Precipitated silicas, methods for their preparation and their use

Description

[0001] The present invention relates to precipitated silicas, processes for their preparation and their use.

[0002] From WO2012059234, elastomer compositions are known which contain at least one isoprene elastomer and a silica as a reinforcing inorganic filler, wherein the silica has a CTAB surface area between 40 m 2 < / g and 525 m 2 < / g, BET surface area between 45 m 2 < / g and 550 m 2 < / g, a width Ld ((d84 - d16) / d50), measured by particle size XDC after deagglomeration with ultrasound, of at least 0.91, and a pore volume distribution with a ratio V (d5 - d50) / V (d5 - d100) of at least 0.66, and 3-acryloxypropyltriethoxysilane is used as adhesion promoter.

[0003] Furthermore, EP2102104 discloses a process for producing silicas, wherein the silica has a CTAB surface area of ​​40 m 2 / g to 525 m 2 / g, a BET surface area of ​​45 m 2 / g to 550 m 2 / g, a width Ld ((d84 - d16) / d50), measured by XDC grain size analysis after ultrasonic disaggregation, of at least 0.91 and a pore volume distribution V (d5 - d50) / V (d5 - d100) of at least 0.66.

[0004] EP1831297 and WO2006072704 disclose the use of a silica having a BET surface area of ​​at least 60 m 2 / g as an inorganic filler in a thermoplastic polymer material to increase the stiffness of the material while maintaining or improving its impact strength.

[0005] From EP 0 647 591 A1 it is known that the precipitated silica material with the physical and chemical parameters of BET surface area 35 to 350 m 2 / g, BET / CTAB surface area ratio 0.8 to 1.1, pore volume PV 1.6 to 3.4 ml / g, silanol group density (V 2 = NaOH consumption) 6 to 20 ml, average aggregate size 250 to 1500 nm, CTAB surface area 30 to 350 m 2 / g, DBP number 150 to 300 ml / 100 g, V 2 / V 1 according to Hg porosimetry 0.19 to 0.46 and DBP / CTAB 1.2 to 2.4 is used as a filler in vulcanizable rubber compounds and vulcanizates.

[0006] From WO 2020 / 120393 A1 it is known that the precipitated silica material with the physical and chemical parameters of a DOA oil absorption equal to or greater than 200 ml / 100 g; a mean aggregate size D50 equal to or less than 8.7 pm and equal to or greater than the value, expressed in microns, of the parameter A, calculated according to equation (1): A = 23.3 - 0.076 x DOA where DOA is the numerical value of the DOA oil absorption, expressed in mL / 100 g, as a battery pack.

[0007] From US 2005 / 032965 A1 it is known that the precipitated silica, with: a specific CTAB surface area of ​​between 40 and 525 mtg a specific BET surface area between 45 and 550 meg; a size distribution width Ld ((d84-d16) / d50) of the objects, measured by XDC particle size analysis after ultrasonic comminution, of at least 0.91, and a pore volume distribution such that the ratio V(d5-d50) / V(d5-d100) is at least 0.66, as polymer reinforcing fillers.

[0008] From EP 1 764 344 A2 it is known that the precipitated silica with the physical and chemical parameters of relative width y of the pore size distribution 4.0 - 10.0 (g nm) / ml, BET surface area 90 -320 m2 / g, CTAB surface area 100 -200 m2 / g, Sears number V2 25 -40 ml / (5 g), Sears number V2 / CTAB ratio 0.16 - 0.28 ml / (5 m 2 ), wherein the precipitated silica is in the form of granules and that the sieve residue (Ro-Tap) on a 300 gm sieve is at least 80 wt.%.

[0009] Furthermore, silicas with a CTAB surface area between 40 m 2< / g and 525 m 2< / g, a BET surface area between 45 m 2< / g and 550 m 2< / g, a size distribution width Ld ((d84-d16) / d50), measured by XDC particle size analysis after ultrasonic disintegration, of at least 0.91 and a pore volume distribution V (d5 - d50) / V (d5 - d100) of at least 0.66 are known from US2005032965 and WO2008077948.

[0010] A disadvantage of the known silicas in the desired specific surface area is the poor dispersion in rubber compounds and thus poor abrasion properties of the rubber compounds, especially when used as tread compounds.

[0011] The object of the present invention is to provide a silica that, compared to known silicas, exhibits improved dispersion in rubber compounds. At the same time, the silica should, if possible, be in the form of granules so that it can be incorporated as effectively as possible and easily incorporated into the rubber matrix.

[0012] The invention relates to precipitated silicas characterized by the following physico-chemical parameters CTAB surface ≤ 115 m 2 < / g, preferably ≤ 105 m 2 < / g, particularly preferably ≤ 90 m 2 < / g, very particularly preferably 45 m 2 < / g - 90 m 2 < / g, particularly preferably 65 m 2 < / g - 90 m 2 < / g and particularly very preferably 70 m 2 < / g - 90 m 2 < / g, DOA recording ≥ 130 ml / (100 g), preferably ≥ 140 ml / (100 g), particularly preferably 145 ml / (100 g) - 190 ml / (100 g), Ro-Tap > 300 µm ≥ 86%, preferably 86% - 98%, particularly preferably 86% - 95% and in particular 90% - 95%, V (d5 - d50) / V (d5 - d100) < 0.66, preferably 0.30 - 0.65, and in particular 0.30 - 0.64.

[0013] The precipitated silicas according to the invention can have a BET surface area of ​​≤ 125 m 2 < / g, preferably ≤ 115 m 2 < / g, particularly preferably 70 m 2 < / g - 105 m 2 < / g.

[0014] The precipitated silicas according to the invention can have an original Sears number (ml KOH based on 1.5 g silica) of 7.0 - 20.0 ml / (1.5 g), preferably of 9.0 - 15.0 ml / (1.5 g) and particularly preferably of 11.0 - 14.0 ml / (1.5 g).

[0015] The precipitated silicas according to the invention can have a silanol group density of ≥ 5.4 OH / nm 2< , preferably ≥ 5.5 OH / nm 2< .

[0016] The precipitated silicas according to the invention can have a drying loss of 2% - 10%, preferably 4% - 8%.

[0017] The precipitated silicas according to the invention can have a pH of 4.0 - 7.0, preferably 5.5 - 7.0.

[0018] The precipitated silicas according to the invention can have an electrical conductivity of ≤ 1200 µS / cm, preferably 200 µS / cm - 800 µS / cm.

[0019] The precipitated silicas according to the invention can have an ignition residue of 3% - 5%, preferably 4% - 5%.

[0020] The precipitated silicas according to the invention can have a Ro-Tap < 75 µm value of ≤ 10%, preferably ≤ 8%.

[0021] The precipitated silicas according to the invention can have a bulk density of at least 180 g / L, preferably of 200 g / L - 350 g / L, particularly preferably of 250 g / L - 330 g / L and very particularly preferably of 250 g / L - 320 g / L.

[0022] The precipitated silicas according to the invention can have a TAR value (fraction of granules: 3.14 mm - 5.00 mm) of 15% - 60%, preferably 20% - 50%.

