Modified fine particulate carbon materials and method for producing same

Description

[0001] The present invention relates to finely divided modified particulate carbon materials and their use. State of the art

[0002] Finely particulated carbon materials are used in many applications. These range from their use as black pigments to their use as fillers in polymers, such as elastomers, thermoplastics, or thermoplastic elastomers. Such carbon-based materials can include, for example, carbon black, materials with a relatively high carbon content. WO 2010 / 043562 A1 concerns carbon black with a carbon-14 content greater than 0.05 Bq / g and a ΔD50 / Dmode ratio of the aggregate size distribution of less than 0.7, which is produced by thermal-oxidative pyrolysis or thermal cracking of a carbon black feedstock containing renewable carbon black raw materials. Other particulate carbon materials are obtained from renewable raw materials.Such particulate carbon materials have a slightly lower carbon content compared to soot, but exhibit interesting properties due to a high degree of functionalization. Particularly interesting starting materials for the production of particulate carbon materials based on renewable resources are those that can be dissolved completely or partially, such as sugars, starches, or lignin. These wholly or partially dissolved, renewable raw materials can be converted into particulate carbon materials by precipitation processes. Precipitation processes for the production of particulate carbon materials in solution are well known to those skilled in the art.

[0003] For example, lignin dissolved in a base, such as sodium hydroxide, can be used to obtain a lignin-based particulate carbon material by precipitation through the introduction of an acidic gas such as CO₂ or H₂S, or by the addition of an acid such as H₂SO₄. Examples of this prior art are given in WO2006031175, WO2006038863, and WO2009104995.

[0004] Furthermore, lignin dissolved in a base, such as sodium hydroxide, can be used to obtain a lignin-based particulate carbon material by increasing the temperature to conditions of hydrothermal carbonization through precipitation with simultaneous stabilization. Examples of this prior art are described in WO 2016 / 020383 and WO 2017 / 085278.

[0005] DE 10 2018 220946 A1 discloses a process for separating particulate carbon materials by gravity separation and particulate carbon materials that can be produced according to this process.

[0006] Methods for precipitation by introducing an acidic gas, by adding an acid, or by increasing the temperature can also be combined.

[0007] In the production of particulate carbon materials, the adjustment of certain process parameters allows for influencing, in particular, the grain sizes to be obtained (i.e., the size of the agglomerates to be obtained, which may be composed of primary particles) or the grain size distribution, as well as the adjustment of surface parameters, especially the specific surface area, which is also used as a measure of the primary particle size.

[0008] The particle size or particle size distribution can be quantified, for example, by sieve analysis or laser diffraction. Sieve analysis can be performed, for example, on dry particulate carbon material according to DIN 66165. Laser diffraction can be performed, for example, on particulate carbon material dispersed in water according to ISO 13320.

[0009] The primary particle size can be quantified, for example, using methods for determining the specific surface area, such as BET or STSA measurements. A BET measurement determines the sum of the outer and inner surface areas, while an STSA measurement determines only the outer surface area. Suitable methods are specified, for example, in ASTM D 6556-14. When selecting the outgassing temperature, it should be noted that for the investigation of particulate carbon materials, it should be set to a value of approximately 150°C.

[0010] It is known that the average size of the primary particles, or the specific surface area (SPA), influences the properties of materials manufactured using particulate carbon materials, for example, rubber articles produced by compounding the particulate carbon material with elastomers followed by crosslinking. For instance, the abrasion behavior of a rubber article differs depending on whether particulate carbon materials with a higher or lower SPA surface area are used. A similar relationship exists with mechanical properties such as tensile strength. Higher SPA values ​​correlate with higher tensile strength and lower abrasion.When using particulate carbon materials, specific surface area values ​​of at least 5 m² / g, preferably at least 8 m² / g, more preferably at least 10 m² / g, and more preferably at least 15 m² / g or more are often required to obtain high-quality rubber articles.

[0011] A disadvantage of known particulate carbon materials, such as those obtained by precipitation of fully or partially dissolved feedstocks based on renewable raw materials, and especially of lignin-based particulate carbon materials, is the unpleasant odor emanating from the particulate carbon material itself, released during processing, and / or from materials containing the particulate carbon material. This severely limits the potential applications of these otherwise highly interesting particulate carbon materials.

[0012] The unpleasant odor of lignocellulose-based materials is caused in particular by thermal or chemical degradation processes of lignin, hemicellulose and cellulose and other wood components (e.g. resins) that arise during the processing of the wood.

[0013] Compounds that cause the unpleasant odor include sulfur-containing substances such as dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide or dimethyl tetrasulfide, or phenolic substances such as phenol, guaiacol, ethylguaiacol, etc.

[0014] A variety of volatile organic compounds (VOCs) are also released. VOCs are volatile organic compounds that evaporate readily or exist as gases even at lower temperatures, such as room temperature. VOCs are either already present in the wood and are released during processing, or, according to current understanding, they are formed by the degradation of fatty acids, which are themselves decomposition products of wood. Typical transformation products that occur during processing include higher aldehydes and organic acids. Organic acids are formed primarily as breakdown products of the wood components cellulose, hemicellulose, and lignin, with alkanoic acids, such as acetic acid, propionic acid, hexanoic acid, and aromatic acids being preferentially produced.Aldehydes are formed from the basic building blocks of cellulose or hemicellulose during hydrolytic processing. For example, the aldehyde furfural is formed from mono- and disaccharides of cellulose or hemicellulose, while aromatic aldehydes can be released during the partial hydrolytic breakdown of lignin. Other released aldehydes include the higher aldehydes hexanal, pentanal, and octanal.

[0015] Methods for reducing the odor of lignin-based particulate carbon materials are known in the art. These methods rely on the pre-purification of the lignin, for example by extraction processes (WO2013 / 101397), enzymatically catalyzed reactions (DE 10 2006 057566), or treatment with oxidizing components followed by washing (DE 10 1013 001678). They also rely on treatment with, for example, black liquor, evaporation processes, treatment with reducing or oxidizing agents, chlorination reactions, or high-temperature treatments. However, such methods require the treatment of relatively large quantities of material or the use of chemicals, which is disadvantageous in terms of both equipment and cost.

[0016] Methods for treating hydrothermally carbonized lignin at elevated temperatures are known, for example, from EP 3053929. In EP 3053929, hydrothermally carbonized lignin is subjected to stabilization, preferably under an inert gas, for the purpose of finishing, for example, by activation. The hydrothermal carbonization is carried out at temperatures between 150°C and 300°C, preferably between 150°C and 250°C. The stabilization is carried out at a suitable temperature, which is at least 30°C above the temperature of the hydrothermal carbonization. The stabilization temperatures are between 200°C and 700°C, preferably between 300°C and 600°C, ideally between 500°C and 600°C. Thus, with a hydrothermal carbonization temperature of 300°C, the minimum stabilization temperature is 330°C, and with a hydrothermal carbonization temperature of 250°C, the stabilization temperature is 280°C.The heating rate is between 0.1 and 20 °C / min. During this process, gases, mainly oxygen and hydrogen, are released from the material and are preferably removed during treatment. The purpose of this thermal treatment is to stabilize the hydrothermally carbonized lignin so that it is ready for final processing, preferably activation to produce activated carbon.

