Patent ID: 6184408
Filing Date: 2001-02-06
Classification: C01B,C01P,C09C

Abstract:
A method for the preparation of hydrophobic precipitated silica comprising contacting an aqueous suspension of a hydrophilic precipitated silica with (1) a catalytic amount of an acid and (2) an organosilicon compound selected from the group consisting of organosilanes described by formulaR.sup.1.sub.a H.sub.b SiX4-a-b,organosiloxanes described by formulaR.sup.2.sub.n SiO.sub.(4-n)/2,and organodisilazanes described by formula(R.sup.3.sub.3 Si).sub.2 NH,in the presence of (3) a water-miscible organic solvent in an amount sufficient to facilitate reaction of the hydrophilic precipitated silica with the organosilicon compound to form a hydrophobic precipitated silica; where each R.sup.1 is an independently selected hydrocarbon radical comprising 1 to about 12 carbon atoms, each R.sup.2 is independently selected from the group consisting of hydrogen, chlorine, hydroxy, and hydrocarbon radicals comprising 1 to about 12 carbon atoms with the proviso that at least 50 mole percent of the R.sup.2 substituents are hydrocarbon radicals, each R.sup.3 is an independently selected hydrocarbon radical comprising 1 to about 12 carbon atoms, each X is an independently selected hydrolyzable group bonded to silicon, a=1, 2, or 3; b=0 or 1; a+b=1, 2, or 3 with the proviso that when b=1 then a+b=2 or 3; and n is an integer from 2 to 3 inclusive.