Showing papers on "Precipitated silica published in 1998"

Method for preparing hydrophobic precipitated silica

Abstract: A method for the preparation of hydrophobic precipitated silicas which are useful, for example, as reinforcing fillers in rubber compositions. The method comprises two steps, where in the first step an aqueous suspension of precipitated silica is contacted with an organosilicon compound in the presence of a catalytic amount of an acid to effect hydrophobing of the precipitated silica. In the second step the aqueous suspension of the hydrophobic precipitated silica is contacted with a water-immiscible organic solvent at a solvent to silica weight ratio greater than 5:1 to effect separation of the hydrophobic precipitated silica from the aqueous phase.

Readily dispersible precipitated silica

Abstract: Precipitated silica, having the following physico-chemical parameters: BET surface area 120-300 m 2 /g CTAB surface area 100-300 m 2 /g BET/CTAB ratio 0.8-1.3 Sears index (consumption of 6-25 ml 0.1 N NaOH) DBP index 150-300 g/100 g wk coefficient <3.4 Particle size of the degraded <1.0 μm particles Particle size of the non- 1.0-100 μm degradable particles The precipitated silica is prepared by a process in which an alkali metal silicate (preferably soda water-glass) is reacted with mineral acids (preferably sulfuric acid) at temperatures of 60-95° C. at a pH of 7.0-11.0 with continuous stirring, the reaction is continued up to a solids concentration of 40 g-110 g, the pH is adjusted to a value between 3 and 5, and the precipitated silica is filtered off, washed, then dried and, if appropriate, ground or granulated. The precipitated silica is employed as a filler in vulcanizable mixtures for the production of tires.

Preparation and water-absorbent properties of a water-swellable rubber

Abstract: A water-swellable rubber was prepared by blending polychloroprene (CR) with crosslinked sodium polyacrylate (CSP), precipitated silica, poly(ethylene oxide) (PEO), and vulcanizing agents. The preparation process was described and the effect of composition of the water-swellable rubber on its water-absorbent properties such as degree of swelling, swelling rate, and weight loss ratio of CSP was discussed and the optimum composition range was identified: CSP, 25–75 phr; precipitated silica, 10–50 phr; and PEO, 5–30 phr. The reinforcing filler (precipitated silica) and the water-soluble polymer (PEO) were found to improve the water-absorbent properties of water-swellable rubber. The morphology of CSP and the silica in the rubber was studied by scanning electron microscopy, which showed that they were well dispersed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1219–1225, 1998

Addition of salts to improve the interaction of silica with rubber

Abstract: Incorporation of neutral water soluble inorganic salts into a precipitated silica improves the filler dispersion in a compounded rubber, reduces rolling resistance (hysteresis), and improves processability. These properties are achieved without loss of the expected reinforcement effect due to the substitution of inorganic salt for SiO2 in the silica. The properties are seen when a variety of silanes and processing aids are added to the silica.

Precipitated silica used as reinforcing filler for elastomers

Abstract: The invention concerns a novel method for preparing precipitated silica used as reinforcing filler for elastomers. It also concerns novel silica precipitates in the form of powder, granules or, preferably, substantially spherical balls, said silica being characterised in that they contain: a BET specific surface area ranging between 185 and 250 m2/g; a CTAB specific surface area ranging between 180 and 240 m2/g; a porous distribution such that the porous volume V2 consisting of pores with diameter ranging between 175 and 275 A represents less than 50 % of the porous volume V1 consisting of pores with diameter not more than 400 A; a porous volume (V?d1?) consisting of pores with diameter less than 1 νm more than 1.65 cm?3?/g; a fineness number (I.F) between 70 and 100 A; a fines contents (τ?f?) after ultrasound disintegration, of at least 50 %.

