Showing papers on "Precipitated silica published in 1984"

Precipitated silica pigment for silicone rubber

Abstract: Amorphous precipitated high structure silica pigment useful in the reinforcement of silicone rubber is described. The silica pigment is treated with an aqueous solution of a metal, e.g., calcium and barium, which forms a relatively water insoluble, white or colorless sulfate salt in amounts sufficient to provide at least an equal molar amount of the metal compared to the amount of alkali metal in the silica. Silicone rubber reinforced with such silica pigment exhibits a water swell of less than 4 volume percent.

Thixotropic acid-abrasive cleaner

Abstract: A thixotropic cleaner comprising about 6 to 12% of a precipitated silica; about 0.05 to 2.5% of a cationic, nonionic or zwitterionic or amphoteric surfactant, or mixtures thereof, that has the ability to hydrogen bond and mixtures thereof; an acid; and an abrasive. The relationship between the relatively narrow ranges of precipitated silica and hydrogen bonding surfactant is critical and responsible for the favorable viscosity, ability to suspend abrasives, and minimal or lack of syneresis. All of these advantageous characteristics are stable over an extended period of time.

Microcapsules and method for their production

Abstract: Dump release microcapsules are formed of a water-reswellable gel having dispersed therein a sorbtive filler material having a median particle size of not more than 1 micron, such as fumed or precipitated silica. The filler material has an active substance absorbed therein and/or adsorbed thereon. The active material can be 2-chloro-6-(trichloromethyl) pyridine and the gel formed from crosslinked lignin or a lignosulphonate.

The unique properties of precipitated silica in the design of high performance rubber

Abstract: Etude comparative de formulations d'elastomeres et de caoutchouc naturel contenant de la silice ou du noir de carbone: essais mecaniques apres vieillissement

Method of preparing highly siliceous porous crystalline zeolites

Abstract: METHOD OF PREPARING HIGHLY SILICEOUS POROUS CRYSTALLINE ZEOLITES ABSTRACT A process for preparing highly siliceous intermediate pore size zeolites from a forming mixture containing sources of silica, alkali metal cations, organic nitrogen cations and water is provided by using amorphous precipitated silica as the silica source and alkyl amine or diamine as the source of organic nitrogen cations. The use of precipitated silica permits the formulation of a forming mixture having a solids content of greater than about 10 weight percent which results in improved zeolite product synthesis as well as greater control of zeolite product crystal size when amine or diamine directing agents are also present in the zeolite forming mixture.

Der Einfluß von pH, Elektrolytkonzentration und Mischverfahren auf die Flockung von gefällten und pyrogenen Silikahydrosolen durch Polyethylenglykol

Abstract: With a laser photosedimentometer one obtaines parameters which enable characterization of the turbidity and of the sedimentation in the Silica suspension flocculated by the adsorption of Polyethyleneglycols. By continuous addition of the polymer solution to the silica suspension the influences of the time of addition, stirring time, stirring intensity, polymer coverage, concentration of silica, pH and ionic strength on the flocculation state can be quantified. In contrast to pyrogenic silica precipitated silica is only flocculable by decreasing the pH below pH 3.5 or by addition of salt above 10−2 mol/l. The flocculation of pyrogenic silica is markedly dependent on the mixing conditions at high pH and without salt. At high salt concentrations and pH <3.5 the flocculation of precipitated and pyrogenic silicas becomes independent of mixing conditions.

Process for producing precipitated silica

Abstract: 1. Process for the manufacture of precipitated silica that has a low electrolyte content and has been rendered hydrophobic, by precipitating an aqueous sodium silicate solution with sulphuric acid using a dimethylpolysiloxane as the agent imparting the hydrophobic property, characterised in that a) an aqueous emulsion of a dimethylpolysiloxane having a siloxane content of, advantageously, from 1.5 to 3% by weight, calculated on the total weight of the emulsion, is prepared, b) a 10 to 30% by weight aqueous sodium silicate solution and from 1N to 2N sulphuric acid are incorporated simultaneously into the emulsion according to a) in such a manner that the pH of the reaction mixture is in the range of from 6.5 to 8.5 and the temperature of the reaction mixture is from 60 to 80 degrees C and c) the pre-dried precipitated silica is heated to a temperature of from 250 to 300 degrees C.

Refractory lining and process for its manufacture

Abstract: Refractory lining for eg casting boxes comprising a refractory matrix and precipitated silica, the silica being pre­ cipitated in situ to form a structure, imparting to the material a volume weight of from about 08 to about 12 g/cm³, the material being substantially free from carbon, hydrogen and available oxygen; process for the manufacture of such re­ fractory lining