Carbon black, a process for its production and its use

Abstract

Carbon black, characterized in that the content of polycondensed aromatic hydrocarbons, measured according to the PAH method, is less than 5 ppm and the STSA surface area is < 90 m² 2 / g, the toluene extract is less than 0.04%.

Description

[0001] The invention relates to a carbon black, a process for its production and its use.

[0002] Carbon black is widely used as a black pigment, as well as a enhancer and filler. It is produced with varying properties using different processes. The most common method is the oxidative pyrolysis of carbon-containing raw materials. In this process, the raw materials are incompletely combusted at high temperatures in the presence of oxygen. Examples of carbon black production methods in this category include the furnace carbon black process, the gas carbon black process, and the flame carbon black process. Other methods include the acetylene process, the thermal carbon black process, and the plasma process.

[0003] Aromatic carbon black oils are predominantly used as carbon-containing raw materials for carbon black. The product stream of oxidative pyrolysis consists of exhaust gas containing hydrogen and carbon monoxide and finely particulated carbon black suspended therein, which is separated from the exhaust gas in a filter system (Ullmann's Encyclopedia of Industrial Chemistry, 4th edition, Volume 14, pages 633-649).

[0004] Depending on the manufacturing process and conditions, carbon black may be contaminated with small amounts of organic compounds. These organic compounds can consist of a carbon skeleton, which in turn is composed of polycondensed aromatic systems. Depending on the specific compound, the skeleton may be further branched or substituted.

[0005] Compounds whose carbon skeleton consists primarily of polycondensed aromatic systems are usually referred to as polycondensed aromatic hydrocarbons (PAHs). PAHs are considered harmful to health (Sudip K. Samanta, Om V. Singh and Rakesh K. Jain: “Polycyclic aromatic hydrocarbons: environmental pollution and bioremediation”, TRENDS in Biotechnology Vol. 20 No. 6 June 2002, pages 243–248).

[0006] While PAHs are generally not a problem in systems where the carbon black is firmly bound in a matrix or where there is no contact with humans, for some applications, only carbon blacks with a very low PAH content can be used due to the health risks posed by PAHs. This applies, for example, to the use of carbon black in applications involving contact with food.

[0007] For example, the American Food and Drug Administration has limited the PAH content for carbon blacks in contact with food to 0.5 ppm (Code of Federal Regulations, Title 21, Volume 3, Part 170-199, § Colorants for Polymers, High purity Furnace Blacks, Page 372-376; CITE 21CFR178.3297).

[0008] To a certain extent, the PAH content can be influenced during production, for example with furnace carbon black in the reactor. High temperatures and / or late quenching can reduce PAH levels from, for example, 100-150 ppm to 25-40 ppm (US 4138471).

[0009] However, if it is not possible to achieve particularly low PAH levels through reactor operation, the soot can be treated to remove existing PAHs.

[0010] It is known that polycondensed aromatic hydrocarbons on carbon black are reduced by thermal treatment of beaded furnace black in a fluidized bed in the presence of at least 10% oxygen (US 4,138,471). For the compounds benzo(a)pyrene, dibenz(a,h)anthrazene, or 7,12-dimethylbenz(a)anthrazene, amounts of less than 2 ppb each can be achieved.

[0011] Furthermore, it is known to reduce the polycondensed aromatic hydrocarbons on carbon nanomaterials by extraction with a solvent (WO 03 / 021017).

[0012] WO 2008 / 058114 describes carbon blacks with low PAH content and their use in rubber compositions.

[0013] Furthermore, a toner is known (US 6,440,628) which contains, among other things, carbon black with less than 10 ppm PAH content, based on naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthrazene, chrysene, benzo(b)fluoranthene, benzo(a)pyrene, benzo(k,j)fluoranthene, dibenzo(a,h)anthrazene, indeno(1,2,3-cd)pyrene and benzo(g,h,l)perylene.

[0014] Furthermore, rubber mixtures are known containing carbon black with a specific surface area of ​​13-19 m². 2 / g and 0.25-0.28 wt.% polycondensed aromatic hydrocarbons (SU 899589) or a carbon black with a specific surface area of ​​50-57 m² 2 / g and 0.21-0.23 wt.% polycyclic aromatic hydrocarbons (SU 899589).