Effect of silica on iron-based Fischer-Tropsch catalysts

Abstract: The effect of silica addition via coprecipitation and as a binder to a doubly promoted Fischer-Tropsch (F-T) synthesis iron catalyst (100 Fe/5 Cu/4.2 K) was studied. The catalysts (nominally 50 μm particles) were prepared by coprecipitation, followed by binder addition and spray drying at 250 °C in a 1 m diameter, 2 m tall spray dryer. The binder silica content was varied from 0 to 20 wt%. A catalyst with 12 wt% binder silica was found to have the highest attrition resistance. F-T reaction studies over 100 hours in a fixed-bed reactor showed that this catalyst maintained around 95% CO conversion with a methane selectivity of less than 7 wt% and a C 5 + selectivity of greater than 73 wt%. The effect of adding precipitated silica from 0 to 20 parts by weight (pbw) to this catalyst (containing 12 wt% binder silica) was also studied. Addition of precipitated silica was found to be detrimental to attrition resistance and resulted in increased methane and reduced wax formation.

Silica-Base rubber composition intended for the manufacture of highway tires improved resistance to rolling

Abstract: The present invention relates to a rubber composition intended for the manufacture of road tires of improved resistance to rolling having a base of precipitated silica with a relatively high specific surface and special porosity properties.

Precipitated silicas which contain an active substance

Abstract: A precipitated silica which contains an active substance with a characteristic, delayed release of active substance is prepared by adding the active substance during preparation of the precipitated silica. The precipitated silica containing the active substance may be added to oral hygiene agents such as toothpastes, topical fluoride preparations, dental materials or medicinal chewing gums.

Advanced investigations into the silica/silane reaction system.

Abstract: Silica in combination with bifunctional organosilanes (e.g. [Bis(3-triethoxysilylpropyl) tetrasulfane] =TESPT) have recently become more important in the tire application. Their use in tire treads as a replacement of carbon black leads to an improvement in rolling resistance and wet traction without loss in abrasion resistance. The requirements for the attainment of this combination of properties are that the triethoxysilyl groups of TESPT react with the silanol groups on the silica surface during compounding, and the polymer active groups react with the polymer during cure.The reaction of precipitated silica with this silane was investigated. The influence of various parameters (silane concentration, pH, moisture content) on the reaction type, degree of reaction and the reaction kinetics were considered. The results of the investigation obtained using 29Si-CP/MAS solid state NMR spectroscopy agree well with a horizontal reaction model in which a single siloxane bond is first formed with the silica surface (primary reaction), either directly or after (partial) hydrolysis of the silane. After having given off further ethanol, it is followed by condensation reactions between silanol groups of silane molecules which are already bound to the silica surface (secondary reaction).The data of the kinetic studies show a clear difference between the quick primary reaction and the slow secondary reaction. The energy of activation according to Arrhenius was determined for both reactions and was found to be much lower for the secondary reaction. Both reactions become quicker in the acidic and alkaline ranges respectively.The primary reaction accelerates up to a particular H2O content after which the rate remains constant. The secondary reaction on the other hand keeps on accelerating with rising H2O content.Modification with different silane concentrations showed a noticeably higher rate constant at low concentrations and a greater amount of ethanol formed per mol of silane.

Rubber composition containing modified polyisobutylene rubber

Abstract: A rubber composition containing a diene rubber and a modified polyisobutylene rubber having a functional group capable of reacting with a silanol group present on a surface of silica, together with a precipitated silica or a silica-adhered carbon black, having a tan δ at 60° C. of 0.2 or more.

