Lignin-based filler containing rubber compositions for improving thermal conductivity and electrical insulation

Abstract

The present invention relates to a curable rubber composition comprising at least one silicone rubber, at least one curing agent, and at least one lignin-based filler F1, which is different from carbon black, and which has an STSA surface area of up to 200 m² / g, wherein the amount of the at least one curing agent is in a range of from 0.05 to 5.5 phr, a kit-of-parts comprising A) at least a part of said rubber composition, and C) at least said at least one lignin-based filler F1, a cured rubber composition obtainable from said curable rubber composition, a use of said at least one filler F1 for improving the thermal conductivity and / or the electrical volume resistivity of cured rubber compositions, a use of the aforementioned compositions for manufacturing articles, parts and / or components, an thereby obtained articles, parts and / or components, and a process for preparing said article, part and / or component.

Description

[0001] 21003 PC / L024873PCT 1 October 01, 2024

[0002] UPM-Kymmene Corporation

[0003] Lignin-based filler containing rubber compositions for improving thermal conductivity and electrical insulation

[0004] The present invention inter alia relates to a curable rubber composition, a kit-of-parts, a cured rubber composition obtainable from said curable rubber composition, a use of at least one filler inter alia being comprised in said curable rubber composition, a use of said curable rubber composition, said kit-of-parts or said cured rubber composition, an article, part and / or component obtainable from said curable rubber composition, said kit-of-parts or said cured rubber composition, and a process for preparing said article, part and / or component.

[0005] Background of the invention

[0006] Efficient temperature management is important for all kinds of electrical applications like those in the automotive, aerospace, engineering, and / or electrical industry, and is in particular crucial, when large amounts of energy are to be transferred in short times. High energy battery packs required by modern electric vehicles are a prominent example, in which high amounts of heat are generated during driving, but also during charging. However, as the battery lifetime and the maximum performance of such batteries are highly temperature dependent, e.g., to a range of from 20 °C to 35 °C for lithium-ion batteries, such batteries can only be operated in a very narrow temperature range and thus any generated excess heat needs to be removed very efficiently to not exceed these values.

[0007] So-called thermal interface materials (TIM) play a central role in this context, which are often based on polymers, in particular rubbers, due to their electrical insulating nature, which is a prerequisite to avoid any damage by electrical shortages. Unfortunately, pure rubbers are generally characterized by a naturally comparably low thermal conductivity of only, e.g., 0.1 to 0.25 W / (m K), which makes it necessary to incorporate heavy, high density inorganic materials like silica (p (density) of about 2.0 g / cm3), talc (p about 2.6 g / cm3), clay (p about 2.6 g / cm3), and / or aluminum oxides (p about 4.0 g / cm3) in very high amounts such as up to 90 wt.-% based on the total material weight, i.e. , as fillers, into said rubbers. 21003 PC / L024873PCT 2 October 01, 2024

[0008] UPM-Kymmene Corporation

[0009] The use of lighter, carbon-based functional fillers as, e.g., graphite (p about 2.3 g / cm3) or carbon black (p aboutl .8 g / cm3), is also known to prior art. In general, such carbonbased functional fillers often exhibit good thermal conductivities, i.e. , about 25 W / (m K) for graphite and about 0.3 to 0.5 W / (m K) for carbon black (cf., e.g., P.E. Khizhnyak et al., Journal of Engineering Physics 1979, 37, 1073-1075). However, their incorporation in polymers or rubbers used for the application in TIMs is only possible at very low filler loadings, which makes achieving a high thermal conductivity in combination with a low material density and a high electrical insulation at least very difficult.

[0010] Thus, there is a need for providing rubber-based materials, which are not only both light-weighted and thermally conductive, but which at the same time are also highly electrically insulating, and which are especially suitable for the use in automotive, aerospace, engineering, and / or electrical industry, in particular in battery packs, and which can be used, e.g., in form of or as part of a thermal interface material (TIM).

[0011] Problem

[0012] It has been therefore an objective underlying the present invention to provide rubberbased materials, which are not only both light-weighted and thermally conductive, but which at the same time are also highly electrically insulating, and which are especially suitable for the use in automotive, aerospace, engineering, and / or electrical industry, in particular in battery packs, and which can be used, e.g., in form of or as part of a thermal interface material (TIM).

[0013] Solution

[0014] This objective has been solved by the subject-matter of the claims of the present application as well as by the preferred embodiments thereof disclosed in this specification, i.e. by the subject matter described herein.

[0015] A first subject-matter of the present invention is a curable rubber composition comprising at least one silicone rubber, which is curable by means of at least one curing agent, 21003 PC / L024873PCT 3 October 01, 2024

[0016] UPM-Kymmene Corporation at least one curing agent, which is suitable for curing the at least one silicone rubber, and at least one lignin-based filler F1 , which is different from carbon black, and which has an STSA surface area of up to 200 m2 / g, wherein the amount of the at least one curing agent is in a range of from 0.05 to 5.5 phr.

[0017] A further subject-matter of the present invention is a kit-of-parts comprising, in spatially separated form, as part A) at least a part of a curable rubber composition as defined hereinbefore and hereinafter, wherein part A) does, however, not comprise the at least one lignin-based filler F1 as defined hereinbefore and hereinafter, optionally as part B) the remaining part of the curable rubber composition according to the present invention not being present in part A), wherein part B) does, however, not comprise the at least one lignin-based filler F1 as defined hereinbefore and hereinafter, and as part C) at least the at least one lignin-based filler F1 as defined hereinbefore and hereinafter.

[0018] A further subject-matter of the present invention is a cured rubber composition,

[0019] (i) which is obtainable by curing the curable rubber composition as hereinbefore and hereinafter, or by curing a curable rubber composition obtainable by combining and mixing both A), optionally B), and C) of the kit-of-parts according to hereinbefore and hereinafter, or

[0020] (ii) which has a thermal conductivity at 25 °C in a range of from 0.04 to 5.0 W / (m K), an electrical volume resistivity of at least 1 .0 109Q cm, and is obtainable from a curable 21003 PC / L024873PCT 4 October 01, 2024

[0021] UPM-Kymmene Corporation rubber composition comprising at least one rubber, which is curable by means of at least one curing agent, at least one curing agent, which is suitable for curing the at least one rubber, and at least one lignin-based filler F1 , which is different from carbon black and which has an STSA surface area of up to 200 m2 / g, wherein the amount of the at least one curing agent in the rubber composition preferably is in a range of from 0.05 to 5.5 phr.

[0022] A further subject-matter of the present invention is a use of at least one filler F1 as defined hereinbefore and hereinafter for improving the thermal conductivity and / or the electrical volume resistivity of cured rubber compositions such as of the cured rubber composition as defined hereinbefore and hereinafter, preferably for simultaneously improving the thermal conductivity and the electrical volume resistivity such as of the cured rubber composition as defined hereinbefore and hereinafter, more preferably for improving the thermal conductivity, the electrical volume resistivity and at least one physical property selected from density, elongation at break, tensile strength and compression set of cured rubber compositions such as of the cured rubber composition as defined hereinbefore and hereinafter, even more preferably for improving the thermal conductivity, the electrical volume resistivity and at least one physical property selected from density and compression set of cured rubber compositions such as of the cured rubber composition as defined hereinbefore and hereinafter.

[0023] A further subject-matter of the present invention is a use of the curable rubber composition as defined hereinbefore and hereinafter, of the kit-of-parts as defined hereinbefore and hereinafter, or of the cured rubber composition as defined hereinbefore and hereinafter, for manufacturing articles, parts and / or components, which preferably are suitable for use in the automotive and / or aerospace and / or engineering and / or electrical industry, which more preferably are suitable for the manufacture of battery packs, whereby said curable rubber composition, said kit-of- parts, or said cured rubber composition, preferably is used as or is at least part of a thermal interface material (TIM).

[0024] A further subject-matter of the present invention is an article, part and / or component, which is in each case obtainable from the curable rubber composition as defined hereinbefore and hereinafter, or from the kit-of-parts as defined hereinbefore and 21003 PC / L024873PCT 5 October 01, 2024

[0025] UPM-Kymmene Corporation hereinafter, or from the cured rubber composition as defined hereinbefore and hereinafter, and which preferably is suitable for use in the automotive and / or aerospace and / or engineering and / or electrical industry, which more preferably is suitable for use in battery packs, whereby said article, part and / or component most preferably is used as or is at least part of a thermal interface material (TIM).

[0026] A further subject-matter of the present invention is a process for preparing the article, part and / or component as defined hereinbefore and hereinafter, wherein said process comprises at least one step, according to which the curable rubber composition as defined hereinbefore and hereinafter is shaped into the article, part and / or component, preferably before curing has been performed, by at least one of injection molding, compression molding, transfer molding, extrusion, coextrusion, extrusion coating, coating, printing, laminating, and calendering.

[0027] It has been in particular surprisingly found that rubber materials, which are both light- weighted, highly thermally conductive, and also highly electrically insulating at the same time can be achieved by the use of silicone rubbers and lignin-based fillers F1 . It has been surprisingly found that by the use of these materials excellent characteristics for all three aforementioned properties can be achieved simultaneously, i.e., a low density, a high thermal conductivity and a high electrical insulation capacity, whereby materials according to the prior art such as rubber materials comprising carbon blacks as fillers were only able to achieve at most two of the aforementioned characteristics to a sufficient degree, making the inventive composition unique in this regard.