[0023] The precipitated silicas according to the invention can have a PV value of 0.0042 MPa - 414 MPa, 140° measured by Hg porosimetry of 1.00 - 3.00 ml / g, preferably 1.35 - 2.40 ml / g and particularly preferably 1.35 - 2.00 ml / g.

[0024] The precipitated silicas according to the invention can have a pore maximum (Hg, -dV / dlogD, contact angle 140°, surface tension 480 mN / m) of 35 nm - 100 nm, preferably 45 nm - 80 nm and particularly preferably 50 nm - 70 nm.

[0025] The precipitated silicas according to the invention can be used in compacted form and particularly preferably in granular form. At least 50% of the granules resulting from the Ro-Tap > 300 µm fraction can have a maximum dimension of a granule (defined as "grain length") in height, width, or length of at least 1.0 mm, preferably > 1.5 mm, particularly preferably > 2.5 mm, and especially preferably > 3.0 mm.

[0026] The present invention further provides a process for producing the precipitated silica according to the invention, which is characterized in that a) an aqueous solution of an organic and / or inorganic salt and / or an alkali or alkaline earth silicate and / or an organic and / or inorganic base with a pH ≥ 9 is initially introduced, b) water glass and an acidifying agent are simultaneously added to this initial mixture while stirring at 80 - 98 °C for 60 - 120 minutes, preferably at 85 - 98 °C for 80 - 110 minutes, c) the addition of water glass is then stopped and only acid is added in a smaller amount than before in order to achieve a pH of the mixture (measured at 60 °C) of 8.3 - 10.0, d) the mixture is then stirred for 45 min up to 200 min, preferably at 60 - 150 min, further at high temperature ≥ 85 °C, preferably at > 90 °C, but without adding further reactants, e) with sulfuric acid to a pH of approx. 3.5 - 4.5 (measured at 60 °C) and f) filtered, dried, preferably by means of spray drying or spin flash drying units, to a drying loss of < 8% and then granulated.

[0027] The process according to the invention can be carried out at temperatures ≥ 80 °C throughout the entire precipitation process and ageing at ≥ 85 °C. This results in the creation of not only specific surface areas in the range of ≤ 115 m 2 < / g, but also a very high internal structure for this surface area, which is very advantageous for incorporation into a matrix, such as rubber. This is reflected in the high DOA values. These structures are largely retained even after granulation, which actually destroys the structure, since the high silanol group density generated leads to a stabilized structure of the silica.

[0028] The initial charge can be 20% to 90%, preferably 30% to 90%, particularly preferably 40% to 90% of the final precipitate volume. It is possible to use an initial charge with no or only a small amount of electrolyte (salt) and to add the electrolytes continuously or batchwise (preferably at the beginning of the precipitation).

[0029] Optionally, additional organic or inorganic salts can also be added during steps a), b), c), e), or f). This can be done in solution or as a solid, either continuously or as a batch addition. It is also possible to dissolve the salts in one or more components and then add them simultaneously. The salts can contain the following anions and cations: Li +< , Na +< , K +< , Rb +< , Be 2+< , Mg 2< +, Ca 2+< , Sr 2+< , Ba 2+< , H +< , F -< , Cl -< , Br -< , I -< , SO 3 2-< , SO 4 2-< , HSO 4 -< , PO3 3-< , PO 4 3-< , NO 3 -< , NO 2 -< , CO 3 2-< , HCO 3 -< , OH-, TiO 3 2-< , ZrO 3 2-< , ZrO 4 4-< , AlO 2 -< , Al 2 O 4 2-< , BO 4 3-< .

[0030] Suitable organic salts are the salts of formic, acetic, and propionic acid. The alkali or alkaline earth ions mentioned above may be used as cations. The concentration of these salts in the initial charge can be from 0.01 to 5.00 mol / l. Na2SO4 is preferably used as the inorganic salt. The acidulant can be added in steps b), c), and e) in the same or different ways, i.e., with the same or different concentrations and / or feed rates. Analogously, the water glass can also be added to the reaction in steps a) and b) in the same or different ways.

[0031] In addition to water glass (sodium silicate solution), other silicates such as potassium or calcium silicate can also be used. In addition to sulfuric acid, other acidifying agents such as HCl, HNO 3 , H 3 PO 4 or CO 2 can also be used as acidifying agents. The filtration and drying of the silicas are familiar to the person skilled in the art, as described, for example, in EP 1762544 B1 and the patents cited therein. The silica is preferably dried in a flash dryer, spray dryer, stack dryer, belt dryer, rotary tube dryer, flash dryer, spin-flash dryer or jet tower. These drying variants include operation with an atomizer, a single- or two-fluid nozzle or an integrated fluidized bed. After the drying step, the precipitated silica preferably has a particle shape with an average diameter of more than 15 µm, in particular more than 80 µm, particularly preferably more than 200 µm.After drying, granulation can also be carried out using a roller compactor with a downstream crusher, which adjusts the final grain length.

[0032] Another object of the invention is a rubber mixture containing (A) a rubber or a mixture of rubbers and (B) at least one precipitated silica according to the invention.

[0033] Natural rubber and / or synthetic rubber can be used as rubber.

[0034] Preferred synthetic rubbers are described, for example, in W. Hofmann, Kautschuktechnologie, Genter Verlag, Stuttgart 1980. They can be used, among others, Polybutadiene (BR), polyisoprene (IR), styrene / butadiene copolymers, for example emulsion SBR (E-SBR) or solution SBR (L-SBR), preferably with styrene contents of 1 to 60 wt.%, particularly preferably 5 to 50 wt.% (SBR), chloroprene (CR), isobutylene / isoprene copolymers (IIR), butadiene / acrylonitrile copolymers with acrylonitrile contents of 5 to 60, preferably 10 to 50 wt.% (NBR), partially hydrogenated or fully hydrogenated NBR rubber (HNBR), ethylene / propylene / diene copolymers (EPDM), the above-mentioned rubbers which additionally have functional groups, such as carboxy, silanol or epoxy groups, for example epoxidized NR, carboxy-functionalized NBR or silanol (-SiOH) or siloxy-functionalized (-Si-OR)SBR, as well as blends and masterbatches of these rubbers. The latices of the above-mentioned rubbers can also be used, particularly in conjunction with so-called "liquid-phase mixing" or "continuous liquid-phase mixing."

[0035] In a preferred embodiment, the rubbers can be sulfur-vulcanizable. For the production of passenger car tire treads, anionically polymerized L-SBR rubbers (solution SBR) with a glass transition temperature above -50°C, as well as their blends with diene rubbers, can be used. Particular preference is given to using L-SBR rubbers whose butadiene moieties have a vinyl content of more than 20 wt. %. Very particular preference is given to using L-SBR rubbers whose butadiene moieties have a vinyl content of more than 50 wt. %.

[0036] Preferably, mixtures of the above-mentioned rubbers which have an L-SBR content of more than 50% by weight, particularly preferably more than 60% by weight, can be used.

[0037] In particular, polymer blends of non-functionalized and / or functionalized S-SBR / BR and S-SBR / BR / NR grades can be used in tread compounds, often with the addition of resins. These resins can be of natural or synthetic origin and can be chemically modified or present as blends of different resins.