Addition of salt in order to improve interaction between silica and rubber

Abstract: PROBLEM TO BE SOLVED: To obtain a composition having improved dispersedness of a filler and improved processability, and a low tan δ value by incorporating a natural rubber and/or a specified synthetic rubber with microparticulate precipitated silica component containing a specified amount of adherent inorganic salt in a specified ratio. SOLUTION: This composition comprises 100 pts.wt. at least either of a natural rubber and an EPDM rubber, a (halogenated)butyl rubber, a halogenated isobutylene/p-methylstyrene rubber and a synthetic rubber having at least 30 wt.% repeating units derived from at least one 4-8C conjugated diene monomer and about 4 to about 90 pts.wt. microparticulate precipitated silica component containing about 2 to about 35 wt.%, based on the precipitated silica component, adherent inorganic salt (e.g. a chloride, sulfate, a phosphate or a carbonate of Na or K). Therefore, there is no necessity for washing off and removing most of the inorganic salt being a by-product in the production of precipitated silica. This composition can give a vulcanizate having a lowered 50%-strain modulus and an increased 300%-strain modulus.

Tire having a base of precipitated silica with improved rolling resistance

Abstract: A radial carcass tire comprising a tread, two non-stretchable beads, two sidewalls connecting the beads to the tread, and a crown reinforcement located between the carcass and the tread, the crown reinforcement including a diene elastomeric rubber having, as reinforcing filler, a highly dispersible precipitated silica having a CTAB specific area less than or equal to 125 m2/g and a BET specific surface area less than or equal to 125 m2/g.

Silica-filled rubber composition containing two different carbon blacks and tire produced by using the composition

Abstract: PROBLEM TO BE SOLVED: To provide a silica-filled rubber composition containing two different carbon blacks and a tire having a tread produced therefrom. SOLUTION: This rubber composition contains about 100 pts.wt. elastomer based on at least one diene, about 30-120phr particulate fillers comprising silica and carbon blacks (wherein the fillers contain about 15-60phr precipitated silica and about 15-60phr particulate carbon blacks comprising a mixture of a first carbon black having a DBP absorption of about 60-160cc/100g and an iodine value of about 25-85g/kg with a second carbon black having a DBP absorption of about 90-160cc/100g and an iodine value of about 90-150g/kg) and a silane coupling agent having both a part reactive with the surface of silica and a part interactive with an elastomer having a carbon-carbon double bond [the weight ratio of the coupling agent to the precipitated silica being (1:2) to (1:10)].

The Effect of Characteristics of a Seed on Silica Removal from a Model Geothermal Brine by a Seeding Method Using Silica Gel

Abstract: In order to apply a seeding method using silica gel to silica removal from geothermal brines, the effects of the seed particle diameter, initial specific surface area and initial pore diameter on silica removal are experimentally examined using a model geothermal brine. The silica in the brine is precipitated on the internal surface area of pore in the silica gel seeds. The specific surface area of the seed decreases with increasing quantity of precipitated silica. The effects of the particle diameter on the quantity of the final precipitated silica and on the final specific surface area are hardly seen. The quantity of precipitated silica per unit surface area increases with increasing initial pore diameter, and the silica precipitation rate coefficient increases with decreasing particle diameter and with increasing initial pore diameter. When the quanttty of precipitated silica is small, the silica precipitation rate coefficient is proportional to the -0.72 power of the particle diameter.

Rubber composition and tire having tread made therefrom

Abstract: PROBLEM TO BE SOLVED: To obtain an effectively reinforced tire tread rubber by compounding a modified styrene/conjugated diene copolymer elastomer, etc., with a specified surface-modified carbon black in the presence of especially a silica coupling agent. SOLUTION: Diene elastomer (A) containing about 20-100phr of a modified styrene/conjugated diene (e.g. butadiene) copolymer elastomer (A1 ) and 0-8phr of any one (A2 ) of a homo- and co-polymers of a conjugated diene and component A1 in an amount of 100 pts.wt. is compounded with about 30-110phr of modified reinforced carbon black (B1 ) and about 20-110phr of precipitated silica and unmodified carbon black (B2 ) containing a silanol on the surface and a silica coupling agent (C) having part (a group a silanol, titanium oxide or the like) on the surface of component B1 , a part reactive with the silanol on the silica and another part having interaction on one member of component A to obtain a rubber composition intended for use as a tire tread component.

