Thermal interface material

Abstract

The invention relates to a thermal interface material, such as thermally conductive pads or thermally conductive sheets, having good elongation properties, the material being based on an elastomer matrix comprising: from 85 to 100 phr of silicone rubber having a weight-average molar mass, Mw, within a range from 150 to 1000 kg / mol; from 250 to 1000 phr of a thermally conductive filler, the thermally conductive filler comprising more than 50% by mass of alumina relative to the total mass of thermally conductive filler; from 15 to 150 phr of silicone oil having a viscosity at 25°C of less than 150,000 mPa.s; and from 0.2 to 5 phr of a crosslinking agent.

Description

[0001] THERMAL INTERFACE MATERIAL

[0002] The present invention relates to a thermal interface material which can be used in particular to extract heat from an element by generating it, for example in the field of accumulator batteries.

[0003] In the field of electric vehicle propulsion, it is necessary to use very high-power batteries. The high electrical power involved during use (discharging battery) or during recovery (charging battery) causes significant heating.

[0004] Lithium-ion technology is increasingly used in automotive batteries. This technology requires an optimal battery operating temperature range, not only to fully benefit from the reserve power, but also and above all to avoid damage during repeated charge / discharge cycles. To prevent this type of damage, battery temperature regulation / control systems called BMS (Battery Management System) are generally used. The thermal part of the BMS generally includes exchangers with circulating heat transfer fluids (cooling table) and thermal relays that extract calories from the battery. These thermal relays (or thermal interfaces) are called TMM or TIM (Thermal Management / Interface Materials). TMMs come in several forms: gap fillers and pads.

[0005] Space fillers are liquid compositions that are crosslinked at room temperature to freeze the filling of interstitial volumes between the battery and the cooling table. Pads are solid compositions that are shaped into plates of a given thickness. The placement of pads in battery packs requires mechanical crushing to ensure intimate contact between the battery and the cooling table. This placement requires high deformability to avoid breaking the pads.

[0006] The thermal conductivity properties that the pads must have generally require a high volume fraction of thermally conductive fillers in the TMM composition. This can weaken these compositions, risking breakage when the pads are mounted on the batteries or when the batteries themselves are mounted in the vehicle.

[0007] There is therefore a real need to improve the deformability before mechanical rupture of thermal interface materials that can be used in pad form, which must by definition have good thermally conductive properties.

[0008] Document CN112831187 A describes that compositions, based on silicone elastomer comprising spherical alumina, alumina nitride, silicone oil and 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, have good thermal conductive properties, strength and breaking strength.

[0009] Continuing its research, the Applicant unexpectedly discovered that the combined use of silicone rubber, thermally conductive filler, silicone oil and crosslinking agent, at particular rates, makes it possible to solve the aforementioned technical problem by further improving deformability before mechanical rupture.

[0010] Thus, the invention relates to a thermal interface material based on:

[0011] - an elastomer matrix comprising from 85 to 100 pce of silicone rubber having a mass-average molar mass, Mw, in a range from 150 to 1,000 kg / mol,

[0012] - 250 to 1000 pce of a thermally conductive filler, the thermally conductive filler comprising more than 50% by mass of alumina relative to the total mass of thermally conductive filler,

[0013] - from 15 to 150 pce of silicone oil having a viscosity at 25°C of less than 150,000 mPa.s, and

[0014] - 0.2 to 5 pce of a crosslinking agent.

[0015] I- DEFINITIONS

[0016] The expression "composition based on" means a composition comprising the mixture and / or the in situ reaction product of the various constituents used, some of these constituents being able to react and / or being intended to react with each other, at least partially, during the various phases of manufacture of the composition; the composition can thus be in a totally or partially crosslinked state or in a non-crosslinked state. The expression "elastomer matrix" means all the elastomers in the composition. The expression "part by weight per hundred parts by weight of elastomer" (or pce) means, within the meaning of the present invention, the part, by mass per hundred parts of elastomer present in the rubber composition in question.