[0038] The rubber mixture according to the invention may contain additional fillers. The following fillers may be used as such fillers for the rubber mixture according to the invention: Carbon blacks: The carbon blacks can be produced by the lamp black, furnace black, gas black, or thermal process and have BET surface areas of 20 m 2 / g to 200 m 2 / g. The carbon blacks can optionally also contain heteroatoms such as Si. Amorphous silicas, produced for example by precipitation of silicate solutions or flame hydrolysis of silicon halides, have specific surface areas of 5 to 1000 m 2 / g, preferably 20 to 400 m 2 / g (BET surface area), and with primary particle sizes of 10 to 400 nm. The silicas can optionally also be present as mixed oxides with other metal oxides, such as Al, Ga, B, Mg, Ca, Ba, Zn, and titanium oxides. The silicas can also be doped with one or more of these metal ions. Synthetic silicates, such as aluminum silicate, alkaline earth silicates, such as magnesium silicate or calcium silicate, with BET surface areas of 20 to 400 m² / g and primary particle diameters of 10 to 400 nm. Synthetic or natural aluminum oxides and hydroxides. Natural silicates, such as kaolin and other naturally occurring silicas. Natural fibers, especially cellulose, micro- and / or nano-cellulose, and products made from them. Glass fibers and glass fiber products (mats, strands) or glass microspheres.

[0039] Preferably, amorphous silicas, prepared by precipitation of solutions of silicates, having BET surface areas of 20 to 400 m 2 / g, particularly preferably 100 m 2 / g to 250 m 2 / g, can be used in amounts of 5 to 150 parts by weight, in each case based on 100 parts of rubber.

[0040] The fillers mentioned can be used alone or in a mixture.

[0041] The rubber mixture may contain 5 to 150 parts by weight of precipitated silica according to the invention and 0.1 to 20 parts by weight, preferably 1 to 18 parts by weight, particularly preferably 5 to 15 parts by weight, of organosilane, the parts by weight being based on 100 parts by weight of rubber.

[0042] The rubber compound may additionally contain silicone oil and / or alkylsilane.

[0043] The rubber mixture according to the invention may contain other known rubber auxiliaries, such as crosslinkers, vulcanization accelerators, reaction accelerators, retarders, ageing inhibitors, stabilizers, processing aids, plasticizers, waxes or metal oxides, and optionally activators such as triethanolamine, polyethylene glycol or hexanetriol.

[0044] The rubber auxiliaries can be used in conventional amounts, depending, among other things, on the intended use. Typical amounts can be, for example, amounts of 0.1 to 50 wt.%, based on the rubber.

[0045] Sulfur or organic sulfur donors can be used as crosslinkers.

[0046] The rubber mixture according to the invention may contain further vulcanization accelerators. Examples of suitable vulcanization accelerators include mercaptobenzothiazoles, sulfenamides, guanidines, dithiocarbamates, thioureas, thiocarbonates, and their zinc salts, such as zinc dibutyldithiocarbamate.

[0047] The rubber mixture according to the invention can additionally a thiuram sulfide and / or carbamate accelerator and / or the corresponding zinc salts, a nitrogen-containing co-activator, optionally further rubber auxiliaries, and optionally further accelerators. The weight ratio of accelerator to nitrogen-containing co-activator can be equal to or greater than 1.

[0048] The rubber mixture according to the invention may contain tetrabenzylthiuram disulfide or tetramethylthiuram disulfide with at least 0.25 parts by weight, based on 100 parts by weight of rubber, diphenylguanidine with at least 0.25 parts by weight, based on 100 parts by weight of rubber, and cyclohexyl or dicyclohexyl sulfenamide.

[0049] Sulfenamides can preferably be used together with guanidines and thiurams, particularly preferably cyclohexylsulfenamide or dicyclohexylsulfenamide together with diphenylguanidine and tetrabenzylthiuram disulfide or tetramethylthiuram disulfide.

[0050] The vulcanization accelerators and sulfur can be used in amounts of 0.1 to 10 parts by weight, preferably 0.1 to 5.0 parts by weight, based on the rubber used. Particularly preferably, sulfur and sulfenamides can be used in amounts of 1.0 to 4.0 parts by weight, thiurams in amounts of 0.2 to 1.0 parts by weight, and guanidines in amounts of 0.0 to 3.0 parts by weight.

[0051] The invention further provides a process for producing the rubber mixture according to the invention, which is characterized in that the rubber or the mixture of rubbers, the precipitated silica according to the invention and optionally further rubber auxiliaries are mixed in a mixing unit.

[0052] The rubbers are blended with the filler and, if appropriate, rubber auxiliaries in conventional mixing equipment, such as rollers, internal mixers, and mixing extruders. Such rubber mixtures can typically be produced in internal mixers, with the rubbers, filler, the precipitated silica according to the invention, and the rubber auxiliaries first being mixed in one or more successive thermomechanical mixing stages at temperatures between 100°C and 170°C. The order and timing of addition of the individual components can have a decisive influence on the resulting mixture properties. The resulting rubber mixture can typically be admixed with the crosslinking chemicals in an internal mixer or on a roller at temperatures between 40°C and 110°C and processed into the so-called raw mixture for subsequent process steps, such as molding and vulcanization.

[0053] The vulcanization of the rubber mixture according to the invention can be carried out at temperatures of 80 °C to 200 °C, preferably 130 °C to 180 °C, optionally under pressure of 10 bar to 200 bar.

[0054] Moldings can be produced from the rubber mixtures according to the invention by vulcanization.

[0055] The rubber mixture according to the invention can be used for the production of shaped bodies, for example for the production of tires, in particular tire treads, in the tire base or in the tire sidewall, cable sheaths, hoses, drive belts, conveyor belts, roller coverings, shoe soles, sealing elements, such as sealing rings, and damping elements.

[0056] The precipitated silicas according to the invention have the advantage that the corresponding rubber mixtures exhibit improved silica dispersion. Furthermore, the rubber mixtures according to the invention possess improved reinforcement and better tear propagation behavior. Furthermore, the achieved increased dynamic stiffness, determined at 60°C, should lead to greater driving stability, i.e., improved handling on dry roads. Measurement methods Determination of the alkali number

[0057] The alkali number (AZ) is the consumption of hydrochloric acid in ml (with a 50 ml sample volume, 50 ml distilled water, and a hydrochloric acid concentration of 0.5 mol / l) during a direct potentiometric titration of alkaline solutions or suspensions up to a pH of 8.30. This determines the free alkali content of the solution or suspension.

[0058] The pH meter (Knick, type: 766 pH-Meter Calimatic with temperature sensor) and the pH electrode (combination electrode from Schott, type N7680) are calibrated at room temperature using two buffer solutions (pH = 7.00 and pH = 10.00). The combination electrode is immersed in the measuring solution or suspension, which is maintained at 40 °C and consists of 50.0 ml of precipitation suspension and 50.0 ml of deionized water. Hydrochloric acid solution with a concentration of 0.5 mol / l is then added dropwise until a constant pH of 8.30 is established. Due to the slow establishment of equilibrium between the silica and the free alkali content, a waiting time of 15 minutes is required before a final reading of the acid consumption is obtained. For the selected amounts and concentrations, the hydrochloric acid consumption read in ml corresponds directly to the alkali number, which is given dimensionlessly. pH - pH value (warm) of silicas in accordance with DIN EN ISO 787-9 pH measurements during the production of silica are carried out on "warm" silica = measurement at 60 °C.