Fertilizer and its usage

Abstract: PROBLEM TO BE SOLVED: To obtain a fertilizer having high silicate supply power and adsorption use efficiency of silicate for plants by using precipitated silica as the main component obtd. by decomposing a metal silicate with an acid. SOLUTION: A metal silicate (e.g. sodium silicate, potassium silicate, calcium silicate and magnesium silicate) is decomposed with an acid (e.g. sulfuric acid, nitric acid and hydrochloric acid) to obtain an active silica sol. With addition or without addition of a flocculant to the sol, the sol is subjected to flocculation, hydrothermal treatment, washing and drying to produce a fertilizer. Preferably, the precipitated silica used as a fertilizer has about 30 to 800 m /g specific surface area and about >=90% silicon dioxide content, and gives about >=5 ppm concn. within 24 hours after the silica is put in water. When the particle size preferably ranges between sizes of 5-mesh under and 200-mesh on, the obtd. fertilizer has good silicate absorption efficiency. The amt. of the fertilizer to be applied is preferably about 1 to 100 kg per 10 acre field.

Influence of precipitated silica characteristics on the properties of a truck tyre tread, II

Abstract: We compared in our laboratories and in the field precipitated silicas having different specific surface area and/or dispersibilities. An NR truck tyre tread with precipitated silica improves rolling resistance, heat generation and high severity wear. A high dispersibility precipitated silica is better. Only a partial substitution of carbon black by a high specific surface area silica together with adjustment of the formula allows better tread wear performance for all severities together with lower rolling resistance and maintained wet traction.

Aminosilane compound in silica-filled rubber composition

Abstract: PROBLEM TO BE SOLVED: To provide a silica-filled rubber compsn. having high abrasion resistance and impact resilience by compounding a sulfur-vulcanizable elastomer, particulate precipitated silica, a specific aminosilane compd., and a sulfur-contg. organosilicon compd. SOLUTION: 100 pts.wt. at least one fulfur-vulcanizable elastomer selected from among conjugated diene (co)polymers and conjugated diene-arom. vinyl copolymers is kneaded together with 10-250 pts.wt. particulate precipiated silica, 0.5-10 pts.wt. aminosilane compd. represented by formula I [wherein R to R are each 1-8C alkoxy, 1-8C alkyl, or 6C aryl provided at least one of them is alkoxy; R is 1-18C alkylene or 6-10C (alkylated) arylene; and R is H or 1-15C alkyl], and 0.05-10 pts.wt. sulfur-contg. organosilicon compd. represented by formula II or III (wherein n is 2-8) at 140-190 deg.C for 1-20min.

Paper making method using a novel retention system comprising a precipitated silica and a cationic polymer

Abstract: The invention concerns a novel method for making paper based on cellulose fibre in sheet form, wherein a novel retention system comprising a suspension of precipitated silica and a cationic polymer is used for improving in particular the retention of the incorporated mineral fillers. The invention also concerns a method for making paper using a retention system which substantially improves draining. More precisely, the invention concerns the use of a precipitated silica and a cationic polymer comprising a cationic guar gum and/or a cationic starch.

Optimally dispersible precipitated silica particulates, process for their preparation and their use

Abstract: An optimally dispersible precipitated silica particulate, characterized in that it possesses a Δ-value, corresponding to the peak value of the Differential Instrusion located at the Median Pore Diameter, as measured by Hg porosimeter, such that: Δ (ml/g.A) x 103≥0.141 x CTAB (m2/g) - b, wherein the Median Pore Diameter is comprised between 100 and 400 A, the CTAB is between 90 and 400 and the intercept b is 10 or less. Also provided are process for preparing said silica and uses thereof.

Enviromentally safe yellow bug light

Abstract: A yellow bug lamp whose coating is cadmium-free. The coating comprises sulfate precipitated silica, aluminum silicate pigment, zirconium praseodymiun yellow zircon and nickel titanium yellow rutile and has color coordinates of x=0.5341 to 0.5406 and y=0.4400 to 0.4378.

