SWITCHABLE THERMAL CONDUCTIVE INTERFACE MATERIALS

Abstract

Thermal interface materials and compositions. The thermal interface materials are conductive in a first temperature range but reduce their thermal conductivity in a second or higher temperature range. Methods for controlling the thermal stress of a battery or for reducing thermal runaway in a battery are provided, incorporating the disclosed thermal interface materials.

Description

PRIORITY CLAIM

[0001] The present application claims priority over the provisional US patent application number 63 / 470,363, filed on June 1, 2023, the disclosure of which is hereby incorporated in its entirety by reference. TECHNICAL AREA

[0002] The subject matter disclosed herein relates to switchable thermal interface materials. Exemplary compositions for a thermal interface material include a two-component heat-curing matrix and a conductive filler, wherein the thermal interface material is thermally conductive in a first temperature range and the thermal conductivity of the thermal interface material decreases significantly in a second temperature range. BACKGROUND

[0003] Many industrial applications require thermal interface materials (TIMs) or thermal insulation materials that act as heat conductors and / or control thermal loads. In one specific, non-restrictive example, there is a need to contain thermal runaway in batteries used in electric vehicle applications. Current battery pack configurations rely heavily on thermal interface materials to efficiently transfer heat from the batteries to battery module housings and from the housings to cooling plates. However, this configuration becomes problematic if a battery cell catches fire. Specifically, heat can bypass the thermal insulation between the cells via the conductive path created by the TIM materials.With sufficient heat, the temperatures of neighboring cells can exceed the melting point of the battery's polymer cathode-anode separator; this in turn triggers thermal runaway in the neighboring cell.

[0004] Accordingly, there remains an unmet need for a TIM material that efficiently conducts heat under normal operating conditions but drastically reduces its conductivity well before the polymer separator's melting point. This is a material that switches from a conductor to an insulator at a desired temperature. Such switchable thermal interface materials are provided here. SUMMARY

[0005] This summary lists several embodiments of the subject matter disclosed herein and, in many cases, variations and permutations of these embodiments. This summary is merely one example of the numerous and diverse embodiments. The mention of one or more representative features of a given embodiment also serves only as an example. Such an embodiment may typically exist with or without the mentioned features; likewise, these features may be applied to other embodiments of the subject matter disclosed herein, whether or not they are listed in this summary. To avoid excessive repetition, this summary does not list or suggest all possible combinations of such features.

[0006] This discloses thermal interface material compositions comprising a two-component, thermosetting matrix, wherein the two-component, thermosetting matrix has a first component and a second component, and a thermally conductive filler. In some embodiments, the thermal interface material is thermally conductive in a first temperature range, and wherein the thermal conductivity of the thermal interface material decreases substantially in a second temperature range.

[0007] In some embodiments, the first component comprises a resin capable of reacting upon contact with the second component and optionally includes a thermally conductive filler. In some embodiments, the first component comprises an isocyanate resin capable of reacting upon contact with the second component and optionally includes a thermally conductive filler. In some embodiments, the first component comprises a vinyl-functional silicone resin and an addition-curing catalyst capable of reacting upon contact with the second component and optionally includes a thermally conductive filler. In some embodiments, the first component comprises an epoxy resin capable of reacting upon contact with the second component and optionally includes a thermally conductive filler.In some embodiments, the first component comprises an acrylic resin that is able to react upon contact with the second component and optionally includes a thermally conductive filler.

[0008] In some embodiments, the second component comprises a compound capable of reacting with the reactive resin of the first component and / or initiating its polymerization. In some embodiments, the second component comprises an isocyanate-reactive compound capable of reacting with the composition of the first component. In some embodiments, the second component comprises a hydride-functional silicone resin capable of reacting with the composition of the first component. In some embodiments, the second component comprises an epoxide-reactive compound or catalyst capable of reacting with the epoxy resin of the first component and / or initiating its polymerization. In some embodiments, the second component comprises an initiator capable of polymerizing the composition of the first component.

[0009] In some embodiments, the first and second components are configured to mix and react to form a thermal interface matrix.

[0010] In some embodiments, the first temperature range is from approximately -40°C to approximately 80°C, with the second temperature range being from approximately 80°C to approximately 200°C; optionally, the first temperature range is from approximately -40°C to approximately 160°C, with the second temperature range being from approximately 160°C to approximately 250°C. In some embodiments, the thermal interface material reduces the thermal conductivity, optionally by at least approximately 30%, approximately 50%, approximately 75%, approximately 90%, approximately 95%, approximately 99%, or more. In some embodiments, the thermal interface material decreases in apparent conductivity and / or increases the interface or interfacial resistance. In some embodiments, the apparent conductivity of the thermal interface material decreases by at least about 50%, about 75%, about 80%, about 90%, about 95%, about 99% or more when exposed to the second temperature range.

[0011] In some embodiments, the disclosed thermal interface materials further include a component that is able to decompose at elevated temperature and / or change its phase, thereby reducing or decreasing the apparent conductivity of the thermal interface material.

[0012] In some embodiments, the conductive filler contains aluminium trihydrate (ATH).

[0013] In some embodiments, the disclosed thermal interface materials further feature expandable polymeric microspheres.

[0014] Also disclosed herein are methods for producing a thermally conductive interface material, comprising mixing the first component with the second component.

[0015] These and other objectives are achieved wholly or partly by the subject matter disclosed herein. Further objectives and advantages of the subject matter disclosed herein will be apparent to those skilled in the art after studying the following description, drawings, and examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The subject matter disclosed herein may be better understood by reference to the following exemplary figures. The components in the figures are not necessarily to scale; instead, the emphasis is placed on illustrating (often schematically) the principles of the subject matter disclosed herein. In the figures, the same reference numerals denote corresponding parts in the different views. A further understanding of the subject matter disclosed herein may be obtained by reference to an embodiment set forth in the representations of the accompanying figures. Although the embodiment shown is merely an example of systems for carrying out the subject matter disclosed herein, both the organization and the operation of the subject matter disclosed herein in general, together with further aims and advantages thereof, may be more readily understood by reference to the figures and the following description.The figures are not intended to limit the scope of protection of the subject matter disclosed herein, which is specifically set out in the attached or subsequently amended claims, but merely to clarify and provide examples of the subject matter disclosed herein.

