WO2010022544A1 - Procédé de préparation de silices précipitées, silices précipitées et leur utilisation - Google Patents

Procédé de préparation de silices précipitées, silices précipitées et leur utilisation Download PDF

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WO2010022544A1
WO2010022544A1 PCT/CN2008/001556 CN2008001556W WO2010022544A1 WO 2010022544 A1 WO2010022544 A1 WO 2010022544A1 CN 2008001556 W CN2008001556 W CN 2008001556W WO 2010022544 A1 WO2010022544 A1 WO 2010022544A1
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precipitation
process according
silicate
weight
alkali metal
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PCT/CN2008/001556
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English (en)
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Gottlieb-Georg Lindner
Yihmeng Simon Shen
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Evonik Degussa Gmbh
Evonik Degussa (China) Co., Ltd
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Priority to PCT/CN2008/001556 priority Critical patent/WO2010022544A1/fr
Priority to CN2008801309227A priority patent/CN102137813A/zh
Publication of WO2010022544A1 publication Critical patent/WO2010022544A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
    • C01B33/187—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by acidic treatment of silicates
    • C01B33/193—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by acidic treatment of silicates of aqueous solutions of silicates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
    • B60C1/0016—Compositions of the tread
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/34—Silicon-containing compounds
    • C08K3/36—Silica
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
    • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
    • C09C1/28—Compounds of silicon
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/50—Solid solutions
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/19—Oil-absorption capacity, e.g. DBP values
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/88—Isotope composition differing from the natural occurrence

Definitions

  • the invention relates to a new process for preparing precipitated silica, to innovative precipitated silicas, and to their use.
  • Precipitated silicas are speciality chemicals whose properties can be tailored to the desired fields of application. This diversity and variability has resulted in precipitated silicas now being used in numerous fields of application. Examples thereof are identified in Ullmann's Encyclopedia of Industrial Chemistry, Wiley- VCH Verlag GmbH & Co. KGaA, Online Edition, DOI (Digital Object Identifier): 10.1002/14356007.a23_583.pub3, 2008, section 7.4.
  • the properties of precipitated silicas are determined by their preparation processes.
  • the preparation process in turn may be subdivided roughly into the steps of precipitation and precipitation work-up.
  • a mineral acid is added to an initial charge of alkali metal silicate solution.
  • This process can be varied, for example, by adding neutral salts of strong acids and strong bases, such as sodium chloride or sodium sulphate, for instance, to the alkali metal silicate solution.
  • a feature of other processes, which are practiced predominantly at present, is that the precipitation is carried out by simultaneous addition of both reaction components, i.e. the silicate solution and the acidifying agent, to an initial charge.
  • This initial charge may be composed of water, but also of a portion of the silicate solution and/or electrolyte solutions.
  • These preparation processes, with simultaneous addition of the reaction components, are frequently carried out at a constant pH or at a constant alkali number. Precipitation at constant alkali number means that the concentration of the freely available sodium ions in the reaction solution is held constant.
  • Another version of the precipitation reaction involves the use of growth nuclei.
  • a "pre-precipitation reaction” small silica particles are formed in an initial charge and then the precipitation is carried out by simultaneous addition of acid and silicate.
  • the precipitation itself may be controlled by holding the pH or the alkali number constant. Examples thereof are found in EP 0520862 Bl, EP 0670813 Bl, EP 0670814 Bl or EP 0917519 Bl.
  • EP 1 764 344 Al describes a process in which different primary particles are formed as a result of different precipitation rates, with the consequence that, at the end of precipitation, a silica suspension is obtained in which the silica unites the properties of two different precipitated silicas with one another.
  • a further disadvantage of many known processes for preparing precipitated silicas having specific properties is the complexity of the precipitation process.
  • two or more precipitations have to be carried out alongside one another, and the suspensions reunited thereafter, thereby adversely affecting the complexity and the cost of the equipment.