[0028] Moreover, it has been in particular surprisingly found that by incorporating the ligninbased filler F1 into a silicone rubber instead of incorporating other fillers such as graphite or carbon black fillers, the thermal conductivity of the cured rubber composition cannot only be increased, but that the fillers F1 can also be applied in very high loadings, in particular in higher loadings than the other aforementioned fillers, without compromising the relevant properties such as mechanical properties, but in particular the thermal conductivity and electrical resistivity of the cured rubber composition, particularly since the lignin-based renewable fillers F1 have much lower densities than conventional fillers such as graphite or carbon black fillers. 21003 PC I L024873PCT 6 October 01, 2024

[0029] UPM-Kymmene Corporation

[0030] In addition, it has been in particular surprisingly found that the inventive cured compositions are suitable to be used for manufacturing TIMs for high energy battery applications.

[0031] Finally, it has been in particular surprisingly found that the thermal conductivity of the inventive cured compositions is largely identical at 25 °C and at 55 °C, demonstrating that even excess heat outside preferred operating temperature ranges can be efficiently dissipated without increasing the risk of damage to the electrical device.

[0032] Detailed description of the invention

[0033] The term “comprising” as used in the present invention in connection with, for example, the curable rubber composition according to the invention preferably has the meaning “consisting of.” In this context, for example, with regard to the curable rubber composition according to the invention, one or more of the further constituents optionally contained that are mentioned hereinafter may also be contained therein in addition to the constituents mandatorily present therein. All constituents may be present in each of their preferred embodiments mentioned hereinafter.

[0034] The amount of all constituents described herein, such as the constituents contained in the curable rubber compositions according to the invention (comprising in each case all the mandatory constituents and, moreover, all the optional constituents), add up in total to 100% by weight (100 wt.-%) in each case.

[0035] Curable rubber composition

[0036] Any constituents comprised in the curable rubber composition, including the at least one silicone rubber, the at least one curing agent and the at least one lignin-based filler F1 , are described in more detail in the following.

[0037] Silicone rubber

[0038] The at least one silicone rubber is curable by means of at least one curing agent. 21003 PC / L024873PCT 7 October 01, 2024

[0039] UPM-Kymmene Corporation

[0040] A person skilled is aware of silicone rubbers and methods for preparing silicone rubbers, e.g., silicone homo- and copolymers. Silicone homo- and copolymers are preferably prepared by polycondensation of siloxanes, which may be in form of a monomer or of a cycle comprising four siloxane units. Conventionally, the polymerization takes place at temperatures over 100 °C, preferably under alkaline conditions, e.g., in presence of potassium hydroxide and optionally in presence of a catalyst. Generally, the polycondensation is terminated by the addition of water and / or monofunctional silanes. To obtain a silicone copolymer, two or more different siloxanes are mixed in specific ratios during such a reaction.

[0041] Preferably, the at least one silicone rubber is selected from silicone homopolymers and copolymers, silicone based homopolymers and copolymers, and mixtures thereof, more preferably from polysiloxanes (Q), homopolymers of polydimethylsiloxane (MQ), copolymers of dimethyl siloxane and vinyl methylsiloxane (VMQ), copolymers of dimethyl siloxane and phenylmethyl siloxane (PMQ), terpolymers of dimethyl-, phenylmethyl- and vinylmethyl siloxane (PVMQ), terpolymers of dimethyl-, trifluoropropylmethyl- and vinylmethyl siloxane (FVMQ), and mixtures thereof, even more preferably from homopolymers of polydimethyl siloxane (MQ) and copolymers of dimethyl siloxane and vinylmethyl siloxane (VMQ), and mixtures thereof, especially preferably from copolymers of dimethyl siloxane and vinylmethyl siloxane (VMQ).

[0042] The at least one silicone rubber preferably is a room-temperature-vulcanizing silicone rubber (RTV), a high-consistency silicone rubber (HCR) and / or a liquid silicone rubber (LSR), whereby the at least one silicone rubber preferably is a liquid silicone rubber.

[0043] Preferably, if the curable rubber composition comprises VMQ, said VMQ comprises dimethyl siloxane in a range of from 90.0 to 99.9 mol-%, more preferably of from 96.0 to 99.8 mol-%, even more preferably of from 99.0 to 99.7 mol-%, and vinylmethyl siloxane in a range of from 0.01 to 10.0 mol-%, more preferably of from 0.02 to 4.0 mol-%, even more preferably of from 0.03 to 1.0 mol-%, each based on the total amount of silicone based monomeric units, more preferably of all monomeric units, comprised in the VMQ, whereby more preferably no other types of silicone based monomeric units, even more preferably no other types of monomeric units at all, are present within the VMQ. 21003 PC / L024873PCT 8 October 01, 2024

[0044] UPM-Kymmene Corporation

[0045] Preferably, if the curable rubber composition comprises PMQ, said PMQ comprises dimethyl siloxane in a range of from 75.0 to 99.5 mol-%, more preferably of from 82.0 to 97.0 mol-%, even more preferably of from 85.0 to 95.0 mol-%, and phenylmethyl siloxane in a range of from 0.5 to 25.0 mol-%, more preferably of from 3.0 to 18.0 mol- %, even more preferably of from 5.0 to 15.0 mol-%, each based on the total amount of silicone based monomeric units, more preferably of all monomeric units, comprised in the PMQ, whereby more preferably no other types of silicone based monomeric units, even more preferably no other types of monomeric units at all, are present within the PMQ.

[0046] Preferably, if the curable rubber composition comprises PVMQ, said PVMQ comprises dimethyl siloxane in a range of from 75.0 to 99.5 mol-%, more preferably of from 82.0 to 97.0 mol-%, even more preferably of from 85.0 to 95.0 mol-%, and phenylmethyl siloxane in a range of from 0.5 to 25.0 mol-%, more preferably of from 3.0 to 18.0 mol- %, even more preferably of from 5.0 to 15.0 mol-%, and vinylmethyl siloxane in a range of from 0.01 to 10.0 mol-%, more preferably of from 0.02 to 4.0 mol-%, even more preferably of from 0.03 to 1 .0 mol-%, each based on the total amount of silicone based monomeric units, more preferably of all monomeric units, comprised in the PVMQ, whereby more preferably no other types of silicone based monomeric units, even more preferably no other types of monomeric units at all, are present within the PVMQ.

[0047] Preferably, if the curable rubber composition comprises FVMQ, said FVMQ comprises dimethyl siloxane in a range of from 5.0 to 85.0 mol-%, more preferably of from 7.5 to 70.0 mol-%, even more preferably of from 10.0 to 60.0 mol-%, and trifluoropropylmethyl siloxane in a range of from 15.0 to 95.0 mol-%, more preferably of from 30.0 to 92.5 mol-%, even more preferably of from 40.0 to 90.0 mol-%, and vinylmethyl siloxane in a range of from 0.01 to 10.0 mol-%, more preferably of from 0.02 to 4.0 mol-%, even more preferably of from 0.03 to 1 .0 mol-%, each based on the total amount of silicone based monomeric units, more preferably of all monomeric units, comprised in the FVMQ, whereby more preferably no other types of silicone based monomeric units, even more preferably no other types of monomeric units at all, are present within the FVMQ. 21003 PC / L024873PCT 9 October 01, 2024

[0048] UPM-Kymmene Corporation

[0049] Preferably, the at least one silicone rubber has a weight average molecular weight in a range of from 30,000 to 2,000,000 g / mol, preferably of from 40,000 to 1 ,600,000 g / mol, more preferably of from 50,000 to 1 ,400,000 g / mol, even more preferably of from 60,000 to 1 ,200,000 or to 1 ,000,000 g / mol.

[0050] Preferably, if the at least one silicone rubber is a room-temperature-vulcanizing silicone rubber (RTV) and / or a liquid silicone rubber (LSR), it has a weight average molecular weight in a range of from 30,000 to 1 ,000,000 g / mol, more preferably of from 40,000 to 600,000 g / mol, still more preferably of from 50,000 to 400,000 g / mol, even more preferably of from 60,000 to 200,000 or to 150,000 g / mol.

[0051] Preferably, if the at least one silicone rubber is a high-consistency silicone rubber (HCR), it has a weight average molecular weight in a range of from 50,000 to 2,000,000 g / mol, more preferably of from 100,000 to 1 ,600,000 g / mol, still more preferably of from 200,000 to 1 ,400,000 g / mol, even more preferably of from 250,000 to 1 ,200,000 or to 1 ,000,000 g / mol.

[0052] Curing agent

[0053] The at least one curing agent is suitable for curing the at least one silicone rubber.

[0054] Preferably, the at least one curing agent is present in the curable rubber composition in an amount in a range of from 0.06 to 5.0 phr, more preferably of from 0.08 to 4.0 or to 3.5 phr, still more preferably of from 0.09 to 3.0 or to 2.5 phr, even more preferably of from 0.10 to 2.0 phr.

