Micronized modified granular carbon material and method for producing same

Abstract

The present invention relates to a finely divided particulate carbon material, a method for producing the same and uses thereof.

Description

[Technical Field]

[0001] The present invention relates to refined modified particulate carbon materials, methods for their production and their uses. [Background technology]

[0002] Micronized modified granular carbon materials are used in many applications. These range from use as black colorants to use as fillers in polymers, such as elastomers, thermoplastics, or thermoplastic elastomers. Such carbon-based materials can be, for example, carbon black, i.e., materials with a relatively high carbon content. Other granular carbon materials are obtained by regrowing raw materials. Compared to carbon black, such granular carbon materials have a somewhat lower carbon content, but exhibit interesting properties due to their high degree of functionalization. Starting materials of particular interest for the production of granular carbon materials based on regrowing raw materials are those that can be fully or partially dissolved, such as sugars, starches, or lignins. Such fully or partially dissolved starting materials based on regrowing raw materials can be converted into granular carbon materials by precipitation processes. Precipitation processes for the production of dissolved granular carbon materials are well known to those skilled in the art.

[0003] For example, lignin-based granular carbon materials can be obtained from lignin dissolved in, for example, liquid sodium hydroxide by precipitation with the introduction of an acid gas such as CO or H2S or by the addition of an acid such as H2SO4. Examples of this prior art are given in WO2006031175, WO2006038863 or WO2009104995.

[0004] Furthermore, lignin-based granular carbon materials can be obtained from lignin dissolved in a base, for example liquid sodium hydroxide, by raising the temperature, for example to hydrothermal carbonization conditions, and precipitation with simultaneous stabilization. Examples of this prior art are described in WO 2016 / 020383 or WO 2017 / 085278. Methods for precipitation by introduction of acid gas, by addition of acid or by increasing the temperature can further be combined.

[0005] In the production of granular carbon materials, the adjustment of certain process parameters opens up possibilities to influence in particular the resulting particle size (i.e. the size of the resulting aggregates, which may be built up from primary particles) or particle size distribution, as well as the adjustment of surface parameters, in particular the specific surface area (which is also used as a measure of the primary particle size).

[0006] The particle size or particle size distribution can be determined, for example, by sieve analysis or laser diffraction. For example, sieve analysis on dry granular carbon material may be performed according to DIN 66165. Laser diffraction may be performed, for example, on granular carbon material dispersed in water according to ISO 13320.

[0007] The primary particle size may be determined by methods for measuring the specific surface area, such as BET or STSA measurements, where BET measurements determine the sum of the external and internal surface areas, while STSA measurements determine only the external surface area. Suitable measurement methods are given, for example, in ASTM D 6556-14. It should be noted that when choosing the degassing temperature, it should be set to a value of approximately 150°C for the testing of granular carbon materials.

[0008] It is known that the average size or specific surface area of ​​the primary particles has an effect on the properties of materials produced using granular carbon materials, for example, rubber articles produced by compounding granular carbon materials with elastomers with subsequent crosslinking. For example, the wear properties of rubber articles differ depending on whether granular carbon materials with a larger or smaller BET surface area are used. The situation is similar for mechanical properties such as tensile strength. A larger value for BET surface area correlates with a larger tensile strength value and lower wear. Here, when granular carbon materials are used, it is preferable to use a material having a BET surface area of ​​at least 5 m. 2 / g, preferably at least 8m 2 / g, more preferably at least 10m 2 / g, more preferably at least 15m 2 Specific surface area values ​​of 1 / g or more are often required to obtain high quality rubber articles.

[0009] However, a disadvantage of known granular carbon materials, for example obtained by precipitation of raw materials based on the regeneration of lignin-based granular carbon materials that have been dissolved in whole or in part, is the unpleasant odor that emanates from the granular carbon material itself, that is released during the processing of the granular carbon material, and / or that emanates from materials that contain the granular carbon material, which severely limits the possible applications of the granular carbon material, but which is of great interest in itself.

[0010] The unpleasant odor of lignocellulosic materials is caused in particular by the thermal or chemical decomposition processes of lignin, hemicellulose and cellulose and other wood components (e.g. resins) formed during wood processing.

[0011] Compounds that cause unpleasant odors include sulfur-containing substances such as dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide or dimethyl tetrasulfide, or phenolic substances such as phenol, guaiacol, ethyl guaiacol, etc.

[0012] Furthermore, various volatile organic compounds are released. Volatile organic compounds, also known as VOCs, include volatile organic substances that easily evaporate or are already present as gases at low temperatures, such as room temperature. Volatile organic compounds (VOCs) are either already present in wood materials and are released from them during processing, or, according to current knowledge, they are formed by the decomposition of fatty acids, which then become wood decomposition products. Typical conversion products that occur during processing are, for example, higher aldehydes or, again, organic acids. Organic acids result, particularly from the decomposition of wood components cellulose, hemicellulose, and lignin, with the formation of most alkanoic or aromatic acids, such as acetic acid, propionic acid, and hexanoic acid. Aldehydes are formed from the basic building blocks of cellulose or hemicellulose during hydrolysis processing. Thus, for example, the aldehyde furfural is formed from the monosaccharides and disaccharides of cellulose and hemicellulose, respectively, while aromatic aldehydes can be released during digestion by partial hydrolysis of lignin. Other aldehydes released are, inter alia, the higher aldehydes hexanal, pentanal or octanal.

[0013] Methods for reducing the odor of lignin-based granular carbon materials are known in the prior art. On the one hand, they rely on pre-purification of lignin, for example, by extraction processes (WO 2013 / 101397), enzyme-catalyzed reactions (DE 10 2006 057566), treatment with oxidizing components with subsequent washing (DE 10 1013 001678), and on the other hand, on the treatment of black liquor, for example, by evaporation processes, treatment with reducing or oxidizing agents or also chlorination reactions, and high-temperature treatments. However, such methods require the treatment of relatively large amounts of material or involve the use of chemicals, which is disadvantageous both in terms of equipment and financial costs.

[0014] A method for treating hydrothermally carbonized lignin at high temperatures is known, for example, from EP 3053929. In EP 3053929, hydrothermally carbonized lignin is subjected to stabilization, preferably under inert gas, for the purpose of final processing, e.g., activation. Hydrothermal carbonization is carried out at temperatures between 150 and 300°C, preferably between 150 and 250°C. Stabilization is carried out at a suitable temperature, which is at least 30°C higher than the hydrothermal carbonization temperature. The stabilization temperature is between 200 and 700°C, preferably between 300 and 600°C, ideally between 500 and 600°C. Thus, a minimum stabilization temperature of 330°C results in a hydrothermal carbonization temperature of 300°C, and a stabilization temperature of 280°C results in a hydrothermal carbonization temperature of 250°C. Here, the heating rate is between 0.1 and 20°C / min. In the process, gases (primarily oxygen and hydrogen) escape from the material, which is preferably subjected to reduced pressure during processing. The purpose of this heat treatment is to stabilize the hydrothermally carbonized lignin so that it is ready for final processing, preferably activation, to produce activated carbon.