  • the incorporation of holding steps, and the use of different precipitation rates have negative impacts on the space-time yield and/or complicate the effort involved in control, thereby increasing the susceptibility to error.
  • An objective of the present invention was to provide a simple process for preparing precipitated silicas that nevertheless allows the preparation of precipitated silicas which exhibit outstanding application properties across a broad application spectrum.
  • the intention is that the precipitated silicas obtained by the new process ought to have good properties not only as a filler for tyres but also as a filler in mechanical rubber goods such as footwear soles, for example. Further objects, not stated explicitly, will become apparent from the overall context of the following description, examples and claims.
  • the present invention accordingly provides a process for preparing precipitated silicas which comprises the following steps: a) preparing an initial charge of water or an aqueous solution of an alkali metal silicate and/or alkaline earth metal silicate, b) simultaneously metering alkali metal silicate and/or alkaline earth metal silicate and acidifying agent into this initial charge with stirring at 80 to 100 0 C, c) reacidifying the precipitation suspension to a pH of 2.5 to 6.0, d) filtering, washing and drying, and which is characterized in that the alkali metal silicate and/or alkaline earth metal silicate used in steps a) and/or b) has an alkali metal oxide and/or alkaline earth metal oxide content in the range from 4% to 7% by weight and a silicon dioxide content in the range from 14% to 23% by weight, in that the acidifying agent used in step b) and/or c) is an acidifying agent selected from the group consisting of sulphuric acid having a concentration of 90%
  • steps c) and d) for the resulting suspension to be afterstirred at 60 to 100°C for 1 to 90 minutes.
  • Step b) may likewise be optionally interrupted for 1 to 60 minutes to allow the silica particles obtained to age, but typically this is not necessary.
  • the present invention further provides precipitated silicas obtainable by the process of the invention.
  • a final subject of the present invention is the use of the precipitated silicas of the invention as a filler in pneumatic tyres, tyre treads for summer tyres, winter tyres and all-year tyres, car tyres, tyres for utility vehicles, motorcycle tyres, tyre body parts, cable sheathing, hoses, drive belts, conveyor belts, roll coverings, footwear soles, gasket rings and damping elements, and also, more generally, MRG (mechanical rubber goods).
  • silicate solution and also "alkali metal silicate and/or alkaline earth metal silicate solutions” are used synonymously.
  • the process of the invention uses a silicate solution which - in comparison to that used in EP 1764344 Al - is more highly diluted by at least 10%, preferably at least 15%, more preferably at least 20%.
  • the alkali metal oxide and/or alkaline earth metal oxide content of the silicate solution used in accordance with the invention is in the range from 4% to 7% by weight, preferably in the range from 5% to 6.5% by weight, more preferably from 5.5% to 6.5% by weight.
  • the silicate solution used in the process of the invention is especially sodium silicate solution (waterglass) and/or potassium silicate solution.
  • the silicon dioxide content of the silicate solution used in accordance with the invention is 14% to 23% by weight, preferably 18% to 22% by weight, more preferably 20% to 22% by weight, and is therefore likewise lower by at least 10%, preferably at least 15%, more preferably at least 20% than in conventional processes.
  • the modulus, i.e. the weight ratio of silicon dioxide to alkali metal oxide and/or alkaline earth metal oxide, in the silicate solution used in accordance with the invention is preferably 2.0 to 5.75, more preferably 2.5 to 4.5, very preferably 3 to 4, and with more particular preference 3.2 to 3.7.
  • the silicate solution is employed as a dilute solution, while the acidifying agent is used as a concentrated solution.
  • the amount of water that must be heated is less.
  • a greater span of silicas can be prepared.
  • the inventors are of the view that when the acid (acids) is diluted, a dissociation equilibrium comes about in general within a very short time. The attainment of equilibrium in the case of a sodium silicate solution, in contrast, occurs over the course of several hours. As a result, and owing also to the different compositions of the waterglasses, different products are formed.
  • concentrated mineral acids such as hydrochloric acid, sulphuric acid, nitric acid or phosphoric acid or CO 2 .