[0059] The procedure is based on DIN EN ISO 787-9 with the following specifications: A 5% (w / w) aqueous suspension of the sample to be tested is prepared. Deionized (DI) water is used for this purpose.

[0060] The sample suspension is shaken on a shaker for at least 5 minutes before pH measurement.

[0061] The pH measurement is carried out on a previously calibrated pH meter from Metrohm, type: 780 with pH electrode type 6.0228.000 (Metrohm). CTAB surface - determination according to ISO 5794-1 G

[0062] The method is based on the adsorption of buffered CTAB (N-cetyl-N,N,N-trimethylammonium bromide) in aqueous solution on the "outer" surface of silica, also referred to as the "rubber-active surface." Non-adsorbed CTAB is back-titrated using NDSS (dioctyl sodium sulfosuccinate solution). The endpoint of the titration is determined at the maximum increase in turbidity of the solution.

[0063] The test is carried out in accordance with ISO 5794-1 G with the following specifications, additions and deviations: During sample preparation, coarse samples of silicas and silicates are preferably finely ground using a suitable mill or ground in a mortar and sieved through a 90 µm sieve and not, as described in the standard, ground in a mortar and fractionated through a 150 µm sieve.

[0064] Suspensions of test sample and CTAB solution with an expected CTAB surface area of ​​less than 200 m 2 / g are stirred for 10 minutes. Suspensions of test sample and CTAB solution with an expected CTAB surface area of ​​greater than or equal to 200 m 2 / g are stirred for 35 minutes, as described in the standard.

[0065] After adsorption, the silica is filtered through a 0.2 µm polyamide filter.

[0066] The filtrate is titrated on a Metrohm titroprocessor with an autosampler and Tirando 809. The Metrohm Spectrosense 523 nm phototrode is used. BET surface area (N 2 , multi-point) - determination according to DIN ISO 9277

[0067] This method is used to determine the specific N2 surface area of ​​silica using the BET method based on DIN ISO 9277. This method determines the measured value by low-temperature adsorption of nitrogen at defined partial pressures. The analysis is performed as a multi-point determination and shows an approximately linear behavior in the partial pressure range (p / po) of 0.05 - 0.20 when determining a total of five measurement points.

[0068] The procedure is based on DIN ISO 9277 with the following specifications: Granulated samples are carefully crushed with a spatula before weighing and then baked under vacuum for 60 minutes at (160 + / - 2) °C on the vacuum baking thermostat VacPrep ™< 061 from MICROMERITICS.

[0069] To determine the BET surface area, the following 5 relative pressure points (p / po) are recorded during the adsorption phase: 0.0500; 0.0875; 0.1250; 0.1625 and 0.2000.

[0070] The TriStar 3000 series (3000 / 3020 / 3030) from MICROMERITICS with static volumetric measuring method and Dewar vessel is used for the measurements. Ro-Tap > 300 µm; Ro-Tap < 75 µm - sieve analysis based on ISO 5794-1 Annex F

[0071] Sieve analysis is performed using a rotary sieve shaker (Tyler Ro-Tap RX-29 timer-operated sieve shaker). The method is based on ISO 5794-1 Annex F. For the sieve analysis, test sieves with different mesh sizes are stacked on top of each other (test sieve with metal mesh, ISO 3310-1, nominal mesh size 75 µm, 200 mm sieve diameter; test sieve with metal mesh, ISO 3310-1, nominal mesh size 150 µm, 200 mm sieve diameter; test sieve with metal mesh, ISO 3310-1, nominal mesh size 300 µm, 200 mm sieve diameter). The sieve stack is placed in the test sieve shaker in the order listed. The sieve residues are determined as follows: The sample is gently homogenized before analysis. On a precision balance, 100 g is weighed into a beaker with an accuracy of 0.01 g, and the sample is quantitatively transferred to the top sieve (300 µm). Ro-Tap sieving is performed for 5 minutes with a tapper.After sieving, the sieve tower is removed and the fraction is weighed on the sieve pan, the 75 µm, the 150 µm and the 300 µm sieve.

[0072] Calculation of sieve residues Ro − Tap < 75 μm in % = AS ⋅ 100 % / E as well as Ro − Tap > 300 μm in % = A 300 ⋅ 100 % / E and Ro − Tap > 150 μm in % = A 150 ⋅ 100 % / E with A300 = Residue on the 300 µm sieve in g AS = Residue in the sieve pan in g E = Sample weight in g pH value - Determination of silicas according to DIN EN ISO 787-9

[0073] The procedure is based on DIN EN ISO 787-9 with the following specifications: Granulated sample material is pulverized using a mortar before weighing.

[0074] A 5% (w / w) aqueous suspension of the sample to be analyzed is prepared using deionized (DI) water.

[0075] The sample suspension is shaken on a shaker for at least 5 minutes before pH measurement.

[0076] The pH measurement is carried out at 23 °C + / - 2 °C on a previously calibrated pH meter from Metrohm, type: 780 with pH electrode type 6.0228.000 (Metrohm). Loss on drying - Determination based on DIN EN ISO 787-2

[0077] The weight loss of a sample heated for 2 h at 105°C in a drying oven is determined.

[0078] The procedure is based on DIN EN ISO 787-2 with the following specifications: The weighing bottle (with ground-glass lid; diameter approx. 80 mm, height approx. 30 mm) is heated with the lid removed for approx. 1 h at 105 °C. After cooling in a desiccator, the lid is replaced. The weight is determined to the nearest 0.01 g on a precision balance. 5 g to 10 g of the sample (initial weight depends on the bulk density) are precisely weighed and spread in an even layer on the bottom of the weighing bottle. Carefully open the weighing bottle and heat it in a drying oven for 2 h at (105 + 2) °C (the lid is heated along with the lid, but the weighing bottle is not yet sealed).

[0079] Then carefully close the weighing bottle with the lid, let it cool in the desiccator and weigh it back to the nearest 0.01 g. calculation

[0080] Fl ü chtige Anteile / % = E − A ⋅ 100 % E E = weight in g A = weight in g Original Sears number (SN) - Determination on hydrophilic silicas

[0081] By titrating silica with potassium hydroxide standard solution 0.1 mol / L in the range from pH 4 to pH 9, the Sears number can be determined as a measure of the number of free silanol groups.

[0082] The determination method is based on the following chemical reactions, where ≡SiOH symbolizes a silanol group of the silica: Implementation:

[0083] Approximately 10.0 g of powdered, spherical, or granular silica is uniformly ground for 60 seconds using a Fritsch mill (Pulverisette 14 with 80 µm sieve) at 10,000 rpm. Approximately 1.50 g of the treated silica is weighed to the nearest 0.1 mg into a 250 ml beaker and mixed with 150 ml of NaCl solution (ß(NaCl) = 200 g / L with hydrochloric acid c(HCl) = 1 mol / L, adjusted to pH 3). After the sample is completely wetted, the suspension is dispersed using an Ultra Turrax PT1300D (Polytron) for 30 seconds at a speed of 20,000 rpm.

