Precipitated silica, its manufacturing method, and its uses

Abstract

The present invention relates to precipitated silica having 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). It is prepared by stirring at a high temperature of 85°C for 45 min to 200 min, e) acidifying with sulfuric acid to a pH of approximately 3.5 - 4.5 (measured at 60°C), f) filtering the mixture, drying to a drying loss of < 8%, and then granulating. The silica according to the present invention can be used, in particular, for the manufacture of rubber blends for making tires, cable sheathing materials, hoses, drive belts, conveyor belts, roll coverings, shoe soles, sealing elements, and damping elements.

Description

Technology Field

[0001] The present invention relates to precipitated silica, a method for manufacturing the same, and uses the same. Background Technology

[0002] WO2012059234 discloses an elastomer composition comprising at least one isoprene elastomer, silica as a reinforcing inorganic filler, and 3-acryloyloxypropyltriethoxysilane as an adhesion promoter, wherein the silica is 40 m 2 / g to 525 m 2 Surface area of ​​CTAB per g, 45 m 2 / g to 550 m 2 It has a BET surface area of ​​ / g, a particle size XDC measured after deagglomeration by ultrasound, a Ld ((d84-d16) / d50) range of at least 0.91, and a pore volume distribution with a V (d5-d50) / V (d5-d100) range of at least 0.66.

[0003] In addition, a method for manufacturing silica from EP2102104 is known, wherein the silica is 40 m 2 / g to 525 m 2 Surface area of ​​CTAB per g, 45 m 2 / g to 550 m 2 It has a BET surface area of ​​ / g, an Ld ((d84-d16) / d50) range of at least 0.91 as measured by XDC particle size analysis after sonication, and a pore volume distribution V (d5-d50) / V (d5-d100) of at least 0.66.

[0004] EP1831297 and WO2006072704 specify at least 60 m as an inorganic filler in thermoplastic polymer materials to increase material stiffness while maintaining or improving impact resistance. 2 It is disclosed that silica having a BET surface area of ​​ / g is used.

[0005] Also 40 m from US2005032965 and WO2008077948 2 / g to 525 m 2 Surface area of ​​CTAB per g, 45 m 2 / g to 550 m 2 Silica is known having a BET surface area of ​​ / g, a size distribution range of at least 0.91 Ld ((d84-d16) / d50) measured by XDC particle size analysis after ultrasonic splitting, and a pore volume distribution V (d5-d50) / V (d5-d100) of at least 0.66.

[0006] One disadvantage of known silica within the desired specific surface area range is poor dispersion in rubber mixtures and the resulting poor wear characteristics of the rubber mixture, particularly when used as a tread mixture.

[0007] The object of the present invention is to provide silica having improved dispersion in a rubber mixture compared to known silica. At the same time, in order to have excellent incorporation into the rubber matrix and easy workability, the silica should exist in pellet form if possible. Specific details for implementing the invention

[0008] The present invention provides precipitated silica characterized by the following physicochemical parameters:

[0009] CTAB surface area ≤ 115 m 2 / g, preferably ≤ 105 m 2 / g, more preferably ≤ 90 m 2 / g, more preferably 45 m 2 / g-90 m 2 / g, particularly preferably 65 m 2 / g-90 m 2 / g, very particularly preferably 70 m 2 / g-90 m 2 / g,

[0010] DOA absorption ≥ 130 ml / (100 g), preferably ≥ 140 ml / (100 g), more preferably 145 ml / (100 g)-190 ml / (100 g),

[0011] Ro-Tap > 300 μm ≥ 86%, preferably 86%-98%, more preferably 86%-95%, particularly 90%-95%,

[0012] V (d5-d50) / V (d5-d100) < 0.66, preferably 0.30-0.65, particularly 0.30-0.64.

[0013] The precipitated silica according to the present invention is ≤ 125 m 2 / g, preferably ≤ 115 m 2 / g, more preferably 70 m 2 / g-105 m 2 It can have a BET surface area of ​​ / g.

[0014] The precipitated silica according to the present invention has a Seas water content of 7.0-20.0 ml / (1.5 g), preferably 9.0-15.0 ml / (1.5 g), more preferably 11.0-14.0 ml / (1.5 g). 원재료 It can have (ml of KOH based on 1.5 g of silica).

[0015] The precipitated silica according to the present invention has ≥ 5.4 OH / nm 2 , preferably ≥ 5.5 OH / nm 2 It can have a silanol group density.

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

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

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

[0019] The precipitated silica according to the present invention may have 3%-5%, preferably 4%-5%, of ignition residue.

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

[0021] The precipitated silica according to the present invention may have a bulk density of at least 180 g / l, preferably 200 g / l-350 g / l, more preferably 250 g / l-330 g / l, and most preferably 250 g / l-320 g / l.

[0022] The precipitated silica according to the present invention may have a TAR value of 15%-60%, preferably 20%-50% (grained grains: fraction of 3.14 mm-5.00 mm).

[0023] The precipitated silica according to the present invention may have a PV value of 0.0042 MPa-414 MPa, 140°, and a value of 1.00-3.00 ml / g, preferably 1.35-2.40 ml / g, more preferably 1.35-2.00 ml / g, as measured by the Hg pore measurement method.

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

[0025] Precipitated silica according to the present invention can be used in a compressed form, more preferably in the form of pellets. Here, it is possible for at least 50% of the granular crystals derived from the Ro-Tap > 300 μm fraction to have a maximum dimension of the granular crystals in terms of height, width, or length (defined as "grain length") of 1.0 mm or more, preferably > 1.5 mm, more preferably > 2.5 mm, and particularly preferably > 3.0 mm.

