MXPA01002038A - Carbon black, method for producing carbon black and use of the same - Google Patents

Abstract

The inventive carbon black is characterised by an STSA surface of between 20 and 180 m2/g, a 24M4-DBP-absorption of between 40 and 140 ml/100g, a specific BET surface of between 20 and 250 m2/g, in that it contains 0.01 to 20 wt%silicon in relation to its total weight and in that it has a ratio of tan&dgr;0/tan&dgr;60 greater than 3.37-0.0068•STSA. The inventive carbon black is produced by adding silicon-containing compounds are added and mixed with the of carbon black raw material during the oxidative pyrolysis of the same and optionally, using carbon black oil as the fuel. The inventive carbon black can be used as a filler in rubber mixtures, preferably for tyres.

Description

BLACK OF SMOKE, PROCEDURE FOR ITS PREPARATION AS WELL AS ITS USE DESCRIPTION OF THE INVENTION Blacks of smoke are known to the Ullmanns Enzyklopadie der tec nischen Chemie, 4a. edition (1977) volume 14, pages 633 to 648. The most important processes for the preparation of carbon black are based on the oxidation pyrolysis of the raw materials for carbon blacks. Here the raw materials for carbon black at high temperatures in the presence of oxygen are incompletely calcined. Examples of this method for preparing carbon black include the oven process, the gas process and the flame process. Polinuclear aromatic carbon black oils are used as raw materials for carbon black. The carbon blacks are used as fillers and as reinforcers in the preparation of rubber mixtures in the tire industry. Typical rubber mixtures contain in addition to natural or synthetic rubber, carbon black, mineral oils and other additives such as sulfur as a vulcanizing agent. The blacks of smoke influence on the resistance to the wear, the resistance to the rolling, as well as the behavior of slip humid of those rims HeE: 127011 made with these rubber mixtures. For the rubber mixtures that serve as the bearing surface of the rims, so-called mixtures for the bearing surface, a high resistance to wear is required with simultaneously a bearing resistance as small as possible, and good wet sliding behavior. A low rolling resistance leads to a lower fuel consumption in the vehicle. The rolling resistance and wet sliding properties are modified by the viscoelastic properties of the mixture for bearing surfaces. In the case of periodic deformation, the viscoelastic behavior can be described by means of a mechanical loss factor tand and in cases of stretching and upsetting, by means of the dynamic stretching module | E * |. Both magnitudes depend strongly on the temperature. The wet sliding behavior of the mixture for bearing surfaces is correlated with the loss factor at 0 ° C and the rolling resistance with the loss factor at 60 ° C. The greater the loss factor at low temperatures, the better the usual wet slip behavior of the tire mixture. To avoid bearing resistance, however, a loss factor as small as possible at high temperatures is required. The wear resistance and the viscoelastic properties, and also the loss factor of the mixtures for bearing surfaces, are essentially determined by means of the reinforcing carbon blacks that are used. An important characteristic value of the carbon black effective for the rubber of the surface portion, is the specific surface in particular, the CTAB surface or the STSA. As the CTAB surface or the STSA grows, the resistance to wear and tear increases. Other important parameters of the carbon blacks are the DBP absorption as a measure of the initial structure and the absorption 24 4-DBP as a measure of the residual structure that remains after the mechanical effort of the carbon black. For blends for bearing surfaces, carbon blacks having CTAB surfaces between 80 and 180 m2 / g and absorption values 24M4-DBP between 80 and 140 ml / 100 g are suitable. It is known that ASTM carbon blacks can not influence the temperature dependence of the tand loss factor in such a way that the mixture for bearing surfaces with reduced or even improved rolling resistance has an equal or improved wet sliding behavior. The desired reduction in rolling resistance is associated in a known manner with a worsening of the wet sliding behavior. The blacks of smoke that have a reduced resistance to the bearing, are referred to as carbon blacks "with low hysteresis". It is also known that the rolling resistance of the tires can be reduced by replacing the carbon black with silicic acid (EP 0 447 066 Al). Silane coupling reagents are used to bond the silicic acid to the polymeric units of the rubber. Rubber mixtures containing silicic acid have a loss factor reduced by up to 50%. The task of the present invention is to present carbon blacks that provide rubber mixtures, either of natural rubber or of synthetic rubber or