MY162338A - Silica-based sols and their production and use - Google Patents

Abstract

THE PRESENT INVENTION RELATES TO A PROCESS FOR PRODUCING AN AQUEOUS SILICA-BASED SOL WHICH COMPRISES: (A) PROVIDING A CATIONIC ION EXCHANGE RESIN HAVING AT LEAST PART OF ITS ION EXCHANGE CAPACITY IN HYDROGEN FORM; (B) BRINGING SAID ION EXCHANGE RESIN IN CONTACT WITH AN AQUEOUS ALKALI METAL SILICATE TO FORM AN AQUEOUS SLURRY; (C) STIRRING SAID AQUEOUS SLURRY UNTIL THE PH OF THE AQUEOUS PHASE IS IN THE RANGE OF FROM 5.0 TO 11.5; AND/OR ALTERNATIVELY. STIRRING SAID AQUEOUS SLURRY TO ALLOW PARTICLE AGGREGATION OR MICROGEL FORMATION CORRESPONDING TO AN S VALUE UP TO 45%, AND PH OF THE AQUEOUS PHASE OF AT LEAST 5.0; (D) ADJUSTING THE PH OF SAID AQUEOUS PHASE TO ABOVE 9.0 USING ONE OR MORE MATERIALS COMPRISING AT LEAST ONE ALUMINIUM COMPOUND; AND (E) SEPARATING SAID ION EXCHANGE RESIN FROM THE AQUEOUS PHASE AFTER STEP (C) OR AFTER STEP (D), AND, OPTIONALLY (F) PROVIDING AN AQUEOUS SILICA-BASED SOL HAVING AN S VALUE BETWEEN 10 AND 50%. THE INVENTION ALSO RELATES TO A SILICA-BASED SOL HAVING AN S VALUE WITHIN THE RANGE OF FROM 15 TO 25%, MOLE RATIO SI:AL IN THE RANGE OF FROM 20:1 TO 50:1, MOLE RATIO SI:X, WHERE X = ALKALI METAL, IN THE RANGE OF FROM 5:1 TO 17:1, SIO? CONTENT OF AT LEAST 5% BY WEIGHT AND CONTAINING SILICA-BASED PARTICLES HAVING A SPECIFIC SURFACE AREA OF AT LEAST 300 M?/G. THE INVENTION FURTHER RELATES TO PROCESS FOR PRODUCING PAPER WHICH COMPRISES (i) PROVIDING AN AQUEOUS SUSPENSION COMPRISING CELLULOSIC FIBRES; (j) ADDING TO THE SUSPENSION ONE OR MORE DRAINAGE AND RETENTION AIDS COMPRISING A SILICA-BASED SOL ACCORDING TO THE INVENTION; AND (K) DEWATERING THE OBTAINED SUSPENSION TO PROVIDE A SHEET OR WEB OF PAPER.