[0015] A method for reducing wood odor at high temperatures is known, for example, from EP 3170635. In this process, long wood chips having a length of between 150 and 200 mm, a width of between 15 and 20 mm, and a thickness of between 0.5 and 2 mm are roasted at temperatures of between 150°C and 300°C in an oxygen-poor or oxygen-free atmosphere for a duration of between 1 and 5 hours. The mass loss is between 10 and 30%.

[0016] It would therefore be desirable to be able to provide a method that allows for targeted reduction of odors emanating from the granular carbon material itself, released during processing of the granular carbon material, and / or emanating from materials containing the granular carbon material, by treating, preferably, already obtained granular carbon material without the use of additional processing chemicals. In this way, costs and burdens in terms of equipment can be reduced, but at the same time, the amount of material processed is reduced. However, another requirement of such a process is that the desired properties of the granular carbon material, such as particle size or particle size distribution, or primary particle size or specific surface area, must not be lost during the odor-reducing treatment.

[0017] However, another disadvantage of known granular carbon materials, obtained for example by precipitation of fully or partially dissolved starting materials, in particular lignin-based granular carbon materials, based on the regeneration of the raw materials, is their high polarity, which severely limits the possible applications of granular carbon materials that are of great interest in themselves, especially as additives, reagents or fillers, when they are used with materials having significantly different polarities.

[0018] It would therefore also be desirable to be able to provide a method by which the polarity of a granular carbon material can be selectively adjusted, preferably by processing already obtained granular carbon material. In this way, costs and burdens can be reduced in terms of equipment, but at the same time the amount of material processed is reduced. However, another requirement of such a method is that the desired properties of the granular carbon material, such as particle size or particle size distribution, or primary particle size or specific surface area, must not be lost during the processing to adjust the polarity.

[0019] Also, since the granular carbon material is already a valuable product, the loss of material should not be too great. [Prior art documents] [Patent documents]

[0020] [Patent Document 1] International Publication No. 2006031175 [Patent Document 2] International Publication No. 2006038863 [Patent Document 3] International Publication No. 2009104995 [Patent Document 4] International Publication No. 2016 / 020383 [Patent Document 5] International Publication No. 2017 / 085278 [Patent Document 6] International Publication No. 2013 / 101397 [Patent Document 7] German Patent Application Publication No. 10 2006 057566 [Patent Document 8] German Patent Application Publication No. 10 1013 001678 [Patent Document 9] European Patent No. 3053929 [Patent Document 10] European Patent No. 3170635 [Non-patent literature]

[0021] [Non-Patent Document 1] Determination of surface- accessible acidic hydroxyls and surface area of ​​lignin by cationic dye adsorption; Bioresource Technology, 2014, 169: pages 80-87 Summary of the Invention [Problem to be solved by the invention]

[0022] The present invention therefore aims to provide a corresponding granular carbon material as well as a method for its production, so as to provide the granular carbon material described above. [Means for solving the problem]

[0023] This object is achieved by the subject matter defined in the claims. Preferred embodiments and further aspects of the invention result from the further claims and the embodiments given in the following detailed description.

[0024] In particular, the first subject of the invention is More than 0.20 Bq / g carbon but less than 0.45 Bq / g carbon 14 C content, A particle size distribution D50 of less than 500 μm and greater than 0.5 μm, and OH group density of at least 0.05 mmol / g and at most 0.4 mmol / g 1. A granular carbon material having: The solubility of the granular carbon material in the alkaline liquid is less than 25%; It is a granular carbon material.

[0025] Another subject of the present invention is a method for producing a granular carbon material according to the invention, comprising at least two process steps, in which in a first process step a granular carbon material pCM is provided which corresponds to and is different from a precursor of the granular carbon material according to the invention, which is subsequently modified in a second process step by heating under a gas atmosphere, whereby the granular carbon material according to the invention can then be obtained, which preferably has a reduced odor.

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

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

[0028] Another subject of the invention is a vulcanized rubber composition obtainable by vulcanization of a vulcanizable rubber composition and having a swelling of less than 25% after 7 days in alkaline liquid. DETAILED DESCRIPTION OF THE INVENTION

[0029] The method of the present invention allows for the production of finely divided granular carbon materials having reduced odor and / or reduced OH groups (i.e., reduced polarity) and produced from starting materials based on the regeneration of the raw materials. As mentioned above, such granular carbon materials are another subject of the present invention.

[0030] A distinctive feature of the method according to the invention is that, for example, in a first process step, a finely divided particulate carbon material (hereinafter referred to as pCM) is preferably obtained, the odor of which is reduced in a second process step, thereby obtaining a reduced odor pCM.

[0031] A characteristic feature of the method according to the invention is that, for example, in a first process step, a finely divided particulate carbon material (hereinafter referred to as pCM) is obtained, the OH group density of which (in particular at the surface of the material) is reduced, preferably adjusted, in a second process step, thereby obtaining a pCM with reduced OH groups.

[0032] The method according to the present invention also makes it possible to obtain pCM with reduced odor and reduced OH group density, preferably with an adjusted OH group density. In this respect, the second process step can combine odor reduction with a reduction, preferably adjustment, of the OH group density. In the following, modified pCM is to be understood as odor-reduced pCM or pCM with reduced OH groups, or pCM with reduced odor and reduced OH groups. Modified pCM or micronized modified pCM thus corresponds to the granular carbon material according to the present invention and is obtained after the second process step. Micronized pCM or pCM (both as yet unmodified) thus corresponds to the precursor of the granular carbon material according to the present invention and is obtained after the first process step and used in the second process step.

[0033] According to the present invention, the micronized pCM is obtained in a first process step, preferably in the presence of a liquid, particularly preferably in the presence of water, and is converted to modified pCM in a second process step, preferably in a gas atmosphere. According to the present invention, separation of the liquid from the micronized pCM is preferably carried out between the first and second process steps.

[0034] Both the granular carbon material according to the invention (modified pCM) and its precursor (pCM), respectively, are preferably also referred to as "refined" in the context of the present invention. The term "refined" is hereinafter defined as a function of the BET surface area, the STSA surface area and the D50 of the particle size distribution, respectively. Particularly preferably, "refined" in the sense of the present invention means that the respective granular carbon material has a particle size distribution D50 (D50 value) of less than 500 μm and more than 0.5 μm. As defined hereinafter, this refinement is also referred to as PSD refinement.