their mixtures, a low rolling resistance simultaneously with wet sliding behavior and wear resistance equal or improved. The object of the invention is a carbon black having an STSA surface between 20 and 180 m2 / g, a 24M4-DBP absorption between 40 and 140 ml / 100 g. A specific surface BET between 20 and 250 m / g and a content of 0.01 to 20% of silicon in relation to its total weight, characterized in that rubber mixtures have a ratio tando / tandßo greater than 3.37 - 0.0068. STSA. In one embodiment of the invention, the carbon black, in addition to silicon, may contain 0.01 to 1% by weight of nitrogen. The silicon is added to the carbon black aggregate during the preparation process. For this purpose, for example, compounds containing silicon can be added to the raw materials. Suitable silicon-containing compounds can be organic silicon compounds such as organosilanes, organochlorosilanes, siloxanes and silazanes. In particular, silicone oils, silicon tetrachloride, siloxanes and silazanes can be used. Preferably, silanes and silicone oils can be used. The starting compound has only a reduced influence on the bonding of the silicon atoms in the aggregate of carbon black, with the X-ray photoelectrospectrometry (XPS) and the secondary ion mass spectrometry (SIMS) it can be shown that the atoms of silicon are bound by oxidation and distributed in the carbon black aggregates. The bond by -oxidation, consists mainly of silicon dioxide. Another fraction forms silanol groups. While the silanol groups are essentially on the surface of the carbon black aggregates, the silicon dioxide is evenly distributed across the cross section of the aggregate. In one embodiment of the invention, the silicon may be enriched in areas near the surface of the carbon black aggregate. The groups containing silicon on the surface of the carbon black aggregates influence, after their introduction into the rubber mixtures, the reciprocal action of the filler with the polymeric rubber components. For the covalent attachment of the silanol groups of the carbon blacks in the mixed polymers, bifunctional silanes such as for example SI69 (bis (3-riethoxysilylpropyl) tetrasulfan) from Degussa can be added to the rubber mixtures as a silane coupling reagent. The mixtures for bearing surfaces produced with the carbon blacks containing silicon according to the invention, show, without the addition of a coupling reagent, a greater value of tand and a lower value of tandéo compared to the carbon blacks with the same specific surface and structure. These values correspond to a wet sliding behavior with a clearly reduced simultaneous rolling resistance of the bearing surface. By means of the addition of bifunctional silanes, the rolling resistance of the rubber mixtures can be further improved, ie it can be further reduced. The carbon blacks according to the invention can be prepared according to the furnace carbon black process in accordance with DE 195 21 565 Al. According to the furnace method, oxidation pyrolysis of the raw material is carried out for the carbon black in a reactor coated with a high direct fire resistant material. In that type of reactor, three zones that are longitudinally to the axis of the reactor and through which the reaction means flow sequentially can be differentiated. The first zone, the so-called combustion zone, essentially covers the reactor's calcination chamber. Here a hot process gas is produced in which a fuel, usually hydrocarbon, is burned with an excess of previously hot combustion air or other gases containing oxygen, as a fuel natural gas can be used. Liquid hydrocarbons can also be used as light and heavy fuel oil. In a preferred embodiment of the invention, the raw material for carbon black (carbon black oil) can also be used as a fuel. The combustion of the fuel is usually carried out under an excess of oxygen. The excess of air here produces a complete transformation of the fuel and serves to control the quality of the carbon black. The fuel is usually conducted to the combustion chamber by means of one or more combustion lances. In the second zone of the reactor for carbon black, the so-called reaction or pyrolysis zone, the carbon black is formed. For this, the raw material for the carbon black in general, the so-called carbon black oil, is injected and mixed in the stream of the hot process gas. In relation to the amount of oxygen not completely reacted in the combustion zone, the amount of hydrocarbons introduced into the excess reaction zone is found. Thus, the formation of carbon black normally begins. In case the carbon black oil has also been used as fuel, the formation of carbon black can already be initiated in the combustion zone. In the reaction zone, it is then possible to deposit more carbon black on the carbon black particles formed in the combustion zone.

