Precipitated silica, its manufacturing method and its use

Abstract

The subject of the present invention is a compound having the following physicochemical parameters: CTAB surface area ≦115 m 2 / g, DOA≧130ml / (100g), Ro-Tap>300μm≧86%, V(d5-d50) / V(d5-d100)<0.66. The precipitated silica is produced by a) charging an aqueous solution of organic and / or inorganic salts and / or alkali metal or alkaline earth metal silicates and / or organic and / or inorganic bases having a pH of ≥ 9, b) simultaneously adding water glass and an acidifying agent to this charge with stirring at 80-98°C for 60-120 minutes, c) then stopping the addition of water glass and adding only the acid in smaller amounts than before so that the pH of the mixture (measured at 60°C) is 9.0-10.0, d) then stirring the mixture at an elevated temperature of > 85°C for 45-200 minutes, but without adding any further starting materials, e) acidifying with sulfuric acid to a pH of about 3.5-4.5 (measured at 60°C), f) filtering, drying to loss on drying < 8%, and then granulating. The silica according to the invention can be used in the production of rubber compounds, in particular for the production of tires, cable sheaths, hoses, drive belts, conveyor belts, roller covers, shoe soles, sealing elements and cushioning elements.

Description

Technical Field

[0001] The present invention relates to precipitated silica, a method for producing the same, and use thereof.

[0002] From International Publication No. 2012 / 059234, an elastomer composition containing at least one isoprene elastomer and silica as a reinforcing inorganic filler is known. 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 particle size after ultrasonic deaggregation of at least 0.91, and a ratio V(d5 - d50) / V(d5 - d100) of the pore volume distribution of at least 0.66, and 3-acryloxypropyltriethoxysilane is used as an adhesion promoter.

[0003] Furthermore, a method for producing silica is known from European Patent Application Publication No. 2102104. 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 particle size analysis after ultrasonic crushing of at least 0.91, and a pore volume distribution V(d5 - d50) / V(d5 - d100) of at least 0.66.

[0004] From European Patent Application Publication No. 1831297 and International Publication No. 2006 / 072704, it is known to use 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 rigidity of the material while maintaining or improving the impact resistance of the material.

[0005] Furthermore, from U.S. Patent Application Publication No. 2005 / 032965 and International Publication No. 2008 / 077948, the CTAB surface area is 40 m². 2 / g~525m 2 The value is / g, and the BET surface area is 45m². 2 / g~550m 2 A silica is known that has a particle size distribution width Ld((d84-d16) / d50) of at least 0.91, measured by XDC particle size analysis after ultrasonic crushing, and a pore volume distribution V(d5-d50) / V(d5-d100) of at least 0.66.

[0006] The drawback of known silicas within the target specific surface area range is their poor dispersibility in rubber compounds, and therefore, the inferior wear characteristics of the rubber compound, especially when used as a tread compound.

[0007] The object of the present invention is to provide silica with improved dispersibility in rubber compounds compared to known silica. At the same time, it is desirable that the silica exists as granular as possible so that it can be incorporated as well as possible and introduced into the rubber matrix.

[0008] The subject of this invention is the following physicochemical parameters: CTAB surface area ≦115m 2 / g, advantageously ≤ 105m 2 / g, particularly preferably ≤90m 2 / g, very preferably 45m 2 / g~90m 2 / g, particularly preferably 65m 2 / g~90m 2 / g, especially very preferably 70m 2 / g~90m 2 / g, DOA intake amount ≥130 ml / (100 g), preferably ≥140 ml / (100 g), and particularly preferably 145 ml / (100 g) to 190 ml / (100 g). Ro-Tap > 300 μm ≥ 86%, preferably 86% to 98%, particularly preferably 86% to 95%, especially 90% to 95%. V(d5-d50) / V(d5-d100) < 0.66, preferably 0.30-0.65, especially 0.30-0.64 It is a precipitated silica characterized by the following:

[0009] The precipitated silica according to the present invention has a BET surface area of ​​≤125 m². 2 / g, advantageously ≤115m 2 / g, particularly preferably 70mg 2 / g~105m 2 It can be / g

[0010] The precipitated silica according to the present invention has a Sears number オリジナル The number of mlKOH molecules per 1.5 g of silica can be 7.0 to 20.0 ml / (1.5 g), preferably 9.0 to 15.0 ml / (1.5 g), and particularly preferably 11.0 to 14.0 ml / (1.5 g).

[0011] The precipitated silica according to the present invention has a silanol group density of ≥ 5.4OH / nm 2 , advantageously ≥ 5.5OH / nm 2 It can be.

[0012] The precipitated silica according to the present invention can have a drying loss of 2% to 10%, preferably 4% to 8%.

[0013] The precipitated silica according to the present invention can have a pH value of 4.0 to 7.0, preferably 5.5 to 7.0.

[0014] The precipitated silica according to the present invention can have an electrical conductivity of ≤1200 μS / cm, preferably 200 μS / cm to 800 μS / cm.

[0015] The precipitated silica according to the present invention may have an ignition residue of 3% to 5%, preferably 4% to 5%.

[0016] The precipitated silica according to the present invention can have a Ro-Tap < 75 μm value of ≤ 10%, preferably ≤ 8%.

[0017] The precipitated silica according to the present invention may have a bulk density of at least 180 g / L, preferably 200 g / L to 350 g / L, particularly preferably 250 g / L to 330 g / L, and very particularly preferably 250 g / L to 320 g / L.