[0055] The phr (parts per hundred parts of rubber by weight) specification used herein is the quantity specification commonly used in the rubber industry for rubber compositions. The dosage of the parts by weight of the individual constituents is always based on 100 parts by weight of the total mass of all rubbers present in the respective rubber composition.

[0056] Preferably, the at least one curing agent comprises at least one of curing agents (a), (b), and (c) as defined hereinafter, namely 21003 PC / L024873PCT 10 October 01, 2024

[0057] UPM-Kymmene Corporation

[0058] (a) at least one more preferably organic peroxide, more preferably selected from dialkyl peroxides, alkyl aryl peroxides, diaryl peroxides, alkyl peresters, aryl peresters, diacyl peroxides, polyvalent peroxides and mixtures thereof, even more preferably selected from the group consisting of di-tert-butylperoxide, 2,5-dimethyl-2,5-di(tert-butyl- peroxy)hexane, dicumyl peroxide, tert-butylcumyl peroxide, tert-butyl peroxybenzoate, dibenzoyl peroxide, 1 ,1 -di(tert-butylperoxy)-3,3,5-trimethyl cyclohexane and bis-(tert- butylperoxy)-diisopropylbenzene as well as mixtures thereof, and / or

[0059] (b) at least one silane and / or siloxane, preferably at least one siloxane, preferably comprising at least three Si-H bonds, in particular if the at least one silicone rubber bears vinyl groups, and / or

[0060] (c) at least one alkoxysilane, in particular if the at least one silicone rubber bears hydroxyl groups such as terminal OH-groups.

[0061] Depending on the kind(s) of the at least one silicone rubber present in the curable rubber composition according to the invention, different kinds of curing agents are especially suitable to achieve a sufficient curing. For curing MQ or PMQ silicone rubbers, a curing agent is preferably selected from diacyl peroxides and aryl peresters, e.g., dibenzoyl peroxide or tert-butyl peroxybenzoate. For curing VMQ, PVMQ or FVMQ silicone rubbers, a curing agent is preferably selected from peroxides, more preferably from peroxides listed in item (a) vide supra.

[0062] Preferably, the at least one curing agent comprises at least one curing agent (a) and none of curing agents (b) and (c).

[0063] In addition, if the at least one silicone rubber bears vinyl groups, silanes and / or siloxanes comprising at least three Si-H bonds are especially suitable whereby said silanes can react with the vinyl groups of such a silicon rubber by the means of addition reactions, preferably in presence of a curing catalyst, e.g., a platinum compound such as a Pt (II) catalyst.

[0064] If the at least one silicone rubber alternatively bears hydroxyl groups such as terminal OH-groups, alkoxysilanes are especially suitable whereby said alkoxysilanes can react 21003 PC / L024873PCT 11 October 01, 2024

[0065] UPM-Kymmene Corporation with the hydroxyl groups of such a silicon rubber by the means of condensation reactions.

[0066] Optionally present curing catalyst

[0067] Optionally, at least one curing catalyst is present in the curable rubber composition, which is different from the at least one curing agent, making the curing reaction of at least one of the present curing agents faster.

[0068] Preferably, the at least one curing catalyst is selected from platinum compounds, zinc oxide, thiazoles, and saturated fatty acids with 12 to 24, more preferably 14 to 20 and particularly preferably 16 to 18 carbon atoms, such as stearic acid and the zinc salts of the fatty acids mentioned above, for example.

[0069] Preferably, the at least one platinum compound is selected from platinum nanoparticles optionally present on a support, the support being preferably selected from silicon dioxide, aluminum dioxide and / or carbon, and platinum complexes, the platinum complexes being more preferably selected from platinum halides, platinum olefin complexes, platinum phosphite complexes, platinum alcohol complexes, platinum alkoxide complexes, platinum ether complexes, platinum aldehyde complexes, platinum ketone complexes, platinum vinylsiloxane complexes, trimethylenedipyridineplatinum dichloride, platinum acetylacetonate, dicyclopentadieneplatinum dichloride, dimethylsulfoxide platinum(ll) dichloride, cyclooctadieneplatinum dichloride, gamma-picoline-platinum dichloride, cyclopentadieneplatinum dichloride, and norbornadieneplatinum dichloride, and mixtures thereof.

[0070] The proportion of the at least one curing catalyst in the curable silicone rubber composition according to the invention preferably is 0 or 0.1 to 10 phr, more preferably 0 or 0.2 to 8 phr, even more preferably 0 or 0.2 to 6 phr, most preferably 0 or 0.2 to 3 phr.

[0071] Optionally present co-agent

[0072] Optionally, at least one co-agent is present in the curable rubber composition, which is different from the at least one curing agent and the optionally present curing catalyst. 21003 PC / L024873PCT 12 October 01, 2024

[0073] UPM-Kymmene Corporation

[0074] Co-agents bridge steric effects and suppress reactions that are inactive with regard to cross-linking.

[0075] Preferably, co-agents are selected from monounsaturated and more preferably polyunsaturated organic compounds, which more preferably are selected from the group consisting of di-(meth)acrylates, dimaleinimides, triallyl compounds and unsaturated polymers such as 1 ,2-polybutadiene and trans-polyoctenamere, more preferably having a number-average molecular weight (Mn) of < 10,000 g / mol, particularly preferably of <5,000 g / mol, more particularly preferably of <2,500 g / mol, even more preferably of < 1 ,500 g / mol, still more preferably of < 1 ,000 g / mol, most preferably of <500 g / mol, respectively, as well as mixtures thereof, particularly preferably are selected from the group consisting of ethylene glycoldi(meth)acrylate (EDMA), trimethylolpropane tri(meth)acrylate (TRIM), N,N’-m-Phenylene bismaleimide (MPBM), diallylterephthalate (DATP), triallylcyanurate (TAC), 1 ,4-butandiol di(meth)acrylate and mixtures thereof.

[0076] The proportion of the at least one co-agent in the curable silicone rubber composition according to the invention preferably is 0 or 0.1 to 10 phr, more preferably is 0 or 0.5 to 8 phr, and most preferably is 0 or 1 to 5 phr.

[0077] Lignin-based filler F1

[0078] The at least one lignin-based filler F1 is different from carbon black and has an STSA surface area of up to 200 m2 / g. The method for the determination of the STSA surface area (statistical thickness surface area) is disclosed in the ‘methods’ section hereinafter.

[0079] The above at least one lignin-based filler F1 and its preferred embodiments, as described hereinafter, are also denoted as “at least one filler F1”.

[0080] The terms filler and organic filler are known to a person skilled in the art. Preferably, the filler F1 employed according to the invention is a reinforcing filler, i.e. , an active filler. Reinforcing or active fillers are characterized by a higher specific surface area than inactive fillers and, in contrast to inactive (non-reinforcing) fillers, they can change 21003 PC / L024873PCT 13 October 01, 2024

[0081] UPM-Kymmene Corporation the viscoelastic properties of a rubber by interacting with the rubber within a rubber composition.

[0082] Preferably, the least one filler F1 has an STSA surface area in a range of from 2.5 to 200 m2 / g, more preferably of from 5.0 to <200 m2 / g, even more preferably of from 7.5 to 175 m2 / g, still more preferably of from 10.0 to 150 m2 / g.

[0083] Preferably, the at least one filler F1 has a thermal conductivity at room temperature (preferably at a temperature of from 17 to 23 °C) in a range of from 0.08 to 6.0 W / (m K), more preferably of from 0.12 to 5.0 W / (m K), even more preferably of from 0.16 to 4.0 W / (m K), still more preferably of from 0.20 to 3.5 W / (m K), yet more preferably of from 0.25 to 3.0 or to 2.5 W / (m K), even more preferably of from 0.30 to 2.0 or to 1.5 W / (m K), most preferably of from 0.35 to 1 .0 or to 0.75 or to 0.50 W / (m K).

[0084] Preferably, the least one filler F1 has a BET surface area of up to 200 m2 / g. More preferably, the least one filler F1 has a BET surface area in a range of from 3.0 to 200 m2 / g, more preferably of from 6.0 to <200 m2 / g, even more preferably of from 8.0 to 175 m2 / g, still more preferably of from 12.0 to 150 m2 / g. The method for the determination of the BET surface area (specific total surface area according to Brunauer, Emmett and Teller) is disclosed in the ‘methods’ section hereinafter.

[0085] Preferably, the least one filler F1 has a d99 value of <25 pm, more preferably <20 pm, even more preferably <18 pm, still more preferably <15 pm, yet more preferably <10 pm. The method for the determination of the d99 value is described hereinbelow in the ‘methods’ section and is carried out by means of laser diffraction according to ISO 13320:2009.

[0086] Preferably, the least one filler F1 has a weight average molecular weight in a range of from 1000 to 4000 Da, more preferably of from 1300 to 3700 Da, even more preferably of from 1700 to 3200 Da, yet more preferably of from 2500 to 3000 Da, still more preferably of from 2600 to 2900 Da, most preferably of from 2650 to 2850 Da, in each case when determined based on the soluble fraction of the filler F1. The method for the determination of the weight average molecular weight is described hereinbelow in the ‘methods’ section. 21003 PC / L024873PCT 14 October 01, 2024

[0087] UPM-Kymmene Corporation

[0088] Preferably, the least one filler F1 has a polydispersity index (PDI) in a range of from 1 .5 to 5.0, more preferably of from 1 .8 to 4.5, even more preferably of from 1 .9 to 4.3, still more preferably of from 2.1 to 4.0, yet more preferably of from 2.4 to 3.5, most preferably of from 2.6 to 3.2, when determined based on the soluble fraction of the lignin-based filler. The polydispersity index can be determined by the same method used for determining the weight average molecular weight. The PDI is calculated as the weight average molecular weight divided by the number average molecular weight.