[0026] Additionally, the present invention relates to a method for producing precipitated silica according to the present invention, wherein

[0027] a) An aqueous solution of an organic and / or inorganic salt and / or alkali metal or alkaline earth metal silicate and / or organic and / or inorganic base having a pH of ≥ 9 is initially charged, and

[0028] b) Water glass and an acidifying agent are simultaneously metered and added to the above initial filler while stirring at 80-98°C for 60-120 minutes, preferably at 85-98°C for 80-110 minutes, and

[0029] c) Subsequently, the addition of water glass is stopped, and acid alone is metered in a smaller amount than before to achieve a pH of 8.3-10.0 of the mixture (measured at 60°C), and

[0030] d) Subsequently, without the addition of additional reactants, the mixture is further stirred at a high temperature of ≥ 85°C, preferably > 90°C, for 45 min to 200 min, preferably 60 to 150 min, and

[0031] e) Sulfuric acid is used for acidification to a pH of approximately 3.5-4.5 (measured at 60°C), and

[0032] f) The mixture is filtered and, preferably, dried to a drying loss of < 8% by a spray drying or spin flash drying unit, and then pelletized.

[0033] Provides a method characterized by

[0034] The method according to the present invention can be performed at a temperature of ≥ 80°C and can be aged at ≥ 85°C throughout the entire sedimentation process. As a result, approximately ≤ 115 m 2 In addition to a specific surface area of ​​1 / g, a very high-order internal structure is also generated within the aforementioned surface area range, which is highly advantageous for incorporation into a matrix, such as rubber. This is reflected in a high DOA value. These structures are largely preserved even after actual structure-breaking pelletization, because the generated high silanol group density results in a stabilized structure of silica.

[0035] The initial packing may be 20% to 90%, preferably 30% to 90%, and more preferably 40% to 90% of the final volume of the sediment. If present, it is possible to use an initial packing having only a low level of electrolyte (salt) and to add the electrolyte continuously or in batches (preferably when sedimentation begins).

[0036] Optionally, it is also possible to additionally add organic or inorganic salts during steps a), b), c), e), or f). This may be carried out in solution or solid form, and in each case, by continuous or batch addition. It is also possible to dissolve the salt in one or more components and then add them simultaneously. The salt may contain the following anions and cations:

[0037] Li + , Na + , 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- .

[0038] Suitable organic salts are salts of formic acid, acetic acid, and propionic acid. The cations include the aforementioned alkali metal or alkaline earth metal ions. The concentration of these salts in the initial charge may be 0.01 to 5.00 mol / l. The inorganic salt used is preferably Na2SO4. In steps b), c), and e), it is possible to supply the acidifying agent in the same or different manner, that is, at the same or different concentrations and / or feed rates. Likewise, in steps a) and b), it is also possible to supply the water glass to the reaction in the same or different manner.

[0039] It is also possible to use silicates other than water glass (sodium silicate solution), such as potassium silicate or calcium silicate. The acidifying agent used may be sulfuric acid, as well as other acidifying agents, such as HCl, HNO3, H3PO4, or CO2. The filtration and drying of silica are familiar to those skilled in the art and are, for example, as described in EP 1762544 B1 and the patents cited therein. It is preferable to dry the silica in a fluid dryer, spray dryer, multi-stage dryer, belt dryer, rotary dryer, flash dryer, spin-flash dryer, or nozzle tower. These drying methods involve operations using an atomizer, a one- or two-phase nozzle, or an integral fluidized bed. After the drying step, the precipitated silica has a particle shape having an average diameter of preferably greater than 15 μm, particularly greater than 80 μm, and more preferably greater than 200 μm. After drying, it is also possible to perform pelletization using a roll press equipped with a downstream crusher that establishes the final grain length.

[0040] Additionally, the present invention provides a rubber mixture comprising the following:

[0041] (A) rubber or a mixture of rubbers, and

[0042] (B) At least one type of precipitated silica according to the present invention.

[0043] The rubber used may be natural rubber and / or synthetic rubber. Preferred synthetic rubbers are described, for example, in the literature [W. Hofmann, Kautschuktechnologie [Rubber Technology], Genter Verlag, Stuttgart 1980]. These may include the following:

[0044] - Polybutadiene (BR),

[0045] - Polyisoprene (IR),

[0046] - A styrene / butadiene copolymer (SBR) having a styrene content preferably 1% to 60% by weight, more preferably 5% to 50% by weight, e.g., emulsion SBR (E-SBR) or solution SBR (S-SBR),

[0047] - Chloroprene (CR),

[0048] - Isobutylene / isoprene copolymer (IIR),

[0049] - Butadiene / acrylonitrile copolymer (NBR) having an acrylonitrile content of 5% to 60% by weight, preferably 10% to 50% by weight,

[0050] - Partially hydrogenated or fully hydrogenated NBR rubber (HNBR),

[0051] - Ethylene / propylene / diene copolymer (EPDM),

[0052] - The aforementioned rubbers also having functional groups, e.g., carboxy, silanol, or epoxy groups, e.g., epoxidized NR, carboxy-functionalized NBR, or silanol (-SiOH)- or siloxy (-Si-OR)-functionalized SBR,

[0053] and mixtures and masterbatches of these rubbers. Particularly in relation to liquid-phase mixing or continuous liquid-phase mixing, it is also possible to use the latex of the aforementioned rubber.