[0035] As already mentioned above, the granular carbon material according to the invention is preferably also referred to in the context of the present invention as "modified" granular carbon material or modified pCM. In this sense, the term "modified" means that the carbon material is obtained from a finely divided granular carbon material pCM, which is used as a starting material different from the granular carbon material according to the invention. The granular carbon material according to the invention differs in particular from the finely divided granular carbon material pCM used as a starting material pCM in that it can be obtained by heating the starting material in a gas atmosphere. The heating achieves the above-mentioned modification. In the context of the present invention, the granular carbon material according to the invention is also preferably referred to as a finely divided modified granular carbon material. The above statements apply cumulatively in this respect.

[0036] According to the present invention, the morphology of the refined pCM is only slightly changed in the second process step. Therefore, it is also characteristic of the present method and the granular carbon material according to the present invention that the refinement of the modified pCM is already substantially improved after the first process step. Therefore, the second process step of the present invention is configured so that the refinement of the pCM is barely changed, and only the odor of the refined pCM is substantially reduced, and / or the OH group density of the refined pCM is reduced or adjusted.

[0037] The miniaturized pCM after the first process step is at least 5 m 2 / g, preferably at least 8m 2 / g, more preferably at least 10m 2 / g, more preferably at least 15m 2 / g, particularly preferably at least 20m 2 / g, more preferably at least 30m 2 / g, especially at least 35m 2 It has been shown to be advantageous if the BET surface area is at most 200 m / g. 2 / g preferably up to 180m 2 / g, more preferably up to 150m 2 / g, particularly preferably up to 120m 2 / g. In the following, refinement described in terms of BET surface area will be referred to as BET refinement.

[0038] Advantageously, the BET surface area of ​​the micronized pCM differs from its STSA surface area by at most 20%, preferably at most 15%, more preferably at most 10%. Thus, the pCM preferably has only a low porosity. As an alternative to measuring the BET surface area, the STSA surface area may also be used. In the following, micronization described in terms of the STSA surface area will be referred to as STSA micronization.

[0039] It has further been shown to be advantageous if the micronized pCM has, after the first process step, a particle size distribution D50 of less than 500 μm, preferably less than 250 μm, more preferably less than 100 μm, and particularly preferably 50 μm. Advantageously, the particle size distribution D50 of the micronized pCM is greater than 0.5 μm, more preferably greater than 1 μm, particularly preferably greater than 5 μm, and even more preferably greater than 10 μm. D50 means that 50% of the particles are smaller than the stated value. Hereinafter, micronization described in terms of PSD will be referred to as PSD micronization.

[0040] Thus, the refinement of refined pCM and modified pCM may be described by its PSD refinement and / or BET refinement and / or STSA refinement.

[0041] One configuration of the method according to the invention is characterized by the following. - in a first process step, the micronized pCM is obtained in the presence of a liquid, - which is converted in a gas atmosphere into modified pCM in a second process step, - between the first and second process steps, separation of the liquid from the micronized pCM is carried out, - the size reduction of the modified pCM after the second process step is at most 5 times smaller than the size reduction of the micronized pCM before the second process step; and / or - the odor of the modified pCM is reduced after the second process step compared to the odor of the micronized pCM before the second process step; and / or The OH group density of the modified pCM after the second process step is reduced compared to the OH group density of the micronized pCM before the second process step.

[0042] The size reduction of the pCM is reduced by up to 5 times during the second process step, preferably by up to 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] The decrease in miniaturization means the following: - the D50 of the particle size distribution of the modified pCM 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, greater than the D50 of the particle size distribution of the micronized pCM; and / or the BET surface area of ​​the modified pCM is at most 100%, preferably 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 less than the BET surface area of ​​the micronized pCM; and / or The STSA surface area of ​​the modified pCM is at most 100%, preferably 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 less than the STSA surface area of ​​the micronized pCM.

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

[0045] It has further been shown to be advantageous if the micronized pCM after the first process step has an ash content of less than 15%, preferably less than 12%, 10%, 8%, 6%, 5%, 4%, 3%, 2% by weight. Advantageously, the ash content of the micronized pCM is greater than 0.25%, preferably greater than 0.5%, more preferably greater than 0.75% by weight.

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

[0047] Furthermore, the micronized pCM 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, particularly preferably at most 0.5 mmol / g.

[0048] The micronized pCM more preferably has a particle size of at least 1 OH / nm 2 BET surface area, preferably at least 1.5 OH / nm 2 BET surface area, particularly preferably at least 1.75 OH / nm 2 BET surface area and up to 15 OH / nm 2 BET surface area, preferably up to 12 OH / nm 2 BET surface area, particularly preferably up to 10 OH / nm 2 The OH group density of the BET surface area is shown. The OH group density (OH / nm 2 Measurements of surface-accessible acidic hydroxyls and surface area of ​​lignin by cationic dye adsorption (both in mmol / g and in mmol / g) are performed by Shipponen et al. (Determination of surface-accessible acidic hydroxyls and surface area of ​​lignin by cationic dye adsorption; Bioresource Technology, 2014, 169: 80-87).

[0049] In the following, a preferred embodiment of a first process step for obtaining micronized pCM is described. In the context of the present invention, it is not important whether this first process step is performed immediately before the second process step, or whether this first step is performed significantly prior to the second in terms of time (e.g., so that the pCM from the first step is produced separately and then stored or transported before being subjected to the second step).

[0050] Preferably, the micronized pCM is obtained in a first process step by precipitation of starting materials that are wholly or partly dissolved in a liquid.

[0051] For this purpose, the starting material is preferably wholly or partly 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%, 85% sugars (carbohydrates), starch or lignin.

[0052] Sugar measurements are carried out along the lines of TAPPI T 249cm-00.

[0053] The determination of starch content is carried out along the lines of TAPPI T 419.

[0054] Measurement of Klason lignin content is carried out along the lines of TAPPI T222 Ohm-02. Measurement of acid-soluble lignin content is carried out along the lines of TAPPI T250 UM 250. In what follows, the sum of Klason lignin and acid-soluble lignin is referred to as lignin content.

[0055] Lignocellulose-containing liquids suitable as starting materials are often produced as waste products, for example, in the pulp industry, where large amounts of wood are processed. Depending on the wood processing method, they are usually produced as hydrolyzed lignin, such as Kraft lignin dissolved in black liquor, or as lignin sulfonates. Depending on the pH value in each processing method, hydrogen atoms in the hydroxyl groups typical of lignin may be proportionally replaced with metal cations. Strictly speaking, lignin sulfonates are already chemical derivatives of lignin, since they exhibit additional sulfonate groups introduced during processing.

