillers. For example, hollow fillers include microcapsules (i.e., capsules that typically have a diameter less than 10 micrometers), glass bubbles, expanded polymeric bubbles, ceramic bubbles, and combinations thereof. Exemplary materials are disclosed, for example, in U.S. Patent No. 4,303,730 (Torobin), U.S. Patent No. 4,336,338 (Downs et al.), U.S. Patent No. 5,045,569 (Delgado), and U.S. Patent No. 5,861,214 (Kitano et al.).

[0058] Exemplary hollow glass microspheres (“HGM”) include those marketed by 3M Co. (St. Paul, MN) under the trade designation “3M GLASS BUBBLES” (e.g., grades - KI, K15, S32, K37, S38, S38HS, S38XHS, K46, D32 / 4500, H50 / 10000, S60, S60HS, and iM30K); glass bubbles marketed by Potters Industries, Valley Forge, PA, (an affiliate of PQ Corporation) under the trade designations “Q- CEL HOLLOW SPHERES” and “SPHERICEL HOLLOW GLASS SPHERES” and hollow glass particles marketed by Silbrico Corp., Hodgkins, IL under the trade designation “SIL-CELL.”

[0059] Exemplary hollow ceramic particles include aluminosilicate particles extracted from pulverized fuel ash collected from coal-fired power stations (i.e., cenospheres). Useful cenospheres include those marketed by Sphere One, Inc., Chattanooga, TN, under the trade designation “EXTENDOSPHERES HOLLOW SPHERES” (e g., grades SG, MG, CG, TG, HA, SLG, SL-150, 300 / 600, 350 and FM-1); and those marketed by 3M Company under the trade designation “3M HOLLOW CERAMIC MICROSPHERES” (e.g., grades G-3125, G-3150, and G-3500).

[0060] Generally, thinner walled, lower density hollow inorganic microspheres will result in lower thermal conductivities and better thermal barrier properties. The thickness of the shells may vary as suppliers try to balance low density (typically provided by thinner walls) with high crush strength as may be required to provide the desired compression performance, especially resilience (typically provided by thicker walls). In some cases, the core of the hollow microspheres comprises at least 50 percent, 60, 70, 80, or even 90 percent of the diameter of the hollow microspheres.

[0061] Generally, the hollow inorganic microspheres have an average diameter of no greater than 500 micrometers, e.g., no greater than 400 micrometers. For example, in some cases, the microspheres have an average diameter of no greater than 250 micrometers, for example, no greater than 150, no greater than 100 micrometers, or even no greater than 50 micrometers. Typically, the microspheres have an average diameter of at least 10 or 20 micrometers. For example, in some cases, the microspheres have an average diameter of 10 to 400 micrometers, e.g., 10 to 300, 20 to 250, 20 to 150 or even 20 to 70 micrometers.

[0062] For some applications, lower density hollow microspheres may be selected to lower the thermal conductivity and improve the thermal barrier properties composition. Generally, the microspheres have an average true density of no greater than 1 gram per cubic centimeter. However, even lower densities are preferred, for example, no greater than 0.8, 0.6 or even no greater than 0.4 grams per cubic centimeter. Exemplary hollow glass microspheres have an average true density of 0. 1 to 0.8, 0. 1 to 0.6, 0.1 to 0.5 or 0.2 to 0.5 grams per cubic centimeter.