[0015] Furthermore, EP 1102127 discloses a toner containing a carbon black with less than 15 ppm PAH content, for example compounds such as benzopyrene, anthracene benzopyrene, phenanthrene, pyrene and similar compounds.

[0016] Furthermore, a pigment preparation is known from US 6,087,434 which contains a carbon black with less than 10 ppm PAH content, for example compounds such as naphthalenes, fluorathenes, fluoranthine, pyrene, chrysene, benzopyrenes and similar compounds, and a specific oxygen content of 0.2–0.4 mg / m³. 2 exhibits.

[0017] Additionally, medical contrast agents from US 6,599,496 are known to contain a carbon pigment whose PAH content is reported to be below 0.5 ppm.

[0018] WO 2008 / 058114 describes carbon blacks whose PAH content could be reduced to values ​​of 1-20 ppm or to values ​​≤10 ppm by thermal treatment or extraction.

[0019] Disadvantages of the known carbon blacks include the high proportion of polycondensed aromatic hydrocarbons, which are harmful to health.

[0020] Another disadvantage, especially with thermal treatment of soot, is the relatively strong reduction in the degree of oxidation, or of the volatile components, at 950°C and the associated reduction of the functional groups on the soot surface, so that, especially with oxidized initial soot, the desired surface groups are partially or completely removed.

[0021] The object of the invention is to provide low-surface-weight carbon blacks that have a low PAH value and optionally a high content of volatile components at 950°C.

[0022] The invention relates to a carbon black characterized in that the content of polycondensed aromatic hydrocarbons, measured according to the PAH method, is less than 5 ppm, preferably less than 0.5 ppm, particularly preferably less than 0.4 ppm, and most preferably less than 0.2 ppm, and the STSA surface area, measured according to ASTM D-6556, is < 90 m²2 / g, preferably ≤ 80 m 2 / g, especially preferred 30-80 m 2 / g, especially preferred 55-80 m 2 / g, is, the toluene extract is less than 0.04%.

[0023] The content of polycondensed aromatic hydrocarbons according to the 22 PAH method is calculated from the summation of the following compounds: Naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(ghi)fluoranthene, cyclopenta(cd)pyrene, chrysene, benzo(e)pyrene, perylene, benzo(ghi)perylene, anthantrene, coronene, benzo(a)anthracene, benzo(k)fluoranthene, Dibenz(ah)anthracene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene, benzo(b)fluoranthene and benzo(j)fluoranthene, where benzo(b)fluoranthene and benzo(j)fluoranthene are counted as one.

[0024] In the 22 PAH method, the carbon black is extracted using a Soxhlet apparatus, detection is carried out using gas chromatography, and the calculation is performed taking into account the aforementioned 22 PAHs ("Determination of PAH content of carbon black", Cabot Corporation, Docket 95F-01631, July 8, 1994, established by the US Food and Drug Administration (FDA) (Code of Federal Regulations, Title 21, Volume 3, Part 170-199, § Colorants for Polymers, High purity Furnace Blacks, Page 372-376; CITE 21CFR178.3297)).

[0025] The carbon black according to the invention can have a content of polycondensed aromatic hydrocarbons, measured according to the PAH method, of less than 5 ppm, preferably less than 1 ppm, particularly preferably less than 0.7 ppm, and most preferably less than 0.12 ppm.

[0026] The content of polycondensed aromatic hydrocarbons according to the 15 PAH method is calculated from the summation of the following compounds: Benz(a)anthracene, benzo(k)fluoranthene, dibenz(ah)anthracene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene, benzo(b)fluoranthene and Benzo(j)fluoranthene, dibenz(ah)acridine, dibenz(aj)acridine, 7H-dibenzo(cg)carbazole, dibenzo(ae)pyrene, dibenzo(ah)pyrene, dibenzo(ai)pyrene, dibenzo(al)pyrene and 5-methylchrysene, where benzo(b)fluoranthene and benzo(j)fluoranthene are each counted separately (8th report on carcinogens, US Department of Health and Human Services, page III-869).