  • Concentrated acid means, in the case of hydrochloric acid, a concentration of 34% to 42.7% by weight, preferably 36% to 40% by weight; in the case of sulphuric acid, a concentration of 90% to 98.5% by weight, preferably 93% to 98.5% by weight and very preferably 96% to 98% by weight; in the case of nitric acid, a concentration of 60% to 68% by weight; and, in the case of phosphoric acid, a concentration of 80% to 100% by weight, preferably 80% to 90% by weight, more preferably 80% to 85% by weight.
  • the inventors have found, furthermore, that for the process of the invention it is essential that the pH of the precipitation suspension (measured at 6O 0 C) must fall in the course of precipitation by 1% to 20%, preferably 2% to 15%, more preferably 3% to 10%, very preferably 5% to 10%, based on the pH at the start of precipitation, i.e. at the beginning of the simultaneous addition of silicate solution and acid.
  • "In the course of precipitation" means that the start point is defined by the beginning of the simultaneous addition of silicate solution and acid, and the end point is defined by the ending of the simultaneous addition of silicate solution and acid. Where ageing/maturation steps are to be carried out in the process of the invention, then the end point is taken as the point in time at which silicate solution and acid are added simultaneous for the last time in the process as a whole.
  • the starting pH of the precipitation is adjusted preferably in the range from 8 to 12, more preferably from 9 to 11.5, very preferably in the range from 10 tol l.
  • the pH at the end of precipitation is preferably 6.5 to 11.5, more preferably 7 to 1 1, very preferably 8 to 10.5, with special preference 9 to 10, and with very special preference 9.5 to 10.
  • the concentration of alkali metal ions in the reaction solution - expressed by the Y value - may remain constant during precipitation or may change in the course of precipitation.
  • the Y value reflects the chemical reactions during the precipitation, more particularly the incorporation of ions into the silica framework. From this value it is possible to draw conclusions concerning the underlying structure of the silica and, accordingly, even prior to the physicochemical analysis of the end product, to predict the quality and reproducibility of the product in question.
  • precipitation is carried out such that the Y value during precipitation is held in the range between 4 and 8.
  • the Y value during the precipitation is held in a range between 3 and 6, with more particular preference 3.5 to 5.5.
  • the Y value during precipitation is held constant in the range from 6 to 8, with particular preference 6 to 7.5. In one specific embodiment it has proven to be advantageous if the Y value during precipitation falls by up to 25%, more preferably 5% to 20%, with special preference 10 to 15%, based on the Y value at the start of precipitation.
  • the precipitation is carried out preferably at a temperature of 80 to 95 0 C.
  • the pure precipitation time i.e. the duration of the simultaneous addition of silicate solution and acidifying agent, may in one preferred version of the present invention - without consideration of interruption times - be 50 to 80 min, in another preferred version of the present invention 80 to 120 min, more preferably 80 to 100 min.
  • the feed rates of the acidifying agent and of the silicate solution are chosen such that the desired precipitation time - but also, at the same time, the desired pH profile of the precipitation suspension - can be maintained.
  • Electrolytes for the purpose of the present invention are metal salts or their aqueous solutions which are not incorporated into the amorphous SiO 2 framework, such as, for example, Na, K, Rb, Ba, in each case as sulphate, acetate, halide or carbonate.
  • the fraction of the electrolyte is 0.01% - 26% by weight (calculated as metal ion).
  • metal salts or their solutions to the precipitation mixture that are incorporated into the SiO 2 framework, thus giving silicates.
  • the fraction of these metal ions may be between 0.5% and 50% by weight, preferably 1% to 10% by weight; common ions are Al, Zr, Ti, Fe, Ca and Mg.
  • the precipitated silica suspensions prepared by the process of the invention are filtered in step d) and the filter cake is washed with water.
  • the filtration, liquefaction (e.g. in accordance with DE 2447613) and long or short drying of the silicas of the invention are familiar to the skilled person and can be read, for example, in the documents cited in this description.
