Thermal interface materials

Abstract

The present invention relates to a thermal interface material, such as a thermally conductive pad or thermally conductive sheet, that exhibits good elongation characteristics, and the material is based on: an elastomer matrix containing a silicone rubber with a mass average molar mass (Mw) in the range of 150 to 1000 kg / mol with a viscosity of 85 to 1000 phr; a thermally conductive filler with a viscosity of 250 to 1000 phr containing more than 50% by mass of alumina relative to the total mass of the thermally conductive filler; a silicone oil with a viscosity of less than 150,000 mPa.s at 25°C with a viscosity of 15 to 150 phr; and a crosslinking agent with a viscosity of 0.2 to 5 phr.

Description

Technical Field

[0001] The present invention relates to a thermal interface material that can be used, particularly in the field of batteries, for extracting heat from components that generate heat.

Background Art

[0002] In the field of electric vehicle propulsion, it is necessary to rely on very high-power batteries. The high power employed during use (discharge of the battery) or recovery (charging of the battery) causes a significant heating effect. Lithium-ion technology is increasingly being used in automotive batteries. This technology requires an optimal operating temperature range for the battery, which on the one hand is for fully utilizing the reserve capacity, but more importantly, for avoiding damage during repeated charge / discharge cycles. To prevent this type of damage, a system for regulating / controlling the temperature of the battery, called a BMS (Battery Management System), is commonly used. The thermal part of the BMS generally includes an exchanger with a circulating heat exchange fluid (cooling table), and a thermal relay for extracting heat from the battery. These thermal relays (or thermal interfaces) are called TMM or TIM (Thermal Management / Interface Material). TMM has several forms: gap fillers and pads.

[0003] The gap filler is a liquid composition that crosslinks at ambient temperature to solidify the filling of the gap volume between the battery and the cooling table. The pad, on the other hand, is a solid composition formed into a sheet of a given thickness. To attach the pad within the battery pack, mechanical pressing is required to ensure close contact between the battery and the cooling table. This attachment requires a high degree of deformability so as not to cause damage to the pad. The thermal conductivity that a pad must exhibit generally requires a large volume fraction of thermally conductive filler in the TMM composition. This can weaken these compositions, increasing the risk of damage when the pad is installed on the battery or when the battery itself is installed on the vehicle. [Overview of the Initiative]

[0004] Therefore, there is a genuine need for improved deformability before mechanical failure in thermal interface materials usable in pad form, which by definition must necessarily exhibit good thermal conductivity. Reference CN112831187A describes that a composition based on a silicone elastomer containing spherical alumina, alumina nitride, silicone oil, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane exhibits good thermal conductivity, robustness, and fracture strength properties. During the continuation of that research, the applicant company unexpectedly discovered that by using a combination of silicone rubber, a thermally conductive filler, silicone oil, and a crosslinking agent in specific proportions, it is possible to solve the aforementioned technical problems while further improving the deformability before mechanical failure. Therefore, the subject matter of the present invention is - Elastomer matrix containing silicone rubber with a mass-average molar mass (Mw) ranging from 150 to 1000 kg / mol, and a mass-average molar mass (Mw) of 85 to 100 phr. - A thermally conductive filler with a heat conductivity of 250 to 1000 phr, containing more than 50% by mass of alumina relative to the total mass of the thermally conductive filler. - Silicone oils of 15-150 phr exhibiting a viscosity of less than 150,000 mPa·s at 25℃, and - Crosslinking agent of 0.2~5 phr It is a thermal interface material based on [a certain material]. [Modes for carrying out the invention]

[0005] I-definition The expression "~-based composition" should be understood to mean a composition comprising a mixture of various constituent materials used and / or the products of in situ reactions of those constituent materials, wherein some of these constituent materials are capable of reacting with each other at least partially during the various stages of the production of the composition, and / or are intended to react with each other, and thus can be fully or partially crosslinked or uncrosslinked. The term "elastomer matrix" should be understood to mean the combined elastomers of the composition. The expression "parts per 100 parts by mass of elastomer" (or phr) should be understood, within the scope of the present invention, to mean the mass occupancy rate of elastomer present in the rubber composition under consideration per 100 parts.