[0027] The carbon black according to the invention can achieve a BET surface area (ASTM D-6556) of 10 to 1000 m² 2 / g, preferably from 20 to 120 m 2 / g, exhibit.

[0028] The carbon black according to the invention can have a DBP value (ASTM D-2414) of 10 to 200 ml / 100g, preferably of 20 to 120 ml / 100g.

[0029] The carbon black according to the invention can have a transmission (ASTM D-1618) of greater than 96%, preferably greater than 99%.

[0030] The carbon black according to the invention has a toluene extract (ASTM D-4527) of less than 0.04%, preferably less than 0.03%.

[0031] The soot can be furnace soot, gas soot, channel soot, flame soot, thermal soot, acetylene soot, plasma soot, inversion soots, known from DE 195 21 565 and DE 198 39 925, Si-containing soots, known from WO 98 / 45361 or DE 19613796, or metal-containing soots, known from WO 98 / 42778, arc soot and soots that are by-products of chemical production processes.

[0032] The carbon black according to the invention can have a pH value (ASTM D-1512) of less than 7, preferably less than 6, particularly preferably less than 5, most preferably less than 3.5.

[0033] The carbon black according to the invention can have a volatile content at 950°C (DIN 53552) of > 0.6%, preferably > 2%, particularly preferably > 4.5%, and especially preferably > 12%. The carbon black according to the invention can be oxidized carbon black, preferably oxidized gas carbon black.

[0034] A further object of the invention is a method for reducing the content of polycondensed aromatic hydrocarbons, measured according to the PAH method, characterized in that the initial soot is treated with IR radiation and / or microwave radiation at temperatures of 150 - 600°C, wherein the method is carried out in a device consisting of a reactor, wherein the reactor wall, a part of the reactor wall or a window is transparent to the electromagnetic radiation used and the electromagnetic source is arranged on the outside of the reactor wall in the region of the radiation-transmitting area.

[0035] The initial carbon black can have an STSA surface area (ASTM D-6556) of < 90 m² 2 / g, preferably ≤ 80 m 2 / g, especially preferred 30-80 m 2 / g, especially preferred 55-80 m 2 / g, have.

[0036] The initial carbon black can have a BET surface area (ASTM D-6556) of 10 to 1000 m² 2 / g, preferably from 20 to 120 m 2 / g, exhibit.

[0037] The initial carbon black can have a DBP value (ASTM D-2414) of 10 to 200 ml / 100g, preferably of 20 to 120 ml / 100g.

[0038] The initial carbon black can have a transmission (ASTM D-1618) of greater than 96%, preferably greater than 99%.

[0039] The starting carbon black may contain a toluene extract (ASTM D-4527) of less than 0.04%, preferably less than 0.03%.

[0040] The starting carbon black can be powder, wet- or dry-beaded carbon black. It can be a furnace soot, gas soot, channel soot, flame soot, thermal soot, acetylene soot, plasma soot, inversion soots (known from DE 195 21 565 and DE 198 39 925), silicon-containing soots (known from WO 98 / 45361 or DE 19613796), metal-containing soots (known from WO 98 / 42778), arc soot, or soots that are byproducts of chemical production processes. The starting carbon black can be activated by upstream reactions, such as oxidation, for example with ozone, nitric acid, nitrogen oxides, or hypochlorite.

[0041] The initial soot can be rubber soot or paint soot.

[0042] Other types of carbon black can include: conductivity carbon black, carbon black for UV stabilization, carbon black as a filler in systems such as rubber, bitumen or plastic, and carbon black as a reducing agent in metallurgy.

[0043] Preferably, the starting soot can be a gas soot, preferably an oxidized gas soot.

[0044] Preferably, the treatment can be carried out with electromagnetic radiation under an inert atmosphere.

[0045] The inert atmosphere can be created using nitrogen, noble gas, air-water vapor mixtures, water vapor, or a nitrogen-water vapor mixture. The treatment can be carried out at normal pressure, slight overpressure, or vacuum.

[0046] The transmission of electromagnetic radiation energy can take place without contact and without a carrier medium.