[0017] Methods for reducing the odor of wood at elevated temperatures are known, for example, from EP 3 170 635 B1. In this process, long wood chips with a length between 150 and 200 mm, a width between 15 and 20 mm, and a thickness between 0.5 and 2 mm are torrefied at temperatures between 150°C and 300°C in an oxygen-deficient or oxygen-free atmosphere for a duration of between 1 and 5 hours. The mass loss is between 10 and 30%.

[0018] It would therefore be desirable to provide a process that enables the targeted reduction of odors emanating from the particulate carbon material itself, those released during processing, and / or those originating from materials containing the particulate carbon material, without the use of additional process chemicals, preferably by treating the already obtained particulate carbon material. This would reduce costs and equipment requirements, while simultaneously decreasing the amount of material to be processed. However, a further requirement for such a process is that the desired properties of the particulate carbon material, such as particle size or particle size distribution, primary particle size, or specific surface area, are not lost during the odor reduction treatment.

[0019] A further disadvantage of known particulate carbon materials, obtained, for example, by precipitation of fully or partially dissolved starting materials based on renewable resources, and especially of lignin-based particulate carbon materials, is their high polarity. This severely limits the potential applications of these otherwise highly interesting particulate carbon materials, particularly as additives, reagents, or fillers when used in materials with significantly different polarity.

[0020] It would therefore be desirable to provide a method for selectively adjusting the polarity of particulate carbon material, preferably by treating the already obtained particulate carbon material. This would reduce costs and equipment requirements, while simultaneously decreasing the amount of material to be processed. However, another requirement for such a method is that the desired properties of the particulate carbon material, such as grain size or grain size distribution, primary particle size, or specific surface area, are not lost during the polarity-adjusting treatment.

[0021] The material loss should also not be too high, as the particulate carbon material is already a valuable product. Object of the invention

[0022] The object of the present invention is therefore to provide corresponding particulate carbon materials and methods for their production in order to be able to provide the particulate carbon materials described above. Brief description of the invention

[0023] This problem is solved by the items defined in the claims. Preferred embodiments and further aspects of the present invention will become apparent from the embodiments specified in the further claims and the following detailed description.

[0024] In particular, a first object of the present invention is a particulate carbon material which ∘ a 14< C content of greater than 0.20 Bq / g carbon but less than 0.45 Bq / g carbon, ∘ a D50 particle size distribution of less than 500 µm and more than 0.5 µm, and ∘ an OH group density of at least 0.05 mmol / g and at most 0.4 mmol / g, and wherein ∘ the solubility of the particulate carbon material in alkaline liquids is less than 25%, the solubility being determined according to the method described herein.

[0025] A further object of the present disclosure is a method for producing the particulate carbon material according to the invention, which comprises at least two process steps, wherein in a first process step a particulate carbon material pKM is provided, which represents a precursor of the particulate carbon material according to the invention and is different from it, which is subsequently modified in a second process step by heating in the gas atmosphere, whereby the particulate carbon material according to the invention is then obtainable, which is preferably odor-reduced.

[0026] Another object of the present invention is the use of the particulate carbon material as an additive in polymer mixtures, in particular rubber mixtures such as elastomer mixtures.

[0027] Another object of the present invention is a vulcanizable rubber composition comprising at least one rubber and at least one filler component, wherein the filler component contains at least the particulate carbon material according to the invention.

[0028] Another object of the present invention is a vulcanized rubber composition obtainable by vulcanization of the vulcanizable rubber composition, which exhibits a swelling in alkaline liquids after 7 days of less than 25%, wherein the swelling is determined according to DIN ISO 1817:2015 in 0.1 M NaOH. Detailed description of the invention

[0029] The process of the present disclosure allows the production of finely divided, odor-reduced and / or OH-group-reduced (i.e., with reduced polarity) particulate carbon materials produced from starting materials based on renewable resources. Such particulate carbon materials are, as mentioned above, a further subject matter of the present invention.

[0030] A characteristic feature of the process is, for example, that in a first process step a finely divided, particulate carbon material (hereinafter pKM) is preferably obtained, the odor of which is reduced in a second process step, thereby obtaining the odor-reduced pKM.

[0031] A characteristic feature of the process is, for example, that in a first process step a finely divided, particulate carbon material (hereinafter pKM) is obtained, the OH group density of which (especially on the surface of the material) is reduced, preferably adjusted, in a second process step, thereby obtaining the OH group-reduced pKM.

[0032] The process can also yield a pKM that exhibits reduced odor and reduced OH group density, preferably a controlled OH group density. In this respect, the second process step can combine odor reduction with a reduction, preferably a controlled OH group density. In the following, modified pKM will be understood to mean an odor-reduced or OH group-reduced pKM, or a pKM that is both odor-reduced and OH group-reduced. The modified pKM or the finely modified pKM thus represents the particulate carbon material according to the invention and is obtained after the second process step. Finely divided pKM or pKM (each not yet modified) thus represents a precursor to the particulate carbon material according to the invention and is obtained after the first process step and used in the second process step.

[0033] The finely divided pKM is preferably obtained in the first process step in the presence of a liquid, particularly preferably in the presence of water, and preferably converted into the modified pKM in a gas atmosphere in the second process step. According to the invention, a separation of liquid from the finely divided pKM preferably takes place between the first and second process steps.

[0034] Both the particulate carbon material according to the invention (modified pKM) and its precursor (pKM) are preferably also referred to as "finely divided" within the scope of the present invention. The term "finely divided" is defined below depending on the BET surface area, STSA surface area, and D50 of the particle size distribution. Particularly preferably, "finely divided" within the meaning of the present invention means that the respective particulate carbon material has a D50 (D50 value) of the particle size distribution of less than 500 µm and more than 0.5 µm. This fineness is also referred to below as KGV fineness.

[0035] As mentioned above, the particulate carbon material according to the invention is preferably also referred to as "modified" particulate carbon material or modified pKM within the scope of the present invention. In this context, the term "modified" means that the carbon material is obtained from a finely divided particulate carbon material pKM used as a starting material, which differs from the particulate carbon material according to the invention. The particulate carbon material according to the invention differs in particular from the finely divided particulate carbon material pKM used as a starting material in that it is obtainable by heating the starting material in a gas atmosphere. The aforementioned modification is achieved by this heating process.The particulate carbon material according to the invention is preferably also referred to as finely divided modified particulate carbon material within the scope of the present invention. The foregoing statements apply cumulatively in this respect.

[0036] According to the invention, the morphology of the finely divided pKM is preferably only marginally altered in the second process step. A characteristic feature of the present process and the particulate carbon material according to the invention is that the fineness of the modified pKM is essentially already maintained after the first process step. Therefore, the second process step of the present process is designed such that the fineness of the pKM is only minimally altered and that the odor of the finely divided pKM is essentially reduced and / or the OH group density of the finely divided pKM is reduced or adjusted.