[0063] In another embodiment, the hollow particles are organic in nature, comprising a hollow sphere with a polymeric shell. In one embodiment, these organic particles are derived from expanded polymeric bubbles. Such expanded polymeric bubbles can derive from polymeric microspheres generally include a thermoplastic polymer shell and a core material in the form of a gas, liquid, or a combination (e.g., propane, butane, pentane, isobutene, neopentane, and combinations thereof). Upon heating, the shell softens and core expands, causing the shell to expand without breaking. Upon cooling, the shell rehardens, and the expandable microsphere remains expanded. Examples of suitable thermoplastic resins which may be used as the shell include acrylic and methacrylic acid esters such as polyacrylate; acrylateacrylonitrile copolymer; and methacrylate-acrylic acid copolymer. Vinylidene chloride -containing polymers such as vinylidene chloride-methacrylate copolymer, vinylidene chloride -acrylonitrile copolymer, acrylonitrile -vinylidene chloride-methacrylonitrile methyl acrylate copolymer, and acrylonitrile-vinylidene chloride-methacrylonitrile-methyl methacrylate copolymer may also be used. Useful expandable microspheres include microspheres available from Henkel Corp., Plainfield, Illinois, under the trade designation MICROPEARL (e.g., DocuSign Envelope ID: B430AB41-CFD5-4309- A533-EEEB088E8EF1 10 in grades F30, F80, and F 100); Matsumoto Yushi-Seiyaku Co. Ltd., Osaka, Japan under the designations “F-65”, “FN-100S”, and “FN-100” and microspheres marketed by Akzo- Nobel under the trade designation EXPANCEL (e.g., as EXPANCEL 051 DU 40, EXPANCEL 461 DU 20, EXPANCEL 920 DE 40 AND EXPANCEL 043 DU 80).

[0064] In one embodiment, the expanded hollow organic particles of the present disclosure have a diameter of at least 5, 10, or even 20 micrometers and at most 40, 60, 80, 100, 120, or even 150 micrometers.

[0065] Hollow fillers can be present in the amount of from 5 percent to 50 percent, from 10 percent to 40 percent, or in some embodiments, less than, equal to, or greater than 5 percent, 10, 15, 20, 25, 30, 35, 40, 45 or 50 percent by weight, relative to the overall weight of the composition.

[0066] Non-hollow (i.e., solid) fillers can also be useful in the provided compositions. Examples of non-hollow fillers can be made from quartz (i.e., silica, SiO2); nitrides (e.g., silicon nitride); glasses and fillers derived from, for example, Zr, Sr, Ce, Sb, Sn, Ba, Zn, and Al; feldspar; borosilicate glass; talc; zirconia; titania; low Mohs hardness fillers such as those described in U.S. Patent No. 4,695,251 (Randklev); and submicron silica particles (e.g., pyrogenic silicas such as those available under the trade designations AEROSIL, including “OX 50,” “130,” “150” and “200” silicas from Degussa Corp., Akron, Ohio and CAB-O-SIL M5 silica from Cabot Corp., Tuscola, Ill.). Examples of suitable organic filler particles include filled or unfilled pulverized polycarbonates, polyepoxides, and the like.

[0067] Preferred non-acid-reactive filler particles are quartz (i.e., silica), submicron silica, fumed silica, zirconia, submicron zirconia, glass frit, clays, hydroxides, and non-vitreous microparticles of the type described in U.S. Patent No. 4,503,169 (Randklev). Mixtures of these non-acid-reactive fillers are also contemplated, as well as combination fillers made from organic and inorganic materials.

[0068] Other useful fillers include intumescent fillers. To increase thermal insulation, it can be advantageous for the cured composition to act as an intumescent coating that expands into a foam upon heat exposure. Suitable intumescent fillers include sodium silicates and potassium silicates in hydrated form. Upon exposure to heat, these compounds liberate water, which acts as a foaming agent. When these foaming agents are activated, the coating can expand significantly. In some embodiments, a coating of the cured composition expands in thickness by approximately 100 percent to 5000 percent, as measured relative to its original thickness.

[0069] Intumescent fillers can be present in the amount of from 5 percent to 50 percent, from 10 percent to 45 percent, or in some embodiments, less than, equal to, or greater than 5 percent, 10, 15, 20, 25, 30, 35, 40, 45, or 50 percent by weight, relative to the overall weight of the composition.

[0070] Other useful fillers include refractory and heat-resistant fillers. Such fillers include silicate based refractory materials such as kaolin, mica, chamotte and fire-resistant clays. Another class of refractory fillers includes metal oxides such as aluminum oxide, silicon oxide, magnesium oxide and zirconium oxide or mixtures of oxides such as mullite or kormullite. Another class of refractory fillers includes graphite based materials. Still another class of refractory materials is that of non-oxide materials such as silicon carbide, boron nitride and aluminum nitride. Other classes of refractory fillers include chromites (FeCr2O4) and spinels such as MgA12O4.