[0018] The precipitated silica according to the present invention can have a TAR value (granule fraction: 3.14 mm to 5.00 mm) of 15% to 60%, preferably 20% to 50%.

[0019] The precipitated silica according to the present invention can have a PV value of 1.00 to 3.00 ml / g, preferably 1.35 to 2.40 ml / g, and particularly preferably 1.35 to 2.00 ml / g, measured by the Hg intrusion method at 0.0042 MPa to 414 MPa and 140°.

[0020] The precipitated silica according to the present invention can have a maximum pore size (Hg, -dV / dlogD, contact angle 140°, surface tension 480mN / m) of 35nm to 100nm, preferably 45nm to 80nm, and particularly preferably 50nm to 70nm.

[0021] The precipitated silica according to the present invention can be used in a compacted form, and particularly preferably in the form of granules. In this case, at least 50% of the granules obtained from the Ro-Tap > 300 μm fraction may have a maximum dimension of the granules in height, width, or length (defined as "granule length") of at least 1.0 mm, preferably >1.5 mm, particularly preferably >2.5 mm, and especially preferably >3.0 mm.

[0022] A further subject of the present invention is a method for producing precipitated silica according to the present invention, a) Charge an aqueous solution of an organic and / or inorganic salt with a pH of ≥ 9, and / or an alkali metal or alkaline earth metal silicate, and / or an organic and / or inorganic base. b) Add water glass and an acidifying agent to this charge while stirring at 80-98°C for 60-120 minutes, preferably at 85-98°C for 80-110 minutes. c) Next, stop adding water glass, and add only acid in a smaller amount than before so that the pH of the mixture (measured at 60°C) becomes 8.3 to 10.0. d) The mixture is then stirred for 45 to 200 minutes, preferably 60 to 150 minutes, at a high temperature of ≥85°C, preferably >90°C, without adding any further starting materials. e) Acidify with sulfuric acid to a pH of approximately 3.5-4.5 (measured at 60°C), f) Filter, dry until the loss on drying is <8%, preferably by spray drying or a spin flash drying unit, and then granulate. This method is characterized by the following features.

[0023] The method according to the present invention can be carried out throughout the entire sedimentation process at a temperature of ≥80°C and during aging at ≥85°C. As a result, ≤115m 2 In addition to the specific surface area in the / g range, a highly advanced internal structure is generated within this surface area range, which is very advantageous for incorporation into matrices such as rubber. This is also reflected in the high DOA value. Such a structure remains almost intact even after granulation, which actually breaks down the structure, because the silica structure is stabilized by the resulting high silanol group density.

[0024] The charge can be 20% to 90%, preferably 30% to 90%, and particularly preferably 40% to 90% of the final volume of sedimentation. It is possible to use a charge that contains no electrolyte (salt) or only a small amount, and to add the electrolyte continuously or in batches (preferably in the early stages of sedimentation).

[0025] Optionally, organic or inorganic salts may be added during steps a), b), c), e), or f). This can be done in solution or as a solid, and can be done sequentially or in batches. Alternatively, the salt can be dissolved in one or more components and then added simultaneously. The salt may contain the following anions and cations: Li + kaNa + , K + , Rb + Be 2+ Mg 2+ Ca 2+ Sr 2+ Ba 2+ H + F - Cl - , Br - , I - , SO3 2- SO4 2- HSO4 - , PO3 3- , PO4 3- NO3 - NO2 - CO3 2- , HCO3 - , OH - , TiO3 2- ZrO3 2- ZrO4 4- AlO2 - Al2O4 2- , BO4 3- .

[0026] Suitable organic salts include salts of formic acid, acetic acid, and propionic acid. Suitable cations include the aforementioned alkali or alkaline earth metal ions. The concentration of these salts in the charge can be 0.01 to 5.00 mol / l. Preferably, Na2SO4 is used as the inorganic salt. In steps b), c), and e), the acidifying agent may be supplied in the same manner or in a different manner, that is, at the same concentration and / or supply rate or at a different concentration and / or supply rate. Similarly, the water glass may be supplied to the reaction in steps a) and b) in the same manner or in a different manner.

[0027] In addition to water glass (sodium silicate solution), other silicates such as potassium silicate and calcium silicate can also be used. As an acidifying agent, in addition to sulfuric acid, other acidifying agents such as HCl, HNO3, H3PO4, or CO2 can also be used. Filtration and drying of silica are well known to those skilled in the art, for example, in European Patent No. 1762544 and the patent documents cited herein. Preferably, silica is dried in a fluidized bed dryer, spray dryer, stepwise dryer, belt dryer, rotary tube dryer, flash dryer, spin flash dryer, or nozzle tower. Variations of these drying methods include operation with atomizers, single-phase or two-phase nozzles, or integrated fluidized beds. Preferably, after the drying step, the settled silica has a particle shape with an average diameter greater than 15 μm, particularly greater than 80 μm, and especially preferably greater than 200 μm. After drying, granulation may also be carried out in a roller compactor equipped with a downstream pulverizer, which adjusts the final particle length.

[0028] Further subject matter of the present invention is (A) Rubber or blended rubber, (B) At least one precipitated silica according to the present invention and It is a rubber compound containing [a certain substance].