[0037] It has proven advantageous if the finely divided pKM has a BET surface area of ​​at least 5 m² / g, preferably at least 8 m² / g, more preferably at least 10 m² / g, more preferably at least 15 m² / g, particularly preferably at least 20 m² / g, and more preferably at least 30 m² / g, especially at least 35 m² / g or more. Advantageously, the BET surface area is at most 200 m² / g, preferably at most 180 m² / g, more preferably at most 150 m² / g, and particularly preferably at most 120 m² / g. Hereinafter, the fineness described by the BET surface area is referred to as BET fineness.

[0038] Advantageously, the BET surface of the finely divided pKM deviates from its STSA surface by a maximum of only 20%, preferably by a maximum of 15%, and more preferably by a maximum of 10%. The pKM is therefore preferably low porosity. Alternatively, the STSA surface can be used to measure the BET surface. In the following, the fineness described via the STSA surface is referred to as STSA fineness.

[0039] Furthermore, it has proven advantageous if the finely divided pKM exhibits a D50 particle size distribution of less than 500 µm after the first process step, preferably less than 250 µm, more preferably less than 100 µm, and particularly preferably 50 µm. Advantageously, the D50 particle size distribution of the finely divided pKM is greater than 0.5 µm, more preferably greater than 1 µm, particularly preferably greater than 5 µm, and further preferably greater than 10 µm. D50 means that 50% of the particles are smaller than the specified value. In the following, the fineness described by the particle size distribution is referred to as KGV fineness.

[0040] The fineness of the finely divided pKM and the modified pKM can therefore be described by its KVG fineness and / or BET fineness and / or STSA fineness.

[0041] One design of the procedure is characterized by the fact that In a first process step, a finely divided pKM is obtained in the presence of a liquid, which is then converted into a modified pKM in a gas atmosphere in a second process step, with the liquid being separated from the finely divided pKM between the first and second process steps, the particle size of the modified pKM after the second process step being at most 5 times smaller than the particle size of the finely divided pKM before the second process step, and / or the odor of the modified pKM after the second process step being reduced compared to the odor of the finely divided pKM before the second process step, and / or the OH group density of the modified pKM after the second process step being reduced compared to the OH group density of the finely divided pKM before the second process step.

[0042] The particle size distribution of the pKM decreases during the second process step by a maximum of 5 times, preferably by a maximum of 4 times, 3 times, 2.5 times, 2 times, 1.75 times, 1.5 times, 1.4 times, 1.3 times, 1.2 times, 1.1 times.

[0043] A decrease in particle size distribution means that The D50 of the particle size distribution of the modified pKM is at most 5 times larger, preferably at most 4 times larger, 3 times larger, 2.5 times larger, 2 times larger, 1.75 times larger, 1.5 times larger, 1.4 times larger, 1.3 times larger, 1.2 times larger, 1.1 times larger, than the D50 of the particle size distribution of the finely divided pKM and / or the BET surface area of ​​the modified pKM is at most 100% larger, preferably at most 5 times smaller, preferably at most 4 times larger, 3 times larger, 2.5 times larger, 2 times larger, 1.75 times larger, 1.5 times larger, 1.4 times larger, 1.3 times larger, 1.2 times larger, 1.1 times larger, than the BET surface area of ​​the finely divided pKM and / or the STSA surface area of ​​the modified pKM is at most 100% smaller, preferably at most 100% smaller at most 5 times, preferably at most 4 times, 3 times, 2.5 times, 2 times, 1.75 times, 1.5 times, 1.4 times, 1.3 times, 1.2 times, 1.1 times smaller than the STSA surface area of ​​the finely divided pKM.

[0044] Preferably, the factor by which the BET surface area or the STSA surface area decreases in the second process step is smaller than the factor by which the D50 of the particle size distribution increases in the second process step.

[0045] Furthermore, it has proven advantageous if the finely divided pKM has an ash content of less than 15 wt%, preferably less than 12 wt%, 10 wt%, 8 wt%, 6 wt%, 5 wt%, 4 wt%, 3 wt%, or 2 wt% after the first process step. Advantageously, the ash content of the finely divided pKM is more than 0.25 wt%, preferably more than 0.5 wt%, and further preferably more than 0.75 wt%.

[0046] Furthermore, the finely divided pKM preferably exhibits a carbon content (based on the ash-free dry matter content) of 40 to 80 wt%, preferably 50 to 80 wt%, more preferably 60 to less than 80 wt%.

[0047] Furthermore, the finely divided pKM preferably exhibits an OH group density of at least 0.1 mmol / g, preferably at least 0.15 mmol / g, particularly preferably at least 0.2 mmol / g and at most 0.6 mmol / g, preferably at most 0.55 mmol / g, and particularly preferably at most 0.5 mmol / g.

[0048] The finely divided pKM further preferably exhibits an OH group density of at least 1 OH / nm² < BET surface area, preferably at least 1.5 OH / nm² < BET surface area, particularly preferably at least 1.75 OH / nm² < BET surface area and a maximum of 15 OH / nm² < BET surface area, preferably a maximum of 12 OH / nm² < BET surface area, and particularly preferably a maximum of 10 OH / nm² < BET surface area. The determination of the OH group density (both in mmol / g and in OH / nm² < ) on the material surface is carried out according to Sipponen et al. (Determination of surface-accessible acidic hydroxyls and surface area of ​​lignin by cationic dye adsorption; Bioresource Technology, 2014, 169: 80-87).

[0049] Preferred embodiments of the first process step for obtaining a finely divided pKM are described below. Within the scope of the present invention, it is irrelevant whether this first process step is carried out directly before the second process step or whether this first step occurs significantly before the second (so that, for example, the pKM from the first step is produced separately and then stored or transported before being subjected to the second step).

[0050] Preferably, the finely divided pKM is obtained in the first process step by precipitation of a starting material that is wholly or partially dissolved in a liquid.

[0051] Preferably, the starting material is wholly or partially dissolved in a liquid, preferably water, before the first process step. More preferably, the dissolved starting material before the first process step consists of more than 50%, preferably more than 60%, 70%, 75%, 80%, or 85% sugars (carbohydrates), starches, or lignin.

[0052] The determination of the sugar content is carried out in accordance with TAPPI T 249 cm-00.

[0053] The determination of the starch content is carried out in accordance with TAPPI T 419.

[0054] The determination of the Klason lignin content is carried out in accordance with TAPPI T222 om-02. The determination of the acid-soluble lignin content is carried out in accordance with TAPPI UM 250. In the following, lignin content refers to the sum of Klason and acid-soluble lignin.

[0055] Lignocellulosic liquids, suitable as raw materials, are generated, for example, as waste products in the pulp and paper industry, where large quantities of wood are processed. Depending on the wood processing method, it is produced in large quantities as Kraft lignin, usually dissolved in black liquor, hydrolysis lignin, or lignin sulfonate. Depending on the pH value during the respective processing step, the hydrogen atoms in the hydroxyl groups typical of lignin may be partially replaced by metal cations. Lignin sulfonate is, strictly speaking, already a chemical derivative of lignin, as it possesses additional sulfonate groups introduced during processing.

