Silica gel comprising guanidine carbonate

Abstract

A process of preparing a silica sol is described. The process involves reacting a fresh sol with guanidine carbonate. The reaction may be conducted in the presence of a base (e.g., sodium water glass), and at a pH of from 8 to 12. The process of the present invention may also include concentrating steps. The silica sol prepared by the method of the present invention has a BET surface area of greater than or equal to 100 m 2 /g, and contains from 0.05 to 15% by weight of gaunidinium ions, based on the total weight of the silica gel.

1 - 21 . (canceled) 
     
     
         22 . A silica sol having a BET surface area of from 100 to 1200 m 2 /g, wherein said silica sol comprises from 0.05 to 15% by weight of guanidinium ions and up to 15% by weight of SiO 2 , based on the total weight of the silica sol, wherein said silica sol is free of amine. 
     
     
         23 . The silica sol of  claim 22 , wherein said silica sol has a BET surface area of from 300 to 1200 m 2 /g. 
     
     
         24 . The silica sol of  claim 22 , wherein said silica sol has a pH of from 2 to 12. 
     
     
         25 . The silica sol of  claim 22 , wherein said silica sol is not stabilized with aluminum. 
     
     
         26 . The silica sol of  claim 22 , wherein said silica sol has a molar SiO 2 /N ratio of from 2 to 20. 
     
     
         27 . The silica sol of  claim 22 , wherein said silica sol has a zeta potential of from −20 to −80 mV. 
     
     
         28 . The silica sol of  claim 22 , wherein said silica sol has an Si—O stretching vibration IR band position at a wave number of from 1113 cm −1  to 1080 cm −1 . 
     
     
         29 . A paper retention aid comprising the silica sol of claim  34 .