[0029] Natural rubber and / or synthetic rubber can be used as the rubber. Preferred synthetic rubbers are described, for example, in W. Hofmann, Kautschuktechnologie, Genter Verlag, Stuttgart 1980. The rubber is particularly as follows: - Polybutadiene (BR), - Polyisoprene (IR), - Styrene / butadiene copolymer, for example, emulsion SBR (E-SBR) or solution SBR (L-SBR), having a styrene content of preferably 1 to 60% by weight, particularly preferably 5 to 50% by weight (SBR), - Chloroprene (CR), - Isobutylene / isoprene copolymer (IIR), - Butadiene / acrylonitrile copolymer having an acrylonitrile content of 5 to 60, preferably 10 to 50% by weight (NBR), - Partially hydrogenated or fully hydrogenated NBR rubber (HNBR), - Ethylene / propylene / diene copolymer (EPDM), - The above rubber further having functional groups such as carboxyl groups, silanol groups or epoxy groups, for example epoxidized NR, carboxyl-functionalized NBR, or silanol-functionalized (-SiOH) or siloxy-functionalized (-Si-OR) SBR, These may also be rubber compounds and masterbatches. Furthermore, the aforementioned rubber latex may be used, particularly in relation to so-called "liquid-phase mixing" or "continuous liquid-phase mixing."

[0030] In one preferred embodiment, the rubber may be sulfur vulcanizable. In particular, for the manufacture of passenger car tire treads, an anionic polymerized L-SBR rubber (solution SBR) having a glass transition temperature above -50°C and a mixture thereof with a diene-based rubber can be used. Particularly preferably, L-SBR rubber with a vinyl content of 20% by weight or more of the butadiene component can be used. Very particularly preferably, L-SBR rubber with a vinyl content of 50% by weight or more of the butadiene component can be used.

[0031] Preferably, the above rubber mixture can be used, having an L-SBR content of 50% by weight or more, and particularly preferably 60% by weight or more.

[0032] In particular, non-functionalized and / or functionalized S-SBR / BR and S-SBR / BR / NR type polymer blends can be used in tread compounds, and resins are often added to these polymer blends. These resins may be of natural or synthetic origin, may be chemically modified, or may exist as mixtures of different resins.

[0033] The rubber compound according to the present invention may contain further fillers. As such fillers, the rubber compound according to the present invention may use the following fillers: - Carbon Black: Carbon black can be produced by lamp black method, furnace black method, gas black method or thermal method, 20m 2 / g~200m 2 It has a BET surface area of ​​1 / g. Carbon black is optional and may contain heteroatoms such as Si. - For example, amorphous silica produced by the precipitation of a silicate solution or flame hydrolysis of silicon halide, with a specific surface area of ​​5 to 1000 m² 2 / g, preferably 20-400m 2 The silica has a density of / g (BET surface area) and a primary particle size of 10 to 400 nm. Silica may optionally exist as a mixed oxide with other metal oxides, such as aluminum oxide, galvanic oxide, boron oxide, magnesium oxide, calcium oxide, barium oxide, zinc oxide, and titanium oxide. Silica may also be doped with one or more of these metal ions. - Synthetic silicates such as alkaline earth metal silicates like aluminum silicate, magnesium silicate, and calcium silicate, with a BET surface area of ​​20-400 m² 2 The particle size is / g, and the primary particle diameter is between 10 and 400 nm. - Synthetic or natural aluminum oxide and hydroxide. - Natural silicates such as kaolin, and other naturally derived silicas. - Natural fibers, particularly cellulose, microcellulose and / or nanocellulose, and products composed thereof. - Glass fibers and glass fiber products (mats, strands) or microglass beads.

[0034] Preferably, it is produced by precipitation of a silicate solution, and the BET surface area is 20-400 m². 2 / g, particularly preferably 100m 2 / g~250m 2 Amorphous silica, which is 1 / g, can be used in an amount of 5 to 150 parts by weight per 100 parts of rubber.

[0035] The aforementioned fillers can be used individually or in combination.

[0036] The rubber compound may contain 5 to 150 parts by weight of precipitated silica according to the present invention and 0.1 to 20 parts by weight, preferably 1 to 18 parts by weight, and particularly preferably 5 to 15 parts by weight, of organosilane, where each part by weight is relative to 100 parts by weight of rubber.

[0037] The rubber compound may further contain silicone oil and / or alkylsilane.

[0038] The rubber compound according to the present invention may include, for example, crosslinking agents, vulcanization accelerators, reaction accelerators, reaction retarders, anti-aging agents, stabilizers, processing aids, plasticizers, waxes or metal oxides, and optionally activators, such as triethanolamine, polyethylene glycol or hexanetriol, or other known rubber additives.

[0039] Rubber additives can be used in conventional amounts depending on the intended use. A conventional amount may be, for example, 0.1 to 50% by weight relative to the rubber.

[0040] Sulfur or an organosulfur donor can be used as a crosslinking agent.

[0041] The rubber compound according to the present invention may contain further vulcanization accelerators. Suitable vulcanization accelerators include, for example, mercaptobenzothiazole, sulfenamide, guanidine, dithiocarbamate, thiourea, thiocarbonate, and their zinc salts, such as zinc dibutyldithiocarbamate.

[0042] The rubber compound according to the present invention further, Thiuram sulfide enhancers and / or carbamate enhancers and / or corresponding zinc salts, Nitrogen-containing auxiliary activators, Optionally, further rubber additives, and Optional additional accelerators It may include the following. The weight ratio of the accelerator to the nitrogen-containing auxiliary activator may be 1 or more.

[0043] The rubber compound according to the present invention may contain at least 0.25 parts by weight of tetrabenzyl thiuram disulfide or tetramethyl thiuram disulfide per 100 parts by weight of rubber, at least 0.25 parts by weight of diphenylguanidine per 100 parts by weight of rubber, and cyclohexyl sulfenamide or dicyclohexyl sulfenamide.