[0084] Before titration, the pH meter (pH electrode LL Unitrode from Methrom, type PT1000) is calibrated at room temperature using buffer solutions (pH 4.00, pH 7.00, and pH 9.00). First, the initial pH of the suspension is measured with the pH meter. Then, depending on the result, the pH is adjusted to 4.00 using potassium hydroxide solution (0.1 mol / l) or hydrochloric acid solution (0.1 mol / l). The titration is then carried out using 0.1 mol / l KOH standard solution up to pH 9.00. The consumption of KOH solution in ml from pH 4.00 to pH 9.00 corresponds to V pH4-9 . A blank titration (without the addition of silica) is carried out in the same way. The blank value of the solution describes the volume of potassium hydroxide solution V BL required to titrate the NaCl solution without silica from pH 4 to pH 9.

[0085] The original Sears number based on the original substance with the unit ml / (1.5 g) is calculated as follows: Sears − Zahl original = V pH 4 − 9 − V BL * T * 1 , 5 g / E With T = Titer of the KOH standard solution used E = Sample weight in g

[0086] Silanol group density (SD) - Calculation via the SN, based on the CTAB surface area. The consumption of 0.1 n KOH in ml / (1.5 g) is given via the SN: Applying the CTAB surface area and the Avogadro constant (NA ), the result is: SN ⋅ 0 , 1 mmol 1 , 5 g ⋅ CTAB g m 2 N A

[0087] This results in the silanol group density (SD) in OH / nm 2< : SD = SN ⋅ 0 , 1 ⋅ mmol ⋅ g 1 , 5 g ⋅ CTAB ⋅ m 2 ⋅ N A SD = SN ⋅ 40 , 1476057 nm 2 ⋅ CTAB where in the formulas for SD the SN and the CTAB surface are used dimensionless, since these are already taken into account in the calculation. Ignition residue - Determination according to ISO 3262-1 or ASTM D 6740

[0088] By annealing the precipitated silica for 2 hours at 1000 °C in an annealing furnace, the total water content (physically and chemically bound) and thus the content of all volatile components (loss on ignition) is determined, from which the ignition residue can also be calculated. Implementation:

[0089] Approximately 500 mg of silica are weighed into two porcelain or melting crucibles using a spatula on an analytical balance with an accuracy of ± 0.1 mg. The crucibles, including the silica, are then annealed for 120 ± 5 min in an annealing furnace at 1000 ± 50 °C.

[0090] After annealing, the crucibles are placed in a desiccator containing a suitable desiccant to cool for approximately 1.5–2 hours and then reweighed using an analytical balance. The determination is performed in duplicate.

[0091] Evaluation: First, the loss on ignition is calculated based on the dried substance: GV % = m E · 100 − TV 100 − m A m E · 100 − TV 100 · 100 GV (separated): Loss on ignition based on the 2 h at 105 °C dried substance in % m E : Mass of weighed silica in g mA: Mass of calcined silica in g TV: Loss on drying 2 h at 105 °C in %

[0092] The residue on ignition relative to the original substance is calculated as follows: GV orig . = GV getr . S ∗ 100 − TV / 100 und daraus folgend GR orig . = 100 % − TV − GV orig .

[0093] The drying loss is determined according to the method "Determination of drying loss based on DIN EN ISO 787-2" (see above). TAR - Granule abrasion using friability test

[0094] For abrasion using the granule friability test, the fine and coarse silica fractions are removed, and the 3.15 mm - 5.00 mm fraction is selected. The granule fraction is subjected to repeated mechanical stress in a rotating friability chamber (e.g., ERWEKA TAR 220 with friability drums on the left and right) for 30 minutes. The resulting fine fraction is then separated using a 500 µm sieve. The mass difference in % corresponds to the granule abrasion. The determination of abrasion is carried out as a double determination.

[0095] A representative 50 g sample of the silica to be analyzed is taken. The 3.15 mm - 5.00 mm particle size fraction is carefully sieved by hand (test sieves with metal mesh, ISO 3310-1, 200 mm sieve diameter - nominal mesh size 500 µm, 3.15 mm, 5 mm, and sieve pan). This eliminates fines and very coarse particles. Weigh (5.00 ± 0.1) g of the 3.15 mm - 5 mm fraction precisely on an analytical or precision balance. If the sieved amount is insufficient, the measurement cannot be performed. A representative portion of the sample must be taken. The sample is placed in the friability drum, which is attached to the abrasion tester. The device is operated for 30 minutes at 65 rpm. The material is then quantitatively placed on a 500 µm sieve and the adhering fines are removed by gentle shaking / agitation. The granulate particles are then weighed to the nearest 0.01 g on a precision or analytical balance. Evaluation:

[0096] Abrieb % = E − A ∗ 100 % E Abrasion: Abrasion by means of granulate friability test in % E: Weight of the sieved fraction 3.15 - 5 mm in g A: Residue after loading and separation of the fine fraction in g

[0097] The measurement result is the mean value of two individual measurements and is given in % with one decimal place. DOA recording - determination based on ISO 19246

[0098] To perform the test, 12.50 ± 0.02 g of the sample is placed in the kneader chamber of the Brabender Absorptometer E with extended functionality / evaluation unit. Dioctyl adipate (e.g., Plastomoll®< DOA) is then added while continuously kneading at a rate of 4 mL / min. The kneader speed is 125 rpm. Based on the raw data curve, the program calculates a polynomial. The 70% value of the maximum torque of this polynomial is used to determine the DOA uptake relative to the original material in mL / (100 g). The determination is based on ISO 19246.

[0099] For silica granules, the determination is carried out based on the grain fraction 1.0 - 3.15 mm, which must be established beforehand by sieving with the appropriate sieves.

[0100] The following settings must be made in the measuring device’s software: Measurement condition

[0101] Dosing rate (burette): 4.0 mL / min Kneader speed: 125 rpm Temperature: 23,0 °C Evaluation

[0102] Torque threshold: 100 mNm End: 60 s after reaching maximum torque Torque limit: 10,000 mNm polynomial

[0103] Start: 50% of the maximum torque End: 20 s after reaching the maximum

[0104] Using suitable reference materials with different DOA uptakes, the Brabender ®< software can be used to perform individual normalization of the measuring mixer. Based on the determined normalization function (linear equation Y = a*x + b), the DOA uptake (normalized) relative to the original substance is expressed in mL / (100 g) as the 70% value of the torque maximum taken from the measurement report. Electrical conductivity - Determination according to DIN EN ISO 787-14

[0105] The electrical conductivity of silica is determined in accordance with DIN EN ISO 787-14. Compared to the specifications of this standard, the following modifications were made: A 4% aqueous suspension is prepared (4.00 g of silica per 100 ml of deionized water) and measured.

[0106] The suspension is measured directly, not the filtrate.

[0107] The measurement is carried out at 20.0 °C ± 0.5 °C and the conductivity is given for the reference temperature of 20 °C.