[0071] Refractory fillers can be present in the amount of from 5 percent to 50 percent, from 10 percent to 45 percent, or in some embodiments, less than, equal to, or greater than 5 percent, 10, 15, 20, 25, 30, 35, 40, 45 or 50 percent by weight, relative to the overall weight of the composition.

[0072] The sum total of fillers, distinct from the one or more flame retardants, can be present in the amount of from 1 percent to 70 percent, or in some embodiments, less than, equal to, or greater than 1 percent, 2, 3, 4, 5, 7, 10, 15, 20, 25, 30, 35, 40, 45, 55, 60, 65 or 70 percent by weight, relative to the overall weight of the composition.Battery Assemblies and Methods

[0073] The provided light-curable compositions can be advantageously deployed as protective coatings in various applications, including the battery assemblies illustrated in FIG. 1-5. Broadly speaking, the light-curable compositions have potential applications in and on various components including, but not limited to, cells, cell wrapping, cell housings, busbars, electrical cables, vent protection structures, barrier coatings, battery housings, and battery enclosure lids.

[0074] The provided light-curable compositions can be used for different methods of disposing the provided curable compositions on various components. For example, these can include a single nozzle configuration, slot die extrusion of a flat coating, spray coating, multi-channel dispensing, doctor blade coating, and dipping.

[0075] An exemplary substrate can be coated with any of the provided curable compositions disclosed herein, which is subsequently cured to form a protective coating. For the sake of illustration, coated structures in FIGS. 1-5 are represented by either shading or dashed lines.

[0076] FIG. 1 shows a cylindrical battery cell 10 with an aluminum cell casing 12, coated with cured composition 14 as denoted by the shaded region. FIG. 2 shows an assembly 20 that includes a battery housing 22. Disposed on the battery housing 22 is a cured composition 24 along three separate regions, as depicted. FIG. 3 shows an assembly 30 that includes a battery lid 32, on which is disposed a cured composition 34. The battery housing 22 and battery lid 32 may be made from steel or plastic. FIG. 4 shows an assembly 40 comprised of a busbar 42 made from an electrical conductor and a cured composition 44 disposed thereon. FIG. 5 shows an assembly 50 comprised of an electrical cable 52 with a cured composition 54 disposed thereon.

[0077] The provided light-curable compositions can be cured in different ways as shown in FIG. 6, which illustrates a curing station of light-curable composition or simultaneous curing and FIG. 7, which shows an apparatus providing simultaneous coating and curing of the composition.

[0078] FIG. 6 shows a curing station 101 useful for curing of a provided composition 122 after it has been deposited onto substrate 100, which is part of an assembly 106. In this method, the curing station 170 is positioned over the assembly 106 as shown. The curing station 170 includes a radiation source 172 that emits actinic radiation 174 directly onto composition 122, thereby curing the composition 122 in situ. Suitable actinic radiation is not particularly limited, and can include ultraviolet (UV) light, visible light, infrared light, and electronic beam radiation.

[0079] As shown, the assembly 106 is coupled to a conveyor belt 176 enabling it to be translated horizontally such that the composition 122 on the substrate 100 can be cured progressively across the length of the assembly 106. It is understood that the source 172 can emit radiation 174 over any width dimension. Where the width dimension is less than the width of the assembly 106, multiple scans could be used.

[0080] Curing time can vary depending on the thickness of the coated composition 112. In some embodiments, the exposure time to actinic radiation required to cure the composition can be as low as 60seconds, 50, 40, 30, 20, 15, 10 or even 5 seconds. The thickness of the cured composition can be from 0.2 millimeters to 10 millimeters.

[0081] FIG. 7 shows an alternative curing station 201 in which curing of composition 122 happens at the same time as disposing on substrate 200. In this embodiment, a radiation source 272 and a slot die 280 are mechanically coupled to each other by strut 282 with a fixed separation distance relative to each other. In a preferred embodiment, the radiation source 272 and slot die 280 are mounted a robot arm capable of being translated across all surfaces of the substrate 200 sought to be coated. Here, the slot die 280 extrudes onto the substrate 200 a curable composition 282 in sheet-like configuration, which is then cured by exposure to actinic radiation from the radiation source 272. It is to be understood that any number of other dispensing mechanisms can be used, including single and multi-channel nozzles, sprayers, dipping baths, doctor blades, and combinations thereof.