The carbon black oil can be injected into the reactor in different ways. Suitable is, for example, an oil injection lance or one or more radial oil lances which are arranged in a vertical plane in the direction of flow at the edge of the reactor. A reactor along the direction of flow may have several planes with radial oil lances. In the upper part of the oil lances are spray or injection nozzles with which the carbon black oil is mixed in the process gas stream. With the simultaneous use of carbon black oil and gaseous hydrocarbons such as methane, as a raw material for carbon black, the hydrocarbons in the form of gas can be injected separately from the carbon black oil through a proprietary assembly. of spears for gas, in the stream of hot waste gas. In the third zone of the carbon black reactor is the separation zone (quench zone), the formation of carbon black is interrupted by rapid cooling of the process gas containing carbon black. Thus, unwanted side reactions are avoided. The interruption of the reaction is usually achieved by spraying water with the appropriate spray nozzles. "Frequently the carbon black reactor has several points along the reactor to spray water, that is to say" suffocate ". In this way, the residence time of the carbon black in the reaction zone can be varied.In a subsequently connected heat exchanger, the residual heat of the process gas is used to preheat the combustion air and the carbon black oil. that the known processes for producing carbon black in a furnace, have as objective a combustion as complete as possible of the fuel in the calcination chamber, or in the combustion zone, the process according to the invention to produce the carbon black it is based on the fact that by means of the incomplete combustion of the fuel in the combustion zone, carbon germs are formed that with the waste gas stream They are transported to the reaction zone and there they initiate a formation of carbon black induced by the germ with the raw material of carbon black introduced in the process. The incomplete combustion of the fuel, however, does not mean that the fuel is burned in a smaller proportion of oxygen. In addition, the process according to the invention starts from an excess of air or gases containing oxygen in the calcination chamber. Here they can be used as in the case of conventional blacks, K factors between 0.3 and 1.2. Preferably K factors are used between 0.6 and 0.7. To obtain carbon black germs despite excess air, there are several methods. In a preferred variant of the process according to the invention, starting from liquid hydrocarbons as fuels, instead of natural gas in the reactor's calcination chamber, an excess of air or gases containing oxygen is burned. Liquid hydrocarbons burn more slowly than gaseous hydrocarbons, since they must first be converted to the gaseous form, that is, they must evaporate, in spite of the excess of oxygen with the liquid hydrocarbons as well as combustion, the carbon black germs can also be produced. which, in case there is enough time and the temperature is high enough, they can burn again or in the case of rapid cooling, they can grow forming larger carbon black particles. The formation of carbon black induced by germs is based on the fact that the germs formed in the combustion of liquid hydrocarbons under an excess of oxygen are put directly in contact with the carbon black oil and this induces the growth of the germs. Another variant of the process according to the invention uses natural gas as fuel. Germ formation is obtained when the gas flow velocity of the combustion lances is selected so low that a poor mixing of the natural gas in the hot stream of the combustion air is deliberately obtained. The formation of carbon black germs in the case of non homogeneous fire where, due to the flash of the particles formed also corresponds to that of the flames. In this way of proceeding, it is equally important as the combustion of the liquid hydrocarbons, that the germs formed immediately after formation are put in contact with the carbon black oil. It is provided by means of a calcination chamber or a large combustion zone that the germs can react with the oxygen present in excess in the combustion zone. If complete combustion is also allowed in the combustion zone of the carbon black reactor, then the formation of germ-induced carbon black does not occur. The carbon blacks according to the invention can be prepared by mixing the described silicon-containing compounds with the raw materials for the carbon black, or sprayed separately in the combustion chamber or in the pyrolysis zone of the reactor for black of smoke. The mixing of the silicon-containing compounds in the carbon black oil can be carried out in the form of a solution, when the compounds are soluble in the carbon black or are in the form of an emulsion. By means of these measures the introduction of the silicon atoms in the primary particles of carbon black is achieved. To separately spray the silicon-containing compounds, in the pyrolysis zone of the carbon black reactor, one or more oil lances used to spray the raw material can be used. For the preparation of carbon blacks by inversion, the process of carbon black in the oven is modified. While the process for the conventional production of carbon black in the furnace, has