[0044] Preferably, sulfenamide can be used in combination with guanidine and thiuram, and particularly preferably, cyclohexylsulfenamide or dicyclohexylsulfenamide can be used in combination with diphenylguanidine and tetrabenzylthiuram disulfide or tetramethylthiuram disulfide.

[0045] The vulcanization accelerator and sulfur can be used in an amount of 0.1 to 10 parts by weight, preferably 0.1 to 5.0 parts by weight, relative to the rubber used. Particularly preferably, sulfur and sulfenamide can be used in an amount of 1.0 to 4.0 parts by weight, thiram in an amount of 0.2 to 1.0 part by weight, and guanidine in an amount of 0.0 to 3.0 parts by weight.

[0046] A further subject of the present invention is a method for producing a rubber compound according to the present invention, characterized by mixing rubber or a blended rubber, precipitated silica according to the present invention, and optionally further rubber additives in a mixing unit.

[0047] The mixing of rubber, fillers, and optionally rubber additives can be carried out using conventional mixing units such as rollers, internal mixers, and mixing extruders. Typically, such rubber compounds can be produced in an internal mixer, in which the rubber, fillers, precipitated silica, and rubber additives according to the present invention are mixed at 100°C to 170°C in one or more consecutive thermomechanical mixing steps. In this case, the order and timing of the addition of each component can have a decisive effect on the properties of the resulting mixture. Typically, the rubber compound thus obtained and a crosslinking agent are mixed in an internal mixer or roller at 40°C to 110°C, and this can be processed to produce a so-called crude compound for subsequent process steps such as molding or vulcanization.

[0048] The vulcanization of the rubber compound according to the present invention can be carried out at a temperature of 80°C to 200°C, preferably 130°C to 180°C, and optionally under a pressure of 10 bar to 200 bar.

[0049] A molded article can be manufactured from the rubber compound according to the present invention by vulcanization.

[0050] The rubber compound according to the present invention can be used in the manufacture of molded articles, such as tires, particularly tire treads in the tire substructure or tire sidewall, cable sheaths, hoses, drive belts, conveyor belts, roller covers, shoe soles, sealing elements such as seal rings, and cushioning elements.

[0051] The precipitated silica according to the present invention has the advantage that the corresponding rubber compound exhibits improved silica dispersibility. Furthermore, the rubber compound according to the present invention exhibits improved reinforcing properties and tear propagation behavior. In addition, an improvement in dynamic stiffness, as measured at 60°C, is achieved, resulting in higher driving stability, i.e., improved handling behavior on dry road surfaces.

[0052] Measurement method Measurement of alkalinity The alkali value (AZ) refers to the amount of hydrochloric acid consumed (ml) in a direct potentiometric titration of an alkaline solution or suspension up to pH 8.30 (using 50 ml of sample, 50 ml of distilled water, and 0.5 mol / l hydrochloric acid). Here, the free alkali content in the solution or suspension is measured.

[0053] A pH meter (Knick, Model 766 pH-Meter Calimatic with temperature sensor) and a pH electrode (Schott, Model N7680 combination electrode) are calibrated at room temperature using two buffer solutions (pH=7.00 and pH=10.00). The combination electrode is immersed in a measurement solution or suspension, heated to 40°C, consisting of 50.0 ml of precipitated suspension and 50.0 ml of deionized water. A 0.5 mol / l hydrochloric acid solution is then added dropwise until a constant pH of 8.30 is reached. A 15-minute waiting period is required before the final acid consumption can be read, as equilibrium between silica and free alkali is slowly established. At the selected amount and concentration, the read hydrochloric acid consumption (ml) directly corresponds to the alkali value, which is expressed as dimensionless.

[0054] pH - pH value of silica (at temperature) according to DIN EN ISO 787-9 pH measurement during silica production is performed using "warm" silica, meaning measurement is taken at 60°C.

[0055] This procedure shall be carried out in accordance with DIN EN ISO 787-9, with the following specific modifications: Prepare a 5% (m / m) aqueous suspension of the test sample. Use completely desalinated (DI) water for this.

[0056] Shake the sample suspension in a shaker for at least 5 minutes before measuring the pH.

[0057] pH measurements are performed using a pre-calibrated Metrohm Model 780 pH meter equipped with a 6.0228.000 pH electrode (Metrohm).

[0058] CTAB surface area - Measurement in accordance with ISO 5794-1 G This method is based on adsorbing an aqueous buffer solution of CTAB (N-cetyl-N,N,N-trimethylammonium bromide) onto the "outer" surface of silica, which is also called the "effective rubber surface." The unadsorbed CTAB is back-titrated with NDSS (sodium dioctyl sulfosuccinate solution). The titration endpoint is indicated by the maximum increase in the turbidity of the solution.

[0059] The procedure should be carried out in accordance with ISO 5794-1 G, with the following specificizations, additions, and modifications: During the sample preparation process, the coarse particle samples of silica and silicates are preferably finely ground in a suitable mill or ground in a mortar and pestle and sieved with a 90 μm sieve, without grinding in a mortar and pestle and classification with a 150 μm sieve as described in the standard.

[0060] Test sample and CTAB surface area of ​​200 m 2 Stir the suspension with the CTAB solution, which is expected to be less than / g, for 10 minutes. The test sample and the CTAB surface area of ​​200m² 2The suspension with the CTAB solution, which is expected to be at a concentration of 1 / g or more, is stirred for 35 minutes as specified in the standard.