[0017] In this document, unless expressly stated otherwise, all percentages (%) indicated are percentages (%) by mass.

[0018] On the other hand, any interval of values ​​designated by the expression "between a and b" represents the range of values ​​from more than a to less than b (i.e., excluding the limits a and b), while any interval of values ​​designated by the expression "from a to b" means the range of values ​​from a to b (i.e., including the strict limits a and b). In this document, when an interval of values ​​is designated by the expression "from a to b", the interval represented by the expression "between a and b" is also and preferably designated.

[0019] The compounds mentioned in the description may be of fossil or bio-sourced origin. In the latter case, they may be, partially or totally, derived from biomass or obtained from renewable raw materials derived from biomass. Similarly, the compounds mentioned may also come from the recycling of materials already in use, i.e. they may be, partially or totally, derived from a recycling process, or obtained from raw materials themselves derived from a recycling process. This includes, in particular, polymers, plasticizers, fillers, etc.

[0020] Unless otherwise stated, all glass transition temperature “Tg” values ​​described herein are measured in a known manner by DSC (Differential Scanning Calorimetry) according to ASTM D3418 (1999).

[0021] II- DESCRIPTION OF THE INVENTION

[0022] II- 1 Elastomer matrix

[0023] According to the invention, the elastomer matrix of the thermal interface material is based on 85 to 100 phr of silicone rubber having a mass-average molar mass (Mw) in a range from 150 to 1,000 kg / mol. Below 150 kg / mol, the silicone rubber has a consistency and viscoelastic behavior of the silicone such that it is difficult to handle and process. In addition, if the Mw of the silicone rubber is too low, the effectiveness of the crosslinking is reduced. Above 1,000 kg / mol, the silicone rubber has a high consistency and its processing becomes complex and requires significant transformation energies. Preferably, the silicone rubber has an Mw in a range from 300 to 900 kg / mol, preferably from 500 to 800 kg / mol.

[0024] The macrostructure (Mw, Mn and Ip) of the silicone rubber is determined by size exclusion chromatography (SEC): solvent tetrahydrofuran; temperature 35°C; concentration 1 g / l; flow rate 1 ml / min; solution filtered on a 0.45 pm porosity filter before injection; Moore calibration with polystyrene standards; set of 3 "WATERS" columns in series ("STYRAGEL" HR4E, HR1 and HR0.5); detection by differential refractometer ("WATERS 2410") and its associated operating software ("WATERS EMPOWER").

[0025] The thermal interface material according to the invention may comprise a single or a mixture of silicone rubber having the aforementioned Mw. In particular, the silicone rubber is selected from the group consisting of polydimethylsiloxanes (PDMS), polymethylarylsiloxanes (in particular polymethylphenylsiloxanes) and mixtures thereof. Preferably, the silicone rubber is selected from the group consisting of PDMS and mixtures thereof.

[0026] The silicone rubber may have vinyl functions. For example, the silicone rubber may not have vinyl functions or may have them at a molar level that is less than 2%, preferably less than 1%, preferably less than 0.5%. When the silicone rubber has vinyl functions, the molar fraction of vinyl functions within the silicone rubber may be between 0.01% and 2%, preferably between 0.05% and 1%, preferably between 0.08% and 0.5%.

[0027] The molar fraction of vinyl function within silicone rubber is determined by NMR spectrometry 1 H, 13 C. NMR spectra are recorded on a Brüker Avance III 500 MHz Spectrometer equipped with a BBIz-grad 5 mm “broadband” cryoprobe. The quantitative 'H NMR experiment uses a single 30° pulse sequence and a 5 second repetition delay between each acquisition. 64 to 256 accumulations are performed. The NMR experiment 13 Quantitative C uses a 30° single-pulse sequence with proton decoupling and a 10-second repetition delay between each acquisition. 1024 to 10240 accumulations are performed. Two-dimensional experiments are used for the purpose of determining the structure of polymers. NMR measurements are carried out at 25°C. the copolymers being in solution in a deuterated solvent (approximately 25 mg of elastomer in 1 mL), generally deuterated chloroform (CDCh). The elastomer matrix may comprise elastomers other than silicone rubber, but this is neither mandatory nor preferred. Preferably, the elastomer matrix does not comprise an elastomer other than silicone rubber having an Mw in the range of 150 to 1000 kg / mol or comprises less than 15 phr, preferably less than 10 phr, preferably less than 5 phr. More preferably, the elastomer matrix comprises only, i.e. 100 pce, silicone rubber having an Mw in a range from 150 to 1,000 kg / mol, preferably from 300 to 900 kg / mol, preferably from 500 to 800 kg / mol.