[0054] In a preferred embodiment, the rubber may be sulfur-vulcanizable. For the manufacture of automobile tire treads, it is possible to use anionically polymerized S-SBR rubber (solution SBR) having a glass transition temperature greater than -50°C, and also mixtures thereof with diene rubber. Particularly preferably, it is possible to use S-SBR rubber in which the butadiene component has a vinyl content of more than 20 weight%. Very particularly preferably, it is possible to use S-SBR rubber in which the butadiene component has a vinyl content of more than 50 weight%.

[0055] It is possible to use a mixture of the aforementioned rubbers having an S-SBR content of preferably more than 50 weight%, more preferably more than 60 weight%.

[0056] More specifically, it is possible to use polymer blends of unfunctionalized and / or functionalized S-SBR / BR and S-SBR / BR / NR grades in the tread compound, often also with the addition of resins. These resins may be of natural or synthetic origin and may be in a chemically modified form or in the form of a blend of different resins.

[0057] The rubber mixture according to the present invention may include additional fillers. The following fillers may be used as such fillers for the rubber mixture according to the present invention:

[0058] - Carbon Black: Carbon black can be manufactured by the lamp-black process, furnace-black process, gas-black process, or thermal process, and 20 m 2 / g to 200 m 2 It can have a BET surface area of ​​1 / g. Carbon black may also optionally contain heteroatoms, for example, Si.

[0059] - For example, it is prepared by precipitation from a silicate solution or flame hydrolysis of silicon halides, and 5 to 1000 m 2 / g, preferably 20 to 400 m 2 Amorphous silica having a specific surface area (BET surface area) of g / g and a primary particle size of 10 to 400 nm. The silica may optionally also be in the form of a mixed oxide with other metal oxides, such as oxides of Al, Ga, B, Mg, Ca, Ba, Zn, and titanium. The silica may also be doped with one or more of these metal ions.

[0060] - 20 to 400 m 2Synthetic silicates having a BET surface area of ​​10 to 400 nm and a primary particle diameter of 10 to 400 nm, such as aluminum silicate, alkaline earth metal silicates such as magnesium silicate or calcium silicate.

[0061] - Synthetic or natural aluminum oxide and synthetic or natural aluminum hydroxide.

[0062] - Natural silicates, such as kaolin and other naturally occurring silicas.

[0063] - Natural fibers, particularly cellulose, micro- and / or nano-cellulose and products manufactured therefrom.

[0064] - Glass fibers and glass-fiber products (mats, strands) or glass microbeads.

[0065] Preferably, it is prepared by precipitation from a silicate solution, and 20 to 400 m 2 / g, more preferably 100 m 2 / g to 250 m 2 It is possible to use amorphous silica having a BET surface area of ​​1 / g in an amount of 5 to 150 parts by weight based on 100 parts of rubber in each case.

[0066] The mentioned fillers can be used alone or as a mixture.

[0067] The rubber mixture may comprise 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, more preferably 5 to 15 parts by weight of an organosilane, wherein the parts by weight are based on 100 parts by weight of rubber.

[0068] The rubber mixture may additionally contain silicone oil and / or alkylsilane.

[0069] The rubber mixture according to the present invention may include other known rubber aids, such as crosslinking agents, vulcanization accelerators, reaction accelerators, reaction retarders, antioxidants, stabilizers including aging stabilizers, processing aids, plasticizers, waxes or metal oxides, and optionally activators such as triethanolamine, polyethylene glycol or hexanetriol.

[0070] Rubber additives may be used in a typical amount determined by factors including the end use. The typical amount may be, for example, 0.1% to 50% by weight based on the rubber.

[0071] The crosslinking agent used may be a sulfur or organic sulfur donor.

[0072] The rubber mixture according to the present invention may include other vulcanization accelerators. Examples of suitable vulcanization accelerators that can be used include mercaptobenzothiazole, sulfenamide, guanidine, dithiocarbamate, thiourea, thiocarbonate, and also zinc salts thereof, for example, zinc dibutyldithiocarbamate.

[0073] The rubber mixture according to the present invention may additionally include the following:

[0074] Thiuram sulfide accelerator and / or carbamate accelerator and / or corresponding zinc salt,

[0075] Nitrogen-containing co-activator,

[0076] Optionally other rubber additives, and

[0077] Arbitrarily different accelerators.

[0078] The weight ratio of the accelerator to the nitrogen-containing co-activator may be 1 or more.

[0079] The rubber mixture according to the present invention may comprise at least 0.25 parts by weight of tetrabenzylthiuram disulfide or tetramethylthiuram disulfide based on 100 parts by weight of rubber, at least 0.25 parts by weight of diphenylguanidine based on 100 parts by weight of rubber, and cyclohexyl- or dicyclohexylsulfenamide.

[0080] Preferably, it is possible to use sulfenamide together with guanidine and thiuram, and more preferably, cyclohexylsulfenamide or dicyclohexylsulfenamide together with diphenylguanidine and tetrabenzylthiuram disulfide or tetramethylthiuram disulfide.

[0081] The vulcanization accelerator and sulfur may be used in an amount of 0.1 to 10 parts by weight, preferably 0.1 to 5.0 parts by weight, based on the rubber used. Particularly preferably, it is possible to use sulfur and sulfenamide in an amount of 1.0 to 4.0 parts by weight, thiuram in an amount of 0.2 to 1.0 parts by weight, and guanidine in an amount of 0.0 to 3.0 parts by weight.