[0056] In one embodiment of the present process, black liquor, a lignocellulosic liquid, is used as the starting material. Black liquor is a lignin-containing liquid that is produced as waste material in an alkaline fractionation process for biomass, e.g., in a KRAFT process or a hydroxide process. The pH of the black liquor is alkaline, typically between 12 and 14. Besides lignin, black liquor can contain other organic and inorganic components. A characteristic of black liquor is that the lignin content of the organic dry matter is over 50%, particularly over 60% or even over 70%, and thus significantly higher than the lignin content of woody biomass, which is between 15% and 35%.

[0057] If the starting material consists of more than 50% lignin, then the finely divided pKM is preferably obtained by precipitation of lignin wholly or partially dissolved in a liquid by introducing an acidic gas and / or by adding an acid and / or by precipitation. Such processes are generally known to those skilled in the art and are described in WO2006031175, WO2006038863, or WO2009104995. Advantageously, these processes are controlled such that, after the first process step, a finely divided pKM is present, characterized by particle size distribution, BET surface area, and / or STSA surface area as described above.

[0058] If the starting material consists of more than 50% lignin, then the finely divided pKM is preferably obtained alternatively by precipitation and simultaneous stabilization under hydrothermal carbonization (HTC) conditions. Such processes are generally known to those skilled in the art and are described in WO2016 / 020383 or WO2017 / 085278 (precipitation and simultaneous stabilization). Advantageously, these processes are controlled such that, after the first process step, a finely divided pKM is present, characterized by particle size distribution, BET surface area, and / or STSA surface area as described above.

[0059] Alternatively, the finely divided pKM is preferably obtained in the first process step by hydrolysis from a solid starting material, preferably wood or straw. Here, the solid starting material is comminuted before and / or during hydrolysis to such an extent that, after the first process step, it is present as a finely divided pKM characterized by particle size distribution, BET surface area, and / or STSA surface area, as described above. Since the carbohydrates contained in the starting material dissolve during hydrolysis, the finely divided pKM has a higher lignin content than the starting material. Such finely divided pKM obtained by hydrolysis advantageously have a lignin content of more than 60 wt%, preferably more than 65 wt%, and particularly preferably more than 70 wt%. Advantageously, these processes are controlled such that, after the first process step, a finely divided pKM is present, characterized by particle size distribution, BET surface area, and / or STSA surface area, as described above.

[0060] Preferred embodiments of the second process step are described below. As mentioned above, the finely divided pKM obtained after the first process step can be converted into a finely divided modified pKM according to the invention by means of the second process step.

[0061] In the second process step, the pKM is converted into the modified pKM in a gas atmosphere.

[0062] Advantageously, the second process step does not take place in atmospheric air, but rather in a process atmosphere. A process atmosphere is understood to mean, for example: Air enriched with inert gases, having an oxygen content of less than 15 vol.%, preferably less than 10 vol.%, more preferably less than 5 vol.%, and particularly preferably less than 3 vol.%; the absolute pressure of the air enriched with inert gas can be selected as required and is preferably a maximum of 2000 mbar, more preferably a maximum of 1500 mbar, and more preferably at least 100 mbar, more preferably at least 200 mbar, 250 mbar, 500 mbar, or 750 mbar. An inert gas; the absolute pressure of the inert gas can be selected as required and is preferably a maximum of 2000 mbar, more preferably a maximum of 1500 mbar, and more preferably at least 100 mbar, more preferably at least 200 mbar, 250 mbar, 500 mbar, or 750 mbar. Air reduced in pressure to less than 750 mbar, preferably less than 500 mbar, more preferably less than 250 mbar, in some cases less than 100 mbar.

[0063] Advantageously, the oxygen content of a process atmosphere consisting of air enriched with inert gas is at least 0.1 vol.%, preferably at least 0.5 vol.%, and particularly preferably at least 1 vol.%.

[0064] A suitable inert gas within the meaning of the present invention is, in particular, nitrogen, carbon dioxide, superheated steam, or gases released from the pKM during the second process step. Although the gas released from the pKM during the second process step also contains, for example, carbon monoxide, hydrogen, methane, or hydrogen sulfide, etc., it is referred to in this document as an inert gas. The pressure can be selected according to available options or requirements when using air enriched with an inert gas or when using an inert gas as the process atmosphere, as already described above. The process is simplest from an apparatus perspective when operating at ambient pressure or only a slight negative or positive pressure, for example, at ±50 mbar, preferably ±25 mbar, and particularly preferably ±10 mbar.

[0065] The second process step is preferably controlled (for example, by selecting the temperature profile, the maximum temperature, the process atmosphere, and optionally the pressure) such that the mass loss of the pKM in the second process step is less than 20%, preferably less than 15%, and more preferably less than 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, or less. A certain mass loss is necessary during the second process step of the process according to the invention to reduce the content of odor-intensive substances and / or to reduce, preferably to adjust, the OH group density. This mass loss will typically be at least 1% or more, preferably at least 2% or more, and in some cases 5% or more. This ensures and achieves that not too much material is lost and, on the other hand, that the desired odor reduction and / or reduction of the OH group density is achieved.This also ensures the suitability of the modified pKM for use as a filler, for example in elastomers.

[0066] Regardless of the choice of process atmosphere for the second process step, the process temperature in the second process step should exceed a minimum temperature and not exceed a maximum temperature. The maximum temperature is 300°C, preferably 250°C or less, more preferably 240°C, particularly preferably 235°C or less, further preferably 230°C or less, particularly preferably 225°C, in some preferred cases 220°C, further preferably also 210°C, and in rare cases also 200°C or less. The minimum temperature is 80°C, preferably 100°C, preferably 120°C, more preferably 130°C or more, further preferably 150°C or more, particularly preferably 160°C or more, particularly preferably 170°C or more, and in some cases 180°C or more. The holding time during which the pKM is held at the process temperature in the process atmosphere during the second process step can be selected over a wide range.Suitable values ​​are 1 second or more and 5 hours or less. Preferably, the holding time is 60 minutes or less, more preferably 30 minutes or less, most preferably 15 minutes or less, and in some cases less than 10 minutes. When the second process step is operated continuously, the holding time refers to the average residence time.

[0067] Preferably, the OH group density of the finely divided pKM is adjusted during the second process step. Advantageously, this adjustment is achieved by selecting the process temperature, preferably in combination with the process atmosphere, and particularly preferably by adjusting the oxygen content of the process atmosphere.

[0068] By combining a low process temperature, for example preferably below 250°C, more preferably below 240°C, particularly preferably below 235°C or less, furthermore preferably below 230°C, particularly preferably below 225°C, in some preferred cases below 220°C, furthermore preferably also below 210°C, and in rare cases even below 200°C, with an adjustment of the oxygen content, the OH group density can be precisely controlled without subjecting the material to high thermal stress. This ensures optimal preservation of the fine particle size, minimizes odor, and additionally controls the OH group density.

[0069] It has proven advantageous that in the second process step, the pKM is not only treated under the process atmosphere during the holding time, but that the heating and cooling also take place under the process atmosphere.

[0070] If the pKM was obtained in the first process step, for example, by precipitation with combined stabilization from softwood lignin under hydrothermal carbonization conditions, a second process step, for example, at a maximum treatment temperature of 250°C or less, can achieve a mass loss of only 10% or less, with a simultaneous loss of BET surface area of ​​approximately 5 m² / g or less (i.e., if the pKM has a BET surface area of ​​40 m² / g, this drops to a maximum of 35 m² / g). At the same time, odor tests show a significant reduction in unpleasant odor development. This reduction was observed both in the odor-reduced pKM itself, during the production of a rubber article filled with the odor-reduced pKM, and in the rubber article compared to one containing pKM that had not undergone the second process step.