[0017] For a more complete understanding of the subject matter revealed herein, reference is now made to the following figures, in which: Fig. Figure 1 is a representation of the undesired spread of heat or heat via the battery cell-conventional TIM cooling plate arrangement during a thermal event in current battery arrangements. Fig. 2 is a representation of the concept of a switchable TIM that blocks / limits conductive heat transfer at elevated temperatures. Fig.3 shows the influence of the exposure temperature on the volume thermal conductivity of samples based on conventional and switchable TIM technologies, based on the formulations listed in Tables 1-4. Fig. 4 shows the influence of the exposure temperature on the volume thermal conductivity for TIMs in Tables 4 and 5 based on expandable microspheres (120°C operating temperature) of different concentrations, and in Table 1 based on the conventional TIM. Fig. 5 shows the influence of the exposure temperature on the volume thermal conductivity for the TIMs of Tables 6 to 8. Fig. 6 shows the influence of the exposure temperature on the volume thermal conductivity for the TIMs of Tables 9 to 11. DETAILED DESCRIPTION

[0018] The subject matter disclosed herein will now be described in more detail, describing some, but not all, embodiments of the subject matter disclosed herein. In fact, the subject matter disclosed herein can be embodied in many different forms and should not be interpreted as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure satisfies the applicable legal requirements. I. Definitions

[0019] The terminology used here serves only to describe certain embodiments and is not intended to limit the subject matter disclosed herein.

[0020] Although it is assumed that the following terms are well known to a person skilled in the art in this field, the following definitions are given to facilitate the explanation of the subject matter disclosed herein.

[0021] All technical and scientific terms used herein have, unless otherwise defined below, the same meanings as generally known to a person skilled in the art in this field. References to techniques used herein refer to techniques generally known in the art, variations of those techniques, or substitutions by equivalent techniques known to a person skilled in the art in this field. Although it is assumed that the following terms are well known to a person skilled in the art in this field, the following definitions are given to facilitate the explanation of the subject matter disclosed herein.

[0022] In describing the subject matter disclosed herein, it should be noted that a number of techniques and steps are revealed. Each of these steps has individual advantages and can also be used in conjunction with one or more, and in some cases even all, of the other disclosed techniques.

[0023] For the sake of clarity, this description therefore refrains from unnecessarily repeating every possible combination of the individual steps. Nevertheless, the description and the claims should be read in such a way that such combinations are entirely within the scope of the invention and the claims.

[0024] In accordance with long-standing patent law conventions, the terms "a", "an", and "that" in this application, including the claims, refer to "one or more". Thus, for example, the reference to "a cell" includes a plurality of such cells, and so on.

[0025] Unless otherwise stated, all numbers expressing quantities of ingredients, reaction conditions, etc., and used in the description and claims are to be understood in all cases as modified by the term "approximately". Accordingly, the numerical parameters given in this description and the accompanying claims are, unless otherwise stated, approximate values ​​that may vary depending on the desired properties to be achieved with the subject matter disclosed herein.

[0026] As used herein, the term “approximately”, when used to refer to a value or quantity of a composition, dose, sequence identity (e.g., when comparing two or more nucleotide or amino acid sequences), mass, weight, temperature, time, volume, concentration, percentage, etc., shall include deviations of ±20% in some embodiments, ±10% in some embodiments, ±5% in some embodiments, ±1% in some embodiments, ±0.5% in some embodiments, and ±0.1% in some embodiments, from the specified quantity, since such deviations are reasonable for carrying out the disclosed processes or using the disclosed compositions.

[0027] The term "including," which is synonymous with "including," "containing," or "characterized by," is inclusive or open and does not exclude additional, unmentioned elements or process steps. "Including" / "including" is a technical term used in claim language, meaning that the mentioned elements are essential, but other elements can be added and still constitute a design within the scope of the claims.

[0028] As used here, the phrase "consisting of" excludes all elements, steps, or components not specified in the claim. If the phrase "consisting of" appears in a clause of the main part of a claim and does not immediately follow the preamble, it limits only the element specified in that clause; other elements are not excluded from the claim as a whole.

[0029] As used here, the expression “essentially consisting of” limits the scope of a claim to the specified materials or steps and to those which do not substantially affect the fundamental and novel characteristics of the claimed subject matter.

[0030] With regard to the terms “comprising”, “consisting of” and “essentially consisting of”, the subject matter disclosed and claimed herein may, if one of these three terms is used, include the use of one of the other two terms.

[0031] As used here, the term "and / or" in the context of a list of units refers to units that exist individually or in combination. For example, the expression "A, B, C and / or D" includes A, B, C and D individually, but also all combinations and subcombinations of A, B, C and D.

[0032] The term "thermal conductivity" is used here to describe the measure of a material's ability to conduct heat. In the context of a thermal interface material (TIM), the heat transfer from one interface to another is a function of the thermal conductivity (also referred to as "volume conductivity") of the TIM itself, as well as the interface resistances between the TIM and the connecting interfaces. Furthermore, it is known in engineering that the term "apparent (thermal) conductivity" is used to describe the ability of a TIM to conduct heat from one interface to another for a given thickness of the bonding layer bridging the interfaces, thus taking into account both the thermal conductivity of the TIM and the resistances of the TIM-substrate interfaces.In accordance with the present invention, the switchable TIM can change the apparent thermal conductivity not only by influencing the bulk thermal conductivity of the material, but also by increasing the thickness of the TIM and / or the interface resistances of the TIM-substrate interfaces.

[0033] The terms "epoxy-", "epoxide", and "oxirane", as used here, refer to a chemical functional group that has a three-membered ring structure, consisting of one oxygen atom and two carbon atoms connected by single bonds. Thus, an epoxy group can have the following structure:

[0034] The term "silyl" refers to groups that contain silicon atoms (Si).

[0035] The term "silane" refers to a molecule that contains a silicon atom.

[0036] As used here, the terms "siloxy" and "silyl ether" refer to groups or compounds that have a silicon-oxygen bond (Si-OR), where R is an organic group, such as a substituted or unsubstituted alkyl or aryl group (i.e., methyl, ethyl, phenyl, etc.). In some embodiments, the terms refer to compounds that have one, two, three, or four alkoxy, aralkoxy, or aryloxy groups bonded to a silicon atom. Each alkyloxy, aralkoxy, or aryloxy group may be the same or different.

[0037] As used here, a “monomer” refers to a molecule that can undergo polymerization and thereby contribute constitutional units, i.e., an atom or a group of atoms, to the essential structure of a macromolecule.

[0038] As used here, “macromolecule” refers to a molecule with a high relative molecular mass whose structure features multiple repetitions of units derived from molecules with a low relative molecular mass, e.g., monomers and / or oligomers.

[0039] An “oligomer” refers to a molecule with medium relative molecular mass whose structure has a small number (e.g. 2, 3, 4, 5, 6, 7, 8, 9 or 10) of repeating units derived from molecules with lower relative molecular mass.