[0082] As another possibility, source 272 and slot die 280 can be mounted at variable distance relative to each other. For example, both can be fixtured onto different robot arms and moved independently of each other.

[0083] It is understood that the sources 172, 272 can emit radiation 174, 274 over any width dimension. Where the width dimension is less than the width of the assembly 106, 206, multiple scans could be used. Curing time can vary depending on the thickness of the coated composition 112, 212. In some embodiments, the exposure time to actinic radiation required to cure the composition can be as low as 60 seconds, 50, 40, 30, 20, 15, 10 or even 5 seconds.EXAMPLESMaterials

[0084] The materials used in these Examples and Comparatives are listed in Table 1 below:

[0085] Table 1. MaterialsTest Methods

[0086] Tensile Test

[0087] Tensile elongation measurements were performed according to ISO 527 by stamping out dog bone specimens from cured plates of the light-curable composition. The dog bone specimens had a total length of 115 mm, a width of 25 mm and an inner width of 6 mm. This test was performed with a Zwick tensile testing equipment at a speed of 50 mm / min.

[0088] Thermal Conductivity

[0089] The thermal conductivity of the cured fdms was determined according to ASTM D5470. The thermal conductivity of the cured fdm was measured at ambient temperature at a pressure of 100 kPa.

[0090] Flammability Test

[0091] Flammability of the cured fdm was tested according to UL94. This test was performed with a vertical burning test set up using a 75 mm (width) by 150 mm (length) sample according to UL94 (ASTM D 4804 or ISO 9773). The flame was applied centrally to the middle point of the bottom edge of the specimen so that the burner is 10 mm below the point of the lower end of the specimen. The burner maintains the flame at this position for 10 seconds. Afterwards the burner was removed and the time for ignition, the duration of burning and flaming particles or drops are documented. Additionally, a second pass with burner was applied if the material did not ignite or bum.

[0092] Hardness Test

[0093] The Shore Hardness of cured coatings was measured according to DIN EN ISO 868. Measurements reflected the average of 5 replicated measurements.

[0094] Rheometric testing

[0095] The flow curve of the uncured resin was determined using a parallel plate rheometer fixture. The shear rate was varied at ambient conditions from 0.1 s-1 to 100 s-1.

[0096] Dielectric Strength

[0097] Dielectric Strength measurements were performed according to DIN EN 60243-2 (DC) and DIN EN 60243-1 (AC). The samples with a dimension of around 10cm x 10cm and a thickness of around 2mm need to be stamped out from cured plates of the light-curable composition. Before the measurements, the precise thickness has to be determined with calibrated thickness gauge. The test was performed with a dielectric breakdown tester. Within the test the maximum voltage, which is needed to produce a dielectric breakdown through the material, es reached. The Dielectric Strength is expressed in terms of volts per unit thickness. The average of 6 replicated measurements was reported.

[0098] Volume Resistivity

[0099] Volume resistivity measurements were performed according to DIN EN 62631-3-1. Samples with a dimension of around 15 cm x 15 cm and a thickness of around 2 mm were stamped out from cured plates of the light-curable composition. Before the measurements, the precise thickness has to be determined with calibrated thickness gauge. The samples were then disposed between 2 electrodes. For 60 s, a voltage of 500 V is applied and the resistance is measured. The average of 5 replicated measurements was reported.

[0100] Surface Resistivity

[0101] Surface resistivity measurements were performed according to DIN EN 62631-3-2 using the same set up as for volume resistivity measurements. The average of 5 replicated measurements was reported.

[0102] Comparative Tracking Index

[0103] The CTI (Comparative Tracking Index) was performed according to DIN EN 60112. The samples with a dimension of around 5 cm x 10 cm and a thickness of minimum 3 mm need to be stamped out from cured plates of the light-curable composition. If the material is thinner than 3 mm it was stacked until 3 mm are reached. During the test, one drop of the test solution A (0.1 % (weight %) ammonium chloride (NH4C1) in distilled water) falls on the sample surface every 30 seconds. The material has to withstand 5 times 50 drops / 600 V and 100 drops / 575 V (CTI group I) or 5 times 50 drops / 400 V and 100 drops / 375 V (CTI group II) for passing the test. The results are documented with pictures and marked as either a pass or fail.