[0082] Additionally, the present invention provides a method for preparing a rubber mixture according to the present invention, characterized in that a rubber or a mixture of rubbers, precipitated silica according to the present invention, and optionally an additional rubber aid are mixed in a mixing unit.

[0083] Blending of rubber, fillers, and optional rubber aids can be performed in conventional mixing units, such as rolls, internal mixers, and mixing extruders. This type of rubber mixture can typically be prepared by first incorporating rubber, fillers, precipitated silica according to the present invention, and rubber aids in an internal mixer, and then mixing at 100 to 170°C in one or more sequential thermomechanical mixing stages. The order and timing of addition of individual components can have a decisive influence on the properties of the resulting mixture. Typically, the resulting rubber mixture can be mixed with crosslinking chemicals in an internal mixer or on rolls at 40 to 110°C, and the mixture can be processed to provide a so-called tempered mixture for subsequent steps of the process, such as molding and vulcanization.

[0084] The rubber mixture according to the present invention can be vulcanized at a temperature of 80°C to 200°C, preferably 130°C to 180°C, optionally under a pressure of 10 bar to 200 bar.

[0085] The rubber mixture according to the present invention can be used to manufacture a molded article by vulcanization.

[0086] The rubber mixture according to the present invention can be used for the manufacture of molded articles, for example, tires, particularly tire treads, tire carcasses or tire sidewalls, cable sheathing materials, hoses, drive belts, conveyor belts, roll coverings, shoe soles, gasket elements, for example, gasket rings, and damping elements.

[0087] The precipitated silica according to the present invention has the advantage that the corresponding rubber mixture has improved dispersion of silica. Furthermore, the rubber mixture according to the present invention has improved reinforcement and better tear propagation characteristics. In addition, increased dynamic stiffness is achieved at 60°C, which will result in higher driving stability, i.e., improved handling characteristics on dry road surfaces.

[0088] Test method:

[0089] Determination of alkaline water

[0090] Alkaline water (AN) is understood to mean the amount of hydrochloric acid consumed in ml when directly potentiometrically titrating an alkaline solution or suspension to a pH of 8.30 (for a sample volume of 50 ml, 50 ml of distilled water and a hydrochloric acid concentration of 0.5 mol / l are used). This determines the free alkali content of the solution or suspension.

[0091] The pH instrument (Knick, model: 766 pH meter Calimatic with temperature sensor) and the pH electrode (composite electrode from Schott; model: N7680) are calibrated at room temperature using two types of buffer solutions (pH = 7.00 and pH = 10.00). The composite electrode is immersed in a standard solution or suspension equilibrated at 40°C, consisting of 50.0 ml of precipitation suspension and 50.0 ml of deionized water. Subsequently, a hydrochloric acid solution with a concentration of 0.5 mol / l is added dropwise until a constant pH of 8.30 is established. Since equilibrium between the silica and free alkali content is only slowly established, a waiting time of 15 min is required before the acid consumption can be finally read. Given the selected molar amount and concentration, the hydrochloric acid consumption read in ml corresponds directly to the alkali water, which is recorded dimensionlessly.

[0092] pH - pH of silica according to DIN EN ISO 787-9 (heated)

[0093] During the manufacture of silica, pH measurements are performed on "heated" silica = measurements at 60℃.

[0094] The procedure follows DIN EN ISO 787-9, wherein the provisions are as stated below:

[0095] Prepare a 5% (m / m) aqueous suspension of the sample to be analyzed. For this purpose, demineralized (DM) water is used.

[0096] Before measuring pH, vortex the sample suspension in a vortexer for at least 5 minutes.

[0097] pH is measured using a pre-calibrated pH meter model 780 from Metrohm with a pH electrode 6.0228000 (Metrohm).

[0098] CTAB surface area - determined according to ISO 5794-1 G

[0099] The method is based on the adsorption of a buffered aqueous solution of CTAB (N-cetyl-N,N,N-trimethylammonium bromide) onto the "external" surface of silica, also referred to as a "rubber-active surface." The unadsorbed CTAB is back-titrated with NDSS (dioctyl sodium sulfosuccinate solution). The endpoint of the titration is when the opacity of the solution rises to a maximum.

[0100] The procedure follows ISO 5794-1 G, wherein the provisions, additions, and changes are as described below:

[0101] In the sample preparation process, instead of crushing specimens of silica and silicates in the form of coarse particles with a mortar and pestle and separating them by a 150 μm sieve as described in the standard method, they are preferably ultrafinely ground by a suitable mill or crushed with a mortar and pestle and sieved through a 90 μm sieve.

[0102] 200 m 2 A suspension consisting of a test specimen having an estimated CTAB surface area of ​​less than / g and a CTAB solution is stirred for 10 minutes. According to the standard method, 200 m 2 A suspension consisting of a test specimen having an expected CTAB surface area of ​​1 / g or more and a CTAB solution is stirred for 35 minutes.

[0103] After adsorption, the silica is filtered through a 0.2 μm polyamide filter.

[0104] The filtrate is titrated using a Metrom titration apparatus equipped with an autosampler and a Tyrando 809. The phototrode used is Spectrosense 523 nm from Metrom.

[0105] BET surface area (N2, multipoint) - determined according to DIN ISO 9277

[0106] The method is used to determine the N2 specific surface area of ​​silica by the BET method according to DIN ISO 9277. In this method, the measurement is determined by the low-temperature adsorption of nitrogen at a defined partial pressure. The analysis is performed as a multipoint determination, and in the case of determination of a total of 5 measurement points, it presents substantially linear behavior in the partial pressure range of 0.05–0.20 (p / po).