[0028] Examples of silicone rubber useful for the purposes of the invention and commercially available include Elastosil® R401-10, Elastosil® R401-25, Elastosil® R401-70, Elastosil® R401-90 or Elastosil®R402-75 from Wacker.

[0029] II-2 Thermally conductive charge

[0030] The thermal interface material according to the invention is based on 250 to 1000 phr of thermally conductive filler, the thermally conductive filler comprising more than 50% by mass of alumina relative to the total mass of thermally conductive filler.

[0031] The thermally conductive filler may thus be composed of a mixture of several thermally conductive fillers including more than 50% by mass of alumina, but this is neither obligatory nor preferred. Preferably, the thermally conductive filler comprises more than 60% by mass, preferably more than 75% by mass, preferably more than 90% by mass, preferably 100% by mass of alumina. In other words, the thermally conductive filler preferably does not comprise any filler other than alumina, or comprises less than 40% by mass, preferably less than 25% by mass, preferably less than 10% by mass.

[0032] Alumina can be in different forms, in particular in the form of particles. Preferably, the alumina is present in the form of particles whose median diameter D50 is in a range from 2 to 150 pm, preferably from 10 to 100 pm, preferably from 20 to 70 pm. The D50 represents the diameter of the particles for which 50% of the volume of all the particles has a smaller diameter and 50% of the volume has a larger diameter.

[0033] Examples of commercially available alumina include Silatherm® 1432-006 or 1432-400 or Silatherm ©VST1432-006 or VST1432-400 from Quarzwerke. Advantageously, the content of the thermally conductive filler in the thermal interface material according to the invention is in a range from 370 to 720 phr, preferably from 380 to 600 phr, preferably from 390 to 500 phr, the thermally conductive filler comprises more than 60% by mass, preferably more than 75% by mass, preferably more than 90% by mass, preferably 100% by mass of alumina.

[0034] Regardless of the pce rate of thermally conductive filler in the thermal interface material, it is preferable that the volume rate of the thermally conductive filler in the thermal interface material is within a range of 40% to 60%, preferably 42% to 58%, preferably 45% to 56%, and that the thermally conductive filler comprises more than 60% by mass, preferably more than 75% by mass, preferably more than 90% by mass, preferably 100% by mass of alumina.

[0035] II-3 Silicone oil

[0036] The thermal interface material according to the invention is based on 15 to 150 pce of silicone oil having a viscosity at 25°C of less than 150,000 mPa.s.

[0037] The viscosity of silicone oil is determined at 25°C and atmospheric pressure using the Brookfield technique. Brookfield viscosity characterizes liquid substances in a known manner. The apparent viscosity using the Brookfield method is measured at a given temperature (e.g., 25°C) according to the European and international standard EN ISO 2555 (1999). For example, a type A viscometer (e.g., RVT model) or type B viscometer (e.g., HAT model) is used at a rotation frequency preferably equal to 10 or 20 min. 1 , with a mobile number (1 to 7) adapted to the measured viscosity range (according to Annex A of standard EN ISO 2555). The viscosity is expressed in mPa.s or centipoise (cP) (1 cP = 1 mPa.s).

[0038] Advantageously, the silicone oil has a viscosity at 25°C in a range from 20 to 90,000 mPa.s, preferably from 40 to 50,000 mPa.s, preferably from 50 to 20,000 mPa.s. More preferably, the silicone oil has a viscosity at 25°C in a range from 20 to 20,000 mPa.s, preferably from 40 to 5,000 mPa.s, preferably from 50 to 2,000 mPa.s.