[0056] Thus, in one embodiment of the present method, black liquor is used as the lignocellulose-containing liquid used as starting material. Black liquor is a lignin-containing liquid obtained as waste liquor in alkaline biomass comminution processes, for example, in the KRAFT process or hydroxide process. The pH value of black liquor is usually in the alkaline range, with a pH value of 12-14. In addition to lignin, black liquor can contain further organic or inorganic components. A characteristic feature of black liquor is that the proportion of lignin in the organic dry matter is greater than 50%, in particular greater than 60% or even greater than 70%, and therefore significantly higher than the proportion of lignin in woody biomass, which is present at 15% to 35%.

[0057] If the starting material consists of more than 50% lignin, then the finely divided pCM is preferably obtained by precipitation of the lignin dissolved in liquid, in whole or in part, by introduction of an acid gas and / or by addition of an acid and / or by precipitation. Such methods are known in principle to those skilled in the art and are described in WO 2006031175, WO 2006038863 or WO 2009104995. Advantageously, these methods are controlled so that, after the first process step, finely divided pCM is present, characterized by the particle size distribution, BET surface area and / or STSA surface area described above.

[0058] Alternatively, if the starting material consists of more than 50% lignin, the finely divided pCM is obtained by precipitation and simultaneous stabilization, preferably under conditions of hydrothermal carbonization (HTC). Such processes are known in principle to those skilled in the art and are described in WO 2016 / 020383 or WO 2017 / 085278 (precipitation and simultaneous stabilization). Advantageously, these methods are controlled so that, after the first process step, finely divided pCM is present, characterized by the particle size distribution, BET surface area, and / or STSA surface area described above.

[0059] Alternatively, the finely divided pCM is preferably obtained by hydrolysis of a solid starting material, preferably wood or straw, in a first process step. In this process, the solid starting material is ground before and / or during hydrolysis to such an extent that, after the first process step, it is present as finely divided pCM characterized by the particle size distribution, BET surface area, and / or STSA surface area described above. Because the carbohydrates contained in the starting material pass through the solution during hydrolysis, the finely divided pCM has an increased lignin content compared to the starting material. Such finely divided pCM obtained by hydrolysis advantageously has a lignin content of more than 60% by weight, preferably more than 65% by weight, and particularly preferably more than 70% by weight. Advantageously, these methods are controlled so that, after the first process step, finely divided pCM is present characterized by the particle size distribution, BET surface area, and / or STSA surface area described above.

[0060] In the following, a preferred embodiment of the second process step is described. As mentioned above, the micronized pCM obtained after the first process step can be converted into micronized modified pCM according to the present invention by the second process step.

[0061] According to the present invention, the pCM is converted to modified pCM in a gas atmosphere in a second process step.

[0062] Advantageously, the second process step is not carried out under air but under a process atmosphere, which is understood to mean, for example: - inert gas-enriched air having an oxygen content of less than 15% by volume, preferably less than 10% by volume, more preferably less than 5% by volume, particularly preferably less than 3% by volume; the absolute pressure of the inert gas-enriched air can be selected as required and is preferably at most 2000 mbar, more preferably at most 1500 mbar, preferably at least 100 mbar, more preferably at least 200 mbar, 250 mbar, 500 mbar, 750 mbar. - inert gas; the absolute pressure of the inert gas may be selected as required, preferably at most 2000 mbar, more preferably at most 1500 mbar, preferably at least 100 mbar, more preferably at least 200 mbar, 250 mbar, 500 mbar, 750 mbar. Reduced pressure air having a pressure of less than 750 mbar, preferably less than 500 mbar, more preferably less than 250 mbar, and in some cases less than 100 mbar.

[0063] Advantageously, the process atmosphere, consisting of air enriched with inert gas, has an oxygen content of at least 0.1% by volume, preferably at least 0.5% by volume, particularly preferably at least 1% by volume.

[0064] Suitable inert gases in the sense of the present invention are in particular nitrogen, carbon dioxide, superheated steam or gases released from the pCM during the second process step. The gases released from the pCM during the second process step also include, for example, carbon monoxide, hydrogen, methane or hydrogen sulfide, which are referred to in this document as inert gases. When using inert-gas-enriched air or when using an inert gas as the process atmosphere, as already indicated above, the pressure may be selected according to the respective possibilities or requirements. The simplest method from an equipment standpoint is to carry out the process at atmospheric pressure or simply at a slightly negative or positive pressure, for example ±50, preferably ±25 mbar, particularly preferably ±10 mbar.

[0065] The second process step is preferably controlled (e.g., by selecting the temperature profile, maximum temperature, process atmosphere, and possibly pressure) so that the mass loss of the pCM in the second process step is less than 20%, preferably less than 15%, more preferably less than 10%, 9%, 8%, 7%, 6%, 5%, 4%, or 3% or less. A certain mass loss is required during the second process step of the method according to the present invention to reduce the odorant content and / or to reduce, preferably adjust, the OH group density. This mass loss is usually at least 1%, preferably at least 2%, and in some cases 5% or more. This ensures that not too much material is lost, while still achieving the desired odor reduction and / or OH group density reduction. In this way, the suitability of the modified pCM for use, for example, as a filler in elastomers can also be ensured.

[0066] Regardless of the process atmosphere selected for the second process step, the process temperature of the second process step should exceed the minimum temperature but not exceed the maximum temperature. The maximum temperature is 300°C, preferably 250°C or less, more preferably 240°C, particularly preferably 235°C or less, even more preferably 230°C or less, particularly preferably 225°C, in some preferred cases 220°C, even more preferably also 210°C, and in rare cases even 200°C or less. The minimum temperature is 80°C, preferably 100°C, preferably 120°C, preferably 130°C or more, more preferably 150°C or more, particularly preferably 160°C or more, especially preferably 170°C or more, and in some cases 180°C or more. The residence time during which the pCM is held in the process atmosphere at the process temperature in the second process step may be selected over a wide range. A suitable value is 1 second or more and 5 hours or less. Preferably, the residence time is 60 minutes or less, more preferably 30 minutes or less, particularly preferably 15 minutes or less, and in some cases less than 10 minutes. With respect to continuous operation of the second process step, the residence time should be understood as the average residence time.

[0067] Preferably, the OH group density of the micronized pCM is adjusted during the second process step, advantageously by selecting the process temperature, preferably in combination with the process atmosphere, particularly preferably by adjusting the oxygen content of the process atmosphere.

[0068] For example, by combining a low process temperature, preferably below 250°C, more preferably below 240°C, particularly preferably below 235°C, even more preferably below 230°C, particularly preferably below 225°C, in some preferred cases below 220°C, more preferably also below 210°C, and in rare cases even below 200°C, with adjustment of the oxygen content, the OH group density can be adjusted as desired without subjecting the material to high heat stress. This maintains fineness as much as possible, reduces odor as much as possible, and also adjusts the OH group density.