  • the filtration and the washing of the silica take place preferably in such a way that the conductivity of the end product is ⁇ 2000 ⁇ S/cm and particularly ⁇ 1300 ⁇ S/cm.
  • the silica of the invention is preferably dried in a pneumatic dryer, spray dryer, staged dryer, belt dryer, B ⁇ ttner dryer, rotary tube dryer, flash dryer, spin-flash dryer or nozzle tower dryer.
  • These drying variants include operation with an atomizer, a single-fluid or two-fluid nozzle or an integrated fluid bed.
  • Spray drying may be carried out, for example, in accordance with US 4094771.
  • Nozzle tower drying may be carried out, for example, as described in EP 0937755.
  • the contents of US 4094771 and of EP 0937755 are hereby explicitly incorporated into the content of the present specification.
  • the precipitated silicas of the invention may be present in the form of a powder having a particle size d 50 of 1 to 80 ⁇ m as determined by means of laser diffraction.
  • the powder particles may have an irregular or else a regular external form, i.e. they may also be substantially spherical, for example.
  • the precipitated silicas of the invention are in the form of substantially spherical particles (microgranules) having a particle size d 5 o of 80 ⁇ m to 1000 ⁇ m as determined by means of sieve residue analysis (Alpine).
  • the silicas of the invention are prepared preferably by means of nozzle tower drying, as described in EP 0937755, and exhibit an external form that is characteristic of this drying method (see figures in EP 0937755).
  • the content of EP 0937755 is hereby explicitly incorporated into the content of the present specification.
  • the precipitated silicas of the invention are in the form of granules (d 50 > 1000 ⁇ m (Alpine sieve residue)), and following granulation have a particle size distribution such that by means of sieve residue analysis (Ro-Tap) at least 80% by weight of the particles are larger than 300 ⁇ m and not more than 10% by weight are smaller than 75 ⁇ m.
  • Granulation may be carried out using, for example, a roll press from Alexanderwerk AG, Remscheid.
  • the powder product is deaerated by a vacuum system, without further addition of binders or liquids, via a horizontal feed system with single or double screw, and is introduced uniformly between the double-sidedly mounted, vertically disposed rolls. This presses the powder to a flake product, which is brought to the desired maximum granule size by means of a crusher.
  • the precipitated silicas of the invention can be ground.
  • the techniques for optional grinding of the silicas of the invention are known to the skilled person and can be read for example in Ullmann, 5 1 edition, B2, 5-20.
  • For the grinding of the silicas of the invention it is preferred to use impact mills or opposed-jet mills.
  • the milling parameters are preferably chosen such that the ground product has a d 50 of the volume-based particle distribution curve, determined by means of laser diffraction, of between 1 and 15 ⁇ m, preferably 3 to 10 ⁇ m, more preferably 4 to 10 ⁇ m.
  • the products thus ground, but also the unground products can also be employed in non-rubber applications, such as for support material, for example.
  • the particle size of the powders of the invention is 15 to 80 ⁇ m. These powders are suitable with particular preference for applications for reinforcement of rubber products.
  • the precipitated silicas obtained by the process of the invention can be used as a filler in pneumatic tyres, tyre treads for summer tyres, winter tyres and all-year tyres, car tyres, tyres for utility vehicles, motorcycle tyres, tyre body parts, cable sheathing, hoses, drive belts, conveyor belts, roll coverings, footwear soles, gasket rings and damping elements.
  • the Y value is determined using sulphuric acid as standard solution and phenolphthalein as indicator.
  • the Y value is calculated as follows:
  • V volume of sulphuric acid consumed in the titration
  • ml N normality of the acid
  • a sample of 50-100 ml of the initial charge or precipitation suspension is taken and the pH is determined at 60 0 C according to known processes.
  • This method is used to determine the solids content of filter cakes by removal of the volatile fractions at 105°C.