[0107] The procedure follows DIN ISO 9277, the specifications of which are as follows:

[0108] Before weighing, the pelletized sample is carefully crushed with a spatula and then degassed under reduced pressure at (160 + / - 2)°C for 60 minutes using a Micromerits VacPrep™ 061 exhaust degassing thermostat.

[0109] To determine the BET surface area, the following five relative pressure points (p / po) are recorded during the adsorption step: 0.0500; 0.0875; 0.1250; 0.1625 and 0.2000.

[0110] For measurement, the TriStar 3000 series (3000 / 3020 / 3030) from Micromerics is used with a static volumetric test method and a Dewar flask.

[0111] Ro-Tap > 300 μm; Ro-Tap < 75 μm - Sieve analysis according to ISO 5794-1 Appendix F

[0112] Sieve analysis is performed using a rotary sieving machine (Tyler's Ro-Tap RX-29 analytical sieving machine with a timer switch). The method is performed in accordance with ISO 5794-1 Appendix F. For sieve analysis, test sieves of various mesh sizes are stacked sequentially (metal sieve, ISO 3310-1, analytical sieve with a nominal mesh size of 75 μm and a sieve diameter of 200 mm, metal sieve, ISO 3310-1, analytical sieve with a nominal mesh size of 150 μm and a sieve diameter of 200 mm, metal sieve, ISO 3310-1, analytical sieve with a nominal mesh size of 300 μm and a sieve diameter of 200 mm). The stack of sieves is inserted into the analytical sieving machine in the specified order. The sieve residue is determined by the following method: the sample is gently homogenized before determination. Weigh 100 g with a precision balance to an accuracy of 0.01 g and place it in a beaker, then quantitatively transfer the sample to the top sieve (300 μm). Perform Ro-Tap sieving using a tapper for 5 minutes. After sieving, remove the sieve stack and weigh the sieve pan and the fractions on the 75 μm, 150 μm, and 300 μm sieves.

[0113] Calculation of sieve residue

[0114] Ro-Tap < 75 μm (%) = AS 100% / E

[0115] and also

[0116] Ro-Tap > 300 μm (%) = A300 · 100% / E

[0117] and

[0118] Ro-Tap > 150 μm (%) = A150 · 100% / E

[0119] Here

[0120] A300 = Residue in g on a 300 μm sieve

[0121] AS = Residue in grams within the sieve pan

[0122] E = Starting weight in g

[0123] pH - Determination of silica according to DIN EN ISO 787-9

[0124] The procedure follows DIN EN ISO 787-9, wherein the provisions are as stated below:

[0125] The pelletized sample material is finely ground using a mortar and pestle before weighing.

[0126] Prepare a 5% (m / m) aqueous suspension of the sample to be analyzed. For this purpose, demineralized (DM) water is used.

[0127] Before measuring pH, vortex the sample suspension in a vortexer for at least 5 minutes.

[0128] pH is measured at 23°C + / - 2°C using a pre-calibrated pH meter model 780 from Metrom with a pH electrode 6.0228000 (Metrom).

[0129] Loss on drying - determined according to DIN EN ISO 787-2

[0130] The weight loss of a sample heated in a drying cabinet at 105°C for 2 hours is determined.

[0131] The procedure follows DIN EN ISO 787-2, wherein the provisions are as stated below:

[0132] Heat a weighing bottle (with a flanged lid; diameter approx. 80 mm, height approx. 30 mm) at 105°C for about 1 hour with the lid open. After cooling in a desiccator, insert the lid. The weight is determined with a precision balance to an accuracy of 0.01 g. Accurately weigh a sample of 5 g to 10 g (weight varies depending on bulk density) and spread it into a uniform layer at the base of the weighing bottle. Carefully open the weighing bottle and heat it in a drying cabinet at (105 ± 2)°C for 2 hours (the lid is also heated, but the weighing bottle is not yet closed with it).

[0133] After that, carefully close the lid of the weighing bottle, let it cool in a desiccator, and re-weigh it to an accuracy of 0.01 g.

[0134] calculate

[0135]

[0136] E = Starting weight in g

[0137] A = Final weight in g

[0138] Sears 원재료 (SN) - Crystals for hydrophilic silica

[0139] Seas number as a measure of the number of free silanol groups by titrating silica with a standard 0.1 mol / l potassium hydroxide solution in the pH range of 4 to 9 원재료 It is possible to determine.

[0140] The determination method is based on the following chemical reaction, where ≡SiOH is considered to represent the silanol group of silica:

[0141]

[0142] procedure:

[0143] Approximately 10.0 g of powdered, spherical, or granular silica is uniformly crushed for 60 seconds at 10,000 rpm using a Fritsch mill (Pulverisette 14 equipped with an 80 μm screen). Approximately 1.50 g of the thus treated silica is weighed to an accuracy of 0.1 mg and placed in a 250 ml beaker, and mixed with 150 ml of NaCl solution (adjusted to pH 3 using β(NaCl) = 200 g / l and hydrochloric acid c(HCl) = 1 mol / l). After complete wetting of the sample, the suspension is dispersed for 30 seconds at a speed of 20,000 rpm using an Ultra Turrax PT1300D (Polytron).