[0071] The process disclosed herein can therefore achieve a good balance between the desired minimization of odor and / or reduction of OH group density and the simultaneous, largely unchanged preservation of the desired material properties as well as minimal mass loss. Neither the use of process chemicals nor complex procedures is necessary. Furthermore, the maximum temperature of the treatment according to the invention is in a comparatively low range, which is advantageous both in terms of cost and process control.

[0072] Preferably, the second process step is carried out in a moving bed, a fluidized bed, or a fluidized stream. More preferably, the second process step can be combined with the separation of liquid. Advantageously, the separation of liquid is achieved at least partially by its evaporation. Advantageously, the evaporation of liquid is carried out to a dry matter content of >80%, preferably >85%, in such a way that the finely divided pKM reaches a temperature of at least 35°C, preferably at least 40°C, during evaporation.

[0073] Advantageously, the evaporation of the liquid preferably to a dry matter content of >80%, more preferably >85%, is carried out in such a way that the finely divided pKM reaches a temperature of at most 130°C, preferably at most 125°C, more preferably at most 120°C, and particularly preferably at most 115°C, during evaporation, and further preferably at most 95°C, and particularly preferably at most 90°C. Advantageously, the finely divided pKM is only heated to the process temperature of the second process step once it has a dry matter content of more than 85%, more preferably at most 90%, and particularly preferably at most 95 wt%.

[0074] As already described above, the modified pKM obtained according to the invention, preferably based on lignin and preferably obtained by precipitation or precipitation with combined stabilization, for example under conditions of hydrothermal carbonization, are also proposed for use in rubber compounds.

[0075] Within the scope of the present invention, it has also been shown that modified pKMs produced according to the invention are also altered in their polarity and / or hydrophobicity and are, for example, more compatible for use in hydrophobic or low-polarity elastomer compounds than pKMs produced according to the prior art. Preferably, elastomer compounds with modified pKMs swell only to a limited extent in alkaline liquids. Preferably, the mass increase of the elastomer compound with modified pKMs after 7 days in the medium is less than 25%, more preferably less than 15%, and most preferably less than 10%.

[0076] As mentioned above, the first object of the present invention is a modified pKM, which is provided in particular by the method disclosed herein, namely a particulate carbon material which ∘ a 14< C content of greater than 0.20 Bq / g carbon but less than 0.45 Bq / g carbon, ∘ a D50 particle size distribution of less than 500 µm and more than 0.5 µm, and ∘ an OH group density of at least 0.05 mmol / g and at most 0.4 mmol / g, and wherein ∘ the solubility of the particulate carbon material in alkaline liquids is less than 25%, the solubility being determined according to the method described herein.

[0077] Preferably, the particulate carbon material according to the invention has, a 14< C content of greater than 0.23 Bq / g carbon, preferably less than 0.45 Bq / g carbon and / or a carbon content based on the ash-free dry matter between 60 wt.% and 80 wt.% and / or no glass transition temperature measurable according to DIN 53765-1994 and / or a content of volatile components measured at 950°C according to DIN 53552 of more than 30 wt.% and / or a content of volatile components measured at 200°C according to DIN 53552 of less than 5 wt.%.

[0078] Advantageously, the BET surface area of ​​the modified pKM is at least 5 m² / g, preferably at least 8 m² / g, more preferably at least 10 m² / g, further preferably at least 15 m² / g, particularly preferably at least 20 m² / g, and further preferably at least 30 m² / g, especially at least 35 m² / g or more. Advantageously, the BET surface area of ​​the modified pKM is at most 200 m² / g, preferably at most 180 m² / g, further preferably at most 150 m² / g, and particularly preferably at most 120 m² / g.

[0079] Advantageously, the BET surface of the modified pKM deviates from its STSA surface by a maximum of only 20%, preferably by a maximum of 15%, and more preferably by a maximum of 10%. The modified pKM is therefore preferably low porosity.

[0080] The D50 of the particle size distribution of the modified pKM is less than 500 µm, preferably less than 250 µm, more preferably less than 100 µm, and particularly preferably less than 50 µm. The D50 of the particle size distribution of the modified pKM is more than 0.5 µm, preferably more than 1 µm, particularly preferably more than 5 µm, and furthermore preferably more than 10 µm. Most preferably, the D50 of the particle size distribution of the modified pKM is more than 5 µm, and furthermore preferably more than 10 µm.

[0081] Advantageously, the modified pKM has an ash content of less than 15 wt%, preferably less than 12 wt%, 10 wt%, 8 wt%, 6 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt% or less. Advantageously, the ash content of the modified pKM is more than 0.25 wt%, preferably more than 0.5 wt%, and further preferably more than 0.75 wt%. Most preferably, the modified pKM has an ash content of less than 4 wt%, 3 wt%, 2 wt% or less and more than 0.25 wt%, preferably more than 0.5 wt%, and further preferably more than 0.75 wt%.

[0082] The modified pKM also exhibits an OH group density of at least 0.05 mmol / g, preferably at least 0.075 mmol / g, and particularly preferably at least 0.1 mmol / g. The modified pKM has an OH group density of at most 0.4 mmol / g, preferably at most 0.35 mmol / g, particularly preferably at most 0.3 mmol / g, in some cases less than 0.25 mmol / g, and in rare cases less than 0.2 mmol / g.

[0083] The modified pKM is only partially soluble in alkaline liquids. The solubility of the modified pKM is less than 25%, preferably less than 15%, and particularly preferably less than 10%. The soluble fraction is determined according to the method described below. Preferably, the alkaline liquids are aqueous solutions of NaOH, particularly preferably aqueous solutions with a concentration of 0.1 mol / L.

[0084] The modified pKM preferably exhibits a reduced odor. In particular, the proportion of sulfur-containing and phenolic substances emitted is reduced. The emission of some VOCs, such as acetic acid, was also reduced. A method for determining the emission quantity is described below.

[0085] Preferably, the modified pKM has a dimethyl sulfide content of at most 1 mg / kg, preferably at most 0.5 mg / kg, further preferably less than 0.1 mg / kg, and moreover preferably less than 0.05 mg / kg, in particular less than 0.01 mg / kg.

[0086] Preferably, the modified pKM has a proportion of guaiacol and methylguaiacol (creosol) of a maximum of 1 mg / kg each, preferably a maximum of 0.5 mg / kg, further preferably less than 0.1 mg / kg, and moreover preferably less than 0.05 mg / kg, in particular less than 0.01 mg / kg.

[0087] Preferably, the modified pKM has a naphthalene content (DIN EN 16181:2017-11 / Draft) of less than 5 mg / kg. Preferably, the sum of the 18 EPA PAHs excluding BG (DIN EN 16181:2017-11 / Draft) is less than 5 mg / kg. Preferably, no content (< 0.1 mg / kg) of benzo(a)anthracene, chrysene, benzo(b)fluorathen, benzo(k)fluranthe, benzo(a)pyrene, indenol(1,2,3-cd)pyrene, dibenzene(a,h)anthracene, benzene(ghi)perylene, benzo(e)pyrene, and benzo(j)fluoranthene is detectable in the modified pKM (DIN EN 16181:2017-11 / Draft).