[0108] Determination of pore radii and pore volumes based on Hg intrusion according to DIN 66133

[0109] The pore radii, the corresponding pore volume, and the pore distribution of silica samples were determined in a pressure range of 0.003 to 420 MPa. The determination was carried out using the AutoPore IV 9520 from Micromeritics in accordance with DIN 66133.

[0110] The sample is dried in a drying oven at 105 ± 2 °C for 2 h.

[0111] For the measurement, the prepared sample is weighed into the Micromeretics Type 16 penetrometer. Approximately 330 mg are weighed to an accuracy of 0.001 g. The penetrometer is then slowly evacuated to 50 µm Hg in the low-pressure port of the measuring device and left at this pressure for 5 minutes. The penetrometer is then filled with mercury, first in the low-pressure port and then in the high-pressure port, up to a pressure of 420 MPa, and the measurement curve (pressure / volume curve) is recorded. The Autopore device is operated according to the Micromeretics operating instructions and is software-controlled. Each measurement is corrected for an empty penetrometer measurement. The entire measuring range is 0.003 - 420 MPa.

[0112] The following are used to calculate the measurement results from the measurement curve: Pore ​​maximum: Hg, -dV / dlogD; contact angle 140°, surface tension 480 mN / m in nm PV value: Hg, 0.0042 - 414 MPa; contact angle 140°, surface tension 480 mN / m in ml / g V (d5 - d50) / V (d5 - d100): Determined from Hg porosimetry according to WO2008077948. Bulk density - Determination according to ASTM D 1513

[0113] A 1000 ml measuring cylinder (with 20 ml graduations) with a powder funnel attached (funnel capacity at least 1 L) is tared on a precision balance (accuracy 0.1 g). The sample to be tested is mixed thoroughly by carefully rotating the sample container. With granules, particular care must be taken to ensure that additional fine particles are not generated. After mixing, between 500 mL and 700 mL of silica are carefully transferred into a 1 L beaker (with coarse graduations). The silica sample is poured in one go via the funnel into the measuring cylinder. After settling (without mechanical compaction), the bulk volume is read to the nearest 5 mL. Care must be taken to ensure that the filling volume is between 500 ML and 700 mL. At the same time, the weight of the sample is determined to an accuracy of ± 0.1 g to calculate the bulk density.

[0114] Calculation of bulk density: D = 1000 ⋅ m V Herein mean: DBulk density in g / L VVolume of the sample after pouring in mL mMass of the sample in g

[0115] The determination is performed in duplicate. If the two results differ by more than 3%, a third value is used to calculate the average. The result is expressed without decimal places.

[0116] Examples Example 1

[0117] In a reactor with a propeller stirrer system, 1140 L of water and 150 kg of water glass are placed and heated to 88.8 °C. Within 100 minutes, 727.9 kg of water glass (density 1.345 kg / L, 27% SiO 2 , 8% Na 2 O) and 77.6 kg of sulfuric acid (density 1.84 kg / L, 96% H 2 SO 4 ) are added simultaneously, so that the AZ in the reaction mixture is 24 - 27.

[0118] Sulfuric acid (density 1.84 kg / L, 96% H2SO4) is then added so that the pH in the reaction mixture is 8.6 (measured at 60 °C).

[0119] The temperature in the precipitation tank is increased to 94 °C within 5 minutes and the suspension is aged for 55 minutes at 94 °C with stirring.

[0120] Subsequently, sulfuric acid (density 1.84 kg / L, 96% H 2 SO 4 ) is added at a rate of 0.70 kg / min until a pH of 7 (measured at 60 °C) is reached. Then, sulfuric acid is added at a rate of 0.35 kg / min until a pH of 4.0 (measured at 60 °C) is reached.

[0121] The resulting suspension is filtered as usual, washed with water, and subjected to spin-flash drying. The resulting powder is granulated, i.e., compacted in a roller compactor and subsequently crushed in a crusher. Example 2

[0122] In a reactor with a propeller stirring system, 1164 L of water and 150 kg of water glass are placed (AZ 25 - 26) and heated to 89.0 °C. Water glass is added simultaneously within 100 minutes at an average dosing rate of 7.3 kg / min (density 1.345 kg / L, 27% SiO2, 8% Na2O) and sulfuric acid (density 1.84 kg / L, 96% H2SO4) at an average dosing rate of 0.82 kg / min.

[0123] Subsequently, further sulfuric acid (density 1.84 kg / L, 96% H 2 SO 4 ) is added so that the pH in the reaction medium is 8.5 (measured at 60 °C).

[0124] The temperature in the precipitation tank is increased to 94 °C within 5 minutes and the suspension is aged for 55 minutes at 94 °C with stirring.

[0125] Subsequently, further sulfuric acid (density 1.84 kg / L, 96% H2SO4) is added at a dosage rate of 0.70 kg / min, initially up to a pH of 7 (measured at 60 °C) and then further acidified at a dosage rate of 0.35 kg / min up to a pH of 4.0 (measured at 60 °C).

[0126] The resulting suspension is filtered as usual, washed with water, and subjected to spin-flash drying. The resulting powder is granulated, i.e., compacted in a roller compactor and subsequently crushed in a crusher.

[0127] The silicas have the analytical parameters given in Table 1. Table 1: parameter Unit Reference Silica I Silica according to the invention I Silica II according to the invention Example 1 Example 2 BET surface area (N 2 , multi-point) m 2 < / g 74 77 90 CTAB surface m 2 < / g 80 82 90 DOA recording ml / (100 g) 123 148 169 Ro-Tap > 300 µm % 84,5 94,3 94,9 Ro-Tap < 75 µm % 3,5 1,3 1,5 Sears number original ml / (1.5 g) 10,6 11,7 12,4 Silanol group density OH / nm 2< 5,3 5,7 5,5 Drying loss % 6,1 5,7 5,4 PH value 7,7 6,5 7,1 Electrical conductivity µS / cm 806 1180 176 Ignition residue % 4,1 4,4 4,1 Bulk density g / l 347 314 298 TAR % not measurable 22,4 21,0 V(d5-d50) / V(d5-d100) 0,65 0,64 0,64 PV value ml / g 1,27 1,42 1,54 Pore ​​Maximum nm 61 61 57

[0128] The reference silica 1 is ZEOSIL ®< 1085 GR from Solvay SA. Example 3 Rubber technical examination