[0039] The silicone oils may be functionalized or not. Preferably, the silicone oil is a silicone oil having no hydroxyl function and / or no vinyl function. More preferably, the silicone oil has no polar function and / or no function comprising a double bond. As an example of a silicone oil useful for the purposes of the invention and commercially available, mention may be made of the grades AK-50, AK-100, AK-1000, AK-10000 or even the grade AK-100000 from the company Wacker.

[0040] The silicone oil content is in a range from 15 to 150 phr. Outside this range, it has been found that the mechanical properties (elongation at break, breaking stress) were not satisfactory at thermally conductive filler content in accordance with the invention. Preferably, the silicone oil content in the thermal interface material is in a range from 15 to 80 phr, preferably from 20 to 60 phr.

[0041] Advantageously, the mass ratio of the thermally conductive filler to the silicone oil is within a range from more than 4.2 to 35, preferably from 5 to 30, preferably from 10 to less than 20, preferably from 10 to less than 18.

[0042] In order to further improve the mechanical properties of the thermal interface material, the level of silicone oil that can be used may be adapted according to the viscosity of the silicone oil used. For example, the thermal interface material may comprise from 15 to 35 phr, preferably from 20 to 30 phr of a silicone oil having a viscosity at 25°C of between 50,000 and 150,000 mPa.s.

[0043] Preferably, the thermal interface material comprises from 15 to 60 phr, preferably from 15 to 40 phr, preferably from 20 to 35 phr of a silicone oil having a viscosity at 25°C in a range from 5,000 to 50,000 mPa.s, preferably from 5,000 to 20,000 mPa.s.

[0044] More preferably, the thermal interface material comprises from 15 to 90 phr, preferably from 15 to 80 phr, preferably from 20 to 75 phr of a silicone oil having a viscosity at 25°C of between 20 and 5,000 mPa.s, preferably from 50 to 1,500 mPa.s.

[0045] II-4 Crosslinking agent

[0046] The thermal interface material according to the invention is based on 0.2 to 5 phr of a crosslinking agent. The crosslinking agent may be any crosslinking agent for crosslinking a silicone rubber. Advantageously, the crosslinking agent is a peroxide or a mixture of several peroxides. It may be any peroxide known to those skilled in the art. Among the peroxides, well known to those skilled in the art, it is preferable to use an organic peroxide in the context of the present invention.

[0047] The term "organic peroxide" refers to an organic compound, i.e. one containing carbon, with an -OO- group (two oxygen atoms linked by a single covalent bond). During the crosslinking process, the organic peroxide decomposes at its unstable 0-0 bond into free radicals. These free radicals allow the creation of crosslinking bonds.

[0048] The organic peroxide is preferably selected from the group comprising or consisting of dialkyl peroxides, monoperoxycarbonates, diacyl peroxides, peroxyketals or peroxyesters.

[0049] Preferably, the dialkyl peroxides are selected from the group comprising or consisting of dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, 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)hexyne-3, 2,5-dimethyl-2,5-di(t-amylperoxy)hexyne-3, a,a'-di-[(t-butyl-peroxy)isopropyl]benzene, a,a'-di-[(t-amyl-peroxy)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.

[0050] Some monoperoxycarbonates such as 00-tert-butyl-0-(2-ethylhexyl) monoperoxycarbonate, OO-tert-butyl-O-isopropyl monoperoxycarbonate and OO-tert-amyl-O-2-ethyl hexyl monoperoxycarbonate, may also be used.

[0051] Among the diacyl peroxides, the preferred peroxide is benzoyl peroxide.