[0069] It has been found to be advantageous that not only is the pCM treated in the second process step under process atmosphere during the residence time, but also that the heating and cooling take place under process atmosphere.

[0070] When pCM is obtained in a first process step from softwood lignin, for example by precipitation with combined stabilization under hydrothermal carbonization conditions, a mass loss of only 10% or less is observed, with a maximum temperature of the treatment of 250°C or less, of about 5 m 2 / g or less with a concomitant loss of BET surface area (i.e., pCM of 40 m 2 / g, this is up to 35 m 2 / g). At the same time, odor tests show a significant reduction in the occurrence of unpleasant odors. This reduction was found not only for the odor-reduced pCM itself, but also during the manufacture of rubber articles using the odor-reduced pCM as a filler, as well as for rubber articles using pCM that had not undergone the second process step, compared to other articles using pCM.

[0071] The method according to the present invention can thus achieve a good balance between the desired odor minimization and / or reduction of OH group density, while simultaneously preserving the maximum desired material properties and mass loss. This does not require the use of process chemicals or complicated procedures. Furthermore, the maximum temperature of the treatment according to the present invention is in a relatively 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 in an entrained flow. Furthermore, preferably, the second process step may be combined with separation of the liquid. Advantageously, separation of the liquid is carried out at least in part by evaporation thereof. Advantageously, evaporation of the liquid is carried out to a dry matter content of >80%, preferably >85%, so that the micronized pCM reaches a temperature of at least 35°C, preferably at least 40°C, during evaporation.

[0073] Advantageously, evaporation of the liquid is carried out to a dry matter content of >80%, preferably >85%, so that the micronized pCM reaches a temperature during evaporation of at most 130° C., preferably at most 125° C., more preferably at most 120° C., particularly preferably at most 115° C., even more preferably at most 95° C., and in particular at most 90° C. Advantageously, the micronized pCM is only raised to the process temperature of the second process step if it has a dry matter content of more than 85%, more preferably more than 90%, particularly preferably more than 95% by weight.

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

[0075] In the context of the present invention, it has also been shown that modified pCM prepared according to the present invention is also suitable for use in polar or hydrophobically modified elastomeric compounds, e.g., more hydrophobic or less polar than pCM prepared according to the prior art. Preferably, elastomeric compounds containing modified pCM swell only conditionally in alkaline liquids. Preferably, after 7 days in the medium, the weight gain of the elastomeric compounds containing modified pCM is less than 25%, preferably less than 15%, more preferably less than 10%.

[0076] As mentioned above, a first subject of the present invention is in particular the modified pCM provided by the method according to the invention, namely More than 0.20 Bq / g carbon but less than 0.45 Bq / g carbon 14 C content, D50 of particle size distribution less than 500 μm and greater than 0.5 μm, having an OH group density of at least 0.05 mmol / g and at most 0.4 mmol / g, The granular carbon material has a solubility in an alkaline liquid of less than 25%.

[0077] Preferably, the granular carbon material according to the invention comprises: - More than 0.23 Bq / g carbon, but preferably less than 0.45 Bq / g carbon 14 and / or - has a carbon content of between 60% and 80% by weight based on ash-free dry matter, and / or - does not have a measurable glass transition temperature according to DIN 53765-1994, and / or - have a content of volatile constituents of more than 30% by weight, measured at 950°C according to DIN 53552, and / or - have a content of volatile constituents of less than 5% by weight, measured at 200°C according to DIN 53552.

[0078] Advantageously, the modified pCM has a BET surface area of ​​at least 5 m 2 / g, at least 8m 2 / g, more preferably at least 10m 2 / g, more preferably at least 15m 2 / g, particularly preferably at least 20m 2 / g, more preferably at least 30m 2 / g, especially at least 35m 2 Advantageously, the BET surface area of ​​the modified pCM is at most 200 m 2 / g, preferably up to 180m 2 / g, more preferably up to 150m 2 / g, particularly preferably up to 120m 2 / g.

[0079] Advantageously, the BET surface area of ​​the modified pCM differs from its STSA surface area by at most 20%, preferably at most 15%, more preferably at most 10%. Thus, the modified pCM preferably has a small amount of porosity.

[0080] The modified pCM has a particle size distribution D50 of less than 500 μm, preferably less than 250 μm, more preferably less than 100 μm, and particularly preferably less than 50 μm. Advantageously, the modified pCM has a particle size distribution D50 of greater than 0.5 μm, preferably greater than 1 μm, particularly preferably greater than 5 μm, and even more preferably greater than 10 μm. Particularly preferably, the modified pCM has a particle size distribution D50 of greater than 5 μm, and even more preferably greater than 10 μm.

[0081] Advantageously, the modified pCM has an ash content of less than 15% by weight, preferably less than 12%, 10%, 8%, 6%, 5%, 4%, 3%, 2% or less by weight. Advantageously, the ash content of the modified pCM is greater than 0.25% by weight, preferably greater than 0.5% by weight, and more preferably greater than 0.75% by weight. Particularly preferably, the modified pCM has an ash content of less than 4% by weight. less than , 3 mass %、 It has an ash content of 2% by mass or less and greater than 0.25% by mass, preferably greater than 0.5% by mass, and more preferably greater than 0.75% by mass.

[0082] Furthermore, the modified pCM 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 pCM exhibits an OH group density of at most 0.4 mmol / g, preferably at most 0.35 mmol / g, and particularly preferably at most 0.3 mmol / g, and in some cases less than 0.25 mmol / g, and in rare cases less than 0.2 mmol / g.

[0083] The modified pCM is only conditionally soluble in alkaline liquids. The solubility of the modified pCM 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 liquid refers to an aqueous solution of NaOH, particularly preferably an aqueous solution having a concentration of 0.1 mol / l.

[0084] The modified pCM preferably has reduced odor. Therefore, the rate of emission of phenolic substances, especially sulfur-containing substances, is reduced. However, it is possible to reduce the emission of some VOCs, such as acetic acid. One method for measuring the amount of emission is described below.

[0085] Preferably, the modified pCM has a proportion of dimethyl sulfide of at most 1 mg / kg, preferably at most 0.5 mg / kg, more preferably less than 0.1 mg / kg, even more preferably less than 0.05 mg / kg, especially less than 0.01 mg / kg.

[0086] Preferably, the modified pCM has a proportion of guaiacol and methylguaiacol (creosol) each of at most 1 mg / kg, preferably at most 0.5 mg / kg, more preferably less than 0.1 mg / kg, even more preferably less than 0.05 mg / kg, especially less than 0.01 mg / kg.