[0089] Preferably, the at least one filler F1 has an ash content in a range of from 0.1 to 3.0 wt.-%, more preferably of from 0.1 to 2.5 wt.-%, even more preferably of from 0.2 to 2.0 wt.-%, still more preferably of from 0.3 to 1 .5 wt.-%, yet more preferably of from 0.4 to 1 .0 wt.-%.

[0090] Preferably, the at least one filler F1 has a solubility in 0.1 M NaOH in a range of from 1 to 40 wt.-%, more preferably of from 3 to 35 wt.-%, even more preferably of from 5 to 30 wt.-%. The method for the determination of the solubility is disclosed in the ‘methods’ section hereinafter.

[0091] Preferably, the at least one filler F1 has a density of at most 1.50 g / cm3More preferably, the at least one filler F1 has a density of 1.00 to 1.50 g / cm3, even more preferably of 1 .15 to 1 .35 g / cm3, still more preferably of 1 .10 to 1 .40 g / cm3. The method for the determination of the density is disclosed in the ‘methods’ section hereinafter.

[0092] Preferably, the least one filler F1 has a carbon content in a range from >60% by weight to <90% by weight, more preferably from >60% by weight to <85% by weight, even more preferably from >60% by weight to <80% by weight. The method for the determination of the carbon content is disclosed in the ‘methods’ section hereinafter.

[0093] Preferably, the at least one filler F1 has an oxygen content in a range from >8% by weight to <30% by weight, more preferably from >10% by weight to <30% by weight, even more preferably from >15% by weight to <30% by weight, relative to the ash-free and water-free filler, respectively. The oxygen content can be determined by high- 21003 PC / L024873PCT 15 October 01, 2024

[0094] UPM-Kymmene Corporation temperature pyrolysis, for example using the EuroEA3000 CHNS-0 Analyzer of the company EuroVector S.p.A.

[0095] Preferably, the at least one filler F1 has at least one kind of functional groups that is selected from phenolic OH groups, phenolate groups, aliphatic OH groups, carboxylic acid groups, carboxylate groups and mixtures thereof.

[0096] Preferably, the at least one filler F1 has a pH value in a range from 6 to 10, more preferably in a range of from 6 to 9, even more preferably in a range from 7 to 9, still more preferably in a range from 7 to <9.

[0097] The term “lignin-based” in the sense of the present invention preferably means that one or more lignin moieties and / or one or more lignin scaffolds are present in the filler F1. Lignins are solid biopolymers that are incorporated into plant cell walls and thus effect the lignification of plant cells. As such, they are present in biomass and in particular in biologically renewable raw materials, and they therefore represent - in particular in hydrothermally treated form - an environmentally friendly filler alternative compared to fillers such as carbon blacks that are obtainable from fossil materials.

[0098] The term “lignin-based filler” in the sense of the present invention preferably means that that the filler F1 is present in a form that is obtainable by means of hydrothermal treatment of at least one kind of lignin-containing biomass such as at least one kind of lignin-containing phytomass, wherein the hydrothermal treatment preferably has been carried out at a temperature in a range from >100 °C to <300 °C, more preferably from >150 °C to <250 °C.

[0099] Suitable processes for hydrothermal treatment, in particular of lignins, are, e.g., described in WO 2017 / 085278 A1 and WO 2017 / 194346 A1 as well as in EP 3 470 457 A1 . Hydrothermal treatment in the sense of the present invention preferably means a hydrothermal carbonization (HTC), which in turn may also be referred to as "aqueous carbonization at elevated temperature and pressure". Hydrothermal treatment preferably refers to a hydrothermal carbonization treatment of a lignin-containing material, which is a thermochemical conversion process of the lignin-containing material in an aqueous suspension. The lignin-containing material preferably is 21003 PC / L024873PCT 16 October 01, 2024

[0100] UPM-Kymmene Corporation selected from a group consisting of kraft lignin, steam explosion lignin, biorefinery lignin, supercritical separation lignin, hydrolysis lignin, flash precipitated lignin, biomass originating lignin, lignin from alkaline pulping process, lignin from soda process, lignin from organosolv pulping, lignin from alkali process, lignin from enzymatic hydrolysis process, and any combination thereof. Preferably, the lignin is wood based lignin, which can originate from softwood and / or hardwood, and / or originates from annual plants.

[0101] "Kraft lignin" is to be understood to be originated from kraft black liquor, which is an alkaline aqueous solution of lignin residues, hemicellulose, and inorganic chemicals used in a kraft pulping process. The black liquor from the pulping process comprises components originating from different softwood and hardwood species in various proportions. Lignin can be separated from the black liquor by different techniques including precipitation and filtration. The precipitated lignin can be purified from inorganic impurities, hemicellulose and wood extractives using acidic washing steps. Further purification can be achieved by filtration. "Flash precipitated lignin" is to be understood as lignin that has been precipitated from black liquor in a continuous process by decreasing the pH of a black liquor flow, under the influence of an over pressure of 200 to 1000 kPa, down to the precipitation level of lignin using a carbon dioxide based acidifying agent, preferably carbon dioxide, and by suddenly releasing the pressure for precipitating lignin. The lignin may be derived from an alkali process. The “alkali process” can begin with liquidizing biomass with strong alkali followed by a neutralization process. After the alkali treatment, the lignin can be precipitated in a similar manner as presented above. The lignin may be derived from steam explosion. Steam explosion is a pulping and extraction technique that can be applied to wood and other fibrous organic material. "Biorefinery lignin" is to be understood to mean lignin that can be recovered from a refining facility or process where biomass is converted into fuel, chemicals, and other materials. "Supercritical separation lignin" is to be understood that lignin that can be recovered from biomass using supercritical fluid separation or extraction technique. The lignin may be derived from a “hydrolysis process”. The lignin derived from the hydrolysis process can be recovered from paperpulp or wood-chemical processes. The lignin may originate from an “organosolv process”. Organosolv is a pulping technique that uses an organic solvent to solubilize lignin and hemicellulose. “Enzymatic hydrolysis processes” are to be understood to 21003 PC / L024873PCT 17 October 01, 2024

[0102] UPM-Kymmene Corporation comprise enzymatic hydrolysis of a plant-based feedstock, such as a wood-based feedstock such as enzymatic hydrolysis of cellulose. Enzymatic hydrolysis is a process, wherein enzyme (s) assist (s) in cleaving bonds in molecules with the addition of elements of water.

[0103] The lignin-containing material may be dissolved in alkaline solution first, prior to the hydrothermal treatment, such as NaOH. The dissolution may be accomplished by heating the mixture of lignin and alkaline solution to about 80 °C, adjusting the pH to a value above 7, such as 9 - 11 , and mixing the mixture of lignin and alkaline solution for a predetermined time. The mixing time may be continued for about 2 to 3 hours. The dissolved lignin material may then be subjected to a hydrothermal treatment such as a hydrothermal carbonization treatment. The hydrothermal carbonization treatment may take place in a reactor or if needed in several parallel reactors, working in a batchwise manner. The dissolved lignin material may be preheated before being entered in the reactor (s). The temperature in the reactor(s) may be 150 to 300 °C or to 250 °C and the pressure may be 20 to 30 bar. The residence time in the reactor(s) may be about three to six hours. In the reactor, the lignin is carbonized, whereby a stabilized lignin derivative with a high specific surface area may be precipitated. The formed slurry comprising the carbonized lignin may then be removed and cooled. Consequently, a slurry comprising lignin-based filler F1 is formed. The slurry comprising lignin-based filler F1 may be fed to a separation unit such as a filter press, wherein the precipitated lignin-based filler F1 may be separated from the slurry, e.g., in form of a filter cake. The separated lignin-based filler F1 , which may be present in form of a filter cake, may be crushed and dried. Before crushing or drying, the lignin-based filler F1 may be, if needed, washed. The crushed lignin particles may be dried and used as such as the lignin-based filler. However, preferably after drying, the lignin particles obtained are subsequently subjected to a milling step in order to obtain lignin particles with smaller particle sizes.

[0104] Optionally, the starting material used for the hydrothermal treatment, i.e. , the lignincontaining material, can be reacted with at least one crosslinker before the hydrothermal treatment is carried out. The crosslinker preferably has at least one functional group which can react with the crosslinkable groups of the lignin. Preferably, the crosslinker has at least one functional group selected from aldehyde, carboxylic 21003 PC / L024873PCT 18 October 01, 2024

[0105] UPM-Kymmene Corporation acid anhydride, epoxide, hydroxyl and isocyanate groups or a combination thereof. Preferably, the crosslinker is selected from aldehydes, epoxides, acid anhydrides, polyisocyanates and / or polyols, in particular from aldehydes such as formaldehyde, furfural and / or sugar aldehydes. The crosslinker can react with free ortho and para positions of the phenolic rings, with aromatic and aliphatic OH groups, and / or with carboxyl groups of the lignin.