[0052] Among the peroxyketals, preferred peroxides are selected from the group comprising or consisting of 1,1-di-(t-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl 4,4-di-(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 trimer cyclic peroxide), 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, l,l-di(t-butylperoxy)cyclohexane, l,l-di(t-amylperoxy)cyclohexane and mixtures thereof. Preferably, the peroxyesters are selected from the group consisting of tert-butylperoxybenzoate, tert-butylperoxy-2-ethylhexanoate and tert-butylperoxy-3,5,5-trimethylhexanoate.

[0053] In summary, the organic peroxide is particularly preferably selected from the group consisting of dicumyl peroxide, aryl peroxides, diaryl peroxides, diacetyl peroxide, benzoyl peroxide, dibenzoyl peroxide, ditertbutyl peroxide, tertbutylcumyl peroxide, 2,5-bis(tertbutylperoxy)-2,5-dimethylhexane, n-butyl-4,4'-di(tert-butylperoxy) valerate, OO-(t-butyl)-O-(2-ethylhexyl) monoperoxycarbonate, tert-butyl peroxyisopropylcarbonate, tert-butyl peroxybenzoate, tert-butyl peroxy-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'-di(tert-butylperoxy)-valerate, OO-(t-butyl) O-(2-ethylhexyl) monoperoxycarbonate, tert-butyl peroxyisopropylcarbonate, tert-butyl peroxybenzoate, tert-butyl peroxy-3,5,5-trimethylhexanoate, 1,3(4)-bis(tert-butylperoxyisopropyl)benzene and mixtures thereof.

[0054] 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 RT Vanderbilt Co., or "Luperko" from Wallace & Tiernan, Inc.

[0055] II-5 Possible additives

[0056] The thermal interface material may optionally also include all or part of the usual additives usually used in TMM, such as pigments, protective agents, antioxidants, flame retardants.

[0057] II-6 Preparation of compositions

[0058] The materials in accordance with the invention can be manufactured in suitable mixers, using two successive preparation phases well known to those skilled in the art: - a first thermomechanical working or mixing phase (so-called "non-productive" phase), which can be carried out in a single thermomechanical step during which all the necessary constituents, in particular the elastomer matrix, the thermally conductive filler, any other various additives, with the exception of the crosslinking system, are introduced into a suitable mixer such as a conventional internal mixer (for example of the "Banbury" type). The incorporation of the filler into the elastomer can be carried out in one or more times by thermomechanically mixing.In the case where the filler is already incorporated in whole or in part into the elastomer in the form of a masterbatch as described for example in applications WO 97 / 36724 or WO 99 / 16600, it is the masterbatch which is directly mixed and where appropriate the other elastomers or fillers present in the composition which are not in the form of a masterbatch are incorporated, as well as any other various additives other than the crosslinking system. The non-productive phase can be carried out at high temperature, up to a maximum temperature of between 80°C and 150°C, preferably between 100°C and 120°C, for a duration generally of between 2 and 10 minutes.

[0059] - a second phase of mechanical work (so-called "productive" phase), which can be carried out in an external mixer such as a cylinder mixer, after cooling the mixture obtained during the first non-productive phase to a lower temperature, typically below 120°C, for example between 40°C and 100°C. The crosslinking system is then incorporated, and everything is then mixed for a few minutes, for example between 5 and 15 min.

[0060] Such phases have been described for example in applications EP-A-0501227, EP-A-0735088, EP-A-0810258, WO00 / 05300 or WO00 / 05301.

[0061] The final composition thus obtained is then calendered, for example, in the form of a sheet or a plate.

[0062] These products can then be used for the manufacture of thermal interface materials such as thermally conductive pads or thermally conductive sheets, according to techniques known to those skilled in the art. The composition can in particular be molded and crosslinked, for example at a temperature between 130°C and 200°C, under pressure to form a thermal interface pad.

[0063] II-7 Thermal interface material

[0064] The thermal interface material according to the invention can be used for any application enabling the extraction of heat emitted by an object. For example, it is particularly well suited to transferring heat emitted by an electric car battery during use or during charging.