[0047] A reduction of PAHs to less than 5% of the initial carbon black loading is possible. For microwave (MW) treated samples, lower PAH concentrations can be achieved with increasing residence time.

[0048] In a preferred embodiment, the initial soot is treated with microwave radiation, particularly preferably microwave radiation with 0.9-140 GHz, especially preferably microwave radiation with 2.45 GHz, under an inert atmosphere.

[0049] The carbon black produced by the inventive process can have an STSA surface area of ​​< 90 m² 2 / g, preferably ≤ 80 m 2 / g, especially preferred 30-80 m 2 / g, especially preferred 55-80 m 2 / g, have.

[0050] The carbon black produced by the inventive process can have a BET surface area (ASTM D-6556) of 10 to 1000 m² 2 / g, preferably from 20 to 120 m 2 / g, exhibit.

[0051] The carbon black produced by the inventive process can have a DBP value (ASTM D-2414) of 10 to 200 ml / 100g, preferably of 20 to 120 ml / 100g.

[0052] The carbon black produced by the inventive method can have a transmission (ASTM D-1618) of greater than 96%, preferably greater than 99%.

[0053] The carbon black produced by the process according to the invention can have a toluene extract (ASTM D-4527) of less than 0.04%, preferably less than 0.03%.

[0054] The treatment with electromagnetic radiation is carried out at temperatures of 150-600°C, preferably 300-400°C.

[0055] Treatment with electromagnetic radiation can be carried out in a reaction time of 1-120 min, preferably 5-30 min.

[0056] The method according to the invention is carried out in a device consisting of a reactor, the reactor wall of which, a part of the reactor wall or a window is transparent to the electromagnetic radiation used.

[0057] The wall or window, transparent to the electromagnetic radiation used, can contain glass, quartz glass, or densely sintered Al₂O₃. The reactor wall temperature can be significantly lower than the product temperature.

[0058] The window transparent to the electromagnetic radiation used can be a glass window. The temperature of the irradiated soot can range from 0 to 1000°C. The soot can be kept suspended by means of a levitator (induction, light, sound) or a gas flow (fluidized bed).

[0059] The materials of the reactor can be adapted accordingly with regard to radiation transparency.

[0060] The electromagnetic radiation sources, preferably magnetrons, are protected from the product and arranged on the outside of the reactor wall in the area of ​​the radiation-transmitting region.

[0061] The radiation energy can be transferred in a targeted and focused manner with high power density to the soot located in the reactor without contact, i.e., without a carrier medium.

[0062] The energy input can be controlled and regulated.

[0063] The following are used as radiation sources: IR radiation sources (wavelength λ = 500 µm - 750 nm), such as electric lamps or ceramic emitters, gas-heated catalytic or surface emitters, or gas / oil-heated porous burners, or Microwave emitters (frequencies ω = 900 MHz - 140 GHz), such as magnetrons and gyrotrons.

[0064] Reactor types that do not have moving parts which can be corrosively attacked by soot and PAH substances or the mixture of substances and thus lead to contamination of the manufactured product can be used.

[0065] Reactors can be used for normal, overpressure and underpressure, whereby defined gas atmospheres (for example, inert gas) can be set in the reactor.

[0066] The reactor can be a tubular reactor with an external device for mixing and conveying, for example a

[0067] Reactor with mechanical devices for mixing, such as vibrating / shaking devices, rotary tubes, vibrating conveyors or screw conveyors.

[0068] The reactor can be a fluidized bed, fixed-bed, or bubble column reactor. The reactor can be equipped with devices for mixing the feedstock or feedstock mixture (initial carbon black). Mixing can also be achieved by flowing the substance or mixture through the reactor, for example, using a flow-through reactor, bubble column with or without packing, trickle-bed reactor, fluidized bed reactor, or drop tower.

[0069] In addition to electromagnetic radiation, the reactor may contain an additional device for heat input (hybrid reactor).

[0070] According to the inventive method, energy can be selectively coupled into the product with high energy density and without a carrier medium, whereby the energy dissipation of the electromagnetic radiation within the product heats it internally. Short reaction times can thus be achieved according to the invention.