[0040] A "polymer" refers to a substance that comprises macromolecules. In some embodiments, the term "polymer" can refer to both oligomeric molecules and molecules with a larger number (e.g., > 10, > 20, > 50, > 100) of repetitive units. In some embodiments, "polymer" refers to macromolecules that have at least 10 repetitive units.

[0041] A “copolymer” refers to a polymer that is derived from more than one monomer species.

[0042] An “epoxy resin” can be monofunctional, difunctional, multifunctional, or a combination thereof, as long as the resulting material mixture is liquid at room temperature. The epoxy resin can be aliphatic, cycloaliphatic, aromatic, or the like. The “average” number of epoxy groups per molecule is determined by dividing the total number of epoxy groups in the epoxy-containing material by the total number of epoxy molecules present. Useful epoxy materials generally have an average of at least 1.5 polymerizable epoxy groups per molecule. Preferably, two or more epoxy groups are present per molecule. The polymeric epoxides include linear polymers having terminal epoxy groups (e.g., a diglycidyl ether of a polyoxyalkylene glycol), polymers with oxirane framework units (e.g., polybutadiene polyepoxide), and polymers having pendentive epoxy groups (e.g.,a glycidyl methacrylate polymer or copolymer). The epoxides can be pure compounds, but are generally mixtures containing one, two, or more epoxide groups per molecule.

[0043] The epoxy-containing materials can range from low molecular weight monomers to high molecular weight polymers and can differ significantly in the nature of their backbone and substituent groups. For example, the backbone can be of any type and may include substituent groups that are free of an active hydrogen atom. Examples of permissible substituent groups are halogens, esters, ethers, sulfonates, siloxanes, nitro groups, phosphates, etc. The molecular weight of the epoxy-containing materials can range from about 50 to 100,000 or more. Mixtures of different epoxy-containing materials can also be used in the compositions of this invention.

[0044] In a preferred embodiment, the epoxy resin comprises liquid epoxy resins based on diglycidyl ethers of bisphenol A (DGEBA) or diglycidyl ethers of bisphenol F (DGEBF). Liquid epoxy resins typically have a molecular weight of less than about 500 Daltons and preferably between about 150 and 600 Daltons. A preferred method for determining the molecular weight is gel permeation chromatography (or size exclusion chromatography).

[0045] In some embodiments, a resin matrix may comprise a “silicone” material, compound, or resin. Silicone resins are a type of silicone material formed from branched, cage-like oligosiloxanes. Silicone resins are produced by the hydrolytic condensation of various silicone precursors. Silicone resins encompass a wide range of products, including those with molecular weights ranging from 1,000 to 10,000, which can be used in adhesives, silicone rubbers, coatings, and additives. Polysiloxane polymers with reactive side-group functionalities such as vinyl, acrylate, epoxy, mercaptan, or amine are used to produce thermosetting polymer matrix composites, coatings, and adhesives.

[0046] In some aspects, the use of silicone in the disclosed compositions involves an addition reaction between the vinylsilyl group (Si-CH:CH2) and the hydrosilyl group (Si-H). Addition reactions are used in a variety of applications, including compounds such as silane coupling agents and the curing reactions of silicones. Addition reactions allow for both room-temperature and heat curing, and curing can occur under open or hermetic conditions. These are some of the characteristic features of addition reactions. Furthermore, since addition reactions do not produce byproducts, the cured material exhibits heat resistance in enclosed spaces.

[0047] Silicone fluids suitable for use in embodiments of the present disclosure include silicones with reactive functional groups that are either bonded to or located at the end of the siloxane polymer backbone, e.g., epoxides, amines, hydrides, vinyl, hydroxyl, isocyanate, mercapto, carbinol, etc.; vinyl-functional silicones with vinyl end groups and / or vinyl groups bonded to the siloxane backbone; siloxane backbones may consist of the silicone fluids listed above; vinyl T-structure polymers; and / or hydride-functional polymers with hydride end groups and / or hydride groups bonded to the siloxane backbone.

[0048] A resin matrix component may contain an "acrylic" material that has at least one acrylate and / or methacrylate functional group. The acrylic resin may be monofunctional, difunctional, multifunctional, or a combination thereof, as long as the resulting material mixture is liquid at room temperature. Typical monofunctional acrylic resins contain esters of (meth)acrylic acid, such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, butyl acrylate, cyclohexyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, ethyl acrylate, dicyclopentadienyloxyethyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, glycidyl methacrylate, and tetrahydrofurfuryl methacrylate (THFMA). Other monofunctional resins include OH-functional monoethylene unsaturated monomers such as 3-hydroxypropyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, 4-hydroxycyclohexyl(meth)acrylate, 1,6-hexanediol mono(meth)acrylate and neopentylglycol mono(meth)acrylate.

[0049] Representative resins with more than one functional group include epoxy dimethacrylates, epoxy diacrylates, urethane diacrylates, urethane dimethacrylates, glycol diacrylates, glycol dimethacrylates, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, polyester diacrylates, polyester dimethacrylates, cyclohexane diacrylate, cyclohexane dimethacrylate, trifunctional epoxy novolacacrylates, pentaerythritol triacrylate, and dipentaerythritol pentaacrylate.

[0050] Resins may contain a mixture of aliphatic urethane diacrylate and dipentaerythritol pentaacrylate. Resins may contain a mixture of bisphenol, an epoxy acrylate oligomer, a trifunctional epoxy novalac acrylate, and a trimethylpropane triacylate.

[0051] Furthermore, it is known that acrylic resins undergo addition reactions (e.g., Michael addition reactions) or polymerize via free radicals. The former is a reaction between a nucleophile (Michael donor) and an activated olefin (e.g., an acrylate). Functional groups commonly used as Michael donors include acetoacetates, amines, thiols, and phosphines. In the radical polymerization of acrylates, an initiator is used to generate free radicals and induce polymerization. Common initiators include organic peroxides such as benzoyl peroxide and other diacyl peroxides, hydroperoxides such as cumene hydroperoxide, peresters such as [3-butyl peroxybenzoate], ketone hydroperoxides such as methyl ethyl ketone hydroperoxide, organic salts of transition metals such as cobalt naphthenate, and compounds containing releasable chlorine, such as sulfonyl chloride.Furthermore, it is common practice to apply reducing agents (instead of, for example, heat) to the component containing the acrylic resin. The reducing agent, in combination with organic peroxides under ambient conditions, can initiate the polymerization of the acrylic resin. Representative reducing agents include, but are not limited to, sulfonic acids; azo compounds such as azoisobutyric acid dinitrile; alpha-aminosulfones such as bis(tolysulfonemethyl)benzylamine; tertiary amines such as diisopropanol p-toluidine, diethanol p-toluidine, dimethylaniline, p-halogenated aniline derivatives, and dimethyl p-toluidine; and aminealdehyde condensation products, for example, the condensation products of aliphatic aldehydes such as butyraldehyde with primary amines such as aniline or butylamine.

