Precipitated silica

US5871867A · kind A · utility

Assignee

• Degussa AG · DE

Inventors

• Ralf Rausch · Alzenau, DE
• Heinz Esch · Wesseling, DE
• Robert Kuhlmann · Lechenich, DE
• Guenter Tuerk · Hanau, DE
• Karl Meier · Bornheim, DE
• Walter Meon · Gelnhausen, DE

Key dates

• Filing date: Oct 21, 1997
• Grant date: Feb 16, 1999
• Expiry date: Oct 21, 2017

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 a sodium sulphate content of 4 to 18 wt. %, particularly with the physical-chemical data: ______________________________________ Sodium sulphate content: 4-14 wt. % BET surface area (DIN 66131): 100-190 m.sup.2 /g DBP absorption (anhydrous) 208-250 g/100 g (DIN 53601, ASTM D 2414): 3.0-6.5 wt. % (DIN ISO 787/II) Oversize with >63 .mu.m .ltoreq. 10.0 wt. % ALPINE air-jet sieve >150 .mu.m .ltoreq. 0.1 wt. % >250 .mu.m .ltoreq. 0.01 wt. % ______________________________________ It is prepared by introducing hot water into a precipitation vessel, with stirring, adding water glass, then heating the mixture and maintaining the temperature throughout the remainder of the precipitation period. Water glass and sulphuric acid are added simultaneously during this process. The precipitated silica is then separated from the suspension and the filter cake containing sodium sulphate is dried in a spray drier and ground. The precipitated silica may be used in the production of battery separators.