  • SC solids content
  • the solids content (SC) in % is determined as
  • the pH of the silica is determined in the form of a 5% suspension in water at room temperature in a modified version of DIN EN ISO 787-9. Relative to the specifications of that standard, the initial masses were changed (5.00 g of silica per 100 ml of deionized water). Determination of the moisture content
  • the moisture content of silica is determined in accordance with ISO 787-2 following 2-hour drying in a forced-air drying cabinet at 105°C. This loss of drying is composed predominantly of water moisture.
  • the specific nitrogen surface area (referred to below as BET surface area) of the powder, sphere or granule silica is determined in accordance with ISO 5794-1 /Annex D using an AREA-meter (Strohlein, JUWE).
  • CTAB N-hexadecyl-N,N,N-trimethylammonium bromide
  • ASTM 3765, or NFT 45-007 section 5.12.1.3
  • the adsorption of CTAB takes place in aqueous solution with stirring and ultrasound treatment.
  • unadsorbed CTAB is determined by back-titration with NDSS (dioctylsodium sulphosuccinate solution, "Aerosol OT" solution) using a titroprocessor, the end point being indicated by the maximum clouding of the solution and determined using a phototrode.
  • NDSS dioctylsodium sulphosuccinate solution, "Aerosol OT" solution
  • the temperature throughout all of the operations conducted is 23-25°C, to prevent crystallization of CTAB.
  • the back-titration is based on the following equation:
  • CTAB 0.015 mol/1 in deionized water
  • the consumption of NDSS solution for titrating 5 ml of CTAB solution should be checked 1 x daily prior to each series of measurements. This is done by setting the phototrode, before beginning the titration, at 1000 ⁇ 20 mV (corresponding to a transparency of 100%).
  • the titration vessel is closed with a lid and the contents are stirred with an Ultra Turrax T 25 stirrer (stirrer shaft KV- 18G, 18 mm diameter) at 18 000 rpm for a maximum of 1 minute until wetting is complete.
  • the titration vessel is screwed onto the DL 70 titroprocessor and the pH of the suspension is adjusted with KOH (0.1 mol/1) to a figure of 9 ⁇ 0.05.
  • the suspension is sonicated in the titration vessel for 4 minutes in a ultrasound bath (Bandelin, Sonorex RK 106 S, 35 kHz, 100 W effective or 200 W peak power) at 25°C. This is followed immediately by pressure filtration through a membrane filter under a nitrogen pressure of 1.2 bar. The initial fraction of 5 ml is discarded.
  • a ultrasound bath Bandelin, Sonorex RK 106 S, 35 kHz, 100 W effective or 200 W peak power
  • VA consumption of NDSS solution in ml for titrating the blank sample
  • the moisture content of the silica is determined in accordance with the described methods "Determination of the moisture content”. Determination of the DBP absorption
  • the DBP absorption which is a measure of the absorbency of the precipitated silica, is determined in a method based on standard DIN 53601, as follows: 12.50 g of powder or bead silica of 0-10% moisture content (the moisture content is adjusted if appropriate by drying in a drying cabinet at 105°C) are introduced into the kneader chamber (article number 279061) of the Brabender Absorptometer "E" (without damping of the outlet filter of the torque transducer).
  • the sieve fraction from 1 to 3.15 mm (stainless steel sieves from Retsch) is used (by gently pressing the granules through the sieve with a pore size of 3.15 mm using a plastic spatula).
  • dibutyl phthalate is added dropwise at room temperature to the mixture at a rate of 4 ml/min using the Brabender T 90/50 Dosimat. Its incorporation by mixing takes place with only a small amount of force, and is monitored by means of the digital display. Towards the end of the determination the mixture becomes pasty, which is indicated by a sharp increase in the required force.
  • DBP DBP absorption in g/(100 g)
  • V consumption of DBP in ml
  • D density of DBP in g/ml (1.047 g/ml at 20°C)
  • / initial mass of silica in g
  • C correction value from moisture correction table, in g/( 100 g)
  • the DBP absorption is defined for the anhydrous, dried silica.