[0061] After adsorption, the silica is filtered through a 0.2 μm polyamide filter.

[0062] The filtrate is titrated using a Metrohm titroprozessor equipped with an autosampler and a Tirando 809. A Metrohm Spectrosense 523nm optical sensor is used.

[0063] BET surface area (N2, multi-point) - Measurement in accordance with DIN ISO 9277 This method measures the N2 specific surface area of ​​silica using the BET method in accordance with DIN ISO 9277. The measurement is obtained by low-temperature adsorption of nitrogen at a predetermined partial pressure. The analysis is performed using multi-point measurements, and when a total of five measurement points are obtained, the behavior is nearly linear within the partial pressure range (p / po) of 0.05 to 0.20.

[0064] The procedure shall be carried out in accordance with DIN ISO 9277, but with the following specific modifications: The granulated sample is carefully crushed with a spatula before weighing, and then heated under vacuum at (160+ / -2)°C for 60 minutes using a MICROMERITICS VacPrep® 061 vacuum bake-out thermostat.

[0065] To measure the BET surface area, the following five relative pressure points (p / po) are recorded during the adsorption phase: 0.0500; 0.0875; 0.1250; 0.1625 and 0.2000.

[0066] For the measurements, we use the TriStar 3000 series (3000 / 3020 / 3030) from MICROMERITICS, equipped with a static volumetric measurement method and a Dewar container.

[0067] Ro-Tap > 300 μm; Ro-Tap < 75 μm - Sieve analysis in accordance with ISO 5794-1 Annex F Sieve analysis will be performed using a rotary sieve machine (Tyler Ro-Tap RX-29 analytical sieve machine with timer). This method will be carried out in accordance with ISO 5794-1 Annex F. Test sieves with different mesh sizes will be stacked for sieve analysis (analytical sieve with metal mesh, ISO 3310-1, nominal mesh size 75 μm, sieve diameter 200 mm; analytical sieve with metal mesh, ISO 3310-1, nominal mesh size 150 μm, sieve diameter 200 mm; analytical sieve with metal mesh, ISO 3310-1, nominal mesh size 300 μm, sieve diameter 200 mm). The sieve tower will be installed in the analytical sieve machine in the order described. The residue on the sieve will be measured as follows: The sample will be gently homogenized before measurement. Using a precision balance, weigh 100g into a beaker with an accuracy of 0.01g, and quantitatively transfer the sample to the top sieve (300μm). Perform Ro-Tap sieving with a beater for 5 minutes. After sieving is complete, remove the sieving tower and weigh the fractions on the sieving dish and on the 75μm, 150μm, and 300μm sieves.

[0068] Calculation of the residue on the sieve Ro-Tap <75μm (%) = AS × 100% / E and Ro-Tap > 300 μm (%) = A300 × 100% / E and Ro-Tap > 150 μm (%) = A150 × 100% / E And here, A300 = Residue on a 300 μm sieve (g) AS = Residue in the sieving dish (g) E=Initial weight (g) That is the case.

[0069] pH value - Silica measurement in accordance with DIN EN ISO 787-9 This procedure shall be carried out in accordance with DIN EN ISO 787-9, with the following specific modifications: Before weighing the granulated sample material, grind it into a powder using a mortar and pestle.

[0070] Prepare a 5% (m / m) aqueous suspension of the test sample. Use completely desalinated (DI) water for this.

[0071] Shake the sample suspension in a shaker for at least 5 minutes before measuring the pH.

[0072] pH measurements are performed at 23°C ± 2°C using a pre-calibrated Metrohm 780 pH meter equipped with a 6.0228.000 pH electrode (Metrohm).

[0073] Loss on drying - Measured according to DIN EN ISO 787-2 The weight loss of the sample heated on a drying rack at 105°C for 2 hours is measured.

[0074] This procedure shall be carried out in accordance with DIN EN ISO 787-2, with the following specific modifications: Heat a weighing glass bottle (with a ground-glass lid; approximately 80 mm in diameter and 30 mm in height) at 105°C for about 1 hour with the lid removed. After cooling in a desiccator, put the lid back on. Measure the weight to the nearest 0.01 g using a precision balance. Accurately weigh 5 g to 10 g of sample (initial weight depends on bulk density) and spread it evenly in a layer at the bottom of the weighing glass bottle. Carefully open the weighing glass bottle and heat it on a drying rack at (105 + 2)°C for 2 hours (heat the lid as well, but the weighing glass bottle is not yet sealed with the lid).

[0075] Next, carefully close the lid of the weighing glass bottle, allow it to cool in a desiccator, and weigh again in 0.01g increments.

[0076] calculation

number

[0077] Sears number オリジナル (SN) - Measurement of hydrophilic silica The number of free silanol groups in silica can be determined by titrating it with a 0.1 mol / L potassium hydroxide solution in the pH range of 4 to 9, using the Sears number as an indicator. オリジナル It is possible to find this.

[0078] The measurement method is based on the following chemical reaction, where ≡SiOH represents the silanol group of silica: [ka]

[0079] procedure: Approximately 10.0 g of powdered, spherical, or granular silica is uniformly ground using a Fritschmill (Pulverisette 14 with 80 μm sieve) at 10,000 rpm for 60 seconds. Approximately 1.50 g of the thus processed silica is weighed into a 250 ml glass beaker in 0.1 mg increments and mixed with 150 ml of NaCl solution (β(NaCl) = 200 g / L, hydrochloric acid c(HCl) = 1 mol / L adjusted to pH 3). After completely wetting the sample, the suspension is dispersed using an Ultra Turrax PT1300D (Polytron) at a rotation speed of 20,000 rpm for 30 seconds.