[0065] The thermal interface material according to the invention may be in any form and at any thickness enabling it to perform its function. Preferably, the thermal interface material is chosen from the group consisting of thermally conductive pads and thermally conductive sheets. Furthermore, the thermal interface material preferably has a thickness in a range from 0.2 to 10 mm, preferably from 0.5 to 8 mm, preferably from 1 to 6 mm, preferably more than 1 to 6 mm, preferably from 1.1 to 6 mm.

[0066] III- EXAMPLES

[0067] III- 1 Preparation of the compositions

[0068] In the following examples, the rubber compositions were produced as described in point II.6 above. In particular, the “non-productive” phase was carried out in a 0.4 liter mixer for 3.5 minutes, for an average paddle speed of 50 revolutions per minute until a maximum drop temperature of 90°C was reached. The “productive” phase was carried out in a cylinder tool at 40°C for 5 to 10 minutes. The crosslinking of the composition was carried out at a temperature of 150°C for 30 minutes, under pressure. From the crosslinked plates obtained, test pieces were cut out to measure the tensile mechanical properties (modulus and elongation).

[0069] III-2 Measurements and tests used

[0070] Mechanical properties

[0071] These tensile tests allow the determination of yield stresses and properties at break. Processing of the tensile records also allows the plotting of the modulus curve as a function of elongation. The modulus used here is the nominal (or apparent) secant modulus measured at first elongation, calculated by referring to the initial section of the specimen. The stresses at break (CR in MPa) and the elongations at break (AR in %) are measured at 23 °C ± 2 °C, according to standard NF T 46-002 of September 1988. The energy at break is equal to the product of the elongation at break and the stress at break.

[0072] Thermal conductivity

[0073] Cylindrical samples measuring 40 mm x 8 mm were made by molding. A Hotkisk TPS 1000 device was used to determine thermal conductivity using the TPS (Transient Plane Source) method. A heat flux with a power of 80 mW was applied to the sample for 10 seconds. The thermal conductivity of the sample was thus determined by the observed temperature variation, itself determined by measuring the variation in electrical resistance of the material via a Wheatstone bridge in the sample.

[0074] III-3 Rubber composition tests

[0075] The examples presented below aim to compare the elongation at break properties of compositions in accordance with the present invention (C1 to C10) with two control compositions (T1 and T2).

[0076] Table 1 presents the tested compositions (in pce), as well as the results obtained.

[0077] The compositions in accordance with the invention differ from the control compositions by the levels of thermally conductive filler and silicone oil, the volume fraction of thermally conductive filler being constant.

[0078] [Table 1]

[0079] (a) Silicone elastomer R401 / 70 from Wacker and mass Mn= 350kg / mol, mass Mw= 620kg / mol

[0080] (SEC RI PS)

[0081] (b) Alumina Silatherml432-006 from the company Quarzwerke with a D50 size of 46 gm

[0082] (cl) Wacker AK10000 silicone oil with a viscosity of 10000 mPa.s

[0083] (d) Dicumyl peroxide from Sigma-Aldrich

[0084] [Table 2]

[0085] (a), (b), (d): See Table 1

[0086] (c2) Wacker AK100 silicone oil with a viscosity of 100 mPa.s

[0087] (c3) Wacker AK1000 silicone oil with a viscosity of 1000 mPa.s

[0088] (c4) Wacker AK100000 silicone oil with a viscosity of 100000 mPa.s

[0089] The results presented in Table 1 above show that the compositions in accordance with the invention all have elongations at break that are much higher than the control compositions, without having too much of an impact on the thermal conductivity of the composition, or even without impacting it at all. In particular, increasing the silicone oil content at a constant volume fraction of thermally conductive filler makes it possible to improve the elongation at break and the breaking energy. Comparison of compositions C1, C5, C8 and C10 or compositions C4 and C7 shows that the lower the viscosity of the oil, the better the elongation at break and the breaking stress at a given rate. The highest elongations at break are achieved when the viscosity of the silicone oil is the lowest and when the levels of these silicone oils are the highest.

[0090] Thus, the compositions in accordance with the invention make it possible to obtain highly deformable thermal interface materials, which make them particularly interesting for use in particular as thermally conductive pads or sheets.