  • moist precipitated silicas are used, it is necessary to take account of the correction value C for the calculation of the
  • DBP absorption This value can be determined from the correction table below; for example, a silica water content of 5.8% would imply an add-on of 33 g/(100 g) for the DBP absorption.
  • the moisture content of the silica is determined in accordance with the "Determination of the moisture content or loss on drying" method.
  • test sieves - analytical sieves with a metal sieve fabric (DIN ISO 565 T.2) in different nominal mesh sizes with a sieve diameter of 200 mm in each case - are stacked atop one another in a sieve tower in the following order:
  • E initial mass of granules in g.
  • a 8 final mass on sieve tray in g.
  • the laser diffraction instrument LS 230 (Coulter) and the liquid module (small volume module plus, 120 ml, Coulter) are warmed up for 2 h, the module is rinsed three times with DI water and calibrated, and in the case of hydrophobic precipitated silicas it is rinsed three times with ethanol.
  • the homogeneous suspension of 1 g of silica in 40 ml of DI water is added, using a 2 ml single-use pipette, to the liquid module of the instrument, in such a way that a constant concentration with a light absorption of 8% to 12% is achieved and the instrument reports "OK". Measurement takes place at room temperature. From the raw data plot, the software calculates the particle size distribution and the d 50 figure (median value), on the basis of the volume distribution, taking into account the Mie theory and the optical model parameters (.rfd file).
  • This determination of sieve residue is an air-jet sieving method based on DIN ISO 8130-1, using an Alpine S 200 air-jet sieve instrument.
  • sieves whose mesh size is > 300 ⁇ m are included.
  • the sieves must be chosen such that they yield a particle size distribution from which the d5Q value can be determined in accordance with Figure 2. Graphical representation and evaluation take place in the same way as in ISO 2591-1, section 8.2.
  • the d50 value is that particle diameter in the cumulative particle size distribution at which the particle diameter of 50% of the particles is less than or equal to that of the particles whose particle diameter is the d5Q value.
  • a precipitation vessel with a capacity of 90 m 3 is charged with 42 m 3 of water. 0.95 m 3 of waterglass (Na 2 O content 6.1% by weight, SiO 2 content 20.7% by weight) is added. The initial charge is subsequently heated to 91.8 0 C.
  • the pH of the initial charge at the start of precipitation i.e. of simultaneous addition of waterglass and sulphuric acid (about 98.0 ⁇ 0.5% by weight) to the initial charge, is 10.3.
  • the Y value at the start of precipitation is 5.3.
  • the silica feed with a solids content of about 20% by weight and a pH of about 5.8, is subsequently spray-dried such that the end product has a pH of 6.2, measured in the form of a 5% suspension.
  • the spray-dried product is then granulated by means of a roll granulator. Roll granulation takes place by means of two shaping rolls pressed together.
  • the powder product without further addition of binders or liquids, is deaerated by means of a vacuum system (underpressure 0.08 bar) and introduced uniformly between the double-sidedly mounted, vertically arranged rolls. At a rotary speed of 18-20 rpm and a pressure of 70-80 bar, the pressed powder is comminuted by means of a crusher (mesh size 10 mm). The fine fraction is sieved off with a vibration sieve (mesh size 1 x 10 mm) and returned to the powder feed.
  • Example 2 The physicochemical data of a representative sample of the resulting powder product (Example Ia) and granulated product (Example Ib) are listed in Table 1.
  • Example 2 The physicochemical data of a representative sample of the resulting powder product (Example Ia) and granulated product (Example Ib) are listed in Table 1.
  • a precipitation vessel with a capacity of 90 m 3 is charged with 40 m 3 of water. 1.27 m 3 of waterglass (Na 2 O content 6.1%, SiO 2 content 20.5%) are added. The initial charge is subsequently heated to 87 0 C.
  • the pH of the initial charge at the start of precipitation i.e. of simultaneous addition of waterglass and sulphuric acid (about 98.0 ⁇ 0.5% by weight) to the initial charge, is 10.5.