[0144] Before titration, calibrate the pH meter (LL Unitrod pH electrode from Metrom, Model: PT1000) at room temperature using buffer solutions (pH 4.00, pH 7.00, and pH 9.00). First, measure the starting pH of the suspension using the pH meter, and then adjust the pH to 4.00 using potassium hydroxide solution (0.1 mol / l) or hydrochloric acid solution (0.1 mol / l) according to the result. Subsequently, perform the titration to pH 9.00 using a 0.1 mol / l standard KOH solution. V represents the amount of KOH solution consumed in ml from pH 4.00 to pH 9.00. pH4-9 It corresponds to. A blank titration (without the addition of silica) is performed in the same manner. The blank 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 Describes.

[0145] Sears number in ml / (1.5 g) units based on the original substance 원재료 is calculated as follows:

[0146] Sears 원재료 = (VpH4-9 - V BL ) * T * (1.5 g) / E

[0147] Here, T = the titer of the standard KOH solution used

[0148] E = Initial mass of the sample in g

[0149] Silanol group density (SD) - Calculated via AN based on CTAB surface area

[0150] AN provides a consumption of 0.1 n KOH in units of ml / (1.5 g):

[0151]

[0152] CTAB surface area and Avogadro constant (N A Applying ) provides the following:

[0153]

[0154] This is OH / nm 2 Provides the silanol group density (SD) of the unit:

[0155]

[0156] Here, the AN and CTAB surface areas are used in a dimensionless form in the formula for SD because they have already been considered in the calculation.

[0157] Ignition residue - determined according to ISO 3262-1 or ASTM D 6740

[0158] By igniting precipitated silica in an ignition furnace at 1000°C for 2 hours, the total water content (physically and chemically bonded) and the content of all volatile components (loss on ignition) are determined, and it is also possible to calculate the ignition residue from this.

[0159] procedure:

[0160] In each case, about 500 mg of silica is weighed using an analytical balance with an accuracy of ± 0.1 mg and placed into two magnetic crucibles or melting crucibles using a spatula. Afterwards, the crucibles with the silica are subjected to ignition in an ignition furnace at (1000 ± 50)°C for (120 ± 5) min.

[0161] After ignition, the crucible is placed in a desiccator with a suitable desiccant for about 1.5-2 hours to cool, and then re-weighed using an analytical balance. The crystallization is performed in duplicate.

[0162] Evaluation: First, calculate the loss on ignition based on the dry material:

[0163]

[0164] IL (DM) : Loss on ignition in % based on material dried at 105°C for 2 hours

[0165] m E : Mass of weighed silica in grams

[0166] m A : Mass of silica in grams after ignition

[0167] DL: Loss on drying in % at 105°C for 2 hours

[0168] Calculate the residual ignition based on the original material as follows:

[0169] IL(orig.) = IL( DM ) * (100 - DL) / 100, therefore

[0170] IR(orig.) = 100% - DL - IL(orig.)

[0171] The loss on drying for this purpose is determined by the method of "Determination of loss on drying according to DIN EN ISO 787-2" (see above).

[0172] TAR - Wear rate by fracture test of pelletized materials

[0173] For the wear rate by the pulverization test of the pelletized material, fine and coarse fractions of silica are removed, and a 3.15 mm–5.00 mm fraction is used. The pelletized material fraction is subjected to repeated mechanical stress for 30 minutes in a rotating pulverization chamber (e.g., an ERWEKA TAR 220 with pulverization drums on the left and right). Afterward, the resulting fine fraction is removed by a 500 μm sieve. A mass difference in % corresponds to the wear rate of the pelletized material.

[0174] The determination of the wear rate is performed in two stages.

[0175] Take a representative 50 g sample of the silica to be analyzed. Sieve the 3.15 mm–5.00 mm grain fraction by careful manual sieving (metal sieve, ISO 3310-1, sieve diameter 200 mm – nominal mesh size 500 μm, 3.15 mm and 5 mm analytical sieves, and sieve pan). This excludes fine particles and very coarse particles. Accurately weigh (5.00 ± 0.1) g of the 3.15 mm–5 mm fraction using an analytical or precision balance. If the sieved amount is insufficient, the measurement cannot be performed. A representative sample volume must be taken. Introduce the sample into a crushing drum; mount it on a wear tester. Operate the instrument at 65 rpm for 30 minutes. Afterward, quantitatively apply the material to a 500 μm sieve to remove the attached fine fraction by moderate vortexing / motion. Next, the pelletized material particles are re-weighed with a precision or analytical balance to an accuracy of 0.01 g.

[0176] evaluation:

[0177]

[0178] Wear rate: Wear rate in % based on the fracture resistance test of pelletized materials

[0179] E: Starting weight in g of the sieved 3.15-5 mm fraction

[0180] A: Residual in g units after applying stress and removing derivatives

[0181] The measurement result is the average of two individual measurements and is recorded in the % unit to the first decimal place.

[0182] DOA absorption amount - determined according to ISO 19246

[0183] For the procedure, a sample of 12.50 ± 0.02 g is introduced into the kneader chamber of a Brabender absorption system E equipped with an extended function / evaluation unit. Subsequently, under continuous kneading, dioctyl adipate (e.g., Plastomol® DOA) is metered in at a metering rate of 4 ml / min. The kneader speed is 125 rpm. The program calculates a polynomial using the raw data curve. The 70% value of the maximum torque of this polynomial is used to determine the DOA absorption amount in ml / (100 g) based on the original material. The determination is carried out in accordance with ISO 19246.

[0184] In the case of pelletized silica, crystallization is carried out using a grain fraction of 1.0-3.15 mm, which must be pre-formed by sieving with a suitable sieve.