[0087] Preferably, the modified pCM has a naphthalene content of less than 5 mg / kg (DIN EN 16181:2017-11 / draft). Preferably, the sum of the 18 EPA-PAHs (excluding BG) (DIN EN 16181:2017-11 / draft) is less than 5 mg / kg. Preferably, the content of benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indenol[1,2,3-cd]pyrene, dibenzo[a,h]anthracene, benzo[ghi]perylene, benzo(e)pyrene, and benzo[j]fluoranthene is not detectable (<0.1 mg / kg) in the modified pCM (DIN EN 16181:2017-11 / draft).

[0088] Preferably, the modified pCM has the following characteristics: outgassing properties, each determined by thermal desorption analysis according to VDA 278 (05 / 2016): - 2-Methoxyphenol - Phenol - Guaiacol - 4-Methoxy-3-methyl-phenol - 4-propanol guaiacol - 2-Methoxy-4-methylphenol - 2-Methoxy-4-ethylphenol - 4-Propylguaiacol - of methanol, The content of modified pCM is less than 50 μg / g, preferably less than 25 μg / g, particularly preferably less than 15 μg / g, even more preferably less than 10 μg / g, particularly preferably less than 5 μg / g, and in some cases less than 1 μg / g of modified pCM.

[0089] Preferably the OAN of the modified pCM is greater than 150 ml / 100 g, more preferably greater than 151 ml / 100 g, especially greater than 151 ml / 100 g.

[0090] Preferably, the OAN of the modified pCM is less than 200 ml / 100 g, particularly preferably less than 180 ml / 100 g, in particular less than 170 ml / 100 g.

[0091] Preferably, the electrical resistivity of an SBR polymer mixture crosslinked with sulfur and filled with 120 phr of modified pCM is greater than 1.0E10 Ohm·cm.

[0092] Preferably, the modified pCM can be obtained by a method comprising at least two process steps, in which in a first process step a granular carbon material pCM is provided which corresponds to and is different from the precursor of the granular carbon material according to the invention, which is subsequently modified in a second process step by heating under a gas atmosphere, thereby obtaining the granular carbon material according to the invention, which preferably has a reduced odor.

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

[0094] Preferably, the OH group density of the granular carbon material pCM used is reduced or adjusted by heating in a gas atmosphere according to a second process step, thereby obtaining a modified pCM having an OH group density as defined above.

[0095] Preferably, the second process step is not carried out under atmospheric pressure, but under a process atmosphere consisting of air enriched with an inert gas having an oxygen content of less than 15% by volume, preferably less than 10% by volume, more preferably less than 5% by volume, particularly preferably less than 3% by volume, wherein the oxygen content is preferably at least 0.1% by volume, particularly preferably at least 0.5% by volume, and especially preferably at least 1% by volume.

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

[0097] Preferably, the process temperature of the second process step is at most 50° C. lower and at most 50° C. higher than the temperature of subsequent processing and / or use, and the process temperature does not exceed the maximum temperature or fall below the minimum temperature.

[0098] Preferably, the D50 of the particle size distribution of the modified granular 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, greater than the D50 of the particle size distribution of the granular carbon material pCM provided in the first process step.

[0099] Another subject of the present invention is a method for producing a granular carbon material according to the invention, comprising at least two process steps, in which in a first process step a granular carbon material pCM is provided which corresponds to and is different from a precursor of the granular carbon material according to the invention, which is subsequently modified in a second process step by heating under a gas atmosphere, whereby the granular carbon material according to the invention can then be obtained, which preferably has a reduced odor.

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

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

[0102] The rubber composition may also comprise at least one vulcanization system containing at least one crosslinking agent. Examples of such crosslinking agents are sulfur and / or peroxide. Examples of rubbers that can be used are natural rubber (NR) and halobutyl rubber, then preferably chlorobutyl rubber (CIIR; chloro-isobutene-isoprene rubber) and bromobutyl rubber (BIIR; bromo-isobutene-isoprene rubber), butyl rubber or isobutylene-isoprene rubber (HR; isobutene-isoprene rubber), styrene-butadiene rubber (SBR), then preferably SSBR (solution-polymerized SBR) and / or ESBR (emulsion-polymerized SBR), polybutadiene (BR, butadiene rubber), acrylonitrile-butadiene rubber (NBR, nitrile rubber) and / or HNBR (hydrated NBR), chloroprene (CR), polyisoprene (IR), ethylene-propylene-diene rubber (EPDM), and mixtures thereof.

[0103] Another subject of the present invention is a vulcanized rubber composition obtainable by vulcanization of a vulcanizable rubber composition, which has a swelling of less than 25% after 7 days in alkaline liquid, the swelling being determined in 0.1 mol NaOH according to DIN ISO 1817:2015.

[0104] Measurement method 1. 14 Measurement of C content 14 The determination of the C content (content of biologically based carbon) is carried out by the radiocarbon method according to DIN EN 16640:2017-08.

[0105] 2. Measurement of particle size distribution The particle size distribution can be determined by laser diffraction of the material dispersed in water (1% by weight in water) according to ISO 13320:2009. The volume fraction is specified, for example, as D50 in μm (the diameter of the particles of 50% of the volume of the sample is less than this value).

[0106] 3. Carbon content measurement The carbon content is determined by elemental analysis according to DIN 51732: 2014-7.

[0107] 4. Measurement of dry matter content The dry matter content of the samples was determined along the lines of DIN 51718:2002-06 as follows: For this purpose, they were heated to a drying temperature of 105°C in an MA100 moisture balance from Sartorius. The dried samples, if not already in powder form, were powdered in a mortar or by grinding. Approximately 2 g of the sample to be measured was weighed into the appropriate aluminum pan of the moisture balance, and then the measurement was started. As soon as the mass of the sample did not change by more than 1 mg in 30 seconds, this mass was considered constant and the measurement was terminated. The dry matter content then corresponded to the declared content in % by mass of the sample. Duplicate measurements were performed at least once for each sample. Weighted average values ​​were reported.

[0108] 5. Ash content measurement The water-free ash content of the samples was determined by thermogravimetric analysis according to the DIN 51719 standard as follows: Before weighing, the samples were ground or mortared. Before ash measurement, the dry matter content of the weighed material was determined. The sample material was weighed to the nearest 0.1 mg in a crucible. The furnace containing the sample was heated to a target temperature of 815°C at a heating rate of 9°K / min and then held at this temperature for 2 hours. The furnace was then cooled to 300°C, after which the sample was removed. The sample was cooled to room temperature in a desiccator and weighed again. The remaining ash was related to the initial mass, and thus the mass percent ash was determined. Three measurements were performed for each sample, and the average value was reported.