[0006] In this document, unless otherwise specified, all percentages (%) expressed are mass percentages (%). Furthermore, any interval of values ​​expressed as "between a and b" represents the range of values ​​from greater than a to less than b (in other words, the limit values ​​a and b are excluded), whereas any interval of values ​​expressed as "a to b" means the range of values ​​from a to b (in other words, the strict limit values ​​a and b are included). In this document, when an interval of values ​​is expressed as "a to b", the interval expressed as "between a and b" also takes precedence.

[0007] The compounds mentioned in this description may be fossil-derived or bio-based. In the latter case, they may be partially or completely derived from biomass, or obtained from renewable starting materials derived from biomass. Similarly, the compounds mentioned may also be derived from the recycling of previously used materials; in other words, they may be partially or completely derived from a recycling process, or the starting materials themselves may be derived from a recycling process. Polymers, plasticizers, and fillers are particularly relevant. Unless otherwise specified, all glass transition temperature (Tg) values ​​described in this document are measured by differential scanning calorimetry (DSC) in accordance with ASTM D3418 (1999) standards using known methods.

[0008] II. Description of the Invention II-1 Elastomer Matrix According to the present invention, the elastomer matrix of the thermal interface material is based on a silicone rubber with a mass-average molar mass (Mw) in the range of 150 to 1000 kg / mol and a viscosity of 85 to 100 phr. Below 150 kg / mol, the silicone rubber exhibits the viscosity and viscoelastic behavior of silicone, which complicates its handling and processing. Furthermore, if the Mw of the silicone rubber is too low, the effectiveness of crosslinking decreases. Above 1000 kg / mol, the silicone rubber exhibits high viscosity, complicating its processing and requiring high deformation energy. Preferably, the silicone rubber has an Mw in the range of 300 to 900 kg / mol, preferably 500 to 800 kg / mol. The macrostructure (Mw, Mn, and PDI) of silicone rubber is determined by: size exclusion chromatography (SEC); solvent: tetrahydrofuran; temperature: 35°C; concentration: 1 g / l; flow rate: 1 ml / min; filtration of the solution through a filter with a porosity of 0.45 μm before injection; Moore calibration using polystyrene standards; three Waters columns in series (Styragel HR4E, HR1, and HR0.5); detection by differential refractometer (Waters 2410) and associated operating software (Waters Empower).

[0009] The thermal interface material according to the present invention may contain only one type of silicone rubber exhibiting the above-mentioned Mw value, or it may contain a mixture of silicone rubbers. In particular, the silicone rubber is selected from the group consisting of polydimethylsiloxane (PDMS), polymethylarylsiloxane (especially polymethylphenylsiloxane), and mixtures thereof. Preferably, the silicone rubber is selected from the group consisting of PDMS and mixtures thereof. Silicone rubber may exhibit vinyl functional groups. For example, silicone rubber may not exhibit vinyl functional groups, or may exhibit them in a molar content of less than 2%, preferably less than 1%, preferably less than 0.5%. When silicone rubber exhibits vinyl functional groups, the molar fraction of vinyl functional groups in the silicone rubber may be between 0.01% and 2%, preferably between 0.05% and 1%, preferably between 0.08% and 0.5%.

[0010] The mole fraction of vinyl functional groups in silicone rubber is 1 H and 13 Determined by 13C NMR spectroscopy. The NMR spectrum is recorded using a Bruker Avance III 500 MHz spectrometer equipped with a BBI z-grad 5 mm "broadband" cryoprobe. Quantitative 1 The 1H NMR experiment uses a single 30° pulse sequence and a 5-second repetition time between each acquisition. 64–256 integrations are performed. Quantitatively... 13 The 13C NMR experiment uses a single 30° pulse sequence with proton decoupling and a 10-second repetition time between each acquisition. 1024–10240 integrations are performed. The aim is to determine the polymer structure. 1 H / 13 A 2D NMR experiment is used. NMR measurements are performed at 25°C, and the copolymer is present in a solution in a deuterated solvent (approximately 25 mg of elastomer per 1 ml), which is typically deuterated chloroform (CDCl3).