[0088] Preferably, the modified pKM contains a proportion of the outgassable individual compounds. 2-methoxyphenol phenol guaiacol 4-methoxy-3-methyl-phenol 4-propanol guaiacol 2-methoxy-4-methylphenol 2-methoxy-4-ethylphenol 4-propylguaiacol methanol, each determined according to thermal desorption analysis according to VDA 278 (05 / 2016), of less than 50 µg / g modified pKM, preferably of 25 µg / g modified pKM, particularly preferably of less than 15 µg / g modified pKM, furthermore preferably of less as 10 µg / g modified pKM, in particular preferably less than 5 µg / g modified pKM, in some cases less than 1 µg / g modified pKM.

[0089] Preferably, the OAN of the modified pKM is higher than 150 ml / 100 g, particularly preferably higher than 151 ml / 100 g, and especially above 151 ml / 100 g.

[0090] Preferably, the OAN of the modified pKM is lower than 200 ml / 100 g, particularly preferably lower than 180 ml / 100 g, and especially less than 170 ml / 100 g.

[0091] Preferably, the electrical resistance of a sulfur-crosslinked SBR polymer mixture filled with 120 phr modified pKM is greater than 1.0 E 10 Ohm * cm.

[0092] Preferably, the modified pKM is obtainable by a process which includes at least two process steps, wherein in a first process step the particulate carbon material pKM is provided, which represents a precursor of the modified particulate carbon material and is different from it, which is then modified in a second process step by heating in the gas atmosphere, whereby the modified pKM is then obtainable, which is preferably odor-reduced.

[0093] Preferably, the particulate carbon material pKM obtainable according to the first process step exhibited a D50 particle size distribution of less than 500 µm and more than 0.5 µm before heating in the gas atmosphere.

[0094] Preferably, by heating in the gas atmosphere according to the second process step, the OH group density of the particulate carbon material pKM used is reduced or adjusted, making the modified pKM available with an OH group density as defined above.

[0095] Preferably, the second process step does not take place under atmospheric air, but under a process atmosphere consisting of air enriched with an inert gas, which has an oxygen content of less than 15 vol.%, preferably less than 10 vol.%, more preferably less than 5 vol.%, and particularly preferably less than 3 vol.%, wherein the oxygen content is preferably at least 0.1 vol.%, particularly preferably at least 0.5 vol.%, and most particularly preferably at least 1 vol.%.

[0096] Preferably, the particulate carbon material pKM provided in the first process step is obtained by precipitation of a starting material, preferably a lignin-based starting material, which is wholly or partially dissolved in a liquid.

[0097] Preferably, the process temperature in the second process step is a maximum of 50 °C below and a maximum of 50 °C above the further processing temperature and / or the operating temperature, and the process temperature does not exceed a maximum temperature and does not fall below a minimum temperature.

[0098] Preferably, the D50 of the particle size distribution of the modified particulate carbon material obtainable after the second process step is at most 5 times, preferably at most 4 times, 3 times, 2.5 times, 2 times, 1.75 times, 1.5 times, 1.4 times, 1.3 times, 1.2 times, 1.1 times larger than the D50 of the particle size distribution of the particulate carbon material pKM provided in the first process step.

[0099] A further object of the present disclosure is a method for producing the particulate carbon material according to the invention, which comprises at least two process steps, wherein in a first process step a particulate carbon material pKM is provided, which represents a precursor of the particulate carbon material according to the invention and is different from it, which is subsequently modified in a second process step by heating in the gas atmosphere, whereby the particulate carbon material according to the invention is then obtainable, which is preferably odor-reduced.

[0100] Another object of the present invention is the use of the particulate carbon material according to the invention as an additive in polymer mixtures, in particular rubber mixtures such as elastomer mixtures.

[0101] Another object of the present invention is a vulcanizable rubber composition comprising at least one rubber and at least one filler component, wherein the filler component contains at least the particulate carbon material according to the invention.

[0102] The rubber composition can also contain at least one vulcanization system, which includes at least one crosslinking agent. Examples of such crosslinking agents are sulfur and / or peroxides. Examples of usable rubbers are natural rubber (NR), halobutyl rubbers, preferably selected from the group consisting of chlorobutyl rubbers (CIIR) and bromobutyl rubbers (BIIR), butyl rubber or isobutylene isoprene rubber (IIR), styrene butadiene rubber (SBR), preferably SSBR (solution-polymerized SBR) and / or ESBR (emulsion-polymerized SBR), polybutadiene rubber (BR), acrylonitrile butadiene rubbers (NBR) and / or HNBR (hydrogenated NBR), chloroprene (CR), and polyisoprene (IR). Ethylene propylene diene rubber (EPDM), and mixtures thereof.

[0103] A further aspect of the present invention is a vulcanized rubber composition obtainable by vulcanization of the vulcanizable rubber composition, which exhibits a swelling in alkaline liquids after 7 days of less than 25%. The swelling is determined according to DIN ISO 1817:2015 in 0.1 mol NaOH. Determination methods 1. Determination of the <14C content

[0104] The determination of the 14< C content (content of bio-based carbon) is carried out using the radiocarbon method according to DIN EN 16640:2017-08. 2. Determination of the particle size distribution

[0105] The particle size distribution can be determined by laser diffraction of the material dispersed in water (1 wt% in water) according to ISO 13320:2009. The volume fraction is given, for example, as D50 in µm (the diameter of the particles comprising 50% of the sample volume is less than this value). 3. Determination of carbon content

[0106] The carbon content is determined by elemental analysis according to DIN 51732: 2014-7. 4. Determination of dry matter content

[0107] The dry matter content of the sample was determined according to DIN 51718:2002-06 as follows. For this purpose, the Sartorius MA100 moisture balance was heated to a drying temperature of 105 °C. The dry sample, if not already in powder form, was ground into a powder. Approximately 2 g of the sample to be measured were weighed onto a suitable aluminum dish in the moisture balance, and the measurement was then started. As soon as the weight of the sample did not change by more than 1 mg for 30 seconds, this weight was considered constant, and the measurement was stopped. The dry matter content then corresponds to the displayed content of the sample in wt.%. At least one duplicate determination was carried out for each sample. The weighted mean values ​​are reported. 5. Determination of ash content

[0108] The anhydrous ash content of the samples was determined by thermogravimetric analysis according to DIN 51719 as follows: Before weighing, the sample was ground or crushed. Prior to ash determination, the dry matter content of the weighed material was determined. The sample material was weighed into a crucible to an accuracy of 0.1 mg. The furnace, including the sample, was heated to a target temperature of 815 °C at a rate of 9 °K / min and then held at this temperature for 2 hours. The furnace was then cooled to 300 °C before the samples were removed. The samples were cooled to ambient temperature in a desiccator and weighed again. The remaining ash was compared to the initial weight to determine the ash content by weight. Three determinations were performed for each sample, and the average value is reported. 6. Determination of the BET and STSA surface area of ​​organic fillers

[0109] The specific surface area was determined by nitrogen adsorption according to the standard ASTM D 6556 (2019-01-01) for carbon black. The BET surface area (specific total surface area according to Brunauer, Emmett, and Teller) and the external surface area (STSA surface area; statistical thickness surface area) were also determined according to this standard as follows.