[0109] 6. Measurement of BET and STSA surface areas of organic fillers The specific surface area was determined by nitrogen adsorption according to the ASTM D 6556 (2019-01-01) standard for industrial carbon black, according to which the BET surface area (total specific surface area according to Brunauer, Emmett and Teller) and external surface area (STSA surface area; statistical thickness surface area) were determined as follows:

[0110] The samples to be analyzed were dried at 105°C to a dry matter content of >97.5% by weight before measurement. Furthermore, the measuring cell was dried in an oven at 105°C for several hours before weighing the sample. The sample was then filled into the measuring cell using a funnel. If there was any contamination on the upper part of the measuring cell shaft during filling, it was cleaned using an appropriate brush or pipe cleaner. If material (carrying static electricity) was blown up, glass wool was additionally weighed into the sample. The glass wool was used to contain material that could blow up during the firing process and contaminate the equipment.

[0111] The samples to be analyzed were calcined for 2 hours at 150°C, and the Al2O3 standards were calcined for 1 hour at 350°C. The following N2 doses were used for the measurements, depending on the pressure range: p / p0 = 0 - 0.01:N2 dose: 5ml / g p / p0 = 0.01 - 0.5:N2 dose: 4ml / g.

[0112] To determine the BET, extrapolation was performed in the range of p / p0 = 0.05–0.3, including at least six measurement points. To determine the STSA, extrapolation was performed in the range of adsorbed N2 layer thicknesses from t = 0.4–0.63 nm (corresponding to p / p0 = 0.2–0.5), including at least seven measurement points.

[0113] 7. Measurement of Solubility in Alkaline Media The measurement of alkaline solubility is carried out according to the method described below: 1. To determine the solubility of a solid sample, it must be present in the form of a dry, fine powder (dry matter content >98%). If this is not the case, the dry sample must be ground or thoroughly mortared before determining the solubility. 2. Solubility is determined in triplicate. For this purpose, 2.0 g of each dry sample is weighed into 20 g of 0.1 M NaOH. However, if the determined pH value of the sample is <10, the sample is discarded and 2.0 g of dry filler is weighed into 20 g of 0.2 M NaOH instead. In other words, depending on the pH value (<10 or >10), either 0.1 M NaOH (pH >10) or 0.2 M NaOH (pH <10) is used. 3. The alkaline suspension is shaken at room temperature for 2 hours at a shaker speed of 200 per minute. If the liquid comes into contact with the lid during the process, the shaker speed must 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. After centrifugation, the solid is washed twice with distilled water by repeating steps 4 to 6. 7. The solid is dried in an oven at 105°C for at least 24 hours until constant mass is achieved. 8. Alkaline solubility is calculated as follows: Alkali solubility of sample [%] = mass of insoluble fraction after centrifugation, filtration and drying [g] × 100 / mass of dried product obtained in item 2 [g]

[0114] 8. pH measurement The pH was determined along the lines of the ASTM D 1512 standard, as described below. The dried sample, if not already in powder form, was pulverized in a mortar or grinder. In each case, 5 g of sample and 50 g of fully deionized water were weighed into a glass beaker. The suspension was heated to a temperature of 60°C with constant stirring using a magnetic stirrer equipped with a heating function and a stirring bar, and the temperature was maintained at 60°C for 30 minutes. The heating function of the stirrer was then turned off to allow the mixture to cool while stirring. After cooling, the evaporated water was replenished by adding fully deionized water again and stirring was resumed for 5 minutes. The pH value of the suspension was determined with a calibrated measuring device. The temperature of the suspension should be 23°C (±0.5°C). Duplicate measurements were performed for each sample, and the average value was reported.

[0115] 9. Measurement of Glass Transition Temperature The measurement of the glass transition temperature is carried out in accordance with DIN 53765-1994.

[0116] 10. Measuring emissions The content of outgassed organic compounds (emissions) is determined by thermal desorption analysis according to VDA 278 (05 / 2016). The total outgassed organic emissions are given as the sum of the measurements from the VOC and FOG cycles. The concentrations of the individual components are determined by assigning signal peaks based on the mass spectrum and retention indices.

[0117] 11. Measurement of OH group density The determination of surface-accessible acidic hydroxyl groups (OH group density), including phenolic and phenolate groups, was carried out qualitatively and quantitatively by colorimetry according to Shipponen. The method by Shipponen is based on the adsorption of the alkaline dye Azure B to the acidic hydroxyl groups available on the filler surface and is described in detail in the paper "Determination of surface-accessible acidic hydroxyls and surface area of ​​lignin by cation dye adsorption" (Bioresource Technology 169 (2014) pp. 80-87). The amount of surface-accessible acidic hydroxyl groups is given in mmol / g of filler.

[0118] The present invention will now be described in more detail with reference to exemplary embodiments, which should not, however, be construed as limiting. [Example]

[0119] In the first step, micronized granular carbon material was produced from lignin by hydrothermal treatment in water.

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

[0121] The lignin was mixed with water under stirring and thus diluted to a dry matter content (DM content) of 11%. 7.5 g of sodium hydroxide was then added per 100 g of dry matter. The mixture was heated to 80° C. under 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 for a period of 480 minutes at 220° C. The resulting suspension was subsequently cooled to room temperature.

[0123] This resulted in a pH of 8.8.

[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. 2 / g BET and 37.2m 2 / g STSA was measured at multiple points.

[0125] The resulting lignin suspension was then dewatered and pressed in a filter press to a DM content of 39.4%, thus obtaining a filter cake.

[0126] The D50 of the particle size distribution of the sample of suspended solid matter 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. 2 / g BET and 36.1m 2 / g STSA was measured at multiple points.

[0128] The resulting filter cake represents the (modified) granular carbon material pCM which is micronized and further processed in a second step.

[0129] In a second step, the micronized modified granular carbon material (according to the invention) was recovered from the micronized granular carbon material pCM by heating in a gas atmosphere.

[0130] From the micronized granular carbon material pCM obtained after the first step, samples were taken and treated under different conditions in a second step (samples 1-5) or were not treated in a second step but were only dried in air (reference sample REF).

[0131] Each sample was individually fed into a rotary smoke tube furnace that was continuously purged with nitrogen. The samples were first dried at a temperature of 80°C and then heated to the process temperature shown in Table 1 below, held for the indicated time, and using the indicated gas composition. The samples were then cooled back to room temperature.

[0132] [Table 1]

[0133] Each resulting micronized granular carbon material was then analyzed, measuring the parameters given in Table 2 below:

[0134] [Table 2]

[0135] Samples 1-5 and the reference REF were each mixed as fillers into an EPDM matrix. After vulcanization, the specimens were swollen in aqueous NaOH (0.1 M). The swelling after 7 days is shown in Table 3 below. The swelling is determined according to DIN ISO 1817:2015:

[0136] [Table 3]

[0137] The lower the determined solubility of each sample in 0.1% NaOH (see Table 2), the lower the determined swelling in aqueous NaOH of vulcanizates containing each sample as filler.