[0011] The elastomer matrix may contain elastomers other than silicone rubber, but this is neither essential nor preferable. Preferably, the elastomer matrix does not contain elastomers other than silicone rubber exhibiting an Mw in the range of 150 to 1000 kg / mol, or contains such elastomers in an amount of less than 15 phr, preferably less than 10 phr, preferably less than 5 phr. More preferably, the elastomer matrix contains only silicone rubber exhibiting an Mw in the range of 150 to 1000 kg / mol, preferably 300 to 900 kg / mol, preferably 500 to 800 kg / mol, in other words, 100 phr of such silicone rubber. Examples of commercially available silicone rubbers used for the requirements of the present invention include Wacker's Elastosil® R401-10, Elastosil® R401-25, Elastosil® R401-70, Elastosil® R401-90, or Elastosil® R402-75.

[0012] II-2 Thermally conductive fillers The thermal interface material according to the present invention is based on a thermally conductive filler with a thermal conductivity of 250 to 1000 phr, and the thermally conductive filler contains more than 50% by mass of alumina relative to the total mass of the thermally conductive filler. The thermally conductive filler may consist of a mixture of several thermally conductive fillers containing more than 50% by mass of alumina, but this is neither essential nor preferable. Preferably, the thermally conductive filler contains more than 60% by mass, preferably more than 75% by mass, preferably more than 90% by mass, and preferably 100% by mass of alumina. In other words, the thermally conductive filler preferably contains no fillers other than alumina, or contains less than 40% by mass, preferably less than 25% by mass, and preferably less than 10% by mass of fillers other than alumina. Alumina can be supplied in different forms, particularly in particulate form. Preferably, the alumina exists in particulate form, and its median diameter D50 is in the range of 2 to 150 μm, preferably 10 to 100 μm, and preferably 20 to 70 μm. D50 represents the particle size in which 50% of the total volume of the particles has a diameter smaller than D50 and 50% of the total volume has a diameter larger than D50.

[0013] Examples of commercially available alumina include Silatherm® 1432-006 or 1432-400 manufactured by Quarzwerke, or Silatherm® VST 1432-006 or VST 1432-400. Advantageously, the thermal conductive filler content in the thermal interface material according to the present invention is in the range of 370 to 720 phr, preferably 380 to 600 phr, and preferably 390 to 500 phr, and the thermal conductive filler contains more than 60% by mass, preferably more than 75% by mass, preferably more than 90% by mass, and preferably 100% by mass of alumina. Regardless of the PHR content of the thermal conductive filler in the thermal interface material, the volume content of the thermal conductive filler in the thermal interface material is preferably in the range of 40% to 60%, preferably 42% to 58%, and preferably 45% to 56%, and the thermal conductive filler preferably contains more than 60% by mass, preferably more than 75% by mass, preferably more than 90% by mass, and preferably 100% by mass of alumina.

[0014] II-3 Silicone oil The thermal interface material according to the present invention is based on a 15-150 phr silicone oil exhibiting a viscosity of less than 150,000 mPa·s at 25°C. The viscosity of the silicone oil is determined at 25 °C and atmospheric pressure according to the Brookfield technique. The Brookfield viscosity characterizes a liquid substance in a known manner. The apparent viscosity according to the Brookfield process is measured at a given temperature (e.g., 25 °C) according to European and international standard EN ISO 2555 (1999). For example, a viscometer of type A (e.g., RVT model) or type B (e.g., HAT model) is preferably used at a rotational speed equal to 10 or 20 minutes -1 with several spindles (1 - 7) suitable for the viscosity range to be measured (in accordance with Appendix A of the EN ISO 2555 standard). The viscosity is expressed in mPa·s or centipoises (cP) (1 cP = 1 mPa·s).

