Showing papers on "Precipitated silica published in 1972"

Preparation of reinforcing amorphous silica

Abstract: An amorphous, pulverulent, dry silica is prepared which is particularly useful for reinforcing rubber. It is produced by: A. PREPARING SEED PARTICLES BY ADDING A MINERAL ACID TO A DILUTE ALKALI METAL SILICATE SOLUTION CONTAINING 1 TO 3% BY WEIGHT OF SiO2 to form a sol having a pH of about 4.5 - 6.5 and allowing the sol to set into a firm aquagel, B. DILUTING AND DISPERSING THE AQUAGEL IN WATER TO FORM AN AQUEOUS DISPERSION OF AQUAGEL SEED PARTICLES, C. MIXING WITH SAID DISPERSION AN ALKALI METAL SILICATE SOLUTION, D. ADDING ACID TO SAID SEED DISPERSION-ALKALI METAL SILICATE MIXTURE AT A TEMPERATURE OF ABOUT 75* - 100* C to quickly lower the pH to about 1 to 4 and precipitate silica, E. SEPARATING THE WET PRECIPITATED SILICA FROM THE ASSOCIATED LIQUID AND DRYING THE FRESHLY PRECIPITATED SILICA.

Quaternary ammonium silicate for polishing silicon metal

Abstract: I have developed an improved composition for use in the very exacting procedure of polishing soft thin wafers such as silicon which is to be used as a semi-conductor. This composition is a blend of quaternary ammonium silicate and a microfine precipitated silica whereby the proper pH for polishing with microfine silica is obtained and maintained without the necessity of continuous testing.

Improvements in or relating to the production of rubbers

Abstract: 1282285 Rubberized cloth VSESOJUZNY NAUCHNO-ISSLEDOVATELSKY INSTITUT SINTETICHESKOGO KAUCHUKA IMENI AKADEMIKA S V LEBEDEVA 17 July 1969 36045/69 Heading B5N [Also in Divisions C3 and D1] A rubberized cloth is obtained by laminating a rubber tape with a glass cloth impregnated with a solution of a similar rubber, the rubber composition comprising (a) a borosiloxane and/or a phosphoborosiloxane polymer having a B : Si ratio of 1 : 2-200 and a P : Si ratio, where P is present, of 1 : 10-300, (b) an uncured organopolysiloxane gum, (c) 10-30 pbw per 100 of the siloxane polymers of a compound of a transition metal (of groups Ib, IIb, IIIb, IVb, Vb, VIb, VIIb or VIII of the Periodic Table), and (d) a reinforcing or semi-reinforcing filler Preferred proportions are: (a) 2-50 pbw, (b) 50-98 pbw, (c) 10-30 pbw and (d) 30-35 pbw, (a) and (b) totalling 100 There may also be present 1-5 pbw of a low molecular weight polysiloxane, 1-10 pbw of a dialkyl sebacate, 0A1-1 pbw of a saturated fatty acid, and 0A5- 1 pbw of PTFE The rubber stock may be cured by irradiation or a peroxide, and is dissolved in an organic solvent used to impregnate glass cloth In examples a polydimethysiloxane gum containing some vinyl groups is mixed with a borosiloxane or phosphoborosiloxane, a reinforcing silica filler and ferric oxide or hydroxide or zirconium oxide, and optionally acetic acid (Example 3), PTFE (Example 4) or a liquid polysiloxane (Example 5); the mixture is formed into sheets or tapes In Examples 3-5 the tapes are pressed on to one or both sides of a glass cloth tape impregnated with a hydrocarbon solution of a similar composition containing also a precipitated silica, CaCO 3 and dioctyl sebacate The tapes are cured by gamma irradiation or by a peroxide incorporated into the rubber