  • the Y value at the start of precipitation is 6.6.
  • the resulting suspension is filtered using a membrane filter press, and the filter cake is washed with water.
  • the filter cake with a solids content of about 20% by weight, is then liquefied in a dissolver.
  • the silica feed with a solids content of about 20% by weight and a pH of about 5.8, is subsequently spray-dried in such a way, by a drying operation with metered addition of ammonia, that the end product has a pH of 6.2, measured in the form of a 5% suspension.
  • the spray-dried product is then granulated by means of a roll granulator. Roll granulation takes place by means of two shaping rolls pressed together.
  • the powder product without further addition of binders or liquids, is deaerated by means of a vacuum system (underpressure 0.08 bar) and introduced uniformly between the double-sidedly mounted, vertically arranged rolls.
  • a vacuum system underpressure 0.08 bar
  • the pressed powder is comminuted by means of a crusher (mesh size 10 mm).
  • the fine fraction is sieved off with a vibration sieve (mesh size 1 x 10 mm) and returned to the powder feed.
  • Example 3 The physicochemical data of a representative sample of the resulting powder product (Example 2a) and granulated product (Example 2b) are listed in Table 1.
  • Example 3 The physicochemical data of a representative sample of the resulting powder product (Example 2a) and granulated product (Example 2b) are listed in Table 1.
  • a precipitation vessel with a capacity of 90 m 3 is charged with 40 m 3 of water. 1.26 m 3 of waterglass (Na 2 O content 6.3, SiO 2 content 21.4) are added. The initial charge is subsequently heated to 84°C. The pH of the initial charge at the start of precipitation, i.e. of simultaneous addition of waterglass and sulphuric acid (about 98.0 ⁇ 0.5% by weight) to the initial charge, is 10.5. The Y value at the start of precipitation is 6.6.
  • the resulting suspension is filtered using a membrane filter press, and the filter cake is washed with water.
  • the filter cake with a solids content of about 20% by weight, is then liquefied in a dissolver.
  • the silica feed with a solids content of about 20% by weight and a pH of about 5.8, is subsequently spray-dried such that the end product has a pH of 6.2, measured in the form of a 5% suspension.
  • the spray-dried product is then granulated by means of a roll granulator. Roll granulation takes place by means of two shaping rolls pressed together.
  • the powder product without further addition of binders or liquids, is deaerated by means of a vacuum system (underpressure 0.08 bar) and introduced uniformly between the double-sidedly mounted, vertically arranged rolls.
  • a vacuum system underpressure 0.08 bar
  • the pressed powder is comminuted by means of a crusher (mesh size 10 mm).
  • the fine fraction is sieved off with a vibration sieve (mesh size 1 x 10 mm) and returned to the powder feed.
  • Example 3a The physicochemical data of a representative sample of the resulting powder product (Example 3a) and granulated product (Example 3b) are listed in Table 1.
  • Table 1 The physicochemical data of a representative sample of the resulting powder product (Example 3a) and granulated product (Example 3b) are listed in Table 1.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Silicon Compounds (AREA)

Abstract

La présente invention concerne un procédé de préparation de silices précipitées, des silices précipitées et leur utilisation en tant que charge dans un élastomère. Ce procédé comprend les étapes consistant à préparer un chargement initial; à ajouter simultanément une dose de silicate et une dose d'agent acidifiant au chargement initial et à réacidifier la suspension précipitée jusqu'à obtention d'un pH de 2,5 à 6,0, le silicate utilisé comportant un oxyde métallique à hauteur de 4 à 7 % en poids et du dioxyde de silicium à hauteur de 14 à 23 % en poids et l'agent acidifiant étant choisi dans le groupe constitué de l'acide sulfurique à hauteur de 90 à 98,5 % en poids, de l'acide chlorhydrique à hauteur de 34 à 42,7 % en poids, de l'acide nitrique à hauteur de 60 à 68 % en poids, de l'acide phosphorique à hauteur de 80 à 100 % en poids, de l'acide carbonique ou du CO2 et du bisulfite de sodium ou du SO2.