[0071] The inventive method makes it possible to produce products that are extremely low in impurities.

[0072] To carry out the method according to the invention, the following can be used: Fig. 1 Infrared (IR) feed tube reactor shown or the one in Fig. The two microwave fixed-bed / fluidized-bed reactors shown are used.

[0073] Index list for IR delivery tube reactor ( Fig. 1): 1. Initial soot dosage 2nd lock 3. IR-transparent reactor 4. Carbon black for heat treatment 5. Transport gas flow 6. Vibration drive 7. Product rejection 8. IR emitter modules with 8a one or more IR-transparent windows 9. Electrical control for the IR emitter modules 10. Trace heating 11. Exhaust gas flow

[0074] According to Fig. 1. The initial carbon black or carbon black mixture is fed into the reactor 3 via the metering device 1 and the airlock 2. It falls as a solid powder or granules 4 to the bottom of the reactor 3 for PAH removal and is transported to the product discharge 7 by a vibrating conveyor 6. A gas stream 5, usually heated, can also be passed through the reactor and used to remove the gaseous products, primarily PAHs and their decomposition products.

[0075] During the transport of the metered soot through the reactor, the soot is cleaned by means of the IR emitter modules 8, which are electrically controlled via the device 9. The IR radiation is coupled into the reactor via the IR-transparent window 8a and then causes the soot to heat up rapidly.

[0076] The gas stream 11 is discharged from the reactor via the heated transport line 10.

[0077] Index list for microwave fixed-bed / fluidized-bed reactors ( Fig. 2): 12. Initial soot dosage 13th Lock 14 MW transparent reactor 15. Carbon black for heat treatment as a fixed bed, fluidized bed or bubble column 16. Transport gas flow 17. Inflow surface 18. Product rejection 19. Resonator with 19a one or more MW-transparent windows 20. Microwave source 21. Trace heating 22. Exhaust gas flow

[0078] According to Fig. 2. The initial soot or soot mixture is fed to the microwave reactor 14 via the metering device 12 and the airlock 13. The starting material, as a substance or mixture, falls onto the inlet plate 17 for PAH purification by means of a fixed bed, fluidized bed, or bubble column 15, against the flow of the transport gas 16. If necessary, the excess soot 15 can be discharged via the discharge device 18.

[0079] The soot 15 is conveyed and / or kept in motion by means of the transport gas stream 16 towards the microwave field – generated by the microwave emitter source 20 and the resonator 19. The microwave radiation penetrates the reactor through the window 19a with virtually no loss.

[0080] During the transport of the dosed soot through the reactor, the soot is cleaned by means of microwave radiation treatment.

[0081] The gas stream 22 is discharged from the reactor via the heated transport line 21.

[0082] The gas used in the apparatus can be inert gas, nitrogen, or a nitrogen / water vapor mixture.

[0083] Another object of the invention is the use of the carbon black according to the invention as a filler, enhancer filler, UV stabilizer, conductivity carbon black or pigment.

[0084] The carbon black according to the invention is used in rubber, plastics, printing inks, inks, inkjet inks, toners, varnishes, paints, adhesives, batteries, pastes, paper, fuel cells, bitumen, concrete and other building materials. It can be used as a reducing agent in metallurgy and as conductive carbon black.

[0085] The carbon black according to the invention can be used in particular for applications in materials with food contact, for packaging printing inks, for toner applications or inkjet inks.

[0086] Another object of the invention is the use of a plastic mixture, which is characterized in that it contains at least one plastic and a carbon black according to the invention.

[0087] The plastic mixture according to the invention can contain 40–99.9 wt.%, preferably 90–98 wt.%, of plastic, based on the plastic mixture. The plastic mixture according to the invention can contain 0.1–60 wt.%, preferably 1.5–3 wt.%, carbon black according to the invention, based on the plastic mixture. The plastic can be a thermoplastic polymer, a thermosetting polymer, a thermoplastic elastomer, preferably polyolefin, particularly preferably polyethylene and polypropylene, polyvinyl chloride, melamine-formaldehyde resin, phenolic resin, epoxy resin, polyamide, polyester, polyoxymethylene, polymethyl methacrylate, polycarbonate, polystyrene, polyethylene terephthalate or acrylonitrile butadiene styrene polymer, as well as mixtures or copolymers of the above components.