[0080] Before titration, calibrate the pH meter (Methrom pH electrode LL Unitrode, PT1000 model) at room temperature using buffer solutions (pH 4.00, pH 7.00, and pH 9.00). First, measure the initial pH of the suspension with this pH meter, and then adjust the pH to 4.00 with potassium hydroxide solution (0.1 mol / l) or hydrochloric acid solution (0.1 mol / l) depending on the result. Then, titrate with 0.1 mol / l KOH measurement solution until the pH reaches 9.00. The amount of KOH solution consumed (ml) from pH 4.00 to pH 9.00 is V pH4-9This corresponds to the following. Blind titration (without adding silica) is performed in the same way. The blind value of the solution is the volume V of potassium hydroxide solution required to titrate a silica-free NaCl solution from pH 4 to pH 9. BL It represents.

[0081] Sears number of the original substance in units of ml / (1.5g) オリジナル The following: Sears number オリジナル =(V pH4-9 -V BL )×T×(1.5g) / E It is calculated from, and here, T = Titration volume of the KOH measurement solution used E = Initial weight of the sample (g) That is the case.

[0082] Silanol group density (SD) - Calculated using SN ratio relative to CTAB surface area. The SN ratio allows us to obtain the consumption rate of 0.1n KOH in ml / (1.5g) units:

number

[0083] CTAB surface area and Avogadro's constant (N A Applying this, the result is as follows:

number

[0084] From this, the silanol group density (SD) is OH / nm 2 Obtained in units:

number

[0085] Here, in these equations, SD, SN, and CTAB surface area are already taken into consideration in the calculation, so they are used dimensionless.

[0086] Ignition residue - Measurement in accordance with ISO 3262-1 or ASTM D 6740. By heating precipitated silica in a ignition furnace at 1000°C for 2 hours, the total water content (physically and chemically bound) and, consequently, the total volatile component content (loss on ignition) can be determined, and the ignition residue can also be obtained from this.

[0087] procedure: Approximately 500 mg of silica is weighed into each of the two porcelain crucibles or molten crucibles using a spatula on an analytical balance with an accuracy of ±0.1 mg. The crucibles containing the silica are then heated in a strong furnace at (1000 ± 50) °C for (120 ± 5) minutes.

[0088] After ignition, the crucible is cooled in a desiccator containing an appropriate desiccant for approximately 1.5 to 2 hours, and then weighed again using an analytical balance. The measurement is performed as a duplicate measurement.

[0089] Evaluation: First, calculate the loss on ignition for the dry material:

number

[0090] The ignition residue relative to the original substance is calculated as follows: GV(orig.)=GV( getr.S ) × (100 - TV) / 100 Therefore, GR(orig.) = 100% - TV - GV(orig.) That is the case.

[0091] In addition, the loss on drying is measured using the method described in "Measurement of loss on drying in accordance with DIN EN ISO 787-2" (see above).

[0092] TAR - Abrasion rate of granules by crushing test For the abrasion rate in the granular crushing test, the fine and coarse silica particles are removed, and the fraction with particles between 3.15 mm and 5.00 mm is used. This granular fraction is subjected to repeated mechanical loading for 30 minutes in a rotating crushing chamber (e.g., ERWEKA TAR 220 with crushing drums on both sides). The resulting fine particles are then separated and removed using a 500 μm sieve. The weight difference (%) corresponds to the abrasion rate of the granules.

[0093] The wear rate will be measured using a dual measurement method.

[0094] Take a representative 50g sample of silica to be analyzed. Carefully sieve the 3.15mm to 5.00mm particle fraction by hand (using a metal sieve mesh, ISO 3310-1, sieve diameter 200mm - analytical sieve with nominal mesh sizes of 500μm, 3.15mm, 5mm and sieve pan). This removes fine and very coarse particles. Accurately weigh the 3.15mm to 5mm fraction (5.00±0.1g) using an analytical balance or precision balance. If the sieved amount is insufficient, measurement cannot be performed. It is necessary to take a sample amount from a representative portion. Place this sample amount into a crushing drum and mount it in an abrasion tester. Operate this instrument at 65rpm for 30 minutes. Afterwards, quantitatively sift the material through a 500μm sieve and remove any adhering fine particles by moderate shaking / movement. Afterward, the granular material is weighed again to the nearest 0.01g using a precision balance or analytical balance.

[0095] evaluation:

number

[0096] The measurement results are the average of two individual measurements and are expressed as a percentage to one decimal place.

[0097] DOA intake - Measurement in accordance with ISO 19246 For the procedure, 12.50 ± 0.02 g of the sample is placed in the mixing chamber of a Brabender absorption meter "Expansion Function / Evaluation Unit E". Then, dioctyl adipate (e.g., Plastomol® DOA) is added at a supply rate of 4 mL / min under constant mixing conditions. The kneader rotation speed is 125 rpm. A polynomial is calculated using a program based on the raw data curve. The 70% value of the maximum torque of this polynomial is used to determine the amount of DOA taken up in mL / (100 g) related to the raw material. The measurement is performed in accordance with ISO 19246.

[0098] In the case of silica granules, measurement is performed using a particle fraction of 1.0 to 3.15 mm. This fraction can be prepared in advance by sieving using an appropriate sieve.