[0185] The following settings must be made in the measuring instrument software:

[0186] Test conditions

[0187] Metering rate (burette): 4.0 ml / min

[0188] Mixer speed: 125 min-1

[0189] Temperature: 23.0℃

[0190] evaluation

[0191] Torque threshold: 100 mNm

[0192] Termination: 60 s after achieving maximum torque

[0193] Torque limit: 10,000 mNm

[0194] polynomial

[0195] Start: 50% of maximum torque

[0196] Termination: 20 seconds after reaching the maximum

[0197] It is possible to perform individual standardization of the analytical kneader with the assistance of Brabender® software using suitable reference materials with different DOA absorption amounts. Based on the identified standardization function (linear equation Y = a*x + b), the DOA absorption amount (standardized) in ml / (100 g) based on the original material, expressed as 70% of the maximum torque value, is taken from the recorded measurement value.

[0198] Electrical conductivity - determined according to DIN EN ISO 787-14

[0199] The electrical conductivity of silica is determined according to DIN EN ISO 787-14. The following procedural changes are made in comparison with the provisions of this standard method:

[0200] A 4% aqueous suspension (4.00 g of silica per 100 ml of deionized water) is prepared and analyzed.

[0201] Measurements are performed directly on the suspension rather than the filtrate.

[0202] Measurements are taken at 20.0℃ ± 0.5℃, and conductivity is recorded against a reference temperature of 20℃.

[0203] Determination of pore radius and pore volume based on Hg penetration according to DIN 66133

[0204] In a pressure range of 0.003 to 420 MPa, the pore radius, corresponding pore volume, and pore distribution of the silica sample are determined. Determination is performed using Micromerics’ AutoPore IV 9520 in accordance with DIN 66133.

[0205] Dry the sample in a drying cabinet at 105 ± 2℃ for 2 hours.

[0206] For measurement, the prepared sample is weighed and placed into the Micromeretics Model 16 penetrometer. Approximately 330 mg is weighed with an accuracy of 0.001 g. Subsequently, the penetrometer is slowly evacuated to 50 μm Hg through the instrument's low-pressure port and left at this pressure for 5 minutes. Afterward, mercury is filled into the penetrometer first through the low-pressure port and then through the high-pressure port to a pressure of 420 MPa, and the measurement curve (pressure / volume curve) is recorded. The Autopore instrument is operated according to the Micromeretics operating instructions and is software-controlled. Each measurement is corrected by the penetrometer's blank measurement. The full measurement range is 0.003–420 MPa.

[0207] The measurement result is calculated from the measurement curve as follows:

[0208] Crafting Max:

[0209] Hg, -dV / dlogD; contact angle 140°, surface tension 480 mN / m, nm units

[0210] PV:

[0211] Hg, 0.0042 - 414 MPa; contact angle 140°, surface tension 480 mN / m, ml / g units

[0212] V (d5 - d50) / V (d5 - d100):

[0213] It is determined from the Hg pore measurement method according to WO2008077948.

[0214] Bulk density - determined according to ASTM D 1513

[0215] Weigh a 1000 ml graduated cylinder (with 20 ml markings) fitted with a powder funnel (at least 1 L capacity) using a precision balance (0.1 g accuracy). Carefully rotate the sample container to thoroughly mix the sample to be analyzed. In the case of pelletized materials, particular care must be taken to ensure that no additional fines are generated. After mixing, use a scoop to carefully transfer 500 ml to 700 ml of silica into a 1 L beaker (with approximate divisions). Pour the entire silica sample together into the graduated cylinder through the funnel. After standing (without mechanical densification), read the volume of the bulk material with an accuracy of 5 ml. Here, ensure that the filling volume is between 500 ml and 700 ml. At the same time, to calculate the bulk density, check the weight of the sample with an accuracy of ± 0.1 g.

[0216] Calculation of bulk density:

[0217]

[0218] In the above formula:

[0219] Bulk density in units of D g / l

[0220] V Volume of the sample in ml after cavitation

[0221] Mass of the sample in mg

[0222] Decisions are made in duplicate. If the two results differ by more than 3%, a third value is used to calculate the average. The results are recorded without decimal points.

[0223] Examples

[0224] Example 1

[0225] 1140 l of water and 150 kg of water glass are initially charged into a reactor equipped with a propeller stirrer system 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 so that the AN of the reaction mixture becomes 24-27.

[0226] After that, sulfuric acid (density 1.84 kg / l, 96% H2SO4) is added so that the pH of the reaction mixture becomes 8.6 (measured at 60°C).

[0227] The temperature of the settling vessel is increased to 94°C within 5 minutes, and the suspension is aged at 94°C for 55 minutes while stirring.

[0228] After that, additional sulfuric acid (density 1.84 kg / l, 96% H2SO4) is supplied at a metering rate of 0.70 kg / min until a pH of 7 (measured at 60°C) is achieved. Then, additional sulfuric acid is added at a metering rate of 0.35 kg / min until a pH of 4.0 (measured at 60°C) is achieved.

[0229] The resulting suspension is filtered as usual, washed with water, and subjected to spin-flash drying. The powder obtained in this way is pelletized, that is, compressed in a roll press, and then crushed by a crusher.

[0230] Example 2

[0231] A reactor equipped with a propeller stirrer system is initially filled with 1164 l of water and 150 kg of water glass (AN 25-26) and heated to 89.0°C. Within 100 minutes, the following are added simultaneously: water glass (density 1.345 kg / l, 27% SiO2, 8% Na2O) at an average metering rate of 7.3 kg / min and sulfuric acid (density 1.84 kg / l, 96% H2SO4) at an average metering rate of 0.82 kg / min.