[0052] A resin matrix component may contain an “isocyanate” material having at least two free isocyanate groups, including aliphatic, cycloaliphatic, and aromatic compounds. Representative isocyanates include, without limitation, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, methylenediphenyl diisocyanates such as 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, m- and p-phenylene diisocyanate, polymethylenepoly(phenyl isocyanate), hexamethylene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), isophorone diisocyanate, and other aliphatic, heterocyclic, and aromatic polyisocyanates, including mixtures of such polyisocyanates.

[0053] Isocyanates react with a wide variety of nucleophiles, including alcohols, amines, and even water, exhibiting higher reactivity than structurally analogous isothiocyanates. Examples include molecules selected from the group comprising polyethers, polyesters, and aliphatic hydrocarbons. Furthermore, isocyanate-reactive resins can include those containing at least two active hydrogen atoms selected from the group consisting of hydroxyl, primary amine, secondary amine, thiol, urethane, urea, carboxylic acid, amide, and water.

[0054] As used here, the term "room temperature" is understood to mean any temperature between approximately 15°C and approximately 25°C (i.e., approximately 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or approximately 25°C). In some embodiments, the term "room temperature" is a temperature between approximately 18°C ​​and approximately 24°C or between approximately 20°C and approximately 25°C.

[0055] Although not essential to the core aspect of the invention, the following substances are common components used in two-component (2K) formulations to control, among other things, properties such as rheology, flammability, adhesion, and the water content of the raw materials. Such common components may include, but are not limited to, flame retardants, viscosity-reducing additives, shear-thinning additives, adhesion promoters, moisture scavengers, and plasticizers. Such materials, which are not essential to the teaching inherent in the invention, are referred to herein as the "additive package." II. Switchable thermal interface materials

[0056] The present invention relates to thermal interface materials (TIMs) that can drastically reduce their conductivity (heat conductivity) when heated to elevated temperatures. More precisely, in some embodiments, such switchable or transformable TIMs are capable of undergoing significant changes in bulk conductivity, interface or surface resistance, and / or morphology at a predetermined temperature. At least two principal methods for achieving this phenomenon are disclosed and demonstrated herein.

[0057] In a first embodiment, a switchable TIM formulation incorporates expandable polymer microspheres into a thermally conductive formulation. In some aspects, the microspheres expand many times beyond their original volume upon heating, forming foam-like structures that inherently exhibit lower conductivity. Furthermore, in some embodiments, the expansion at elevated temperatures can lead to complete, if not partial, delamination of the TIM, resulting in further resistance to heat transfer across the interface.

[0058] In a second embodiment, a switchable TIM formulation comprises components known to decompose and / or change phase at elevated temperatures, thereby reducing the apparent conductivity of the formulation due to changes in the overall conductivity of the composition, an increase in interface resistances, and / or an increase in the thickness of the TIM layer. More specifically, certain conductive fillers, such as, but not limited to, aluminum trihydrate (ATH), decompose at elevated temperatures, forming water vapor and their respective oxides. The water vapor can then expand and / or diffuse out of the matrix, creating a foam-like structure that inherently exhibits lower conductivity.Furthermore, in some embodiments, the morphological change at elevated temperatures can lead to a complete or at least partial delamination of the TIM, resulting in further resistance to heat transfer via the interface.

[0059] In a third embodiment, the combination of these first two embodiments can lead to an even greater decrease in conductivity and / or to an increase in interface resistance once a predetermined elevated temperature is reached.

[0060] Accordingly, a “switchable TIM” or “transformable TIM” within the meaning of this description includes any TIM that functions as a heat conductor in a first temperature range but changes its functionality at a second or elevated temperature, including a reduction in conductivity, a reduction in interface or surface resistance and / or a morphological change.

[0061] In particular, some embodiments provide thermal interface material compositions comprising a two-component thermally curable matrix, wherein the two-component thermally curable matrix includes a first component and a second component, as well as a thermally conductive filler. In some aspects, the thermal interface material is thermally conductive in a first temperature range, with the thermal conductivity of the thermal interface material decreasing significantly in a second temperature range.

[0062] The first component may contain a resin that can react upon contact with the second component and may optionally contain a thermally conductive filler.

[0063] In another embodiment, the first component comprises an isocyanate resin that can react upon contact with the second component and optionally includes a thermally conductive filler.

[0064] In another embodiment, the first component comprises a vinyl-functional silicone resin and an addition-curing catalyst that can react upon contact with the second component, and optionally includes a thermally conductive filler.

[0065] In another embodiment, the first component comprises an epoxy resin that can react upon contact with the second component and optionally includes a thermally conductive filler.

[0066] Finally, in a further embodiment, the first component comprises an acrylic resin that can react upon contact with the second component and optionally includes a thermally conductive filler.

[0067] Let us now turn to the second component: In some embodiments, the second component comprises a compound that can react with the reactive resin of the first component and / or initiate its polymerization. This embodiment can be coupled with the embodiment in which the first component may comprise a resin that can react upon contact with the second component and optionally includes a thermally conductive filler, as mentioned above.

[0068] In another embodiment, the second component comprises an isocyanate-reactive compound that can react with the composition of the first component. In some embodiments, this can be coupled with the first component, which comprises an isocyanate resin, as mentioned above.

[0069] In another embodiment, the second component can comprise a hydride-functional silicone resin that can react with the composition of the first component. This embodiment can be combined with the embodiment in which the first component comprises a vinyl-functional silicone resin and an addition-curing catalyst that can react upon contact with the second component, and optionally a thermally conductive filler.

[0070] In another embodiment, the second component comprises an epoxide-reactive compound or a catalyst that can react with the epoxy resin component and / or initiate its polymerization.

[0071] In another embodiment, the second component includes an initiator that can polymerize the composition of the first component. Such an embodiment can be coupled with the embodiment in which the first component comprises an acrylic resin that can react upon contact with the second component and optionally includes a thermally conductive filler.

[0072] In some embodiments, the first and second components are configured to mix and react to form a thermal interface matrix.