[0015] Advantageously, the silicone oil exhibits a viscosity within the range of 20 - 90000 mPa·s, preferably 40 - 50000 mPa·s, preferably 50 - 20000 mPa·s at 25 °C. More preferably, the silicone oil exhibits a viscosity within the range of 20 - 20000 mPa·s, preferably 40 - 5000 mPa·s, preferably 50 - 2000 mPa·s at 25 °C. The silicone oil may or may not be functionalized. Preferably, the silicone oil is a silicone oil that does not exhibit hydroxyl functional groups and / or vinyl functional groups. More preferably, the silicone oil does not exhibit polar functional groups and / or functional groups containing double bonds. Examples of silicone oils used for the requirements of the present invention, among those commercially available, include grades AK - 50, AK - 100, AK - 1000, or AK - 10000 from Wacker, or grade AK - 100000 as well. The content of the silicone oil is within the range of 15 - 150 phr. It has been found that outside this range, the mechanical properties (elongation at break, breaking stress) of the thermal conductive filler according to the present invention were not satisfactory. Preferably, the content of the silicone oil in the thermal interface material is within the range of 15 - 80 phr, preferably 20 - 60 phr.

[0016] Advantageously, the mass ratio of the thermally conductive filler to the silicone oil ranges from more than 4.2 to 35, preferably from 5 to 30, preferably less than 10 to 20, preferably less than 10 to 18. In order to further improve the mechanical properties of the thermal interface material, the content of the silicone oil that can be used can be adjusted according to the viscosity of the silicone oil used. For example, the thermal interface material can contain 15 to 35 phr, preferably 20 to 30 phr of a silicone oil having a viscosity between 50,000 and 150,000 mPa·s at 25°C. Preferably, the thermal interface material contains 15 to 60 phr, preferably 15 to 40 phr, preferably 20 to 35 phr of a silicone oil having a viscosity ranging from 5000 to 50,000 mPa·s, preferably from 5000 to 20,000 mPa·s at 25°C. More preferably, the thermal interface material contains 15 to 90 phr, preferably 15 to 80 phr, preferably 20 to 75 phr of a silicone oil having a viscosity between 20 and 5000 mPa·s, preferably between 50 and 1500 mPa·s at 25°C.

[0017] II-4 Crosslinking Agents The thermal interface material according to the present invention is based on 0.2 to 5 phr of a crosslinking agent. The crosslinking agent can be any crosslinking agent that enables the crosslinking of silicone rubber. Advantageously, the crosslinking agent is a peroxide or a mixture of several peroxides. It can be any peroxide known to those skilled in the art. Among the peroxides well-known to those skilled in the art, in the context of the present invention, it is preferable to use an organic peroxide. "Organic peroxide" is understood to mean an organic compound containing an -O-O- group (two oxygen atoms bonded by a single covalent bond), in other words, a compound containing carbon. During the crosslinking process, the organic peroxide decomposes at its unstable O-O bond to give free radicals. These free radicals make it possible to create crosslink bonds. The organic peroxide is preferably selected from the group comprising or consisting of dialkyl peroxides, monoperoxy carbonates, diacyl peroxides, peroxyketals, and peroxyesters.

[0018] Preferably, the dialkylperoxide is selected from the group comprising or consisting of dicumylperoxide, di(t-butyl)peroxide, t-butylcumylperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-amylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexa-3-yne, 2,5-dimethyl-2,5-di(t-amylperoxy)hexa-3-yne, bis[α-(t-butylperoxy)isopropyl]benzene, bis[α-(t-amylperoxy)isopropyl]benzene, di(t-amyl)peroxide, 1,3,5-tri[(t-butylperoxy)isopropyl]benzene, 1,3-dimethyl-3-(t-butylperoxy)butanol, and 1,3-dimethyl-3-(t-amylperoxy)butanol.