[0088] Another object of the invention is the use of an ink characterized in that it contains less than 5% by weight of binder, at least one humectant, a solvent and a carbon black according to the invention.

[0089] The ink according to the invention can contain 5 to 95 wt.%, preferably 30 to 80 wt.%, solvent, based on the ink. The ink according to the invention can contain 0.1 to 10 wt.%, preferably 1 to 5 wt.%, carbon black according to the invention, based on the ink. The solvent can be water, alcohols, ketones, esters, aliphatic or aromatic hydrocarbons.

[0090] Another object of the invention is the use of a printing ink characterized in that it contains at least a binder, a solvent and a carbon black according to the invention.

[0091] The printing ink according to the invention can contain 10 to 30 wt.% binder, based on the printing ink. The printing ink according to the invention can contain 10 to 75 wt.% solvent, based on the printing ink. The printing ink according to the invention can contain 3 to 40 wt.% carbon black according to the invention, based on the printing ink. The solvent can be water, alcohol, ketone, acetate, or any type of oil, or a mixture with at least one of these components.

[0092] Another object of the invention is the use of a toner characterized in that it contains at least a flow agent, a plastic and a carbon black according to the invention.

[0093] The toner according to the invention can contain 30 to 95 wt.%, preferably 60 to 90 wt.%, of plastic, based on the toner. The toner according to the invention can contain 1 to 20 wt.%, preferably 2 to 15 wt.%, of carbon black according to the invention, based on the toner. The plastic can be a polyester resin, a styrene copolymer, or a cycloolefin copolymer. The flow agent can be silica, preferably pyrogenic silica, or carbon black.

[0094] An advantage of the carbon black according to the invention is its low content of harmful polycondensed aromatic hydrocarbons.

[0095] Another advantage is that the carbon blacks according to the invention, despite depleted PAHs, have a comparatively high degree of oxidation, measured as volatile components at 950°C. Examples

[0096] The soot analytical characteristics of the produced soots are determined according to the following standards: STSA surface: ASTM D-6556 BET surface: ASTM D-6556 DBP absorption: ASTM D-2414

[0097] The starting soot used in the examples is a starting soot A beaded, with 83 m 2 / g STSA surface area and an oil number (according to the flow point method DIN EN ISO 787-5) of 460 g / 100g is used. Example 1:

[0098] To reduce the content of polycondensed aromatic hydrocarbons (PAHs), bubble-blasted carbon black is treated in an IR pilot plant as in Fig. The treatment is described in section 1. The residence time and temperature are described in Table 1.

[0099] The starting carbon black is carbon black A. In the test series described here, the PAH content is investigated using the 22 PAH method and the 15 PAH method (Table 1). Table 1: sample Time spent [min] Temp.[°C] STSA[m 2 / g] Purge gas 15 PAH method [mg / kg] Depletion to % of c0 22 PAH method [mg / kg] Depletion to % of c0 1. Carbon black according to the invention 120 450 89,7 N2 0,65 1,1 4,17 0,5 2. Initial soot A(Ref.) - - 82,8 - 61,7 (c0) 100 905,0 (c0) 100

[0100] It was shown that a reduction to less than 1% of the initial PAH loading is possible. Example 2:

[0101] To reduce the content of polycyclic aromatic hydrocarbons (PAHs), granulated carbon black is processed in a microwave system as in Fig. The residence time and temperature are described in Table 2.

[0102] The starting carbon black is carbon black A. In the test series described here, the PAH content is investigated using the 22 PAH method and the 15 PAH method (Table 2). Table 2 sample Time spent [min] Temp.[°C] STSA[m 2 / g] Purge gas 15 PAH method [mg / kg] Depletion to % of c0 22 PAH method [mg / kg] Depletion to % of c0 2. Initial soot A(Ref.) - - 82,8 - 61,7 (c0) 100 905,0 (c0) 100 3. Carbon black according to the invention 5 400 83,0 N2 and and 0,44 0,1 nd = not detectable

[0103] In the sample treated in the microwave, a very strong reduction of PAHs to 0.1% of the initial loading is achieved. Example 3

[0104] In a microwave oven like in Fig.As described in section 2, approximately 80g of initial carbon black A is added. The microwave reactor is purged with nitrogen (5 l / h) before the start of the experiment, then irradiated with microwaves, and after the experiment is completed, cooled under nitrogen to a temperature below 120°C.