[0073] As mentioned herein, the disclosed switchable TIMs are configured to function as thermally conductive under a first temperature range, but then change their functionality at a second or elevated temperature, exhibiting a decrease in conductivity, a decrease in interface resistance, and / or a morphological change. The first temperature range may, in some embodiments and applications, extend from about -40°C to about 80°C, with the second temperature range extending from about 80°C to about 200°C. Alternatively, the first temperature range may extend from about -40°C to about 100°C, with the second temperature range extending from about 100°C to about 250°C. Alternatively, the first temperature range may extend from about -40°C to about 120°C, with the second temperature range extending from about 120°C to about 250°C.Alternatively, the first temperature range can extend from approximately -40°C to approximately 160°C, with the second temperature range extending from approximately 160°C to approximately 250°C.

[0074] Based on the above-mentioned switchable TIM properties, the thermal interface material can reduce the thermal conductivity, optionally by at least about 30%, about 50%, about 75%, about 90%, about 95%, about 99% or more. In some aspects, the reduction in thermal conductivity is approximately 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, and 68%. 69%, approximately 70%, approximately 71%, approximately 72%, approximately 73%, approximately 74%, approximately 75%, approximately 76%, approximately 77%, approximately 78%, approximately 79%, approximately 80%, approximately 81%, approximately 82%, approximately 83%, approximately 84%, approximately 85%, approximately 86%, approximately 87%, approximately 88%, approximately 89%, approximately 90%, approximately 91%, approximately 92%, approximately 93%, approximately 94%, approximately 95%, approximately 96%, approximately 97%, approximately 98% or approximately 99%.

[0075] Additionally, the thermal interface material can reduce thermal conductivity, increase interface / interface resistance, or combine both.

[0076] The thermal conductivity of the thermal interface material can be reduced by at least approximately 50%, approximately 75%, approximately 80%, approximately 90%, approximately 95%, approximately 99% or more when exposed to the second temperature range. In some aspects, the reduction in thermal conductivity when exposed to the second temperature range is approximately 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, and 86%. 87%, approximately 88%, approximately 89%, approximately 90%, approximately 91%, approximately 92%, approximately 93%, approximately 94%, approximately 95%, approximately 96%, approximately 97%, approximately 98% or approximately 99%.

[0077] Regarding the conductive filler, while any suitable filler may be used, in some preferred embodiments the conductive filler may comprise ATH. Other suitable fillers include, but are not limited to, aluminum, aluminum nitride, aluminum oxide (or aluminum oxide), ATH, beryllium oxide, boron nitride, carbon black, calcium carbonate, cobalt, copper, graphite, iron, magnesium oxide (or magnesia), magnesium hydroxide, nickel, silicon carbide, silicon dioxide (or silica), silver, silver-plated copper, talc, titanium dioxide, and zinc oxide.

[0078] The composition of the thermal interface material may, in some aspects, include expandable polymeric microspheres. In some cases, these microspheres expand many times beyond their original volume upon heating, forming foam-like structures that inherently exhibit lower conductivity. Furthermore, in some embodiments, this expansion at elevated temperatures can lead to complete, if not partial, delamination of the TIM, resulting in further resistance to heat transfer across the interface.

[0079] The switchable TIMs disclosed herein are suitable for any industrial application where a thermally conductive material is required under normal operating conditions, but which must change or switch its functionality when conditions are abnormal or outside a desired temperature range. Such a switchable TIM can provide advantageous change functionality with changes in temperature or conditions; an advantage that is suitable for a wide variety of industrial or commercial applications.

[0080] Although not limited to such an application, the currently disclosed subject matter is particularly suitable for and advantageous in electric vehicle (EV) applications, especially in preventing and / or mitigating catastrophic thermal runaway of battery cells. Switchable TIMs would allow the desired heat transfer and thermal conductivity (TC) to and from the battery under normal operating conditions (e.g., -40°C to 80°C); however, the TC would drop dramatically if a cell catches fire. This change, which is triggered at temperatures of around 80°C, would help to significantly reduce the transfer of conductive heat to neighboring cells, thus preventing the spread of the fire. In some embodiments, the first temperature range, or normal operating conditions, can therefore extend from approximately -40°C to approximately 80°C, and the second temperature range, i.e.,If a cell catches fire, the temperature range is approximately 80°C to approximately 200°C, with the first temperature range optionally extending from approximately -40°C to approximately 160°C and the second temperature range extending from approximately 160°C to approximately 250°C.

[0081] In a further embodiment, the article disclosed herein may be suitable for use in electronic components to reduce or prevent damage to the device itself and / or its surroundings due to excessive heat transfer, such as that which typically occurs with conventional TIMs. Examples of electronic components include, but are not limited to, power conversion systems, inductors, transformers, inverters, electrical chokes, AC filters, thermistors, transistors, microprocessor chips, heat spreaders, heat sinks, thermally conductive underfills for flip-chip applications, chargers, control modules, printed circuit boards, electrical switches, and electric motors.

[0082] In some embodiments, the disclosed switchable TIMs can be in the form of a potting compound, an encapsulation, a grease, a gel, a gap filler, an adhesive, an adhesive tape, a pad, or a coating. In a further embodiment, the aforementioned coating is applied in advance to a substrate (e.g., a dielectric coating) which is later to be bonded to another substrate by means of another TIM or a conventional adhesive.

[0083] Furthermore, in some embodiments, the disclosed formulations can facilitate the removal of batteries during maintenance or disassembly / recycling at the end of their service life. In another embodiment, they can facilitate the disassembly, removal, and recycling of electronic components and assemblies.

[0084] To explain: Some embodiments provide materials and methods for mitigating thermal runaway in batteries used in EV applications. Current battery pack assemblies rely heavily on thermal interface material to efficiently transfer heat from the batteries to the battery module housings and from the housings to the cooling plates. However, this becomes problematic if a battery cell catches fire, as in Fig.Figure 1 illustrates this. In particular, heat can bypass the thermal barrier insulation between the cells via the conductive path created by the TIM materials. With sufficient heat, the temperatures of adjacent cells can exceed the melting point of the battery's polymer cathode-anode separator, which in turn triggers thermal runaway in the adjacent cell. Therefore, the present invention provides a TIM material that efficiently conducts heat under normal operating conditions (e.g., -40°C to about 80°C), but whose conductivity drastically decreases well before the melting point of the polymer separator (e.g., about 135°C), as shown in Figure 1. Fig.Figure 2 shows. In some embodiments, the first temperature range or normal operating conditions of a battery in an EV application may range from about -40°C to about 80°C, and the second temperature range, i.e., when a cell of a battery in an EV application catches fire, is between about 80°C and about 200°C, optionally with the first temperature range ranging from about -40°C to about 160°C and the second temperature range ranging from about 160°C to about 250°C.

[0085] The composition of the thermal interface material may also include microspheres which, if present, expand when exposed to the second temperature range, with the microspheres optionally expanding at least 5 times, 10 times, 50 times, 100 times or more beyond their original volume.