as its object a combustion as complete as possible of the fuel in the calcination chamber or in the combustion zone, the procedure in accordance with DE 195 21 565 for the preparation of blacks of smoke by inversion, has for object that by means of an incomplete combustion of the fuel in the zone of combustion germs are formed that are transported with the current of hot waste gas to the reaction zone and there, they initiate a formation of black smoke induced with germs with the raw materials for carbon black introduced. The incomplete combustion of the fuel, however, does not mean that the fuel is burned in a smaller proportion of oxygen. In addition, the process according to the invention starts from an excess of air or gases containing oxygen in the calcination chamber. Here they can be used as in the case of conventional blacks, K factors between 0.3 and 0.9. To obtain carbon black germs despite excess air, according to DE 195 21 565, there are several methods. In a preferred variant of the process according to the invention, starting from liquid hydrocarbons as fuels, instead of natural gas in the reactor's calcination chamber, an excess of air or gases containing oxygen is burned. Liquid hydrocarbons burn more slowly than gaseous hydrocarbons, since they must first be converted to the gaseous form, that is, they must evaporate, in spite of the excess of oxygen with the liquid hydrocarbons as well as combustion, the carbon black germs can also be produced. which, in case there is enough time. and that the temperature is high enough, they can burn again or in the case of a rapid cooling, they can grow forming larger carbon black particles. The formation of carbon black induced by germs is based on the fact that the germs formed in the combustion of liquid hydrocarbons under an excess of oxygen are put directly in contact with the carbon black oil and this induces the growth of the germs.

Another variant of the process according to DE 195 21 656 uses natural gas as fuel. Germ formation is obtained when the gas flow velocity of the combustion lances is selected so low that a poor mixing of the natural gas in the hot stream of the combustion air is deliberately obtained. The formation of germs of carbon black in the case of non homogeneous fire where, due to the flash of the particles formed also corresponds to that of the flames. In this way of proceeding, it is equally important as the combustion of the liquid hydrocarbons, that the germs formed immediately after formation are put in contact with the carbon black oil. It is provided by means of a calcination chamber or a large combustion zone that the germs can react with the oxygen present in excess in the combustion zone. If complete combustion is also allowed in the combustion zone of the carbon black reactor, then the formation of germ-induced carbon black does not occur. Both described variants can also be combined with each other. In this case, liquid hydrocarbons and natural gas or other fuels are fed in the form of gas in suitable proportions simultaneously to the combustion zone. As liquid hydrocarbons, oils such as, for example, carbon black oil itself are preferred. The procedure according to DE 195 21 565 also consists in that in the combustion zone in which the hydrocarbon used is in excess in relation to oxygen, liquid and / or gaseous hydrocarbons are used as fuels and that germs are provided of carbon black for example by means of an insufficient residence time of the liquid hydrocarbons or by means of insufficient mixing of the gaseous hydrocarbons with the combustion air, the carbon black germs that immediately after forming contact with the raw material for the carbon black which is used in relation to the amount of oxygen in an excess, in the reaction zone, the mixture of carbon black gas and reaction gas, can be cooled in the interruption zone by means of spraying with water and the carbon black thus formed is processed in the usual manner. The fuel according to DE 195 21 565 is decisive for the formation of the carbon black and is then designated as the raw material for the primary carbon black. The raw material for the carbon black to be mixed in the reaction zone is correspondingly designated as a secondary raw material and contributes to most of the carbon black formed. In the case of the carbon blacks according to DE 195 21 565, they impart to the blends of carbon black in comparison with conventional carbon blacks, a lower rolling resistance and comparable wet adhesion. Furthermore, through AFM studies (AFM = atomic force microscope) it was found that the investment carbon blacks have a rougher surface than the corresponding standard ASTM carbon blacks and therefore, a better bond with the rubber polymers. In the particle of carbon black (see W. Gronski et al. "NMR Relaxation - A Method Relevant for Technical Properties of Carbon Black Filled Rubbers, International rubber conference 1997, Nürnberg, page 107.) Improved bonding of rubber polymer leads at lower rolling resistance Studies on the wear of rubber blends using investment carbon blacks have shown that these carbon blacks impart to rubber mixtures in the case of reduced loads, better wear resistance. In the case of high loads such as those that occur in the tires of cargo trucks, these rubber mixtures have a high wear.