[0104] Aging tests

[0105] Humidity Chamber: 10 days aging of samples kept in constant condensation (100% humidity, with condensation droplets on the sample) and climate at 40°C according to DIN EN ISO 6270-2.

[0106] Climate Cycle: 10 days aging of sample in a climate cycling test: 4 h at -40°C and 0% humidity, 4 h at 90°C and 15% humidity, 16 h at 38°C and 98% humidity.

[0107] Adhesion Tests

[0108] Pull out Test. Adhesion was characterized according to one failure mode using an adhesion pull out test, performed according to ASTM 4541 using a PosiTest AT adhesion tester from Defelsko Corporation, Ogdensburg, NY, U.S.A.. DP8005 SCOTCHWELD brand Structural Plastic Adhesive by 3M Company was used to bond an aluminum dolly to the top potting coating. The force required to break the bond between the 20-mm diameter dolly and the cured coating was measured in megapascals (MPa). Different substrates used for testing: aluminum plates, aluminum plates with 3 g / m2 lubric oil (Multidraw AF4) and polyamide 6 plates with 30% glass fiber content.

[0109] Thermal / flame / erosion resistance: 3M Torch and Grit Test

[0110] Sample was coated on a 2 mm thick aluminum sheet. The sample was positioned 44.5 mm from the nozzle of a Champion Bench hydrogen torch burner obtained from Bethlehem Apparatus 20 Company Inc, Hellertown, PA, USA. A thermocouple (TC0) was positioned 31.8 mm from the nozzle of the burner and another was placed on the backside center of the aluminum sheet. A blaster gun was loaded with 120 grit aluminum oxide non-shaped media and aligned with the nozzle of the torch at the same distance (44.5 mm) from the sample. The torch of the Champion Bench Burner was adjusted to 1200°C. The media blaster gun 25 was then triggered at 172.4 kPa or 344.7 kPa. A sample was exposed to a maximum of 12 blast cycles each lasting 15 seconds with 10 seconds of active blast time and 5 seconds of inactive blast time at a target location. Sample testing was stopped if a hole caused by either bum through or the media blasts was visible in the layers of the barrier article.

[0111] Rocket test

[0112] Sample was coated on a 0.8 mm galvanized steel substrate (Gardobond 0MBZ3 from BASF Chemetall). The rocket test (HeiBgas Erosionstest / Rocket Test) was performed by Amtas GmbH, Cologne, Germany and is described in following utility model DE 20 2023 107 616 U1. A fixed solid fuel rocket is fired onto the test sample. The rocket jet impulse (force x time in Newton-seconds or N-s) and the temperature evolution on the backside of the test specimen (cold side) is recorded. Maximum cold side temperature is determined.

[0113] Torch only test

[0114] A Usbeck Cartridge Burner 1422 with an Usbeck Cartridge 1430 is used in this test. Sample is placed with a 10 cm distance tip of burner to substrate. Two temperature sensors are used to detect the temperature - lx Temp Clamp Central backside of substrate (Cold Side) and lx Temp Clamp central on substrate (Hot Side). Each sample was treated for 60 seconds with torch flame at temperatures 1000°C- 1200°C.Examples EXI to EX6 and Comparative CE1

[0115] The compositions for Examples EXI to EX6 and CE1 are provided in Table 2 below. Resins were prepared by mixing the acrylates and the photoinitiator 0819 in a speed mixer. Fillers were subsequently added and the composition mixed in a speed mixer at 3000 rpm for 30 s.

[0116] Table 2. Resin compositions and selected properties for CE1 and EX2-EX6

[0117] The coating compositions were coated on a PET liner with a knife coater and a gap of 2 mm. The coatings were cured by LED light exposure using an LED light chamber (Opsytec Dr. Goebel UV- LED Serie L with a LED source having a wavelength of 450 nm) for 30 seconds at 100% power (1400 mW / cm2). The distance from the LED source to the sample was 60 mm. After 30 seconds of exposure the coatings were fully cured and resulted in a solid plate. Performance properties are summarized in Table 3 below.