[0099] The following settings need to be configured in the measuring instrument's software: Measurement conditions Supply rate (burette): 4.0 mL / min Kneader rotation speed: 125 min -1 Temperature: 23.0℃ evaluation Torque threshold: 100 mNm End: 60 seconds after reaching maximum torque. Torque limit: 10,000 mNm polynomial Start: 50% of maximum torque End: 20 seconds after reaching the maximum value

[0100] By using appropriate reference materials with different DOA uptake rates, the Brabender® software can be used to perform individual normalization of the measurement kneader. Based on the obtained normalization function (linear equation Y = a × x + b), the DOA uptake rate (normalized) for the original substance in mL / (100g) units, expressed as 70% of the maximum torque value, can be obtained from the measurement protocol.

[0101] Electrical conductivity - Measurement in accordance with DIN EN ISO 787-14 The electrical conductivity of silica will be measured in accordance with DIN EN ISO 787-14. The following modifications have been made to the procedure compared to the provisions of this standard.

[0102] Prepare a 4% aqueous suspension (4.00 g of silica per 100 ml of demineralized water) and measure it.

[0103] The suspension is measured directly, not the filtrate.

[0104] Measurements were taken at 20.0℃ ± 0.5℃, and the electrical conductivity is shown as the value at the reference temperature of 20℃.

[0105] Measurement of pore size and pore volume based on Hg intrusion in accordance with DIN 66133 The pore size, corresponding pore volume, and pore distribution of silica samples are determined within a pressure range of 0.003 to 420 MPa. Measurements are performed in accordance with DIN 66133 using a Micromeritics AutoPore IV 9520.

[0106] Dry the sample on a drying rack at 105±2℃ for 2 hours.

[0107] For measurement, the prepared sample is weighed into a Micromeritics Model 16 penetrometer. Approximately 330 mg is accurately weighed to the nearest 0.001 g. Then, the penetrometer is slowly evacuated to 50 μmHg through the low-pressure port of the measuring instrument and left at this pressure for 5 minutes. Next, mercury is filled into the penetrometer to a pressure of 420 MPa, first through the low-pressure port and then through the high-pressure port, and the measurement curve (pressure / volume curve) is recorded. The Autopore instrument is operated according to the Micromeritics instruction manual and controlled by software. Each measurement value is corrected by blank measurement of the penetrometer. The entire measurement range is 0.003 to 420 MPa.

[0108] The following is used to calculate the measurement results from the measurement curve: Maximum pore size: Hg, -dV / dlogD; contact angle 140°, surface tension 480mN / m (nm) PV value: Hg, 0.0042~414MPa; contact angle 140°, surface tension 480mN / m (ml / g) V(d5-d50) / V(d5-d100): The Hg impregnation method is used in accordance with International Publication No. 2008077948.

[0109] Bulk density - Measured according to ASTM D 1513 A 1000ml graduated cylinder (20ml divisions) was tared using a precision balance (accuracy 0.1g) fitted with a powder funnel (funnel capacity 1L or more). The sample to be tested was thoroughly mixed by carefully rotating the sample container. Particular care was taken to prevent the formation of further fine particles, especially in the case of granules. After mixing, 500mL to 700mL of silica was carefully transferred using a scoop to a 1L glass beaker (coarse divisions). The silica sample was poured into the graduated cylinder in one go through the funnel. After it descended (without mechanical compression), the bulk volume was read in 5mL increments. At this time, care was taken to ensure that the filled volume was between 500mL and 700mL. Simultaneously, the sample weight was measured to ±0.1g in order to calculate the bulk density.

[0110] Calculation of bulk density: D = 1000 × m / V Here, D represents bulk density (g / L), V represents the volume (mL) of the sample after it has been poured in. m represents the sample weight (g).

[0111] The measurement will be performed using a dual measurement method. If the two results differ from each other by more than 3%, the third value will be used to calculate the average. The results will be presented without decimal points.

[0112] Examples Example 1 In a reactor equipped with a propeller-type stirring system, 1140 L of water and 150 kg of water glass are charged and heated to 88.8°C. Within 100 minutes, 727.9 kg of water glass (density 1.345 kg / L, 27% SiO2, 8% Na2O) and 77.6 kg of sulfuric acid (density 1.84 kg / L, 96% H2SO4) are simultaneously added to adjust the AZ of the reaction mixture to 24-27.

[0113] Next, sulfuric acid (density 1.84 kg / L, 96% H2SO4) is added to adjust the pH of the reaction mixture to 8.6 (measured at 60°C).

[0114] Raise the temperature of the sedimentation tank to 94°C within 5 minutes, and age the suspension at 94°C for 55 minutes while stirring.

[0115] Next, sulfuric acid (density 1.84 kg / L, 96% H2SO4) is added at a supply rate of 0.70 kg / min until the pH reaches 7 (measured at 60°C). Then, more sulfuric acid is added at a supply rate of 0.35 kg / min until the pH reaches 4.0 (measured at 60°C).

[0116] The resulting suspension is filtered as usual, washed with water, and subjected to spin-flash drying. The resulting powder is then granulated, i.e., compressed with a roller compactor and then pulverized with a pulverizer.

[0117] Example 2 In a reactor equipped with a propeller-type stirring system, 1164 L of water and 150 kg of water glass are charged (AZ 25-26) and heated to 89.0°C. Within 100 minutes, water glass (density 1.345 kg / L, 27% SiO2, 8% Na2O) is added simultaneously at an average feed rate of 7.3 kg / min and sulfuric acid (density 1.84 kg / min, 96% H2SO4) is added at an average feed rate of 0.82 kg / min.