[0110] The sample to be analyzed was dried to a dry matter content ≥ 97.5 wt% at 105 °C prior to measurement. Additionally, the measuring cell was dried in a drying oven at 105 °C for several hours before weighing the sample. The sample was then filled into the measuring cell using a funnel. If the upper shaft of the measuring cell became contaminated during filling, it was cleaned with a suitable brush or pipe cleaner. In cases of highly ejected (electrostatic) material, glass wool was weighed in along with the sample. The glass wool served to retain any material that might be ejected during the drying process and contaminate the instrument.

[0111] The sample to be analyzed was baked at 150 °C for 2 hours, the Al₂O₃ standard at 350 °C for 1 hour. The following nitrogen dosage was used for the determination, depending on the pressure range: p / p0 = 0 - 0.01: N2 dosage: 5ml / gp / p0 = 0.01 - 0.5: N2 dosage: 4ml / g.

[0112] To determine the BET, extrapolation was performed in the range of p / p0 = 0.05 - 0.3 with at least 6 measurement points. To determine the STSA, extrapolation was performed in the range of the layer thickness of the adsorbed N 2 from t = 0.4 - 0.63 nm (corresponding to p / p0 = 0.2 - 0.5) with at least 7 measurement points. 7. Determination of solubility in alkaline liquids

[0113] The determination of alkali solubility is carried out according to the method described below: 1. To determine the solubility of a solid sample, it must be in dry, finely powdered form (dry matter content >98%). If this is not the case, the dry sample is ground or thoroughly crushed before the solubility determination. 2. The solubility is determined in triplicate. For this purpose, 2.0 g of dry sample are weighed out into 20 g of 0.1 M NaOH. However, if the determined pH of the sample is <10, this sample is discarded, and instead, 2.0 g of dry filler is weighed out into 20 g of 0.2 M NaOH. Depending on the pH (<10 or ≥10), either 0.1 M NaOH is used (pH ≥10) or 0.2 M NaOH (pH <10). 3. The alkaline suspension is shaken at room temperature for 2 hours at a rate of 200 shakers per minute. Should the liquid touch the lid, the number of shakers should be reduced to prevent this from happening. 4. The alkaline suspension is then centrifuged at 6000 x g. 5.The supernatant from the centrifugation is filtered through a Por 4 frit. 6. The solid after centrifugation is washed twice with distilled water by repeating steps 4 to 6. 7. The solid is dried in a drying oven at 105 °C for at least 24 hours until a constant weight is achieved. 8. The alkaline solubility is calculated as follows: 8. Determination of pH value

[0114] The pH was determined according to ASTM D 1512 as follows. The dry sample, if not already in powder form, was ground into a powder using a mortar and pestle. 5 g of sample and 50 g of fully ionized water were weighed into a beaker. The suspension was heated to 60°C using a magnetic stirrer with a heating element and a stir bar, while stirring continuously. The temperature was maintained at 60°C for 30 minutes. The heating element was then deactivated, allowing the mixture to cool while stirring. After cooling, the evaporated water was replenished by adding more fully ionized water, and the mixture was stirred again for 5 minutes. The pH of the suspension was determined using a calibrated instrument. The temperature of the suspension should be 23°C (± 0.5°C). A duplicate determination was performed for each sample, and the average value is reported. 9. Determination of the glass transition temperature

[0115] The glass transition temperature is measured according to DIN 53765-1994. 10. Determination of the emission quantity

[0116] The content of outgassable organic compounds (emissions) is determined according to thermal desorption analysis as per VDA 278 (05 / 2016). The total outgassable organic emissions are reported as the sum of the measured values ​​from the VOC and FOG runs. The concentration of the individual components is determined by assigning the signal peaks based on the mass spectra and retention indices. 11. Determination of OH group density

[0117] The surface-available acidic hydroxyl groups, including phenolic OH groups and phenolate groups (OH group density), were determined qualitatively and quantitatively using the Sipponen colorimetric method. The Sipponen method is based on the adsorption of the basic dye Azure B to the acidic hydroxyl groups accessible at the filler surface and is described in detail in the article "Determination of surface-accessible acidic hydroxyls and surface area of ​​lignin by cation dye adsorption" (Bioresource Technology 169 (2014) 80-87). The amount of surface-available acidic hydroxyl groups is expressed in mmol / g of filler.

[0118] The invention is explained in more detail below with reference to exemplary embodiments, which, however, are not to be interpreted as restrictive. Example 1:

[0119] In a first step, a finely divided, particulate carbon material was produced from lignin by means of a hydrothermal treatment in water.

[0120] The starting material for the first step was lignin UPM BioPiva 190 (commercially available). This starting material had a solubility of 68.5% in 0.1 M NaOH.

[0121] The lignin was mixed with water while stirring and diluted to a dry matter content (DM content) of 11%. Then, 7.5 g of sodium hydroxide solution was added to every 100 g of dry lignin. The mixture was heated to 80°C while stirring, and after 1 hour a lignin solution with a pH of 10.1 was obtained.

[0122] The lignin solution was then heated to 220°C and hydrothermally treated at 220°C for 480 minutes. The resulting suspension was then cooled to room temperature.

[0123] A pH of 8.8 was established.

[0124] A sample of the suspension was centrifuged at 12,000 rpm and the resulting residue was dried. The dried residue was analyzed for BET and STSA. A multi-point BET of 39.4 m² / g and an STSA of 37.2 m² / g were measured.

[0125] The resulting lignin suspension was then dewatered and pressed in a filter press, mechanically dewatering it to a dry matter content of 39.4%. This yielded a filter cake.

[0126] The D50 of the particle size distribution of a sample of the suspended solid of the filter cake was 5 µm.

[0127] A sample of the filter cake was dried. The dried filter cake was analyzed for BET and STSA. A multi-point BET of 38.3 m² / g and an STSA of 36.1 m² / g were measured.

[0128] The resulting filter cake represents finely divided, particulate carbon material pKM, which is further processed (modified) in the second step.

[0129] In a second step, a finely divided, modified particulate carbon material (according to the invention) was obtained from the finely divided, particulate carbon material pKM by heating in a gas atmosphere.

[0130] Samples were taken from the finely divided, particulate carbon material pKM obtained after the first step and treated under different conditions in the second step (samples 1 to 5) or not treated by means of the second step, but only dried in air (reference sample REF).