Rubber composition filled with silica and its working method

Abstract: PROBLEM TO BE SOLVED: To provide a rubber composition which is a rubber composition filled with silica and include a dispersed precipitated silica and a modified elastomer. SOLUTION: This rubber composition contains 100 pts.wt. at least one kind of sulfur-vulcanizable elastomer which is selected from a conjugated diene homopolymer and a copolymer and from at least one kind of a conjugated diene and an arom. vinyl compd, and 10-150phr precipitated silica bead over which 1-20wt.% silane modified elastomer is dispersed based on the weight of the silica.

Production of hydrophobic precipitated silica

Abstract: PROBLEM TO BE SOLVED: To obtain a hydrophobic precipitated silica in industrial scale by allowing an aq. suspension of a precipitated silica to contact with a water immiscible organic solvent after allowing to contact with a specific organic silicon compound. SOLUTION: The aq. suspension of the hydrophobic precipitated silica obtained by adding an acid catalyst into the aq. suspension containing 5-90 wt.% precipitated silica having 50-100 m /g BET surface area to have Hb SiX4ab , and organosiloxanes expressed by a formula, Rn SiO(4n/2) , (R represents a 1-12C hydrocarbon group, R represents H, hydroxy or a 1-12C hydrocarbon group provided that 50 mol.% of R substituent is a hydrocarbon group, X represents a halogen, a 1-12C alkoxy, (a) represents 1-3, (b) represents 0 or 1, a+b=1 to 3 provided that a+b is 2 or 3 when (b) is 1 and (n) represents 2 or 3) and allowing to contact with each other at 20-150 deg.C is brought into contact with the water immiscible organic solvent so that the ratio of (solvent) : (silica) by weight is >=5:1.

Silica-loaded rubber composition and processing method therefor

Abstract: PROBLEM TO BE SOLVED: To obtain a rubber compsn. which is processed or prepared at a high energy efficiency by mixing a specific sulfur-vulcanizable elastomer with particulate precipitated silica having the surface treated with a trialkoxzysilane. SOLUTION: Particulate precipitated silica with a trialkoxysilane dispersed on the surface thereof is obtd. by dissolving 1-20wt.% trialkoxsilane represented by the formula: R Si(OR )3 (wherein R 1-20C alkyl or 6-24C alkyl; and R is 1-8C alkyl) in a suspension formed by suspending particulate precipitated silica having a BET specific surface area of 40-600m /g, a DBP absorption of 10-400, and an average max, particle size of 0.01-0.05μm is an org. solvent (e.g. chloroform or dichlorometane, subjecting the resultant soln. to reaction at 15-150 deg.C for 2min to 10hr, and filtering and drying the reaction product. The treated silica in an amt. of 10-150phr and at least one sulfur-vulcanizable elastomer selected from among conjugated diene (co)polymers and conjugated diene-arom. vinyl compd. copolymers are kneaded together at 140-190 deg.C for 1-20min.

Precipitated silica containing active agent

Abstract: Precipitated silica that contains an active agent and provides delayed release of the active agent is new. Also claimed is a process for preparing a product as above, in which precipitated silica is produced in known manner and a moderately to sparingly water-soluble active agent is added to the precipitation medium or the precipitate suspension or is dried together with the washed and optionally redispersed silica paste or is ground together with the dried material.

Precipitated silica containing active substance

Abstract: Wirkstoff enthaltende Fallungskieselsaure mit einer charakteristischen, verzogerten Wirkstofffreigabe wird hergestellt, indem man bei der Herstellung der Fallungskieselsaure nach einem bekannten Verfahren den Wirkstoff hinzufugt. Die Fallungskieselsaure kann Mundpflegemitteln, wie Zahnpasten, topischen Fluoridpraparationen, Dentalwerkstoffen oder medizinischen Kaugummis zugesetzt werden.