Claims

Claims 1. Thermal interface material based on: - an elastomer matrix comprising from 85 to 100 pce of silicone rubber having a mass-average molar mass, Mw, in a range from 150 to 1,000 kg / mol, - 250 to 1000 pce of a thermally conductive filler, the thermally conductive filler comprising more than 50% by mass of alumina relative to the total mass of thermally conductive filler, - from 15 to 150 pce of silicone oil having a viscosity at 25°C of less than 150,000 mPa.s, and - 0.2 to 5 pce of a crosslinking agent.

2. Thermal interface material according to claim 1, wherein the silicone rubber is selected from the group consisting of polydimethylsiloxanes (PDMS), polymethylarylsiloxanes and mixtures thereof, preferably the silicone rubber is selected from the group consisting of polydimethylsiloxanes and mixtures thereof.

3. Thermal interface material according to any one of the preceding claims, in which the silicone rubber does not have a vinyl function or has one at a molar level which is less than 2%, preferably less than 1%, preferably less than 0.5%.

4. Thermal interface material according to any one of the preceding claims, wherein the silicone rubber has an Mw in a range from 300 to 900 kg / mol, preferably from 500 to 800 kg / mol.

5. Thermal interface material according to any one of the preceding claims, in which the rate of the thermally conductive filler is within a range from 370 to 720 phr, preferably from 380 to 600 phr, preferably from 390 to 500 phr.

6. Thermal interface material according to any one of the preceding claims, wherein the volumetric content of the thermally conductive filler in the thermal interface material is in a range from 40% to 60%, preferably from 42% to 58%, preferably from 45% to 56%.

7. Thermal interface material according to any one of the preceding claims, wherein the thermally conductive filler comprises more than 60% by mass, preferably more than 75% by mass, preferably more than 90% by mass of alumina.

8. Thermal interface material according to any one of the preceding claims, in which the alumina is present in the form of particles whose median diameter D50 is in a range from 2 to 150 pm, preferably from 10 to 100 pm, preferably from 20 to 70 pm.

9. Thermal interface material according to any one of the preceding claims, in which the silicone oil is a silicone oil having no hydroxyl function and / or no vinyl function.

10. Thermal interface material according to any one of the preceding claims, wherein the silicone oil has a viscosity in a range from 20 to 20,000 mPa.s, preferably from 40 to 5,000 mPa.s, preferably from 50 to 2,000 mPa.s.

11. Thermal interface material according to any one of the preceding claims, in which the level of silicone oil is in a range from 15 to 80 phr, preferably from 20 to 60 phr.

12. Thermal interface material according to any one of the preceding claims, wherein the mass ratio of the thermally conductive filler to the silicone oil is in a range from more than 4.2 to 35, preferably from 5 to 30, preferably from 10 to less than 18.

13. Thermal interface material according to any one of the preceding claims, wherein the crosslinking agent is an organic peroxide preferably selected from the group consisting of dicumyl peroxide, aryl peroxides, diaryl peroxides, diacetyl peroxide, benzoyl peroxide, dibenzoyl peroxide, ditertbutyl peroxide, tertbutylcumyl peroxide, 2,5-bis(tertbutylperoxy)-2,5-dimethylhexane, n-butyl-4,4'-di(tert-butylperoxy) valerate, OO-(t-butyl)-O-(2-ethylhexyl) monoperoxy carbonate, tert-butyl peroxyisopropylcarbonate, tert-butyl peroxybenzoate, tert-butyl peroxy-3,5,5-trimethylhexanoate, l,3(4)-bis(tert-butylperoxyisopropyl)benzene and mixtures thereof.

14. Thermal interface material according to any one of the preceding claims, said material being selected from the group consisting of thermally conductive pads and thermally conductive sheets.

15. Thermal interface material according to any one of the preceding claims, said material having a thickness in a range from 0.2 to 10 mm, preferably from 0.5 to 8 mm, preferably more than 1 to 6 mm.

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