[0131] One sample at a time was fed into a rotary kiln, which was continuously purged with nitrogen. The sample was first dried at a temperature of 80°C and then heated to the process temperature specified in Table 1 below and held for the specified time, during which the specified gas composition was achieved. The sample was then cooled back to ambient temperature. Table 1: Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 REF gas N 2 N 2 N 2 N 2 N 2 Air O 2 < 2% O 2 < 2% O 2 < 2% 2% < O 2 < 5% 2% < O 2 < 5% Temperature [°C] 190 190 220 190 220 105 Time [min] 15 30 15 15 15 15

[0132] The resulting finely divided, particulate carbon material was then analyzed. The parameters listed in Table 2 below were measured: Table 2: Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 REF BET [m²<g] 41,2 41,4 39,8 39,3 37,4 41,1 STSA [m 2< / g] 39,8 39,5 38,4 38,0 35,8 39,5 OH group density [mmol / g] 0,29 0,27 0,27 0,22 0,17 0,30 OH group density [mmol / m²< ] 0,0070 0,0065 0,0068 0,0055 0,0045 0,0073 D50 [µm] 5,6 9,3 10,5 12,4 15,4 4,5 Solubility in AcOH [%] 27,8 27,6 27,3 14,6 13,7 28,7 Solubility in 0.1 M NaOH [%] 24,8 24,3 22,1 15,3 8,5 25,7 Decrease in fineness D50 1,2 2,1 2,3 2,8 3,4 - Decrease in fineness BET 1,0 1,0 1,0 1,0 1,1 - STSA reduction in fineness 1,0 1,0 1,0 1,0 1,1 - VOC, max [µg / g Tol. equiv.] 24 31 22 25 22 639 FOG, max [µg / g Tol. equiv.] 7 10 8 6 8 80 VOC, Phenol 0 0 0 0 0 32 VOC, Guaiacol 0 0 0 0 0 523 VOC, 2-Methoxy-4-methylphenol 0 0 0 0 0 13 VOC, 4-Propylguaiacol 0 0 0 0 0 11 VOCs, Methanol 14 0 14 13 13 11 14C content [Bq / gC] 0,227 0,227 0,228 0,228 0,228 0,228 Carbon content [%] 71,4 71,8 71,6 71,5 71,2 71,2 volatile components 950°C [%] 46,5 46,4 46,6 46,5 46,4 46,8 volatile components 200°C [%] 0,1 0,1 0,1 0,1 0,1 0,1 Ash content [%] 3,0 2,9 2,8 3,0 3,0 2,7

[0133] Samples 1-5 and the reference REF were each mixed as filler into an EPDM matrix. After vulcanization, a test specimen was swollen in aqueous NaOH (0.1 M). The swelling after 7 days is shown in Table 3 below. The swelling was determined according to DIN ISO 1817:2015. Table 3: Vulcanizate containing sample 1 Vulcanizate containing sample 2 Vulcanizate containing sample 3 Vulcanizate containing sample 4 Vulcanizate containing sample 5 Containing vulcanizate REF Swelling [%] 24,5 20,1 19,8 15,7 12,2 40,1

[0134] The lower the determined solubility of the respective sample in 0.1% NaOH (see Table 2), the lower the determined swelling of a vulcanizate containing the respective sample as a filler in aqueous NaOH.

[0135] The mixture for the compounds and the vulcanizates were produced according to the recipe in Table 4 and using the following processes: Table 4: Mixing component Mixture ratio [phr] Keltan 8550C 100,0 zinc oxide 5,0 Stearic acid 1,0 Sunpar 2280 60,0 Material according to one of samples 1 to 5 or the reference sample REF 140,0 PEG 4000 2,0 sulfur 1,5 TMTM 80 1,9 MBTS 0,9 ZDBC 80 3,7

[0136] The mixtures were produced according to the following procedure: The mixtures were produced using a W & P Type GK1.5E mixer (interlocking rotor geometry) with a filling level of 70%, a mixer temperature of 40°C and a rotational speed of 40 rpm.

[0137] Vulcanization was carried out by heating at 160°C according to the optimal t90 time determined in the rheometer.

Claims

1. A particulate carbon material, characterized in that it has ∘ a 14C content that is higher than 0.20 Bq / g carbon, but lower than 0.45 Bq / g carbon, ∘ a D50 of the particle size distribution of less than 500 µm and of more than 0.5 µm, and ∘ an OH group density of at least 0.05 mmol / g and at maximum 0.4 mmol / g, and ∘ the solubility of the particulate carbon material in alkaline liquids is less than 25%, wherein solubility is determined according to the method described in the specification.

2. The particulate carbon material according to claim 1, characterized in that it has an ash content of less than 15% by mass, preferably less than 12% by mass, 10% by mass, 8% by mass, 6% by mass, 5% by mass, 4% by mass, 3% by mass, 2% by mass or less, and more than 0.25% by mass, preferably more than 0.5% by mass, further preferably more than 0.75% by mass.

3. The particulate carbon material according to claim 1 or 2, characterized in that it has a D50 of the particle size distribution of less than 250 µm, preferably of less than 100 µm, particularly preferably 50 µm, and preferably of more than 0.5 µm, further preferably of more than 1 µm, particularly preferably of more than 5 µm, moreover preferably of more than 10 µm.

4. The particulate carbon material according to any one of the preceding claims, characterized in that its solubility in alkaline liquids is less than 15%, preferably less than 10% and the alkaline liquids preferably represent aqueous solutions of NaOH (0.1 mol / l).

5. The particulate carbon material according to any one of the preceding claims, characterized in that it has an OH group density of at least 0.075 mmol / g, particularly preferably at least 0.1 mmol / g, and at maximum 0.35 mmol / g, particularly preferably at maximum 0.3 mmol / g.

6. The particulate carbon material according to any one of the preceding claims, characterized in that it has ∘ a 14C content that is higher than 0.23 Bq / g carbon, but lower than 0.45 Bq / g carbon, and / or ∘ no glass transition temperature measurable according to DIN 53765-1994, and / or ∘ a carbon content relative to the ash-free dry substance between 60% by mass and 80% by mass, and / or ∘ a content of volatile constituents, measured at 950 °C according to DIN 53552, of more than 30% by mass, and / or ∘ a content of volatile constituents, measured at 200 °C according to DIN 53552 of less than 5% by mass.

7. The particulate carbon material according to any one of the preceding claims, characterized in that it has a BET surface area of at least 5 m2 / g, preferably at least 8 m2 / g, further preferably at least 10 m2 / g, moreover preferably at least 15 m2 / g, particularly preferably at least 20 m2 / g, moreover preferably at least 30 m2 / g, in particular at least 35 m2 / g or more, wherein the BET surface area preferably is at maximum 200 m2 / g, even more preferably at maximum 180 m2 / g, further preferably at maximum 150 m2 / g, particularly preferably at maximum 120 m2 / g.

8. The particulate carbon material according to any one of the preceding claims, characterized in that the content of dimethyl sulfide, guaiacol and methylguaiacol (creosol) is below 1 mg / kg, respectively.

9. A use of the particulate carbon material according to any one or more of claims 1 to 8 as an additive in polymer mixtures, in particular rubber mixtures, such as elastomer mixtures.

10. A vulcanizable rubber composition comprising at least one rubber and at least one filler component, wherein the filler component contains at least the particulate carbon material according to any one or more of claims 1 to 8.

11. A vulcanized rubber composition obtainable by vulcanization of the vulcanizable rubber composition according to claim 10, characterized in that it exhibits a swelling in alkaline liquids after 7 days of less than 25%, wherein the swelling is determined according to DIN ISO 1817:2015 in 0.1 M NaOH.