[0106] Biomass as defined herein is any biomass, wherein the term “biomass” herein includes phytomass, i.e., biomass originating from plants, zoomass, i.e., biomass originating from animals, and microbial biomass, i.e., biomass originating from microorganisms including fungi. The biomass particularly preferred herein for the production of the fillers is phytomass, preferably dead phytomass.

[0107] Preferably, the at least one filler F1 has a14C content in a range from 0.20 to 0.45 Bq / g of carbon, more preferably of from 0.23 to 0.42 Bq / g of carbon. The required14C content cited above is achieved by organic fillers obtainable from biomass. Thus, fillers obtained from fossil materials, such as fossil fuels in particular, do not have a corresponding14C content. For example, a carbon black filler obtainable from fossil materials does not have a corresponding14C content.

[0108] Preferably, the least one filler F1 is present in the curable rubber composition in an amount in a range of from 0.25 to 180 phr, more preferably of from 0.75 to 150 phr, even more preferably of from 1.00 to 120 phr, still more preferably of from 1.50 to 100 phr, yet more preferably of from 1 .75 to 90 phr, most preferably of from 2.0 to 80 phr.

[0109] Preferably, the at least one filler F1 may be applicable in small, but also in high amounts into a rubber-based material without any ill-effects.

[0110] Preferably, the relative weight ratio of the at least one filler F1 and the at least one curing agent to each other is in a range of from 3600:1 .0 to 1 .0:1.0, more preferably of from 2500:1.0 to 1.1 : 1.0, even more preferably of from 1500: 1.0 to 1.2: 1.0, still more preferably of from 800:1.0 to 1.3:1.0, yet more preferably of from 400:1.0 to 1.4:1.0, still more preferably of from 200:1.0 to 1.5: 1.0, even more preferably of from 100:1 to 21003 PC / L024873PCT 19 October 01, 2024

[0111] UPM-Kymmene Corporation

[0112] 2.0:1.0, still more preferably of from 50:1.0 to 2.5:1.0, yet more preferably of from 25:1 .0 to 3.0:1 .0, most preferably in a range of from 10:1.0 or 5:1.0 to 3.5:1 .0.

[0113] Optional filler F2

[0114] The curable rubber composition may further contain at least one further filler F2, which is different from filler F1 and preferably is, if present, at least one inorganic and / or at least one organic filler. Examples of inorganic fillers are phyllosilicates such as clay minerals, for example talc, carbonates such as calcium carbonate, silicates such as for example calcium, magnesium, and aluminum silicates, and oxides such as for example magnesium oxide, silica including, e.g., rice husk silica, and / or silicic acid. Examples of organic fillers different from filler F1 are carbon blacks, and other organic fillers, which are different from lignin-based filler F1 , but which are also obtainable from biomass and / or renewable and / or recycled raw materials, for example by means of hydrothermal treatment. Further examples of the at least one further filler F2 are graphites including expanded graphites, and / or graphenes and / or carbon nanotube materials including single-wall and multi-wall nanotubes.

[0115] The carbon black to be used as optionally present filler F2 can be a carbon black obtainable from biomass and / or renewable and / or recycled raw materials, but may also be an industrial carbon black obtainable from fossil materials such as particular a furnace carbon black, as classified as general-purpose carbon blacks under ASTM Code N660 or under ASTM Code N550. Other suitable carbon blacks are thermal blacks, acetylene blacks and / or gas blacks.

[0116] A person skilled in the art is aware that carbon blacks have a high carbon content of at least 95 wt.-%, based on the total weight of the filler. Hence, any optionally present carbon black filler preferably has a higher carbon content than filler F1 .

[0117] Preferably, the least one optionally present filler F2 has an STSA surface area of up to 200 m2 / g, more preferably in a range of from 2.5 to 200 m2 / g, even more preferably of from 5.0 to <200 m2 / g, yet more preferably of from 7.5 to 175 m2 / g, still more preferably of from 10.0 to 150 m2 / g. 21003 PC / L024873PCT 20 October 01, 2024

[0118] UPM-Kymmene Corporation

[0119] Preferably, the least one optionally present filler F2 is present in the curable rubber composition in an amount in a range of from 0 or 0.25 to 180 phr, more preferably of from 0 or 0.75 to 150 phr, even more preferably of from 0 or 1 .00 to 120 phr, still more preferably of from 0 or 1 .50 to 100 phr, yet more preferably of from 0 or 1 .75 to 90 phr, most preferably of from 0 or 2.0 to 80 phr.

[0120] Preferably, however, no other filler than the at least one filler F1 is present in the curable rubber composition.

[0121] Further optional constituents

[0122] The curable rubber composition may contain one or more of the further optional constituents, which preferably are selected from plasticizers / softening agents, antidegradants, antiozonants, processing aid additives, process oils, heat stabilizers, mastication aids, mold release agents, flame resistance agents, stabilizers to improve oil resistance and / or reversion stability, additives to stabilize viscosity, pigments, and mixtures thereof.

[0123] Preferably, the total amount of optional constituents employed is in a quantity of 0 or 1 to 20 phr, more preferably of 0 or 2 to 15 phr, even more preferably of 0 or 5 to 12 phr.

[0124] Kit-of-parts

[0125] A further subject-matter of the present invention is a kit-of-parts comprising, in spatially separated form, as part A) at least a part of a curable rubber composition according to the present invention, wherein part A) does, however, not comprise the at least one lignin-based filler F1 according to the present invention, optionally as part B) the remaining part of the curable rubber composition according to the present invention not being present in part A), wherein part B) does, however, not comprise the at least one lignin-based filler F1 according to the present invention, and 21003 PC / L024873PCT 21 October 01, 2024

[0126] UPM-Kymmene Corporation as part C) at least the at least one lignin-based filler F1 according to the present invention.

[0127] At this point of time, part A) represents a filler-free rubber composition and thus is not yet the curable rubber composition according to the invention. The same applies to optionally present part B). Obtaining the curable rubber composition according to the invention is only possible after mixing the parts A), and optionally B), with C).

[0128] Preferably, rubber(s) and curing agents(s) of the filler-free rubber composition on the one hand and the at least one filler F1 on the other hand are spatially separated from each other in the kit-of-parts and can thus be stored. The kit-of-parts serves for the preparation of a curable rubber composition according to the invention. Thus, for example, the rubber composition constituting the one part of the kit-of-parts comprising rubber(s) and curing agent(s) and optionally other constituents, can be employed as part A) in a first stage for preparing the curable rubber composition according to the invention, and the second part of the kit-of-parts, namely part C), comprising the at least one filler F1 , can be employed in a second stage of said process.

[0129] For example, it is possible that part A) comprises the complete rubber composition according to the present invention except of the at least one filler F1 . In this case, part B) is not needed. It is also possible that part A) comprises only part of the rubber composition according to the present invention except of the at least one filler F1 , e.g., only part of the at least one silicone rubber and / or only part of the at least one curing agent. Another rubber different from the at least one silicone rubber and / or the remaining part of the at least one silicone rubber not present in part A) and / or another curing agent being different from the at least one curing agent and / or the remaining part of the at least one curing agent and / or optionally further constituents can then be used as part B).

[0130] All preferred embodiments described hereinabove in connection with the curable rubber composition according to the invention are also preferred embodiments with regard to the kit-of-parts according to the invention. 21003 PC / L024873PCT 22 October 01, 2024

[0131] UPM-Kymmene Corporation

[0132] Cured rubber composition

[0133] A further subject-matter of the present invention is a cured rubber composition,

[0134] (i) which is obtainable by curing the curable rubber composition according to the invention, or by curing a curable rubber composition obtainable by combining and mixing both A), optionally B), and C) of the kit-of-parts according to the invention, or

[0135] (ii) which has a thermal conductivity at 25 °C in a range of from 0.04 to 5.0 W / (m K), an electrical volume resistivity of at least 1 .0 109Q cm, and is obtainable from a curable rubber composition comprising at least one rubber, which is curable by means of at least one curing agent, at least one curing agent, which is suitable for curing the at least one rubber, and at least one lignin-based filler F1 , which is different from carbon black and which has an STSA surface area of up to 200 m2 / g, wherein the amount of the at least one curing agent in the rubber composition preferably is in a range of from 0.05 to 5.5 phr.

[0136] The preparation of the cured rubber composition according to the invention is carried out preferably in two stages, i.e. , stages 1 and 2. In the first stage (stage 1 ), a curable filler-free rubber composition as a base mixture (masterbatch) is prepared first, by mixing all constituents employed for the preparation of a curable rubber composition with each other, but at least without the at least one filler F1 . In the second stage (stage 2), the at least one filler F1 , and optionally additional constituents such as optionally present curing accelerator(s), are admixed to the curable rubber composition obtained after stage 1 .