[0118] Next, sulfuric acid (density 1.84 kg / L, 96% H2SO4) is added to adjust the pH of the reaction medium to 8.5 (measured at 60°C).

[0119] Raise the temperature of the settling tank to 94°C within 5 minutes, and age the suspension at 94°C for 55 minutes while stirring.

[0120] Next, sulfuric acid (density 1.84 kg / L, 96% H2SO4) is added at a supply rate of 0.70 kg / min until the pH reaches 7 (measured at 60°C), and then the solution is further acidified at a supply rate of 0.35 kg / min until the pH reaches 4.0 (measured at 60°C).

[0121] The resulting suspension is filtered as usual, washed with water, and subjected to spin-flash drying. The resulting powder is then granulated, i.e., compressed with a roller compactor and then pulverized with a pulverizer.

[0122] These silica samples have the analytical parameters shown in Table 1.

[0123] [Table 1]

[0124] Reference silica 1 is ZEOSIL® 1085 GR manufactured by Solvay SA.

[0125] Example 3 Rubber technical testing The formulation used for the rubber compound (Green Tire Compound) is shown in Table 2 below. Here, the unit phr refers to parts by weight based on 100 parts of raw rubber used.

[0126] [Table 2-1] [Table 2-2]

[0127] The rubber compound is manufactured in three stages using an internal mixer, according to the list in the table below (Table 3): [Table 3-1] [Table 3-2] [Table 3-3]

[0128] For general information on the manufacturing methods of rubber compounds and their vulcanized products, see the following book: “Rubber Technology Handbook”, W. Hofmann, Hanser Verlag 1994.

[0129] The vulcanization time for each test specimen was 15 minutes at 165°C. Technical testing of the rubber was performed in accordance with the test methods shown in Table 4.

[0130] [Table 4-1] [Table 4-2] [Table 4-3] [Table 4-4]

[0131] [Table 5-1] [Table 5-2]

[0132] The rubber technology data for the rubber compound according to the present invention, shown in Table 5, demonstrates the superior dispersibility or dispersibility of silica according to the present invention compared to prior art rubber compound 1 (comparison). Rubber compounds 2 and 3 according to the present invention clearly show less undispersed silica when defects on the cross-section of the vulcanized material are directly measured by tactile topography and optically measured using a Dispertester. Consequently, clear improvements are also seen in all reinforcement-related measurements. In tensile tests, stress values ​​can be clearly improved without changing the elongation at break. This is consistent with improvements in Die C and Graves, which are tear propagation results measured under different measurement conditions. DIN wear is also improved in the rubber compound according to the present invention compared to the reference compound. These advantages indicate that tires containing and reinforced with silica according to the present invention exhibit significantly improved wear behavior. Furthermore, the indicative rebound elasticity at 23°C and tanδ at 0°C also show clearly improved values ​​for the wet sliding behavior of such treads. Additionally, high stiffness at high temperatures (E at 60°C) is also demonstrated. * The modulus (maximum value) in RPA indicates that, under these measurement conditions, handling behavior on dry surfaces is improved compared to prior art. Therefore, overall, these rubber compounds and silica according to the present invention can significantly optimize and improve the overall performance of, for example, winter tires, or even more specifically, Nordic winter tires.

Claims

1. The following physicochemical parameters: CTAB surface area ≤ 90 m² ２ / g、 DOA ≧130ml / (100g), Ro-Tap>300μm ≧86%, V(d5-d50) / V(d5-d100) <0.66 Precipitated silica, characterized by the following features.

2. The precipitated silica according to claim 1, wherein the PV value at 0.0042 MPa to 414 MPa and 140° is in the range of 1.00 to 3.00 ml / g.

3. Silanol group density is ≥ 5.4 OH / nm ２ The precipitated silica according to claim 1.

4. The precipitated silica according to claim 1, wherein the bulk density is at least 180 g / L.

5. The precipitated silica according to claim 1, wherein the grain length is ≥ 1 mm.

6. A method for producing precipitated silica according to claim 1, a) Charge an aqueous solution of an organic salt and / or inorganic salt with a pH of ≥ 9, and / or an alkali metal silicate or alkaline earth metal silicate, and / or an organic base and / or an inorganic base. b) To the charge obtained in a), water glass and acidifying agent are simultaneously weighed and supplied while stirring at 80-98°C for 60-120 minutes. c) Next, stop adding water glass, and add only acid in a smaller amount than the amount supplied in b) so that the pH of the resulting mixture (measured at 60°C) is between 8.3 and 10.

0. d) Next, the mixture is stirred at a high temperature of >85°C for 45 to 200 minutes, provided that no further starting materials are added. e) Acidify with sulfuric acid to a pH of 3.5 to 4.5 (measured at 60°C), f) Filter, dry until the loss on drying is <8%, and then granulate. A method characterized by the following features.

7. (A) Rubber or blended rubber, (B) At least one precipitated silica according to claim 1 and A rubber compound containing [a specific ingredient].

8. A method for producing a rubber compound according to claim 7, characterized in that the rubber or blended rubber, the precipitated silica according to claim 1, and optionally further rubber additives are mixed in a mixing unit.

9. Use of the rubber compound according to claim 7 in the manufacture of tires, cable sheaths, hoses, drive belts, conveyor belts, roller covers, shoe soles, sealing elements and cushioning elements.

Images