[0138] Compound mixtures and vulcanizates were prepared according to the formulations in Table 4 and by the following process:

[0139] [Table 4]

[0140] The mixtures were prepared according to the following method: the mixtures were prepared in a W & P Type GK1,5E mixer (intermeshing rotor geometry) at a fill ratio of 70%, a mixing temperature of 40°C and a speed of 40 rpm.

[0141] Vulcanization was carried out by baking at 160°C according to the optimum t90 time determined by rheometer.

Claims

1. A granular carbon material, More than 0.20 Bq / g carbon but less than 0.45 Bq / g carbon １４ C content rate, A particle size distribution D50 of less than 500 μm and greater than 0.5 μm, and an OH group density of at least 0.05 mmol / g and at most 0.4 mmol / g; 1. A granular carbon material having: the solubility of the granular carbon material in the alkaline liquid is less than 25%; The alkaline liquid is an aqueous solution of 0.1M or 0.2M NaOH. A granular carbon material characterized by:

2. 2. Granular carbon material according to claim 1, characterized in that it has an ash content of less than 15% by weight and more than 0.25% by weight.

3. 3. Granular carbonaceous material according to claim 1 or 2, characterized in that it has an ash content of less than 4% by weight and more than 0.5% by weight.

4. 4. A granular carbon material according to any one of claims 1 to 3, characterized in that it has a particle size distribution D50 of less than 250 μm and greater than 1 μm.

5. 5. A granular carbon material according to any one of claims 1 to 4, characterized in that it has a particle size distribution D50 of greater than 5 μm.

6. 6. A granular carbonaceous material according to any one of claims 1 to 5, characterized in that its solubility in alkaline liquids is less than 15%.

7. The granular carbon material according to claim 1, wherein the solubility is determined as follows:

1. To determine the solubility of a solid sample, it must be in the form of a dry, fine powder with a dry matter content >98%. Otherwise, the dry sample must be ground or thoroughly mortared before determining the solubility.

2. Solubility is determined in triplicate. For this purpose, 2.0 g of each dry sample is weighed into 20 g of 0.1 M NaOH, respectively. However, if the determined pH value of the sample is <10, the sample is discarded and 2.0 g of dry filler is instead weighed into 20 g of 0.2 M NaOH. In other words, depending on whether the pH value is <10 or >10, 0.1 M NaOH is used when the pH is >10, and 0.2 M NaOH is used when the pH is <10.

3. The alkaline suspension is shaken at room temperature for 2 hours at a shaker speed of 200 per minute. If the liquid comes into contact with the lid during the process, the shaker speed must be reduced to prevent this from happening.

4. The alkaline suspension is then centrifuged at 6000 x g.

5. The centrifugation supernatant is filtered through a Por 4 frit.

6. After centrifugation, the solid is washed twice with distilled water by repeating steps 4 to 6.

7. The solid is oven dried at 105°C for at least 24 hours to a constant weight.

8. Alkali solubility is calculated as follows: Alkali solubility of sample [%] = mass [g] of insoluble fraction after centrifugation, filtration and drying × 100 / mass [g] of dried product obtained in item 2.

8. 8. A granular carbon material according to any one of claims 1 to 7, characterized in that it has an OH group density of at least 0.075 mmol / g and at most 0.35 mmol / g.

9. More than 0.23 Bq / g carbon but less than 0.45 Bq / g carbon １４ and / or no measurable glass transition temperature according to DIN 53765-1994, and / or having a carbon content of between 60% and 80% by weight based on ash-free dry matter, and / or have a content of volatile components of more than 30% by weight, measured at 950°C according to DIN 53552, and / or has a content of volatile constituents of less than 5% by weight, measured at 200°C according to DIN 53552 9. The granular carbon material according to claim 1, wherein the granular carbon material is a granular carbon material.

10. At least 5m ２ 10. A granular carbon material according to any one of claims 1 to 9, characterized in that it has a BET surface area of ​​200 m2 / g and at most 200 m2 / g.

11. 11. Granular carbonaceous material according to any one of claims 1 to 10, characterized in that the contents of dimethyl sulfide, guaiacol and methylguaiacol (creosol) are each less than 1 mg / kg.

12. A method for producing a granular carbon material as defined in any one of claims 1 to 11, comprising at least two process steps, in a first process step a granular carbon material pCM corresponding to but different from a precursor of the granular carbon material as defined in any one of claims 1 to 11 is prepared, which is subsequently modified in a second process step by heating under a gas atmosphere, thereby obtaining the granular carbon material as defined in any one of claims 1 to 11.

13. 13. The method according to claim 12, characterized in that, before heating in a gas atmosphere, the granular carbon material obtainable according to the first process step had a particle size distribution D50 of less than 500 μm and greater than 0.5 μm.

14. 14. A method according to claim 12 or 13, characterized in that the OH group density of the granular carbon material pCM used is reduced or adjusted by heating in a gas atmosphere in a second process step, thereby obtaining a granular carbon material according to any one of claims 1 to 11 having an OH group density as defined in claim 1 or 8.

15. 15. The method according to any one of claims 12 to 14, characterized in that the second process step is carried out not under atmospheric pressure but under a process atmosphere consisting of air enriched with an inert gas having an oxygen content of less than 15% by volume and at least 0.1% by volume.

16. 16. A method according to any one of claims 12 to 15, characterized in that the granular carbon material pCM provided in the first process step is obtained by precipitation of starting materials dissolved in whole or in part in a liquid.

17. 17. The method according to any one of claims 12 to 16, characterized in that the process temperature of the second process step is at most 50°C lower and at most 50°C higher than the temperature of further processing and / or use, such that the process temperature does not exceed the maximum temperature and does not drop below the minimum temperature.

18. 18. The method according to any one of claims 12 to 17, characterized in that the D50 of the particle size distribution of the modified granular carbon material obtainable after the second process step is up to 5 times larger than the D50 of the particle size distribution of the granular carbon material pCM provided in the first process step.

19. Use of a granular carbon material according to any one of claims 1 to 11 as an additive in polymer mixtures, including rubber mixtures.

20. 12. A vulcanizable rubber composition comprising at least one rubber and at least one filler component, wherein the filler component comprises at least the particulate carbon material of any one of claims 1 to 11.

21. 21. A vulcanized rubber composition obtainable by vulcanization of the vulcanizable rubber composition according to claim 20, characterized in that it exhibits a swelling of less than 25% in an alkaline liquid after 7 days.

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