[0019] Certain monoperoxycarbonates, such as OO-tert-butyl O-(2-ethylhexyl) monoperoxycarbonate, OO-tert-butyl O-isopropyl monoperoxycarbonate, and OO-tert-amyl O-(2-ethylhexyl) monoperoxycarbonate, can also be used. Among diacyl peroxides, benzoyl peroxide is the preferred peroxide. Among peroxyketals, preferred peroxides are selected from the group including or consisting of 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl 4,4-bis(t-butylperoxy)valerate, ethyl 3,3-di(t-butylperoxy)butyrate, 2,2-di(t-amylperoxy)propane, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane (or methyl ethyl ketone peroxide cyclic trimer), 3,3,5,7,7-pentamethyl-1,2,4-trioxepane, n-butyl 4,4-bis(t-amylperoxy)valerate, ethyl 3,3-di(t-amylperoxy)butyrate, 1,1-di(t-butylperoxy)cyclohexane, 1,1-di(t-amylperoxy)cyclohexane, and mixtures thereof. Preferably, the peroxyester is selected from the group consisting of tert-butylperoxybenzoate, tert-butylperoxy-2-ethylhexanoate, and tert-butylperoxy-3,5,5-trimethylhexanoate.

[0020] In summary, the organic peroxide is particularly preferably selected from the group consisting of dicumyl peroxide, aryl peroxide, diaryl peroxide, diacetyl peroxide, benzoyl peroxide, dibenzoyl peroxide, di(tert-butyl) peroxide, tert-butylcumyl peroxide, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, n-butyl 4,4-bis(tert-butylperoxy) valerate, OO-(t-butyl)O-(2-ethylhexyl) monoperoxycarbonate, tert-butylperoxyisopropyl carbonate, tert-butylperoxybenzoate, tert-butylperoxy-3,5,5-trimethylhexanoate, 1,3(4)-bis(tert-butylperoxyisopropyl)benzene, and mixtures thereof. More preferably, the organic peroxide is selected from the group consisting of dicumyl peroxide, n-butyl 4,4-bis(tert-butylperoxy)valerate, OO-(t-butyl)O-(2-ethylhexyl)monoperoxycarbonate, tert-butylperoxyisopropyl carbonate, tert-butylperoxybenzoate, tert-butylperoxy-3,5,5-trimethylhexanoate, 1,3(4)-bis(tert-butylperoxyisopropyl)benzene, and mixtures thereof.

[0021] Examples of commercially available peroxides that can be used in the context of the present invention include Dicup from Hercules Powder Co., Perkadox Y12 from Noury ​​van der Lande, Peroximon F40 from Montecatini Edison SpA, Trigonox from Noury ​​van der Lande, Varox from RTVanderbilt Co., or Luperko from Wallace & Tiernan Inc.

[0022] II-5 Possible Additives The thermal interface material may optionally include all or some of the common additives commonly used in TMMs, such as pigments, protective agents, antioxidants, or flame retardants.

[0023] II-6 Preparation of Compositions The material according to the present invention can be manufactured in a suitable kneader using the following two consecutive preparation steps, which are well known to those skilled in the art: - The first stage, thermomechanical work or mixing ("non-productive" stage), can be carried out in a single thermomechanical stage during which all necessary components other than the crosslinking system, specifically the elastomer matrix, thermally conductive filler, and various other optional additives, are introduced into a suitable mixer, such as a standard closed-type mixer (e.g., a Banbury type). The incorporation of the filler into the elastomer can be carried out once or multiple times during thermomechanical mixing. If the filler is already fully or partially incorporated into the elastomer in the form of a masterbatch, as described, for example, in applications WO97 / 36724 and WO99 / 16600, it is the masterbatch that is directly mixed, and other elastomers or fillers present in the composition that are not in the form of a masterbatch, and various other optional additives, are incorporated as appropriate. The non-programming stage can generally be carried out at a high temperature between 80°C and 150°C, preferably between 100°C and 120°C, for a period of 2 to 10 minutes. - The second stage, the mechanical work ("productive" stage), can be carried out in an external mixer such as an open mill after the mixture obtained during the first non-productive stage has been cooled to a low temperature, typically below 120°C, for example, between 40°C and 100°C. A crosslinking system is then incorporated, and the combined mixture is then mixed for several minutes, for example, 5 to 15 minutes.