[0118] Table 3. Performance properties for CE1 and EX2-EX6 after curing

[0119] Aging test results are shown below in Table 4. Results include those pertaining to different test methods as applied to samples in their initial and aged conditions (sheet material).

[0120] Table 4. Performance properties, initial and after aging.

[0121] EX2 shows in general higher values for tensile strength, dielectric strength, hardness, volume resistivity and lower values for elongation and thermal conductivity. Electric insulation properties (dielectric strength AC&DC, volume resistivity) are maintained at a high level after the Climate Cycle and Humidity Chamber tests.

[0122] Coatings were then applied onto 2 -mm thick substrates before being cured by LED light exposure using an LED light chamber (Opsytec Dr. Goebel UV-LED Serie L with a LED source having a wavelength of 450 nm) for 30 seconds at 100% power (1400 mW / cm2). Table 5 provides pull out test results of samples, initially and after aging. Substrates used in testing include aluminum plates, aluminum plates with 3 g / m2deep drawing oil (Multidraw AF4) and polyamide 6 plates with 30 % glass fiber content.

[0123] Table 5. Pull out test performance properties initial and after aging on different substrates.

[0124] An increase in the pull out force after Humidity Chamber or cycle testing was generally observed for samples on most substrates. On aluminum substrates with oil, EX2 displayed pull out test values exceeding 3 MPa.

[0125] The torch only test at 1200°C for 60 s was performed on EX2 and the results provided in Table6 below.

[0126] Table 6. Results testing EX2 coated on a 2 -mm aluminum plate before and after torch test.

[0127] Applying a 2 mm coating thickness on an aluminum plate of 2 mm thickness (EX2), the maximum temperature on cold site was observed to be 139°C when exposed 60 s to 1000-1200°C, compared to reference (aluminum only) 310°C.Examples EX7 to EX10

[0128] In the following section barrier coatings with reduced density and thermal conductivity are described.

[0129] Therefore, phosphorus-based flame retardants such as ammonium phosphate EXOLIT AP422 or organophosphorus flame retardant EXOLIT OP930 at a reduced level (compared to ATH) between 30 and 60 phr are included. On the other hand, the loading of glass bubbles was increased to around 60 to 64 vol%, with the calculated densities of the coating being in the range of 0.50 to 0.57 g / cm3.

[0130] Table 7. Composition of resins and material properties.

[0131] Table 8. Performance properties after curing.

[0132] As shown in Table 8, reducing the amount of flame -retardant and increasing the amount of glass bubbles provided coatings with low thermal conductivities measuring from 0.09 W / (m-K) to 0.15 W / (m-K). Shore D hardness measured at levels ranging from 27 to 38. Further, EX8 displayed V0 classification.Examples EX11 to EX20

[0133] Additional examples were prepared that incorporate one or more intumescent fillers, providing intumescent behavior in the cured composition. Compositions of intumescent coatings are shown in Table 9.

[0134] EXI 1-EX20 all exhibited intumescent behavior upon exposure to Torch Test. Expansion (final thickness / initial thickness x 100) was in the range of 165% to 252%, depending on the monomer used and filler package. Shore D hardness of the coatings was in the range of 52 to 71 Shore D. All coatings were rated non-flammable UL94 V0.

[0135] Table 9. Compositions of EX 11 -EX20

[0136] Material properties of these samples and corresponding Torch Test results are shown in Table 10.Examples EX21 to EX29

[0137] Additional examples were prepared based on combinations of different monomers and fdlers such as glass bubbles, fused silica, natrium silicate and kaolin. These coating compositions are shown in Table 11.

[0138] These compositions appeared capable of resisting solid fuel rocket jet, as used to simulate a thermal event. As shown in Table 12, the neat 0.8 mm thick steel panel without protective coating reached temperatures >439°C on the backside upon exposure to rocket jet. Visual inspection showed erosion on the surface exposed to the rocket jet and damage of the electrogalvanized zinc layer of the backside of the steel plate. By contrast, all coated panels showed temperatures below 164°C on the backside.