In an embodiment of the invention, carbon blacks can be used by inversion, which are characterized in particular by reduced wear in the case of high loads. It is thus possible to use an oven carbon black with CTAB values between 20 and 190 m2 / g and 24M4-DBP absorption between 40 and 140 ml / g with a tando / tand ratio that in the SSBR / BR rubber mixture complies with the ratio tando / tand60 >; 2.76 - 6.7 X 10"3 X CTAB where the value of tand60 is lower than the value for blacks ASTM with the same surface CTAB and absorption 24M4-DBP That black carbon is characterized because the distribution curve of the diameter The particle size of the carbon black aggregate has an absolute decrease of less than 400000 nm.5 Those blacks which can be used according to the invention comply, in relation to the proportions tand,., / tandcu, with the same requirements of the carbon blacks. of investment known and thus give to the introduction into the rubber mixtures with which the tires are produced, a lower rolling resistance.However, they are characterized against the investment blacks known for a narrow distribution of aggregate size. For the description of the distribution of the sizes of the aggregate the measure known by the statistic "absolute deviation" is used here (see: Lot ar Sachs: "Methods of statistical evaluation s ", Springer-Verlag Berlin, 3rd edition, pages 81 to 83). A curve of the aggregate size distribution formed according to the description is represented as a limitation of the average aggregate size of maximum and minimum values. Under "absolute deviation" is meant the deviation of a symmetric aggregate size distribution. An inclined distribution curve is found when one of the two asymptotes of the elongation curve is elongated. If the left part of the curve is elongated, we speak of a negative inclination, that is, the determination of the absolute deviation gave values less than zero. If the section of the right curve is elongated, then the positive deviation with values greater than zero is found. The known ASTM carbon blacks as well as the investment carbon blacks and the carbon blacks according to the invention have a marked positive differentiable inclination. Surprisingly, it was found that the accepted idea in the state of the art, that a distribution of aggregate sizes of the reinforcing carbon black gives the rubber mixtures a low rolling resistance, can not be generalized. The observed improvement in the carbon blacks by inversion of the rolling resistance of rubber mixtures clearly does not depend on the amplitude of the aggregate size distribution, but is essentially originated by the rough surface of the investment blacks and in better associated bond of the rubber polymer to the upper surface of the carbon black. Compared with known investment blacks with their distribution of relatively large aggregate sizes, it is now possible, according to the invention, to improve their wear resistance in such a way that the amplitude of the aggregate distribution is limited. In particular, the fraction of the carbon black aggregates with large particle diameters should be reduced, when the carbon blacks should impart to the rubber mixtures a lower rolling resistance and simultaneously a better resistance to wear. This is then the case when the standard deviation of the aggregate size distribution is less than 400000, preferably less than 20000 nm3. The absolute deviation of the investment blacks known from DE 195 21 565 is above 400000 nm3, while the absolute deviation of the standard ASTM blacks is below 100000 nm3. The absolute deviation of the distribution of the aggregate sizes of a carbon black can be determined with the help of a centrifuge and the corresponding evaluation of the measured value. The sample of carbon black studied is thus dispersed in an aqueous solution and separated in a disk centrifuge according to its particle size: the larger the particles, the greater their mass and the faster the particles move outwards. Black smoke in the aqueous solution as a consequence of the centrifugal force. They penetrate light limits, with whose help extinction is determined as a function of time. From these data the distribution of the size of the aggregate is calculated, that is, the frequency as a function of the particle diameter. Here you can determine the absolute deviation AS in the following way: here they mean H- the frequency, with a particle diameter xx. Here is the particle diameter of the particles, whose mass corresponds to the average particle mass of the carbon black aggregates, "x is calculated with the help of the particle size distribution. they must be carried out in the range of 1 nm to 3000 nm with equidistant spans of one nanometer The measured values that are eventually missing are calculated by means of linear interpolation.