[0105] The dwell times and temperatures are varied from 1 to 20 minutes and 400 to 600°C, respectively. The time is measured after the target temperature is reached.

[0106] Temperature recording is done via a PC.

[0107] Table 3 shows how to vary different parameters. Table 3: sample Exposure time (min) Temperature (°C) STSA(m 2 / g) Volatile components 950°C% Reduction of volatile components 950°Cum (%) 22 PAH method (ppm) 2. Initial soot A(Ref.) 0 0 82,8 4,4 - 905 4. Carbon black according to the invention 10 400 80,2 3,1 30 1,250 5 Invention 1 600 81,9 1,4 68 4,860 proper soot 6. Carbon black according to the invention 5 600 82,9 1,9 57 1,620 7. Carbon black according to the invention 10 600 78,8 1,6 64 0,357

[0108] In the carbon blacks according to the invention, the PAHs are significantly reduced. At 600°C, the PAHs are reduced to less than 0.4 ppm. Example 4:

[0109] Comparative example of simple temperature treatment in a drying oven: 100g of initial carbon black with 75 m 2 / g STSA surface area and an oil density (according to the yield point method DIN EN ISO 787-5) of 460 g / 100g are distributed on a stainless steel sheet over an area of ​​30 x 30 cm. Tempering is carried out under nitrogen in a drying oven for 1 hour at 300°C. Table 4: sample Time spent [min] Temp.[°C] STSA[m 2 / g] Purge gas 22 PAH method [mg / kg] Depletion to % of c0 Initial soot - - 75 - 1670 (c0) 100 Tempered soot 60 300 74 N2 250 15

[0110] The temperature treatment in the drying oven (Table 4) shows a lower depletion of PAHs compared to the soots produced using the inventive method.

Claims

Carbon black, characterized in that the content of polycondensed aromatic hydrocarbons measured according to the 22 PAH method is less than 5 ppm and the STSA surface area is < 90 m2 / g, and the toluene extract is less than 0.04%. Carbon black according to claim 1, characterized in that the content of polycondensed aromatic hydrocarbons is less than 0.5 ppm. Carbon black according to claims 1 and 2, characterized in that the content of volatile components at 950°C is > 0.6%. Carbon black according to claim 3, characterized in that the content of volatile components at 950°C is > 2%. A method for reducing the content of polycondensed aromatic hydrocarbons, measured according to the PAH method, characterized in that the initial soot is treated with IR radiation and / or microwave radiation at temperatures of 150 - 600°C, wherein the method is carried out in a device consisting of a reactor, wherein the reactor wall, a part of the reactor wall or a window is transparent to the electromagnetic radiation used and the electromagnetic source is arranged on the outside of the reactor wall in the region of the radiation-transparent area. Method for producing the soot according to claim 5, characterized in that an inert atmosphere is used. Method for producing the soot according to claims 5 - 6, characterized in that a gas soot is used as the starting soot. Use of the carbon black according to claims 1 and 2 in rubber, plastics, printing inks, inks, inkjet inks, toners, varnishes, paints, adhesives, batteries, pastes, paper, fuel cells, bitumen, concrete and other building materials. Use of the carbon black according to claim 1 in a plastic mixture, characterized in that the mixture contains at least one plastic and one carbon black according to claim 1. Use of the carbon black according to claim 1 in an ink, characterized in that the ink contains less than 5 wt% binder, at least one humectant, a solvent and a carbon black according to claim 1. Use of the carbon black according to claim 1 in a toner, characterized in that the toner contains at least a flow agent, a plastic and a carbon black according to claim 1. Use of the carbon black according to claim 1 in a printing ink, characterized in that the ink contains at least a binder, a solvent and a carbon black according to claim 1.

Images