PCT/CN2008/001556 2008-09-01 2008-09-01 Procédé de préparation de silices précipitées, silices précipitées et leur utilisation WO2010022544A1 (fr)

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WO2012010712A1 (fr) 2010-07-23 2012-01-26 Rhodia Operations Procede de preparation de silices precipitees
CN103435047A (zh) * 2013-08-17 2013-12-11 福建省三明同晟化工有限公司 一种电池隔板用二氧化硅的制备方法
CN104080736A (zh) * 2012-01-25 2014-10-01 罗地亚运作公司 沉淀二氧化硅制造方法
EP2807118A1 (fr) * 2012-01-25 2014-12-03 Rhodia Operations Procede de preparation de silices precipitees
US9695053B2 (en) 2012-01-25 2017-07-04 Rhodia Operations Process for preparing precipitated silica having specific morphology, particle size and porosity
US9725325B2 (en) 2011-12-23 2017-08-08 Rhodia Operations Process for preparing precipitated silicas
CN108622905A (zh) * 2018-06-27 2018-10-09 怡维怡橡胶研究院有限公司 一种白炭黑及其制备方法与应用
EP2794479B1 (fr) * 2011-12-23 2020-04-08 Rhodia Opérations Procédé de préparation de silices précipitées
EP2807116B1 (fr) * 2012-01-25 2020-04-22 Rhodia Opérations Procédé de préparation de silices précipitées

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CN104475013A (zh) * 2014-12-18 2015-04-01 广西大学 一种变压吸附净化页岩气用吸附剂的制备方法
CN105368411B (zh) * 2015-12-11 2018-04-20 西南石油大学 一种用于降低油气井水泥石脆性的碳酸镁晶须增韧剂

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Cited By (15)

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Publication number Priority date Publication date Assignee Title
WO2012010712A1 (fr) 2010-07-23 2012-01-26 Rhodia Operations Procede de preparation de silices precipitees
EP2595920B1 (fr) * 2010-07-23 2020-04-29 Rhodia Operations Procédé de préparation de silices précipitées
EP2794479B1 (fr) * 2011-12-23 2020-04-08 Rhodia Opérations Procédé de préparation de silices précipitées
US9725325B2 (en) 2011-12-23 2017-08-08 Rhodia Operations Process for preparing precipitated silicas
EP2794480B1 (fr) * 2011-12-23 2020-04-08 Rhodia Opérations Procédé de préparation de silices précipitées
EP2807118A1 (fr) * 2012-01-25 2014-12-03 Rhodia Operations Procede de preparation de silices precipitees
US9695053B2 (en) 2012-01-25 2017-07-04 Rhodia Operations Process for preparing precipitated silica having specific morphology, particle size and porosity
US9695054B2 (en) 2012-01-25 2017-07-04 Rhodia Operations Process for preparing precipitated silica
US10011494B2 (en) 2012-01-25 2018-07-03 Rhodia Operations Process for preparing precipitated silica
CN104080736A (zh) * 2012-01-25 2014-10-01 罗地亚运作公司 沉淀二氧化硅制造方法
EP2807115B1 (fr) * 2012-01-25 2020-04-08 Rhodia Opérations Procédé de préparation de silices précipitées à morphologie, granulométrie et porosité particulières
EP2807116B1 (fr) * 2012-01-25 2020-04-22 Rhodia Opérations Procédé de préparation de silices précipitées
EP2807117B1 (fr) * 2012-01-25 2020-05-13 Rhodia Opérations Procédé de préparation de silices précipitées
CN103435047A (zh) * 2013-08-17 2013-12-11 福建省三明同晟化工有限公司 一种电池隔板用二氧化硅的制备方法
CN108622905A (zh) * 2018-06-27 2018-10-09 怡维怡橡胶研究院有限公司 一种白炭黑及其制备方法与应用

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