The investment carbon blacks according to the invention can be prepared on average from the generic process described in DE 195 21 565. According to this method, the investment carbon black is prepared in a carbon black reactor, which has a longitudinal axis of reactor a combustion zone, a reaction zone and a separation zone. In the combustion zone, a stream of hot waste gases is produced by combustion of a primary raw material for carbon black in oxygen-containing gases. This hot gas stream is conducted from the combustion zone through the reaction zone to the separation zone. A secondary raw material for carbon black in the hot waste gas is mixed in the reaction zone. The formation of carbon black stops in the separation zone by means of the water spray. Here it is used as raw material for primary carbon black oil, a mixture of oil / natural gas or natural gas alone. The combustion of the primary raw material of carbon black in the combustion zone is carried out in such a way that germs of the carbon black are formed with which the secondary raw material for carbon black is directly contacted. In order to obtain the carbon blacks according to the invention, this process must be carried out in such a way that the carbon black that forms has a distribution of aggregate sizes with an absolute deviation of less than 400000 nm3. This can be achieved, for example, by increasing the supply of combustion air, raw materials for primary and secondary carbon black. The described method is not limited to a certain reactor geometry. In fact, it can be adjusted to different types of reactor and reactor sizes. The formation of germs desired in the combustion zone can be adjusted by the technician through different measures. The possible flow sizes for the optimization of the formation of germs using oil as fuel are the ratio of the combustion air / mass of the oil, the type of the pulverizer used for the fuel and the size of the sprayed oil droplets. As a fuel sprayer both a pure pressure sprayer (single material sprayer) and a sprayer for two materials with internal or external mixing, wherein the spraying medium is pressurized air, steam, hydrogen, a inert gas or also a hydrocarbon gas. The combination described above before a liquid fuel with a gaseous one can also be realized for example by means of the use of the fuel in the form of a gas as a spraying medium for the liquid fuel. The invention will now be illustrated with the following drawing. Figure 1 shows a longitudinal section through the reactor used for the preparation of carbon black according to the invention. EXAMPLES A carbon black according to the invention is prepared in the reactor for carbon black 1 shown in FIG. 1. This reactor for carbon black 1 has a calcination chamber 2, in which the hot waste gas is produced. for the pyrolysis of the oil for carbon black through the combustion of oil by driving an excess of oxygen from the air. The fuel is introduced through a lance for axial fuel 3 to the calcination chamber. The fuel lance can be displaced in the axial direction to optimize the formation of germ-induced carbon black. The conduction of the air of occlusion is carried out through the opening 4 in the upper wall of the calcination chamber. The calcination chamber extends conically over the narrow zone 5. When passing through the narrow zone, the reaction gas mixture expands in the calcination chamber 6. With A, B and C designate different positions for the injection of the oil for carbon black in the hot process gas by means of the lances for oil 7. The lances for oil have in their upper part, suitable spray nozzles. In each injection position four injectors are distributed on the periphery of the reactor. The combustion, reaction and separation zones important for the process according to the invention are identified in FIG. 1 by means of Roman numerals I to III. They can not be excessively separated from each other, their axial extension depends on the positioning of the combustion lances, the lances for oil and the lance for the water of suffocation 8. The measurements