[0024] Such stages are described, for example, in applications EP-A-0501227, EP-A-0735088, EP-A-0810258, WO00 / 05300, and WO00 / 05301. The final composition obtained in this way is then calendered, for example, into a sheet or plate. These products can then be used to manufacture thermal interface materials such as thermally conductive pads (or cushions) or thermally conductive sheets, according to techniques known to those skilled in the art. Specifically, the compositions can be molded and crosslinked under temperatures and pressures between 130°C and 200°C, for example, to form thermal interface pads.

[0025] II-7 Thermal Interface Materials The thermal interface material according to the present invention can be used in any application that enables the extraction of heat emitted from an object. For example, it is particularly well suited for transferring heat emitted during the use or recharging of an electric vehicle battery. The thermal interface material according to the present invention can be provided in any shape and thickness, thereby enabling it to perform its function. Preferably, the thermal interface material is selected from the group consisting of thermally conductive pads (or cushions) and thermally conductive sheets. In addition, the thermal interface material preferably has a thickness in the range of 0.2 to 10 mm, preferably 0.5 to 8 mm, preferably 1 to 6 mm, preferably more than 1 to 6 mm, and preferably 1.1 to 6 mm. [Examples]

[0026] III. Example III-1 Preparation of Compositions In the following examples, the rubber composition was produced as described in section II-6 above. Specifically, the "non-pro" stage was carried out in a 0.4-liter kneader for 3.5 minutes at an average blade speed of 50 revolutions per minute until the maximum dropping temperature of 90°C was reached. The "pro" stage was carried out in an open mill at 40°C for 5 to 10 minutes. Crosslinking of the composition was carried out under pressure at a temperature of 150°C for 30 minutes. Test specimens for measuring tensile mechanical properties (modulus and elongation) were cut from the resulting crosslinked plates.

[0027] III-2 Measurements and Tests Used Mechanical properties These tensile tests make it possible to determine the elastic stress and fracture properties. By processing the tensile records, it is also possible to plot the modulus curve as a function of elongation. The modulus used herein is the nominal (or apparent) secant modulus measured at the initial elongation and is calculated by converting it to the initial cross-sectional area of ​​the specimen. The fracture stress (BS, in MPa) and elongation at fracture (EB, in %) are measured at 23°C ± 2°C according to the standard NF T46-002 of September 1988. The fracture energy is equal to the product of the elongation at fracture and the fracture stress. Thermal conductivity A cylindrical sample measuring 40 mm x 8 mm was prepared by molding. The thermal conductivity was determined by the transient planar heat source (TPS) method using a Hot Disk™ TPS 1000 device. A heat flow rate of 80 mW was applied to the sample for 10 seconds. The thermal conductivity of the sample was determined by the temperature change thus observed, which itself was determined by measuring the change in the electrical resistance of the material due to a Wheatstone bridge in the sample.

[0028] III-3 Testing of Rubber Compositions The purpose of the examples presented below is to compare the elongation at break characteristics of the compositions (I1 to I10) according to the present invention with those of two control compositions (C1 and C2). The compositions tested (in phr units) and the results obtained are also shown in Table 1. The composition according to the present invention differs from the control composition in the content of the thermally conductive filler and silicone oil, and the volume fraction of the thermally conductive filler is constant. [Table 1] [Table 2]

[0029] The results presented in Table 1 above show that all compositions according to the present invention exhibit a much greater elongation at break than the control compositions, and in this case, the thermal conductivity of the compositions is not excessively affected, or even not affected at all. Specifically, increasing the content of silicone oil while keeping the volume fraction of the thermally conductive filler constant makes it possible to improve the elongation at break and the energy at break. A comparison of compositions I1, I5, I8, and I10, or compositions I4 and I7, shows that lowering the viscosity of the oil at a given content improves the elongation at break and the stress at break. The greatest elongation at break is achieved when the viscosity of the silicone oil is lowest and the content of these silicone oils is highest.

[0030] Thus, the compositions according to the present invention make it possible to obtain highly deformable thermal interface materials, which are particularly advantageous when used as thermally conductive pads or sheets.