[0137] Alternatively, the preparation of the cured rubber composition according to the invention is carried out preferably in one mixing stage only, wherein all parts of the curable rubber composition including the filler F1 are mixed with each other. For example, said stage can be performed for example in that at first the at least one silicone rubber is added into a suitable mixing chamber or into a suitable mill such as an open mill and mixed, followed by addition of only part of the remaining constituents 21003 PC / L024873PCT 23 October 01, 2024

[0138] UPM-Kymmene Corporation of the curable rubber composition such as only 50 wt.-% of all remaining constituents including the at least one curing agent or the at least one filler F1 , and by then, after mixing, adding the remaining part of all constituents followed by further mixing.

[0139] Before curing, the curable rubber compositions thus prepared may go through processes that are preferably customized or tailored for the final articles. The rubber compositions may be formed into a suitable shape as required for the curing process, preferably by injection molding, compression molding, transfer molding, extrusion, coextrusion, extrusion coating, coating, printing, laminating, and / or calendering. Curing may be carried out in vulcanization molds by means of pressure and temperature, or the curing is carried out without pressure in temperature-controlled channels in which air or liquid materials provide heat transfer, or the curing is performed in an autoclave, or the curing is carried out without pressure at 20 °C to 25 °C within a humid free mold, optionally by the means of condensation or addition reactions.

[0140] Preferably, the cured rubber composition (i) has a thermal conductivity at 25 °C, more preferably at 25 °C and at 55 °C, in a range of from 0.04 to 5.0 or to 4.5 W / (m K), more preferably in a range of from 0.07 to 4.0 or to 3.5 W / (m K), even more preferably in a range of from 0.10 to 3.0 or to 2.5 W / (m K), still more preferably in a range of from 0.12 to 2.0 or to 1.5 W / (m K), yet more preferably of from 0.14 to 1 .0 or 0.5 W / (m K), and / or has an electrical volume resistivity of at least 1 .0 109Q cm, more preferably of at least 1 .0 101° Q cm, even more preferably of at least 1 .0- 1011Q cm, still more preferably of at least 1 .0 1012Q cm, most preferably of at least 1 .0 1013Q cm.

[0141] The cured rubber composition (ii) has a thermal conductivity at 25 °C, preferably at 25 °C and at 55 °C, in a range of from 0.04 to 5.0 or to 4.5 W / (m K), preferably in a range of from 0.07 to 4.0 or to 3.5 W / (m K), more preferably in a range of from 0.10 to 3.0 or to 2.5 W / (m K), even more preferably in a range of from 0.12 to 2.0 or to 1.5 W / (m K), yet more preferably of from 0.14 to 1.0 or 0.5 W / (m K), and has an electrical volume resistivity of at least 1 .0 109Q cm, preferably of at least 1 .0 101° Q cm, more preferably of at least 1.0-1011Q cm, even more preferably of at least 1.0-1012Q cm, most preferably of at least 1 .0 ■ 1013Q ■ cm . 21003 PC / L024873PCT 24 October 01, 2024

[0142] UPM-Kymmene Corporation

[0143] Preferably, the cured rubber composition has a density of at most 1 .40 g / cm3, more preferably of at most 1 .25 g / cm3, even more preferably of at most 1 .20 g / cm3, still more preferably of at most 1.15 g / cm3, even more preferably of at most 1.10 g / cm3.

[0144] All preferred embodiments described hereinabove in connection with the curable rubber composition and the kit-of-parts according to the invention are also preferred embodiments with regard to the cured rubber composition according to the invention.

[0145] Use of the at least one filler F1

[0146] A further subject-matter of the present invention is a use of at least one filler F1 according to the present invention for improving the thermal conductivity and / or the electrical volume resistivity of cured rubber compositions such as of the cured rubber composition according to the present invention, preferably for simultaneously improving the thermal conductivity and the electrical volume resistivity such as of the cured rubber composition according to the present invention, more preferably for improving the thermal conductivity, the electrical volume resistivity and at least one physical property selected from density, elongation at break, tensile strength and compression set of cured rubber compositions such as of the cured rubber composition according to the present invention, even more preferably for improving the thermal conductivity, the electrical volume resistivity and at least one physical property selected from density and compression set of cured rubber compositions such as of the cured rubber composition according to the present invention.

[0147] All preferred embodiments described hereinabove in connection with the curable rubber composition, the kit-of-parts, and the cured rubber composition according to the invention are also preferred embodiments with regard to the use of the at least one filler F1 according to the invention.

[0148] Uses

[0149] A further subject-matter of the present invention is a use of the curable rubber composition, of the kit-of-parts, or of the cured rubber composition each according to the present invention, for manufacturing articles, parts and / or components, which 21003 PC / L024873PCT 25 October 01, 2024

[0150] UPM-Kymmene Corporation preferably are suitable for use in the automotive and / or aerospace and / or engineering and / or electrical industry, which more preferably are suitable for the manufacture of battery packs, whereby said curable rubber composition, said kit-of-parts, or said cured rubber composition each according to the present invention, preferably is used as or is at least part of a thermal interface material (TIM).

[0151] All preferred embodiments described hereinabove in connection with the curable rubber composition, the kit-of-parts, the cured rubber composition, and the use of the at least one filler F1 according to the invention are also preferred embodiments with regard to the use of the curable rubber composition, of the kit-of-parts, or of the cured rubber composition according to the invention.

[0152] Article, part, and / or component

[0153] A further subject-matter of the present invention is an article, part and / or component, which is in each case obtainable from the curable rubber composition, or from the kit- of-parts, or from the cured rubber composition each according to the present invention, and which preferably is suitable for use in the automotive and / or aerospace and / or engineering and / or electrical industry, which more preferably is suitable for use in battery packs, whereby said article, part and / or component most preferably is used as or is at least part of a thermal interface material (TIM).

[0154] Preferably, the article, part and / or component is a TIM or a part thereof.

[0155] Thermal interface materials are known to a person skilled in the art. Their most relevant thermal properties are thermal impedance and thermal conductivity. Thermal impedance is the measure of the total resistance to the flow of heat from a hot surface through an interface material into a cold surface. Thermal conductivity can be calculated from such measured thermal impedance data to calculate the thermal conductivity of an interface material. Further relevant properties of TIMs are their electrical properties such as voltage breakdown and volume resistivity, the latter one being a measure of the bulk electrical resistance of a unit cube of a material. The volume resistivity can give an indication of how well an interface material can limit leakage current between an active component and its grounded metal heat sink. 21003 PC / L024873PCT 26 October 01, 2024

[0156] UPM-Kymmene Corporation

[0157] Further relevant properties of TIMs are their elastomeric properties such as compression deflection, stress relaxation, and compression set.

[0158] All preferred embodiments described hereinabove in connection with the curable rubber composition, the kit-of-parts, the cured rubber composition, the use of the at least one filler F1 and the use of the curable rubber composition, of the kit-of-parts, or of the cured rubber composition according to the invention are also preferred embodiments with regard to the article, part and / or component obtainable from the curable rubber composition, from the kit-of-parts, or from the cured rubber composition according to the invention.

[0159] Process for preparing the article, part, and / or component

[0160] A further subject-matter of the present invention is a process for preparing the article, part and / or component according to the present invention, wherein said process comprises at least one step, according to which the curable rubber composition according to the invention is shaped into the article, part and / or component, preferably before curing has been performed, by at least one of injection molding, compression molding, transfer molding, extrusion, coextrusion, extrusion coating, coating, printing, laminating, and calendering.

[0161] All preferred embodiments described hereinabove in connection with the curable rubber composition, the kit-of-parts, the cured rubber composition, the use of the at least one filler F1 , the use of the curable rubber composition, of the kit-of-parts, or of the cured rubber composition and the article, part and / or component obtainable from the curable rubber composition, from the kit-of-parts, or from the cured rubber composition according to the invention are also preferred embodiments with regard to the process for preparing the article, part and / or component according to the invention. 21003 PC / L024873PCT 27 October 01, 2024

[0162] UPM-Kymmene Corporation

[0163] METHODS

[0164] 1. STSA and BET surface area

[0165] The STSA and BET surface area was each determined according to standard ASTM D6556-21 .

[0166] 2. Carbon content

[0167] The carbon content was determined by elemental analysis according to DIN 51732: 2014-07.

[0168] 3. Particle size distribution

[0169] The particle size distribution was determined by laser diffraction of the material to be investigated dispersed in water (1 % by weight in water) according to ISO 13320:2020. The volume fraction is specified, for example, as d99 in pm (the diameter of the grains of 99% of the volume of the sample is below this value). The values d90 and d25 (in pm) can be determined in the same way.

[0170] 4.14C content

[0171] The determination of the14C content (content of biologically based carbon) was carried out by means of the radiocarbon method according to DIN EN 16640:2017-08.

[0172] 5. Ash content

[0173] The ash content was determined according to the standard DIN 51719:1997-07.

[0174] 6. Solubility in NaOH (aq.)