of the reactor used are presented in the following list: Larger diameter of the - 530 mm calcination chamber Length of the combustion chamber up to the narrow area 1525 mm Length of the conical section of the calcination chamber 1160 mm Diameter of the narrow zone 140 mm Length of the narrow zone 230 mm Diameter of the reaction chamber 240 mm Position of the lances for oil 1! A: + 110 mm B: - 150 mm C: - 140 mm Position of the lances for water of suffocation1 '1: 1355 mm 2: 2900 mm 1) measured at the entrance of the narrow zone (+: after entry, -: before entry). All the carbon blacks prepared in the described reactor are converted into beads by means of the known process before characterization and introduction to the rubber mixtures. For the preparation of the carbon blacks according to the invention, natural gas and a carbon black oil with a carbon content of 91.4% by weight and a hydrogen content of 6.1% by weight are used as fuel. The reaction parameters for the preparation of the carbon blacks according to the invention are presented in Table 1. The carbon blacks Ri, R2 and R3 were prepared as well as the comparative carbon black A4496. For the preparation, silicon oil is added as the silicon-containing compound to the carbon black oil. For the carbon blacks according to the invention Ri to R3 the dosage is selected such that the final carbon black contains 5.6% by weight of silicon.

Table 1: Parameters of the reactor for the preparation of carbon black 5í 1) measured before the entrance to the narrow zone, the carbon blacks R1, R2 and A44T6 are wet-wetted. R3 carbon black is dry-ported The analytical data of the carbon black of the produced carbon blacks were determined according to the following standards and are presented in Table 2: STSA Surface: ASTM D-5816 DBP Absorption: ASTM D-2414 Absorption 24M4-DBP: ASTM D -3493 Table- 2: Analytical data of carbon black Application example The carbon blacks Rl, R2 and R3 as well as the comparative carbon blacks N220 and A4496 are used for the preparation of rubber mixtures. In the rubber mixtures, the viscoelastic properties are determined among others. The viscoelastic properties of the rubber mixtures reinforced with these carbon blacks were determined in accordance with DIN 53513. In particular, the loss factors were determined at 0 ° C and at 60 ° C. The test recipe used for rubber mixtures is presented in table 4.

Table 3: SSBR / BR test recipe The SSBR rubber component is a SBR copolymer polymerized in the solution with a styrene content of 25% by weight and a butadiene content of 75% by weight. The vinyl content of butadiene is 67%. The copolymer contains 37.5 phi of oil and is marketed under the trade name Buna VSL 5025-1 of Bayer AG. Its Mooney viscosity (ML l + 4/100 ° C) is approximately 50. The rubber component BR is a cis 1,4-polybutadiene (Neodymium type) with a 1,4 cis content of at least 96% by weight and a trans 1,4 content of 2% by weight, a content of 1.2 of 1% by weight and a Mooney viscosity of 44 + 5. This component is marketed under the trade name Buna CB 24 of Bayer AG. As an aromatic oil, Naftolen ZD from Chemetall is used. The PD fraction in the Vulcanoz 4020 recipes and the CBS fraction is Vulkacit CZ, DPG is Vulkacit D and TMTD Vulkacit Thiuram, all from Bayer AG. As wax, Protector G35 of HB-Fuller GmbH is used. The introduction of the carbon blacks in the rubber mixture is carried out in three stages corresponding to the following representation in the table: The subsequent determination of the technical properties of the rubber, that is the Shore hardness, the tension values M100 and M300, rebound at 0 and 60 ° C as well as a loss factor as low as 0 and 60 ° C and the dynamic stretch module | E * | at 0 ° C, it is done in accordance with the standards presented. The measuring conditions for the viscoelastic properties are summarized in table 4. Table 4: Determination of the viscoelastic properties according to DIN 53513 Vulcanization of the test bodies Vulcanization temperature 165 ° C Vulcanization duration T9Í, + 5 min (T95: DIN 53529) The median