Precipitated silica

US5851502A · kind A · utility

Assignee

• Degussa AG · DE

Inventors

• Gunter Turk · Hanau, DE
• Gerold Schmidt · Hamburg, DE
• Mustafa Siray · Hanau, DE
• Karl Meier · Bornheim, DE

Key dates

• Filing date: Jul 1, 1996
• Grant date: Dec 22, 1998
• Expiry date: Jul 1, 2016

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02E60/10
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

Precipitated silica with the following physical-chemical characteristics: ______________________________________ BET surface: DIN 66131 100-130 m.sup.2 /g DBP absorption DIN 53601 .gtoreq.275 g/100 g (anhydrous) ASTM D 2414 Loss on drying DIN ISO 787/II (2 h/105.degree. C.) ASTM D 280 3.5-5.5 wt. % JIS K 5101/21 Oversize with ALPINE air-jet sieve: >63 .mu.m .ltoreq.10.0 wt. % >150 .mu.m .ltoreq.0.1 wt. % >250 .mu.m .ltoreq.0.01 wt. % Chloride content: .ltoreq.100 ppm ______________________________________ is prepared by introducing water into a precipitation vessel, adding water glass until an alkali value of 5-15 is reached, then adding further water glass and sulfuric acid simultaneously, interrupting the precipitated silica suspension with sulfuric acid to a pH-value of 8.5, with stirring, then continuing acidification with concentrated sulfuric acid to a pH-value of 4, then separating and washing the precipitated silica which has a solids content in the suspension of approx. 88 g/l, liquefying the filter cake obtained, drying it with a spray drier and grinding it. The precipitated silica may be used for the production of battery separators.