[0086] In some embodiments, methods are provided for controlling the thermal stress on a battery or for reducing thermal runaway in a battery. The method includes providing a thermal interface material disclosed herein and applying the thermal interface material to a battery or positioning the thermal interface material near a battery, wherein, in the event of thermal overload of the battery resulting in a temperature of at least 80°C or more, the conductivity of the thermal interface material decreases by at least approximately 50%. In the event of thermal overload of the battery resulting in a temperature of at least 80°C or more, the conductivity of the thermal interface material decreases by at least approximately 30%, approximately 50%, approximately 75%, approximately 90%, approximately 95%, approximately 99%, or more.In the event of thermal overload of the battery, resulting in a temperature of at least 80°C or higher, the microspheres of the thermal interface material expand by at least approximately 5 times, approximately 10 times, approximately 50 times, approximately 100 times, or more than their original volume. In the event of thermal overload of the battery, resulting in a temperature of at least 100°C or higher, the thermal interface material essentially delaminates from the battery, thereby reducing its thermal conductivity. In some embodiments, the battery is intended for use in an electric vehicle.

[0087] Accordingly, a system for reducing the thermal runaway of an electric vehicle battery is provided here in several aspects. Such a system can comprise an electric vehicle battery and a thermal interface material, as disclosed herein. EXAMPLES

[0088] The following examples are included to further illustrate different embodiments of the subject matter disclosed herein. However, those skilled in the art should recognize, in light of the present disclosure, that many modifications can be made to the specific embodiments disclosed without departing from the scope and extent of the subject matter disclosed herein, and yet the same or a similar result can be achieved. Materials and methods for examples 1-6

[0089] The formulations listed in Tables 1 to 11, with a volume mixing ratio of 1:1 in two parts (2K), provide three examples of conventional TIMs (Tables 1, 6, and 9) and eight illustrative examples of switchable TIMs (Tables 2 to 5, 7 to 8, and 10 to 11). All individual components were prepared according to the following general procedure and tested for their volumetric thermal conductivity. Thermally conductive fillers were dried at 110°C for at least 24 hours prior to use. Liquids and solids (except for expandable microspheres) were placed in a beaker and mixed using a DAC 800.2 VAC Hauschild mixer. The nominal mixing time was 90 seconds at 1000 rpm under vacuum. Subsequently, the sides of the beaker were scraped and the mixture was remixed. The formula was again mixed for a nominal 90 seconds at 1000 rpm under vacuum.For components containing expandable microspheres, these were added before the second mixing step. The individual components were paired with their respective reactive counterparts and then filled into cartridges in a 1:1 ratio (by volume).

[0090] Thermal conductivity measurements were performed on cured samples prepared by dispensing components from cartridges using a static mixing nozzle to create samples with a diameter of approximately 3.2 cm and a thickness of approximately 1.0 cm. The samples were cured for either 24 hours at room temperature or 10 hours at 50°C. The bulk thermal conductivity was measured according to ISO 22007-2 using a hot-disk transient plane source (model 2500 S). To test the influence of exposure temperature on thermal conductivity, the samples were placed in a preheated oven at the desired target temperature for 1 hour, allowed to cool to room temperature, and then tested for thermal conductivity according to ISO 22007-2. Example 1: Conventional 2 W / m·K urethane TIM

[0091] Table 1 lists the ingredients of a conventional, thermally conductive two-component urethane composition containing polyol and isocyanate components. The polyol-containing component also contains thermally conductive aluminum oxide and aluminum trihydrate powders, while the isocyanate-containing component contains aluminum oxide, aluminum trihydrate, and calcium carbonate powders. When the two components are mixed and cured in a 1:1 volume ratio, they combine to form a material with a nominal thermal conductivity of 2 W / m·K. Exposure to temperatures up to 200°C of the cured material results in only minimal changes in thermal conductivity, as shown in [reference to relevant table]. Fig. 3 can be seen. Table 1. Polyol-containing component % by weight Vol% Polyol resin 10.63 22.05 Sn-based catalyst 0.10 0.21 Additive 5.99 11.16 Aluminum oxide powder 18.44 9.99 Aluminum trihydrate powder 64.84 56.59 In total 100.00 100.00 Isocyanate-containing compound % by weight Vol% Isocyanate resin 7.88 15.90 Additive 8.46 17.21 Aluminum oxide powder 18.13 10.03 Aluminum trihydrate powder 48.74 43.45 Calcium carbonate powder 16.79 13.42 In total 100.00 100.00 Example 2: Illustrative examples, 2 W / m·K Switchable urethane TIM

[0092] Tables 2 to 4 list the ingredients of switchable TIMs based on thermally conductive two-component urethane compounds. The polyol-containing component of each TIM comprises thermally conductive aluminum oxide, thermally conductive aluminum trihydrate, and expandable microspheres of varying types and concentrations, while the isocyanate-containing component comprises aluminum trihydrate, aluminum oxide, and / or calcium carbonate powder. Fig.Figure 3 shows the influence of the exposure temperature on the bulk thermal conductivity of the switchable TIMs from Tables 2-4. In contrast to conventional TC urethane (Example 1), all three switchable TIM formulations exhibit a significant decrease (i.e., > 50%) in thermal conductivity when heated to 200°C. Furthermore, the exposure temperature at which the decrease begins (onset temperature) is a function of the type of expandable microspheres used. In these examples, the onset of the decrease in thermal conductivity ranges from a nominal 85°C to a nominal 120°C. The in Fig. The concentration of microspheres shown in Figure 3 is based on the weight fraction of microspheres in the organic fraction of the mixed formulation.