Claims

1. - An elastomer matrix containing 85-100 phr silicone rubber exhibiting a mass-average molar mass Mw in the range of 150-1000 kg / mol. - A thermally conductive filler containing more than 50% by mass of alumina relative to the total mass of the thermally conductive filler, with a thermal conductivity of 250 to 1000 phr. - A silicone oil of 15 to 150 phr exhibiting a viscosity of less than 150,000 mPa·s at 25°C, and - Crosslinking agent of 0.2 to 5 phr A thermal interface material based on [the specified material].

2. The thermal interface material according to claim 1, wherein the silicone rubber is selected from the group consisting of polydimethylsiloxane (PDMS), polymethylarylsiloxane, and mixtures thereof, and preferably the silicone rubber is selected from the group consisting of polydimethylsiloxane and mixtures thereof.

3. The thermal interface material according to any one of claims 1 to 2, wherein the silicone rubber either does not exhibit vinyl functional groups or exhibits vinyl functional groups in a molar content of less than 2%, preferably less than 1%, and preferably less than 0.5%.

4. A thermal interface material according to any one of claims 1 to 3, wherein the silicone rubber exhibits a Mw in the range of 300 to 900 kg / mol, preferably 500 to 800 kg / mol.

5. A thermal interface material according to any one of claims 1 to 4, wherein the content of the thermally conductive filler is in the range of 370 to 720 phr, preferably 380 to 600 phr, and preferably 390 to 500 phr.

6. The thermal interface material according to any one of claims 1 to 5, wherein the volume content of the thermally conductive filler in the thermal interface material is in the range of 40% to 60%, preferably 42% to 58%, and preferably 45% to 56%.

7. The thermal interface material according to any one of claims 1 to 6, wherein the thermal conductive filler contains more than 60% by mass, preferably more than 75% by mass, and preferably more than 90% by mass of alumina.

8. A thermal interface material according to any one of claims 1 to 7, wherein alumina is present in particulate form and its median diameter D50 is in the range of 2 to 150 μm, preferably 10 to 100 μm, and preferably 20 to 70 μm.

9. The thermal interface material according to any one of claims 1 to 8, wherein the silicone oil is a silicone oil that does not exhibit hydroxyl functional groups and / or vinyl functional groups.

10. A thermal interface material according to any one of claims 1 to 9, wherein the silicone oil exhibits a viscosity in the range of 20 to 20,000 mPa·s, preferably 40 to 5,000 mPa·s, and preferably 50 to 2,000 mPa·s.

11. A thermal interface material according to any one of claims 1 to 10, wherein the silicone oil content is in the range of 15 to 80 phr, preferably 20 to 60 phr.

12. The thermal interface material according to any one of claims 1 to 11, wherein the mass ratio of the thermally conductive filler to the silicone oil is in the range of more than 4.2 to 35, preferably 5 to 30, and preferably less than 10 to 18.

13. A thermal interface material according to any one of claims 1 to 12, wherein the crosslinking agent is an organic peroxide preferentially selected from the group consisting of dicumyl peroxide, aryl peroxide, diaryl peroxide, diacetyl peroxide, benzoyl peroxide, dibenzoyl peroxide, di(tert-butyl) peroxide, tert-butylcumyl peroxide, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, n-butyl 4,4-bis(tert-butylperoxy) valerate, OO-(t-butyl)O-(2-ethylhexyl) monoperoxycarbonate, tert-butylperoxyisopropyl carbonate, tert-butylperoxybenzoate, tert-butylperoxy-3,5,5-trimethylhexanoate, 1,3(4)-bis(tert-butylperoxyisopropyl)benzene, and mixtures thereof.

14. The thermal interface material according to any one of claims 1 to 13, wherein the material is selected from the group consisting of thermally conductive pads and thermally conductive sheets.

15. The thermal interface material according to any one of claims 1 to 14, wherein the material has a thickness in the range of 0.2 to 10 mm, preferably 0.5 to 8 mm, and preferably more than 1 to 6 mm.

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