[0129] The formulation used for the rubber compounds (Green Tire Compound) is shown in the following Table 2. The unit phr refers to parts by weight based on 100 parts of the raw rubber used. Table 2: Recipe of the "Green Tire" mixture name ingredient Manufacturing / Distribution Rubber compound 1 (comparison) with reference silica I inventive rubber mixture 2 with inventive silica I inventive rubber mixture 3 with inventive silica II 1st stage phr phr phr Buna VSL 4526-2 S-SBR; see 1< ARLANXEO Deutschland GmbH 96,25 96,25 96,25 Buna CB 24 Nd-BR; sa 2< ARLANXEO Deutschland GmbH 30,00 30,00 30,00 Reference Silica I Solvay SA 90,00 Silica according to the invention I Evonik Resource Efficiency GmbH 90,00 Silica II according to the invention Evonik Resource Efficiency GmbH 90,00 Si266 bifunctional silane Evonik Resource Efficiency GmbH 5,80 5,80 5,80 N330 Carbon black Orion Engineered Carbons GmbH 5,00 5,00 5,00 ZnO RS RAL 844 C ZnO Carl Arnsperger Chemicals GmbH & Co. 2,00 2,00 2,00 Edenor ST1 GS Stearic acid Caldic Deutschland GmbH 2,00 2,00 2,00 Vivatec 500 TDAE H&R GmbH Co. KGaA 8,75 8,75 8,75 Vulkanox HS / LG TMQ LANXESS Germany GmbH 1,50 1,50 1,50 Vulkanox 4020 / LG 6PPD LANXESS Germany GmbH 2,00 2,00 2,00 Protector G 3108 Wax Paramelt BV Netherlands 2,00 2,00 2,00 2nd stage Batch 1st stage Rhenogran DPG-80 DPG 80% Rhein Chemie additives GmbH 2,50 2,50 2,50 3rd stage Batch 2nd stage Richon TBZTD-OP TBzTD WEBER & SCHAER GmbH & Co. KG (produced by Dalian Richon) 0,20 0,20 0,20 Vulkacit CZ / EG-C CBS LANXESS Germany GmbH 1,60 1,60 1,60 sulfur Grinding sulfur HENSELER GmbH 2,00 2,00 2,00 1< Buna ®< VSL 4526-2 HM is a solution styrene-butadiene rubber extended with 37.5 phr TDAE oil; Mooney (1+4 @ 100 °C): 62 ME; Vinyl: 44.5%; Styrene: 26%

[0130] The rubber compound is produced in three stages in an internal mixer according to the following table (Table 3): Table 3: Instructions for mixture preparation mixer HF MIXING GROUP (Harburg-Freudenberger Maschinenbau GmbH) Level 1 GK 1.5 N, filling level 0.73; 70 rpm; chamber temperature: 70 °C; friction 1:1.11 min:sec mixing time Target batch temperature: 145 °C - 155 °C 00:00 - 00:15 At 00:00: Add polymers; Vulkanox HS; Vulkanox 4020; close plunger and mix for 15 s 00:15 - 01:15 At 00:15: Add 45 phr Silica, Si 266; close plunger and mix for 60 s 01:15 Raise the stamp halfway to ventilate and clean the stamp 01:15 - 02:15 Open the oil bag (LD-PE polybag 150 × 200 mm, IGEFA Handelsgesellschaft) before starting the mixing stage and add the soot to the bag; at 01:15: a) Add prepared bag b) 1 / 2 silica c) Protector G 3108 d) Close the plunger and mix for 60 s 02:15 - 03:45 At 02:15: Add ZnO and stearic acid; close the plunger and mix for 90 s; maintain the target batch temperature at 150 °C + / - 5 °C by varying the speed 03:45 Discharge the mixture and batch control by weighing Place the ejected batch onto a laboratory roller heated to 60°C and allow it to form a sheet for 45 seconds at a roller gap of 4 mm and at suitable speeds. Do not cut, fold, or tip the sheet. Then remove the sheet from the roller and, if necessary, take a sample and cut it to the weight for the second mixing stage. The intermediate storage of the sheet before the second mixing stage is 24 + / - 3 hours at 23 + / - 3°C. The waiting time between the 1st and 2nd mixing stages means that all mixtures belonging to a mixing series are mixed directly one after the other without further interruptions after mixing of the first compound in the series has begun. Level 2 GK 1.5 N, filling level 0.70; 75 rpm; chamber temperature: 75 °C; friction 1:1.11 min:sec mixing time Target batch temperature: 145 °C - 155 °C 00:00 - 01:00 At 00:00: Add the 1st stage batch; close the plunger and mix for 60 s 01:00 - 03:00 At 01:00: Add Rhenogran DPG-80; close the ram and mix for 120 s; maintain the target batch temperature at 150 °C + / - 5 °C by varying the speed. 03:00 Discharge the mixture and batch control by weighing Place the ejected batch onto a laboratory roller heated to 60°C and allow it to form a sheet for 45 seconds at a roller gap of 4 mm and at suitable speeds. Do not cut, fold, or tip the sheet. Then pull the sheet off the roller and, if necessary, take a sample and cut it to the weight for the third mixing stage. The intermediate storage of the sheet for the third mixing stage is between 4 and 24 hours at 23 + / -3°C. The waiting time between the 2nd and 3rd mixing stages means that all mixtures belonging to a mixing series are mixed directly one after the other without further interruptions after mixing of the first compound in the series has begun. Level 3 GK 1.5 N, filling level 0.68; 50 rpm; chamber temperature: 50 °C; friction 1:1.11 min:sec mixing time Batch temperature: 90°C - 110°C 00:00 - 02:00 At 00:00: Add the 2nd stage batch and TBzTD, CBS, sulfur; close the plunger and mix for 120 s 02:00 Discharge the mixture and batch control by weighing Place the ejected batch onto a laboratory roller heated to 60 °C and allow it to form a sheet for 20 seconds at a 4 mm gap and appropriate rotation speed. Make three right-hand cuts in the sheet and fold each one over, three left-hand cuts and fold each one over, and then fold the sheet tightly three times. To collect samples, extend the sheet to the required thickness, remove the sample, fold it back together, and place it back on the rotating roller until all required samples have been collected.

[0131] The general process for the production of rubber compounds and their vulcanizates is described in the following book: "Rubber Technology Handbook", W. Hofmann, Hanser Verlag 1994.