[0093] Table 5 lists the ingredients of a switchable TIM based on a thermally conductive two-component urethane composition. The polyol-containing component of each TIM comprises thermally conductive aluminum oxide and expandable microspheres with a nominal expansion temperature of 120°C. The microsphere concentration is 2.5 wt% based on the organic fraction of the mixed formulation. The isocyanate-containing component comprises aluminum trihydrate and calcium carbonate powder and is identical to the isocyanate-containing component in Table 4. Fig.Figure 4 shows the influence of the exposure temperature on the bulk thermal conductivity for the switchable TIMs in Tables 4 and 5 based on expandable microspheres (infusion temperature 120°C) of different concentrations and Example 1 based on the conventional TIM. In contrast to the conventional TIM, the switchable TIMs exhibit a significant decrease in thermal conductivity with increasing temperature. The extent of the decrease is proportional to the concentration of the expandable microspheres. In particular, the switchable TIM from Table 4 based on 5.0 wt% expandable microspheres shows a decrease in conductivity of approximately 63% after exposure at 200°C, compared to a decrease of approximately 38% for the 2.5 wt% formulation (Table 5). Table 2. Polyol-containing component wt.% Vol% Polyol resin 11.04 21.47 Sn-based catalyst 0.10 0.19 Additive 4.96 8.21 Expandable microspheres - 85°C Insertion 1.50 2.70 Aluminum trihydrate powder 82.40 67.43 In total 100.0 100.0 Isocyanate-containing component wt.% Vol% isocyanate resin 8.18 15.49 Additive 8.67 16.50 Aluminum trihydrate powder 64.96 54.37 Calcium carbonate powder 18.19 13.64 In total 100.00 100.00 Table 3. Polyol-containing component wt.% Vol% Polyol resin 10.68 22.25 Sn-based catalyst 0.10 0.21 Additive 3.33 5.31 Expandable microspheres - 100°C insertion 2.93 5.65 Aluminum oxide powder 18.37 9.99 Aluminum trihydrate powder 64.59 56.59 In total 100.00 100.00 Isocyanate-containing component wt.% Vol% isocyanate resin 8.48 17.12 Additive 7.93 15.99 Aluminum oxide powder 18.12 10.03 Aluminum trihydrate powder 48.69 43.44 Calcium carbonate powder 16.78 13.42 In total 100.00 100.00 Table 4. Polyol-containing component wt.% Vol% Polyol resin 10.63 22.10 Sn-based catalyst 0.10 0.21 Additive 4.70 8.31 Expandable microspheres - 120°C insertion 1.45 2.79 Aluminum oxide powder 18.41 9.99 Aluminum trihydrate powder 64.71 56.60 In total 100.00 100.00 Isocyanate-containing component wt.% Vol% isocyanate resin 7.90 15.93 Additive 8.45 17.19 Aluminum oxide powder 18.13 10.03 Aluminum trihydrate powder 48.73 43.44 Calcium carbonate powder 16.79 13.41 In total 100.00 100.00 Table 5. Polyol-containing component wt.% Vol% Polyol resin 10.63 22.07 Sn-based catalyst 0.10 0.21 Additive 5.35 9.75 Expandable microspheres - 120°C insertion 0.72 1.38 Aluminum oxide powder 18.43 9.99 Aluminum trihydrate powder 64.77 56.60 In total 100.00 100.00 Isocyanate-containing component wt.% Vol% isocyanate resin 7.90 15.93 Additive 8.45 17.19 Aluminum oxide powder 18.13 10.03 Aluminum trihydrate powder 48.73 43.44 Calcium carbonate powder 16.79 13.41 In total 100.00 100.00 Example 3: Conventional 2.3 W / m·K silicone TIM

[0094] Table 6 lists the ingredients of a conventional, thermally conductive two-component silicone composition containing a silicone / vinyl component and a silicone-vinyl / hydride component. Both components also contain thermally conductive aluminum trihydrate powder. When mixed and cured in a 1:1 volume ratio, the combination of the two components yields a material with a thermal conductivity of 2.3 W / m·K. Under temperature stress of up to 140°C, the cured material exhibits only a very slight change in thermal conductivity, as shown in [reference to relevant section]. Fig. 5 can be seen. Table 6 Silicone-vinyl / platinum-containing component wt.% Vol% Silicone vinyl resin 14.52 29.32 Pt-based catalyst 0.18 0.35 Additive 2.71 3.49 Aluminum trihydrate powder 82.59 66.84 In total 100.00 100.00 Silicone vinyl / hydride-containing component wt.% Vol% Silicone vinyl resin 7.82 15.98 Silicone hydride resin 6.04 12.34 Additive 2.55 3.22 Aluminum trihydrate powder 83.59 68.46 In total 100.00 100.00 Example 4: Illustrative examples of nominally 2 W / m·K switchable silicone TIMs

[0095] Tables 7 and 8 list the ingredients of switchable TIMs based on thermally conductive two-component silicone compounds containing silicone / vinyl and a silicone-vinyl / hydride component. Both components also contain expandable microspheres (setting temperature 100°C) and thermally conductive aluminum trihydrate powder. When mixed and cured in a 1:1 volume ratio, the combination of these two components yields a material with a nominal volume thermal conductivity of 2 W / m·K. Fig.Figure 5 shows the influence of the exposure temperature on the bulk thermal conductivity for the TIMs from Tables 7 and 8. In contrast to conventional silicone with 2.3 W / m·K (Table 6), the switchable TIM formulations exhibit a significant decrease (i.e., > 63%) in thermal conductivity when heated to 140°C. Furthermore, the higher concentration of microspheres leads to a greater decrease in thermal conductivity when exposed to temperatures above 100°C. Table 7. Silicone-vinyl / platinum-containing component wt.% Vol% Silicone vinyl resin 14.30 28.55 Pt-based catalyst 0.18 0.35 Additive 2.67 3.41 Expandable microspheres - 100°C Insertion 1.50 2.59 Aluminum trihydrate powder 81.35 65.10 In total 100.00 100.00 Silicone vinyl / hydride-containing component wt.% Vol% Silicone vinyl resin 7.70 15.55 Silicone hydride resin 5.95 12.01 Additive 2.51 3.13 Expandable microspheres - 100°C Insertion 1.50 2.67 Aluminum trihydrate powder 82.34 66.64 In total 100.00 100.00 Table 8. Silicone-vinyl / platinum-containing component wt.% Vol% Silicone vinyl resin 14.09 27.82 Pt-based catalyst 0.17 0.33 Additive 2.63 3.31 Expandable microspheres - 100°C Insertion 3.00 5.13 Aluminum trihydrate powder 80.11 63.41 In total 100.00 100.00 Silicone vinyl / hydride-containing component wt.% Vol% Silicone vinyl resin 7.58 15.12 Silicone hydride resin 5.86 11.69 Additive 2.48 3.06 Expandable microspheres - 100°C Insertion 3.00 5.28 Aluminum trihydrate powder 81.08 64.85 In total 100.00 100.00 Example 5: Conventional 3.5 W / m·K silicone TIM