value of the measurements is used each time in five test bodies. The results of the technical studies on rubber are listed in Table 5. Compared to the comparative carbon black, the carbon blacks according to the invention to rubber mixtures have a loss factor reduced to 60 ° C and a loss factor increased to 0 ° C without reagents. By means of the addition of Si69, the loss factor at 60 ° C can be further reduced. Of the rims, which are produced with this type of rubber mixtures, a better wet sliding behavior is expected with simultaneous reduced rolling resistance. The dry pearl black R3 leads to a further reduction of the tand at 60 ° C compared to the wet pearl black Rl. The advantageous behavior of the carbon blacks according to the invention is shown by the graphic representation according to Figure 2. According to Figure 2 for those carbon blacks the proportion tand ... / tand-. is on the STSA surface. Both carbon blacks according to the invention show with the same STSA surface a clear greater proportion tand, also a temperature profile of the loss factor with higher slope. The range of the carbon blacks according to the invention can be clearly defined from conventional carbon blacks. It is found above the straight lines shown in figure 2, which is given by the calculation tand; ./ tand6o = 3.37-0-0068. STSA.

Table 5: Results of rubber technical studies $ It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (8)

1. CLAIMS Having described the invention as above, the content of the following is claimed as property: Claims: 1. Carbon black with an STSA surface between 20 and 180 m2 / g, a 24M4-DBP absorption between 40 and 140 ml / 100 g a specific surface BET between 20 and 250 m2 / g and a content of 0.01 to 20% by weight of silicon in relation to its total weight, characterized in that the carbon black in rubber mixtures has a ratio of tando / tand¿o greater than 3.37-0.0068. STSA. Carbon black according to claim 1, characterized in that in addition to silicon it contains 0.01 to 1% by weight of nitrogen. 3. Process for the preparation of a carbon black according to claim 1, by means of oxidative pyrolysis of carbon black carbon raw materials, characterized in that the carbon black carbon raw materials are added to them. compounds that contain silicon. 4. Process for the preparation of a carbon black according to claim 3, by means of oxidative pyrolysis of carbon black carbon raw materials, characterized in that the silicon-containing compounds are sprayed in the calcining chamber or in the the reaction chamber of the reactor for carbon black. Method according to one of claims 3 or 4, characterized in that organic silicon compounds such as organosilanes, organochlorosilanes, silicic acid esters, siloxanes or silazanes are used as silicon-containing compounds. Method according to claims 3 to 5, characterized in that oil is used for carbon black, oil, an oil / natural gas or natural gas mixture alone and the combustion of the fuel is carried out in such a way that germs are formed and the raw material for carbon black comes in contact with those carbon black germs directly. Method according to claims 3 to 6, characterized in that by varying the mixing of the silicon-containing compound in the carbon black oil, the distribution of the silicon in the carbon black is affected. 8. Use of the carbon black according to claim 1, as reinforcing carbon black in rubber mixtures, especially for tires with lower rolling resistance and better wet sliding behavior. ITS USE SUMMARY OF THE INVENTION Carbon black characterized by a surface STSA between 20 and 180 m2 / g, a 24M4-DBP absorption between 40 and 140 ml / lOOg, a BET surface specifies between 20 and 250 m2 / g, a silicon content of ü.ül to 20% by weight in relation to its total weight and a tand / tand ratio. greater than 3.37 - 0.0068. STSA, 'produced by adding silicon-containing compounds during the oxidative pyrolysis of the raw materials for carbon black and eventually using carbon black oil as fuel. Carbon black can be used as a filler in rubber blends, preferably for tires.