[0132] The vulcanization time for the test specimens is 15 minutes at 165 °C. The rubber-technical test is carried out according to the test methods given in Table 4. Table 4: Regulations for conducting physical tests Test / Procedure R Ohm mixture V ulkanisat physical quantity Unit Test conditions standard MDR; 165°C; 0.5°: Delta torque R Delta torque MDR dNm Test at 165 °C; 0.5 ° DIN 53529 / 3, ISO 6502 Tensile test: Tensile strength V Tensile strength at break MPa Test at 23 °C; standard ring R1; pull-off speed 500 mm / min DIN 53504, ISO 37 Tensile test: Modulus 200% V Stress value at 200% strain MPa Test at 23 °C; standard ring R1; pull-off speed 500 mm / min DIN 53504, ISO 37 Tensile test: Modulus 200% / 50% V Stress value at 200% elongation divided by the stress value at 50% elongation corresponds to the reinforcement ratio -- Test at 23 °C; standard ring R1; pull-off speed 500 mm / min DIN 53504, ISO 37 Tensile test: Elongation at break V Elongation at break % Test at 23 °C; standard ring R1; pull-off speed 500 mm / min DIN 53504, ISO 37 DIN abrasion V DIN abrasion: volume loss mm 3< 10 N DIN ISO 4649, ISO 2781, Method A Tear resistance DIE C; 23 °C V Tear resistance DIE C; 23 °C N / mm Test at 23 °C; standard test specimen; pull-off speed 500 mm / min DIN 53515 test specimen without incision Tear resistance GRAVES; 23°C V Tear resistance N / mm Test at 23 °C; standard test specimen; pull-off speed 500 mm / min DIN 53515 Tear resistance GRAVES; 60°C V Tear resistance N / mm Test at 60 °C; standard test specimen; pull-off speed 500 mm / min DIN 53515 Ball rebound; 23 °C V Rebound resilience / % % Drop height 500 mm, steel ball with d = 19 mm, 28 g ASTM D 2632 RPA strain sweep; 60 °C: G* V complex shear modulus G* MPa RPA: 2nd strain sweep on the vulcanizate 1.6 Hz; 60 °C; 0.28% - 42% Test at 60°C, 1.6 Hz, 0.28%-42.0% ASTM D 6601-02 "Operators Manual RPA 2000" by Alpha Technologies, February 1997 ZWICK force controlled; 60°C: E* V Complex Module E* 16 Hz, 50 N pre-load and 25 N amplitude force, 5 min tempering time, measured value recording after 30 s test time DIN 53513, ISO 4664-1 ZWICK force controlled; 0 °C: tan δ V Loss factor tan δ -- 16 Hz, 50 N pre-load and 25 N amplitude force, 5 min tempering time, measured value recording after 30 s test time DIN 53513, ISO 4664-1 Dispersion: DisperTester 3000 plus (100x) V Rating due to non-dispersed particles % Factory settings; Rating - the higher the value, the better the dispersion ISO 11345:2006; ASTM D7723 Dispersion: TOPO - Peak area V Roughness due to non-dispersed particles % Roughness due to non-dispersed particles => the lower the value, the better the dispersion Based on ASTM D 2663; described in DE 199 17 975 C2 Determination using a topographical method, described under: "Development of a method for characterizing filler dispersion in rubber compounds using surface topography" A. Wehmeier; diploma thesis 1998 at the Münster University of Applied Sciences, Steinfurt Department, Chemical Engineering Department and "Filler dispersion analysis by topography measurements" Degussa AG, Applied Technology Advanced Fillers, Technical Report TR 820. Dispersion: TOPO - Considered sum of peaks V Number of defects due to non-dispersed particles -- Number of defects due to poor dispersion => the lower the value, the better the dispersion Based on ASTM D 2663; described in DE 199 17 975 C2 Determination using a topographical method, described under: "Development of a method for characterizing filler dispersion in rubber compounds using surface topography" A. Wehmeier; diploma thesis 1998 at the Münster University of Applied Sciences, Steinfurt Department, Chemical Engineering Department and "Filler dispersion analysis by topography measurements" Degussa AG, Applied Technology Advanced Fillers, Technical Report TR 820. Table 5: Application data of the examples Rubber compound 1 (comparison) rubber mixture 2 according to the invention rubber mixture 3 according to the invention MDR: 165 °C; 0.5 ° Delta torque MDR dNm 12,7 15,0 14,3 Tensile strength (4 rings R1 @ 23 °C) MPa 9,5 10,7 10,8 Modulus 200% MPa 5,7 6,8 6,5 Modulus 200% / 50% -- 6,6 6,8 6,7 Elongation at break % 300 300 310 DIN abrasion mm 3< 94 80 87 Tear resistance DIE C, 23 °C N / mm 35 38 36 Tear resistance GRAVES, 23 °C N / mm 13 21 16 Tear resistance GRAVES, 60 °C N / mm 22 34 27 Ball rebound, 23 °C % 45 41 43 E*, 60 °C MPa 5,4 6,4 6,0 tan δ, 0 °C Zwick -- 0,393 0,432 0,422 RPA: 2 nd< strain sweep vulcanizate 1.6 Hz; 60°C; 0.28% - 42% Modulus MPa 1,6 2,2 1,9 Dispersion: DisperTester 3000 plus (100x) % 87,6 94,4 91,3 Dispersion: Peak area (Topo) % 19,2 1,7 7,7 Considered sum of peaks -- 334 32 140

[0133] The rubber-technical data of the rubber mixtures according to the invention presented in Table 5 demonstrate the superior dispersion, or dispersibility, of the silicas according to the invention compared to the prior art, rubber mixture 1 (comparison). When measuring defects directly on a section through the vulcanizates, rubber mixtures 2 and 3 according to the invention exhibit significantly less non-dispersed silica using tactile topography measurement and optically using the Dispertester. This also significantly improves all reinforcement-relevant measurements: In the tensile test, the stress values ​​can be clearly improved while maintaining the same elongation at break. This is also consistent with the improved tear propagation results (Die C and Graves test) measured under various test conditions. The DIN abrasion is also improved for the rubber mixtures according to the invention compared to the reference mixture.These advantages indicate that a tire with a tread containing and reinforced with the silicas according to the invention will exhibit significantly improved wear behavior. The indicators ball rebound, 23 °C and tan δ at 0 °C also show clearly improved values ​​for the wet skid behavior of such treads. The high stiffness at high temperatures (E*, 60 °C and modulus (max) in the RPA) under these measuring conditions also indicate improved handling behavior on dry roads compared to the state of the art. All in all, these rubber compounds and the silicas according to the invention are particularly capable of optimizing and improving the overall performance of, for example, winter tires or the even more specialized Nordic Winter Tires to the highest degree.

Claims

1. Precipitated silicas, characterized by the following physicochemical parameters: CTAB surface area≤ 115 m2 / g,DOA≤ 130 ml / (100 g),RoTap > 300 µm≤ 86%,V (d5 - d50) / V (d5 - d100)< 0.66.

2. Precipitated silicas according to Claim 1, characterized in that the CTAB surface area is ≤ 90 m2 / g.

3. Precipitated silicas according to Claim 1, characterized in that the PV value 0.0042 MPa-414 MPa, 140°, is in the range of 1.00-3.00 ml / g.

4. Precipitated silicas according to Claim 1, characterized in that the silanol group density is ≥ 5.4 OH / nm2.

5. Precipitated silicas according to Claim 1, characterized in that the bulk density is at least 180 g / l.

6. Precipitated silicas according to Claim 1, characterized in that the grain length is ≥ 1 mm.

7. Process for producing the precipitated silicas according to Claim 1, characterized in that a) an aqueous solution of an organic and / or inorganic salt and / or an alkali metal and / or alkaline earth metal silicate and / or an organic and / or inorganic base with a pH ≥ 9 is initially charged, b) waterglass and an acidifying agent are metered simultaneously into this initial charge while stirring at 80-98°C for 60-120 minutes, c) then the addition of waterglass is stopped, and acid only is metered in in a smaller amount than before in order to attain a pH of the mixture (measured at 60°C) of 9.0-10.0, d) then the mixture is stirred at high temperature > 85°C for 45 min up to 200 min, but without adding further reactants, e) sulfuric acid is used for acidification to a pH of about 3.5-4.5 (measured at 60°C) and f) the mixture is filtered, dried to a drying loss of < 8% and then pelletized.

8. Rubber mixture comprising (A) a rubber or a mixture of rubbers and (B) at least one precipitated silica according to Claim 1.

9. Process for producing the rubber mixture according to Claim 8, characterized in that the rubber or mixture of rubbers, the precipitated silica according to Claim 1 and optionally further rubber auxiliaries are mixed in a mixing unit.

10. Use of rubber mixtures according to Claim 8 for production of tyres, cable sheaths, hoses, drive belts, conveyor belts, roll coverings, footwear soles, gasket elements and damping elements.