[0175] The solubility was measured in the following manner: First, a sample was dried at a temperature of 60 °C for four hours. A sample mass of 0.5 g was weighed and suspended in 50 ml of 0.1 M NaOH at a concentration of 1 % having a temperature of 22 °C. Mixing was continued for 1 hour, then the sample was placed on a glass microfiber paper (1.6 pm) and the filter paper with the sample was dried at a temperature of 60 °C for 2 hours. The portion of the sample, which has dissolved, could then be determined gravimetrically. 21003 PC / L024873PCT 28 October 01, 2024

[0176] UPM-Kymmene Corporation

[0177] 7. Average molecular weight

[0178] The weight average molecular weight was determined with size exclusion chromatography (SEC) by using 0.1 M NaOH as eluent and a sample amount of about 1 mg / ml, which was dissolved in 0.1 M NaOH. The weight average molecular weights were measured against polystyrene sulfonate standards. UV detector at a wavelength of 280 nm was used. Number average molecular weights as well as polydispersity index were determined also by this method.

[0179] 8. Curing characteristics

[0180] Moving die rheometer (MDR) was used to assess the cure characteristics. Testing was conducted at 180 °C for t90 plus 5 minutes, following ASTM D5289-19a. Minimum and maximum torgue (ML, MH) were measured. Further, the time period was determined in which the torgue, starting from the time of the minimum torgue ML, reaches 90% of the maximum torgue MH, respectively. The time period was designated as too. Further, the time for the viscosity to increase 2 units above ML (designated as ts2) was measured.

[0181] 9. Density

[0182] The density was determined according to ASTM D297-15 (2019).

[0183] 10. Shore A hardness

[0184] Shore A hardness was tested according to ASTM D2240-15 (2021 ).

[0185] 11. Tensile properties

[0186] Tensile properties (tensile strength, elongation at breaks, M100 and M200) were determined following ASTM D412-16 (2021 ).

[0187] 12. Tear strength

[0188] A crescent dumbbell according to ISO 34-1 :2015 was used to determine the tear strength.

[0189] 13. Compression set

[0190] Compression set was measured after 24 hours at 100 °C and 150 °C following ISO 815-1 :2019. 21003 PC / L024873PCT 29 October 01, 2024 UPM-Kymmene Corporation

[0191] 14. Thermal conductivity of cured rubber materials

[0192] Thermal conductivity was determined according to ISO 8301 :1991.

[0193] 15. Electrical conductivity Electrical conductivity was determined according to ISO 787-14:2019.

[0194] 16. Electrical volume resistivity

[0195] Electrical volume resistivity was determined according to ASTM D991-89 (2020). 17. Thermal conductivity of fillers

[0196] The thermal conductivity determined is a matrix thermal conductivity by means of applying a 2-phase test, by using the device TK04 from the company Teka (Berlin, Germany), said device being in accordance with ISO 22007-1 , and by applying a needle probe method. As fluid water has been used. The measurements have been performed at room temperature. The test / method complies with ASTM D5334-14.

[0197] 21003 PC / L024873PCT 30 October 01, 2024

[0198] UPM-Kymmene Corporation

[0199] EXAMPLES

[0200] The following examples further illustrate the invention, but are not to be construed as limiting its scope.

[0201] 1. Preparation

[0202] 1.1 Five examples have been prepared, namely inventive examples 11 , I2, and I3 as well as comparative examples C1 and C2. In each example, 300 g of a commercially available masterbatch comprising a copolymer of dimethylsiloxane and vinylmethylsiloxane (VMQ) as silicone rubber and dicumylperoxide as curing accelerator has been used. In each example, 90 g of a filler has been added to the masterbatch, wherein in case of inventive examples 11 , I2 and I3 one of three different lignin-based fillers L1 , L2 and L3 has been used, respectively, while in case of comparative examples C1 and C2 a carbon black (CB) has been used as filler. Ligninbased filler 1 (UPM BioMotion® X10) has an STSA surface area of about 11 m2 / g, lignin-based filler 2 (UPM BioMotion® X20) has an STSA surface area of about 23 m2 / g, and lignin-based filler 3 (UPM BioMotion® X40) has an STSA surface area of about 40 m2 / g. The thermal and electrical conductivities of lignin-based fillers L2 and L3 as such are shown in Table 1.1 , while the exact compositions of 11 , I2, I3, C1 and C2 are shown in Table 1.2.

[0203] Table 1.1 21003 PC / L024873PCT 31 October 01, 2024 UPM-Kymmene Corporation

[0204] Table 1.2 a: A carbon black classified under ASTM Code N-550 has been used as CB1.b: A carbon black classified under ASTM Code N-772 has been used as CB2.

[0205] 1.2 Each of the compositions shown in Table 1.2 was prepared using a mill mixing device at room temperature (20 °C) and at 2 to 3 rpm in a one-step mixing cycle, following the procedure and conditions outlined in Table 1.3 hereinafter. Each of CB1 and CB2 was ball-milled at 600 rpm for 10 min before it was used.

[0206] Table 1.3

[0207] The compositions were cured in at 180 °C for a period of too + 5 minutes. Afterwards, post curing was performed at a temperature of 200 °C for a period of 4 h.

[0208] 2. Investigation of physical properties of the non-aged cured compositions as well as of the cure characteristics

[0209] 2.1 Some physical properties of the cured compositions of examples 11 , I2 and I3 (all inventive) as well as of examples C1 and C2 (both comparative) have been investigated according to the methods described in the ‘methods’ section. Further, the 21003 PC / L024873PCT 32 October 01, 2024

[0210] UPM-Kymmene Corporation curing characteristics for curing the compositions of examples 11 , I2, I3, C1 and C2 have been investigated as well. The results are summarized in Table 2.1 .

[0211] Table 2.1

[0212] As it is evident from Table 2.1 cured inventive examples 11 , I2 and I3 inter alia show significantly improved (reduced) compression sets at 100 °C as well as at 150 °C in comparison to cured comparative examples C1 and C2. In addition, the densities of 11 , I2 and I3 are lower compared to C1 and C2.

[0213] 3. Investigation of physical properties of the cured compositions after ageing

[0214] 3.1 In order to investigate the effects of ageing with respect to some of the measured properties, ageing of post cured samples of the cured compositions has been performed with hot air for a period of 168 h at a temperature of 150 °C. Hardness,

[0215] M100, M200, tensile strength as well as elongation at break of the cured compositions of examples 11 , I2 and I3 (all inventive), as well as of examples C1 and C2 (both comparative), after aforementioned ageing, have been investigated again according to 21003 PC / L024873PCT 33 October 01, 2024 UPM-Kymmene Corporation the methods described in the ‘methods’ section. The results thereof are summarized in Table 3.1 .

[0216] Table 3.1

[0217] 4. Investigation of thermal conductivity and electrical volume resistivity of the non-aqed cured compositions

[0218] 4.1 The thermal conductivity at 25 °C as well as at 55 °C and the electrical volume resistivity of the cured compositions of examples 11 , 12 and 13 (all inventive) as well as of examples C1 and C2 (both comparative) have been investigated according to the methods described in the ‘methods’ section. The results are summarized in Table 4.1 .

[0219] Table 4.1

[0220] As it is evident from Table 4.1 cured inventive examples 11 , I2 and I3 show significantly improved (increased) electrical volume resistivities in comparison to cured examples C1 and C2 while exhibiting similar thermal conductivities at 25 °C as well as at 55 °C.

Claims

21003 PC / L024873PCT 34 October 01, 2024UPM-Kymmene CorporationCLAIMS1 . A curable rubber composition comprising at least one silicone rubber, which is curable by means of at least one curing agent, at least one curing agent, which is suitable for curing the at least one silicone rubber, and at least one lignin-based filler F1 , which is different from carbon black, and which has an STSA surface area of up to 200 m2 / g, wherein the amount of the at least one curing agent is in a range of from 0.05 to 5.5 phr.

2. The curable rubber composition according to claim 1 , characterized in that the relative weight ratio of the at least one filler F1 and the at least one curing agent to each other is in a range of from 3600:1.0 to 1.0:1.0, preferably of from 2500:1.0 to 1.1 :1.0, more preferably of from 1500:1.0 to 1.2:1.0, even more preferably of from 800:1.0 to 1.3:1.0, yet more preferably of from 400:1.0 to 1.4: 1.0, still more preferably of from 200:1.0 to 1.5: 1.0, even more preferably of from 100:1 to 2.0:1.0, still more preferably of from 50:1.0 to 2.5:1.0, yet more preferably of from 25:1.0 to 3.0:1.0, most preferably in a range of from 10:1.0 or 5:1.0 to 3.5:1.0.

3. The curable rubber composition according to claim 1 or 2, characterized in that the at least one filler F1 has a thermal conductivity at room temperature in a range of from 0.08 to 6.0 W / (m K), preferably of from 0.12 to 5.0 W / (m K), more preferably of from 0.16 to 4.0 W / (m K), even more preferably of from 0.20 to 3.5 W / (m K), still more preferably of from 0.25 to 3.0 or to 2.5 W / (m K), yet more preferably of from 0.30 to 2.0 or to 1 .5 W / (m K), most preferably of from 0.35 to 1 .0 or to 0.75 or to 0.50 W / (m K).

4. The curable rubber composition according to one or more of the preceding claims, characterized in that at least the least one filler F1 has an STSA surface21003 PC / L024873PCT 35 October 01, 2024UPM-Kymmene Corporation area in a range of from 2.5 to 200 m2 / g, preferably of from 5.0 to <200 m2 / g, more preferably of from 7.5 to 175 m2 / g, even more preferably of from 10.0 to 150 m2 / g.