[0096] Table 9 lists the ingredients of a conventional, thermally conductive two-component silicone composition containing a silicone / vinyl component and a silicone-vinyl / hydride component. Both components also contain thermally conductive aluminum trihydrate and zinc oxide powder. When mixed and cured in a 1:1 volume ratio, the combination of the two components yields a material with a thermal conductivity of 3.5 W / m·K. Under temperature stress of up to 140°C, the cured material exhibits only a very slight change in thermal conductivity, as shown in Fig. 6 can be seen. Table 9 Silicone-vinyl / platinum-containing component wt.% Vol% Silicone vinyl resin 7.18 24.85 Pt-based catalyst 0.06 0.11 Additive 1.00 2.54 Aluminum oxide powder 67.01 57.66 Zinc oxide powder 24.75 14.84 In total 100.00 100.00 Silicone vinyl / hydride-containing component wt.% Vol% Silicone vinyl resin 4.74 16.41 Silicone hydride resin 2.49 8.62 Additive 0.91 2.42 Aluminum oxide powder 67.01 57.66 Zinc oxide powder 24.85 14.89 In total 100.00 100.00 Example 6: Illustrative examples of nominally 3.2 W / m·K switchable silicone TIMs

[0097] Tables 10 and 11 list the ingredients of switchable TIMs based on thermally conductive two-component silicone compounds containing silicone / vinyl and a silicone-vinyl / hydride component. Both components also contain expandable microspheres (setting temperature 100°C), thermally conductive aluminum trihydrate, and zinc oxide powder. When mixed and cured in a 1:1 volume ratio, the two components combine to form a material with a nominal volume thermal conductivity of 3.2 W / m·K. Fig.Figure 6 shows the influence of the exposure temperature on the bulk thermal conductivity for the TIMs from Tables 7 and 8. In contrast to conventional silicone with 3.5 W / m·K (Table 9), the switchable TIM formulations exhibit a significant decrease (i.e., > 36%) in thermal conductivity when heated to 140°C. Furthermore, the higher concentration of microspheres leads to a greater decrease in thermal conductivity when exposed to temperatures above 100°C. Table 10. Silicone-vinyl / platinum-containing component wt.% Vol% Silicone vinyl resin 7.11 24.10 Pt-based catalyst 0.06 0.10 Additive 0.99 2.47 Expandable microspheres - 100°C Insertion 1.00 2.99 Aluminum oxide powder 66.34 55.95 Zinc oxide powder 24.50 14.39 In total 100.00 100.00 Silicone-vinyl / hydride-containing component wt.% Vol% Silicone vinyl resin 4.70 15.92 Silicone hydride resin 2.47 8.36 Additive 0.90 2.34 Expandable microspheres - 100°C Insertion 1.00 2.99 Aluminum oxide powder 66.33 55.94 Zinc oxide powder 24.60 14.45 Total 100.00 100.00 Table 11. Silicone-vinyl / platinum-containing component wt.% Vol% Silicone vinyl resin 7.04 23.39 Pt-based catalyst 0.06 0.10 Additive 0.97 2.39 Expandable microspheres - 100°C Insertion 2.00 5.86 Aluminum oxide powder 65.67 54.29 Zinc oxide powder 24.26 13.97 In total 100.00 100.00 Silicone vinyl / hydride-containing component wt.% Vol% Silicone vinyl resin 4.65 15.45 Silicone hydride resin 2.44 8.12 Additive 0.89 2.26 Expandable microspheres - 100°C Insertion 2.00 5.86 Aluminum oxide powder 65.66 54.28 Zinc oxide powder 24.35 14.02 In total 100.00 100.00 QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 470,363

[0001]

Claims

[1] Thermal interface material composition comprising: a two-component, thermosetting matrix, wherein the two-component thermosetting matrix has a first component and a second component; and a thermally conductive filler, wherein the thermal interface material is thermally conductive in a first temperature range, and wherein the thermal conductivity of the thermal interface material decreases significantly in a second temperature range. [2] Thermal interface material composition according to claim 1, wherein the first component comprises a resin which can react upon contact with the second component and optionally comprises a thermally conductive filler. [3] Thermal interface material composition according to claim 1, wherein the first component comprises an isocyanate resin which can react upon contact with the second component and optionally comprises a thermally conductive filler. [4] Thermal interface material composition according to claim 1, wherein the first component comprises a vinyl-functional silicone resin and an addition-curing catalyst which can react upon contact with the second component, and optionally comprises a thermally conductive filler. [5] Thermal interface material composition according to claim 1, wherein the first component comprises an epoxy resin which can react upon contact with the second component and optionally comprises a thermally conductive filler. [6] Thermal interface material composition according to claim 1, wherein the first component comprises an acrylic resin which can react upon contact with the second component and optionally comprises a thermally conductive filler. [7] Thermal interface material composition according to claim 1 or 2, wherein the second component comprises a compound that can react with the reactive resin of the first component and / or initiate its polymerization. [8] Thermal interface material composition according to claim 1 or 3, wherein the second component comprises an isocyanate-reactive compound that can react with the composition of the first component. [9] Thermal interface material composition according to claim 1 or 4, wherein the second component comprises a hydride-functional silicone resin that can react with the composition of the first component. [10] Thermal interface material composition according to claim 1 or 5, wherein the second component comprises an epoxy-reactive compound or catalyst that can react with the epoxy resin of the first component and / or initiate its polymerization. [11] Thermal interface material composition according to claim 1 or 6, wherein the second component comprises an initiator capable of polymerizing the composition of the first component. [12] Thermal interface material composition according to any one of claims 1 to 11, wherein the first and second components are configured to be mixed to form a thermal interface matrix by reaction. [13] Thermal interface material composition according to one of claims 1 to 12, wherein the first temperature range is from about -40°C to about 80°C, wherein the second temperature range is from about 80°C to about 200°C, optionally wherein the first temperature range is from about -40°C to about 160°C, wherein the second temperature range is from about 160°C to about 250°C. [14] Thermal interface material composition according to any one of claims 1 to 13, wherein the thermal interface material reduces the thermal conductivity, optionally by at least about 30%, about 50%, about 75%, about 90%, about 95%, about 99% or more. [15] Thermal interface material composition according to claim 14, wherein the thermal interface material has a decrease in apparent conductivity and / or an increase in interface resistance. [16] Thermal interface material composition according to any one of claims 1 to 15, wherein the apparent conductivity of the thermal interface material is reduced by at least about 50%, about 75%, about 80%, about 90%, about 95%, about 99% or more when exposed to the second temperature range. [17] Thermal interface material composition according to any one of claims 1 to 16, further comprising a component which can decompose at elevated temperature and / or change its phase, thereby reducing the apparent conductivity of the thermal interface material. [18] Thermal interface material composition according to any one of claims 1 to 17, wherein the conductive filler comprises aluminium trihydrate (ATH). [19] Thermal interface material composition according to any one of claims 1 to 18, further comprising expandable polymeric microspheres. [20] Thermal interface material formed from a composition according to any one of claims 1 to 19, wherein the thermal interface material is formed by mixing the first component with the second component. [21] Method for producing a thermal interface material, wherein the method comprises mixing the first component with the second component according to any one of claims 1 to 19.

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