[0139] Table 10. Material properties of EX 11 -EX20

[0140] Table 11. Compositions of EX21-EX29

[0141] Table 12. Material properties of CE2 and EX21-EX29* 439°C was the last temperature measured by the thermocouple

Claims

What is claimed is:

1. A light-curable composition comprising: one or more monofunctional (meth)acrylate monomers with at least one monomer having a homopolymer glass transition temperature of from 0°C to 200°C; a crosslinker selected from multifunctional oligomeric (meth)acrylates, aliphatic urethane (meth)acrylates, aromatic urethane (meth)acrylates, polyester (meth)acrylates, and epoxy (meth)acrylates; one or more adhesion promoters selected from glycidyl (meth)acrylate, 2- hydroxyethyl(meth)acrylate acid phosphate, phosphonate ester-containing (meth)acrylic monomer, phosphate ester-containing (meth)acrylic monomer, silane, and (meth)acrylic acid; a photoinitiator; a flame retardant; and one or more fdlers comprising hollow fdlers, refractory fdlers comprising kaolin, intumescent fdlers, or mixtures thereof.

2. The composition of claim 1, wherein the one or more monofunctional (meth)acrylate monomers comprises one or more cycloaliphatic (meth)acrylates such as, tertiobutyl cyclohexyl acrylate, 3,3,5 trimethyl cyclohexanol acrylate, tricyclododecanemethanol acrylate, menthol (meth)acrylate and isobomyl (meth)acrylate.

3. The composition of claim 1 or 2, wherein the one or more monofunctional (meth)acrylate monomers are present in an amount of from 5 percent to 50 percent by weight, relative to the overall weight of the composition.

4. The composition of any one of claims 1-3, wherein the one or more adhesion promoters include a silane present in an amount of from 0.25 percent to 10 percent by weight, relative to the overall weight of the composition.

5. The composition of any one of claims 1-4, wherein the one or more adhesion promoters include one or more of glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate acid phosphate, phosphonate ester-containing (meth)acrylic monomer, phosphate ester-containing (meth)acrylic monomer or (meth)acrylic acid.

6. The composition of claim 5, wherein the one or more adhesion promoters are present in an amount of from 0.25 percent to 20 percent by weight, relative to the overall weight of the composition.

7. The composition of any one of claims 1-6, wherein the flame retardant comprises a metal hydroxide, aluminum trihydride, magnesium hydroxide, borate, huntite, hydromagnesite, carbonate, talc, halogenated flame retardant, antimony trioxide, phosphorus-based flame retardant, expandable graphite, clay, or combination thereof.

8. The composition of claim 7, wherein the flame retardant is present in an amount of from 15 percent to 50 percent by weight, relative to the overall weight of the composition.

9. The composition of any one of claims 1-8, wherein the hollow fdlers are comprised of glass bubbles, ceramic bubbles, expanded polymeric bubbles, or a mixture thereof.

10. The composition of claim 9, wherein the hollow fillers are present in an amount of from 5 percent to 50 percent by weight, relative to the overall weight of the composition.

11. The composition of any one of claims 1-10, wherein the refractory filler is present in an amount of from 5 percent to 70 percent by weight, relative to the overall weight of the composition.

12. The composition of any one of claims 1-11, wherein the intumescent filler is present in an amount of from 5 percent to 50 percent by weight, relative to the overall weight of the composition.

13. A battery assembly comprising: an assembly surface, optionally comprising a battery housing, battery lid, bus bar, electrical cable, or individual cell housing; and the composition of any one of claims 1-12 disposed and cured thereon.

14. The battery assembly of claim 13, wherein the cured composition has a thickness of from 0.2 millimeters to 10 millimeters.

15. A method of making a battery assembly comprising an assembly surface, the method comprising: applying the composition of any one of claims 1-12 onto the assembly surface; and curing the composition using actinic radiation to form a protective coating that extends over the assembly surface.

16. The method of claim 15, wherein the composition is applied onto the assembly surface using a doctor blade, single dispenser, multichannel dispenser, spraying, dipping, or extrusion coating.

17. The method of claim 16, wherein the application and curing of the composition are provided by a dispensing mechanism and radiation source, respectively, that are mechanically coupled to each other.

18. A battery assembly made using the method of any one of claims 15-17.

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