[0232] After that, additional sulfuric acid (density 1.84 kg / l, 96% H2SO4) is added so that the pH of the reaction medium becomes 8.5 (measured at 60°C).

[0233] The temperature of the settling vessel is increased to 94°C within 5 minutes, and the suspension is aged at 94°C for 55 minutes while stirring.

[0234] After that, additional sulfuric acid (density 1.84 kg / l, 96% H2SO4) is added at a metering rate of 0.70 kg / min to a pH of 7 (measured at 60°C), and then acidification is continued at a metering rate of 0.35 kg / min to a pH of 4.0 (measured at 60°C).

[0235] The resulting suspension is filtered as usual, washed with water, and subjected to spin-flash drying. The powder obtained in this way is pelletized, that is, compressed in a roll press, and then crushed by a crusher.

[0236] Silica has the analysis parameters recorded in Table 1.

[0237]

[0238] Reference silica 1 is ZEOSIL® 1085 GR from Solvay Société Anonym (Solvay SA).

[0239] Example 3

[0240] Investigation of rubber characteristics

[0241] The formulations (green tire compounds) used for the rubber mixture are specified in Table 2 below. In this table, the phr unit refers to parts by weight based on 100 parts of the raw rubber used.

[0242]

[0243]

[0244]

[0245] The rubber mixture is prepared in an internal mixer in 3 stages according to the items in the table below (Table 3):

[0246]

[0247]

[0248]

[0249]

[0250] A general method for manufacturing rubber mixtures and their vulcanized products is described in the literature ["Rubber Technology Handbook", W. Hofmann, Hanser Verlag 1994].

[0251] The vulcanization time for each test specimen at 165℃ is 15 min. The rubber test is conducted according to the test method specified in Table 4.

[0252]

[0253]

[0254]

[0255]

[0256]

[0257]

[0258]

[0259] The rubber data of the rubber mixture according to the present invention presented in Table 5 indicates the superior dispersion / dispersibility of the silica according to the present invention compared to the prior art rubber mixture 1 (Comparative Example). Rubber mixtures 2 and 3 of the present invention clearly have lower levels of optically undispersed silica when directly measuring defects in cross-section through the vulcanized material, by contact topography measurement, and by dispersion testing apparatus. In addition, there are distinct improvements in all measurements related to reinforcement: in tensile testing, stress values ​​show a distinct improvement while maintaining the same elongation at break. This is also consistent with improved die C and Graves tear results under various measurement conditions. Furthermore, the DIN wear rate is also improved in the rubber mixture according to the present invention compared to the reference mixture. These advantages suggest that a tire having a tire tread containing and reinforced with the silica according to the present invention will have a distinct improvement in wear characteristics. The indicators of ball rebound at 23°C and tangent δ at 0°C also additionally suggest clearly improved values ​​for the wet slip characteristics of this tread. The high stiffness at high temperatures under these measurement conditions (E* at 60°C and modulus (max) in RPA) also additionally presents improved handling characteristics on dry road surfaces compared to the prior art. As such, generally, these rubber compounds and silica according to the present invention can optimize and improve the overall performance of very specialized, for example, winter tires or much more specialized Nordic winter tires to a very high degree.

Claims

Claim 1 Precipitated silica:CTAB characterized by the following physicochemical parameters, surface area ≤ 90 m 2 / g, DOA absorption ≥ 130 ml / (100 g), RoTap > 300 μm ≥ 86%, V (d5 - d50) / V (d5 - d100) < 0.

66. Claim 2 Precipitated silica according to claim 1, characterized in that the PV (pore volume) value determined under a pressure of 0.0042 MPa-414 MPa and a contact angle of 140° is in the range of 1.00-3.00 ml / g. Claim 3 In claim 1, the silanol group density is ≥ 5.4 OH / nm 2 Precipitated silica characterized by being. Claim 4 Precipitated silica according to claim 1, characterized by having a bulk density of at least 180 g / l. Claim 5 Precipitated silica according to claim 1, characterized in that the grain length is ≥ 1 mm. Claim 6 A method for producing precipitated silica according to claim 1, comprising: a) initially filling with at least one aqueous solution selected from the group consisting of organic salts, inorganic salts, alkali metal silicates, alkaline earth metal silicates, organic bases, inorganic bases, and combinations thereof, having a pH of ≥ 9; b) simultaneously metering in water glass and an acidifying agent into the initial filling while stirring at 80-98°C for 60-120 minutes; c) subsequently, the addition of water glass is stopped, and acid alone is metered in a smaller amount than before to achieve a pH of 9.0-10.0 of the mixture (measured at 60°C); d) subsequently, without the addition of additional reactants, the mixture is stirred at a high temperature of > 85°C for 45 min to 200 min; e) sulfuric acid is used for acidification to a pH of 3.5-4.5 (measured at 60°C); and f) the mixture is filtered, dried to a drying loss of < 8%, and then pelletized. A method for manufacturing precipitated silica characterized by Claim 7 A rubber mixture comprising: (A) rubber or a mixture of rubbers, and (B) at least one type of precipitated silica according to claim 1. Claim 8 A method for manufacturing a rubber mixture according to claim 7, characterized in that a rubber or a mixture of rubbers, precipitated silica according to claim 1, and optionally additional rubber aids are mixed in a mixing unit. Claim 9 In paragraph 7, a rubber mixture for use in the manufacture of tires, cable sheathing materials, hoses, drive belts, conveyor belts, roll coverings, shoe soles, gasket elements, or damping elements. Claim 10 delete

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