5. The curable rubber composition according to one or more of the preceding claims, characterized in that the least one filler F1 is present in the curable rubber composition in an amount in a range of from 0.25 to 180 phr, preferably of from 0.75 to 150 phr, more preferably of from 1.00 to 120 phr, even more preferably of from 1 .50 to 100 phr, yet more preferably of from 1 .75 to 90 phr, most preferably of from 2.0 to 80 phr.

6. The curable rubber composition according to one or more of the preceding claims, characterized in that the least one filler F1 has a d99 value of <25 pm, preferably <20 pm, more preferably <18 pm, even more preferably <15 pm, still more preferably <10 pm.

7. The curable rubber composition according to one or more of the preceding claims, characterized in that the least one filler F1 has a carbon content in a range from >60% by weight to <90% by weight, preferably from >60% by weight to <85% by weight, more preferably from >60% by weight to <80% by weight.

8. The curable rubber composition according to one or more of the preceding claims, characterized in that the least one filler F1 has a weight average molecular weight in a range of from 1000 to 4000 Da, preferably of from 1300 to 3700 Da, more preferably of from 1700 to 3200 Da, yet more preferably of from 2500 to 3000 Da, still more preferably of from 2600 to 2900 Da, most preferably of from 2650 to 2850 Da, in each case when determined based on the soluble fraction of the filler F1 .

9. The curable rubber composition according to one or more of the preceding claims, characterized in that the at least one curing agent is present in the curable rubber composition in an amount in a range of from 0.06 to 5.0 phr, preferably of from 0.08 to 4.0 or to 3.5 phr, more preferably of from 0.09 to 3.0 or to 2.5 phr, even more preferably of from 0.10 to 2.0 phr.21003 PC / L024873PCT 36 October 01, 2024UPM-Kymmene Corporation10. The curable rubber composition according to one or more of the preceding claims, characterized in that the at least one curing agent comprises at least one of curing agents (a), (b), and (c) as defined hereinafter, namely(a) at least one preferably organic peroxide, preferably selected from dialkyl peroxides, alkyl aryl peroxides, diaryl peroxides, alkyl peresters, aryl peresters, diacyl peroxides, polyvalent peroxides and mixtures thereof, more preferably selected from the group consisting of di-tert-butylperoxide, 2,5-dimethyl-2,5- di(tert-butyl-peroxy)hexane, dicumyl peroxide, tert-butylcumyl peroxide, tertbutyl peroxybenzoate, dibenzoyl peroxide, 1 ,1 -di(tert-butylperoxy)-3,3,5- trimethyl cyclohexane and bis-(tert-butylperoxy)-diisopropylbenzene as well as mixtures thereof, and / or(b) at least one silane and / or siloxane, preferably at least one siloxane, preferably comprising at least three Si-H bonds, in particular if the at least one silicone rubber bears vinyl groups, and / or(c) at least one alkoxysilane, in particular if the at least one silicone rubber bears hydroxyl groups such as terminal OH-groups.11 . The curable rubber composition according to one or more of the preceding claims, characterized in that the at least one silicone rubber is selected from silicone homopolymers and copolymers, silicone based homopolymers and copolymers, and mixtures thereof, preferably from polysiloxanes (Q), homopolymers of polydimethylsiloxane (MQ), copolymers of dimethyl siloxane and vinyl methylsiloxane (VMQ), copolymers of dimethyl siloxane and phenylmethyl siloxane (PMQ), terpolymers of dimethyl-, phenylmethyl- and vinylmethyl siloxane (PVMQ), terpolymers of dimethyl-, trifluoropropylmethyl- and vinylmethyl siloxane (FVMQ), and mixtures thereof, more preferably from homopolymers of polydimethyl siloxane (MQ) and copolymers of dimethyl siloxane and vinylmethyl siloxane (VMQ), and mixtures thereof, even more preferably from copolymers of dimethyl siloxane and vinylmethyl siloxane (VMQ).21003 PC / L024873PCT 37 October 01, 2024UPM-Kymmene Corporation12. The curable rubber composition according to one or more of the preceding claims, characterized in that the at least one silicone rubber has a weight average molecular weight in a range of from 30,000 to 2,000,000 g / mol, preferably of from 40,000 to 1 ,600,000 g / mol, more preferably of from 50,000 to 1 ,400,000 g / mol, even more preferably of from 60,000 to 1 ,200,000 or to 1 ,000,000 g / mol.

13. A kit-of-parts comprising, in spatially separated form, as part A) at least a part of a curable rubber composition as defined in any one or more of the preceding claims, wherein part A) does, however, not comprise the at least one lignin-based filler F1 as defined in one or more of claims 1 to 8, optionally as part B) the remaining part of the curable rubber composition according to the present invention not being present in part A), wherein part B) does, however, not comprise the at least one lignin-based filler F1 as defined in one or more of claims 1 to 8, and as part C) at least the at least one lignin-based filler F1 as defined in one or more of claims 1 to 8.

14. A cured rubber composition,(i) which is obtainable by curing the curable rubber composition as defined in one or more of claims 1 to 12, or by curing a curable rubber composition obtainable by combining and mixing both A), optionally B), and C) of the kit-of- parts according to claim 13, or(ii) which has a thermal conductivity at 25 °C in a range of from 0.04 to 5.0 W / (m K), an electrical volume resistivity of at least 1.0-109Q cm, and is obtainable from a curable rubber composition comprising at least one rubber,21003 PC / L024873PCT 38 October 01, 2024UPM-Kymmene Corporation which is curable by means of at least one curing agent, at least one curing agent, which is suitable for curing the at least one rubber, and at least one ligninbased filler F1 , which is different from carbon black and which has an STSA surface area of up to 200 m2 / g, wherein the amount of the at least one curing agent in the rubber composition preferably is in a range of from 0.05 to 5.5 phr.

15. The cured rubber composition according to claim 14 characterized in that the cured rubber composition (i) has a thermal conductivity at 25 °C, preferably at 25 °C and at 55 °C, in a range of from 0.04 to 5.0 or to 4.5 W / (m K), preferably in a range of from 0.07 to 4.0 or to 3.5 W / (m K), more preferably in a range of from 0.10 to 3.0 or to 2.5 W / (m K), even more preferably in a range of from 0.12 to 2.0 or to 1 .5 W / (m K), yet more preferably of from 0.14 to 1 .0 or 0.5 W / (m K), and / or has an electrical volume resistivity of at least 1.0-109Q cm, preferably of at least 1 .0- 101° Q cm, more preferably of at least 1 .0- 1011Q cm, even more preferably of at least 1 .0- 1012Q cm, most preferably of at least 1.0- 1013Q cm.

16. The cured rubber composition according to claim 14 or 15, characterized in that it has a density of at most 1.40 g / cm3, preferably of at most 1.25 g / cm3, more preferably of at most 1.20 g / cm3, still more preferably of at most 1.15 g / cm3, even more preferably of at most 1.10 g / cm3.

17. A use of at least one filler F1 as defined in one or more of claims 1 to 8 for improving the thermal conductivity and / or the electrical volume resistivity of cured rubber compositions such as of the cured rubber composition as defined in one or more of claims 14 to 16, preferably for simultaneously improving the thermal conductivity and the electrical volume resistivity such as of the cured rubber composition as defined in one or more of claims 14 to 16, more preferably for improving the thermal conductivity, the electrical volume resistivity and at least one physical property selected from density, elongation at break, tensile strength and compression set of cured rubber compositions such as of the cured rubber composition as defined in one or more of claims 14 to 16, even more preferably for improving the thermal conductivity, the electrical volume resistivity and at least one physical property selected from density and21003 PC / L024873PCT 39 October 01, 2024UPM-Kymmene Corporation compression set of cured rubber compositions such as of the cured rubber composition as defined in one or more of claims 14 to 16.

18. A use of the curable rubber composition as defined in one or more of claims 1 to 12, of the kit-of-parts as defined in claim 13, or of the cured rubber composition as defined in one or more of claims 14 to 16, for manufacturing articles, parts and / or components, which preferably are suitable for use in the automotive and / or aerospace and / or engineering and / or electrical industry, which more preferably are suitable for the manufacture of battery packs, whereby said curable rubber composition, said kit-of-parts, or said cured rubber composition preferably is used as or is at least part of a thermal interface material (TIM).

19. An article, part and / or component, which is in each case obtainable from the curable rubber composition as defined in one or more of claims 1 to 12, or from the kit-of-parts as defined in claim 13, or from the cured rubber composition as defined in one or more of claims 14 to 16, and which preferably is suitable for use in the automotive and / or aerospace and / or engineering and / or electrical industry, which more preferably is suitable for use in battery packs, whereby said article, part and / or component most preferably is used as or is at least part of a thermal interface material (TIM).

20. A process for preparing the article, part and / or component as defined in claim 19, wherein said process comprises at least one step, according to which the curable rubber composition as defined in one or more of claims 1 to 12 is shaped into the article, part, and / or component, preferably before curing has been performed, by at least one of injection molding, compression molding, transfer molding, extrusion, coextrusion, extrusion coating, coating, printing, laminating, and calendering.

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