Abstract New alumina coated silica sols are produced by a method which comprises mixing a concentrated deionized silica sol with concentrated solutions of trivalent acid aluminum salts, heating this premix to at least 90 DEG C. for 1-15 minutes to form an alumina reacted silica sol solution, cooling this reacted silica sol solution to form a cooled alumina reacted silica sol solution, diluting with deionized water to about 10 weight percent solids, exposing this diluted alumina reacted silica sol to ultrafiltration through a membrane having a molecular weight cutoff of about 30,000, adding distilled or deionized water to the diluted alumina reacted silica sol during ultrafiltration to wash dissolved salts from this salt solution forming a diluted alumina-coated silica sol having a pH between about 4-5 and a conductivity between about 2,000-4,000 micromhos, concentrating this dilute alumina-coated silica sol to at least 30 weight percent solids, thereby obtaining a stable alumina-coated silica sol.
A method of producing alumina coated silica sols which comprises: A. Mixing a concentrated deionized silica sol with a concentrated solution of trivalent acidic aluminum salts to obtain a premix, B. Heating this premix to at least 90° C. for from 1 to 15 minutes to form an alumina reacted silica sol solution, C. Cooling this alumina reacted silica sol solution to at least 180° F. to form a cooled alumina reacted silica sol solution, D. Diluting this cooled alumina reacted silica sol solution with deionized water to about 10 weight percent solids to form a diluted alumina reacted silica sol, E. Exposing the diluted alumina reacted silica sol to ultrafiltration through a membrane having a molecular weight cutoff of about 30,000, and F. Adding distilled or deionized water to the diluted alumina reacted silica sol during step E to wash dissolved salts from said diluted alumina reacted silica sol to form a dilute alumina coated silica sol having a pH from about 4-5 and a conductivity of from 2000-4000 micromhos, and G. Concentrating this dilute alumina coated silica sol to at least 30 weight percent solids, thereby obtaining said alumina coated silica sols.
Claim 2
Independent Claim
194 words
A method of producing alumina coated silica sols which comprises: A. Mixing a concentrated deionized silica sol with a concentrated solution of trivalent acidic aluminum salts to obtain a premix, B. Heating this premix to at least 90° C. for from 1 to 15 minutes to form an alumina reacted silica sol solution, C. Cooling this alumina reacted silica sol solution to at least 180° F. to form a cooled alumina reacted silica sol solution, D. Diluting this cooled alumina reacted silica sol solution with deionized water to about 10 weight percent solids to form a diluted alumina reacted silica sol, E. Exposing the diluted alumina reacted silica sol to ultrafiltration through a membrane having a molecular weight cutoff of about 30,000, and F. Adding distilled or deionized water to the diluted alumina reacted silica sol during step E to wash dissolved salts from said diluted alumina reacted silica sol to form a dilute alumina coated silica sol having a pH from about 4-5 and a conductivity of from 2000-4000 micromhos, and G. Concentrating this dilute alumina coated silica sol to at least 30 weight percent solids, thereby obtaining said alumina coated silica sols.
Claim 3
Dependent Claim
42 words
The method of claim 1 wherein the concentrated deionized silica sol contains 25.5 weight percent silica, has a pH of 3.0±0.3 units, has a particle size between 15 and 25 millimicrons, and a surface area of about 150 m 2 per gram.
Claim 4
Dependent Claim
22 words
The method of claim 2 wherein the concentrated solution of trivalent acidic aluminum salts contains about 25 weight percent aluminum hydroxy dichloride.
Claim 5
Dependent Claim
12 words
The alumina coated silica sol synthesized by the method of claim 1.
Claim 6
Dependent Claim
14 words
The alumina coated silica sol synthesized by the method of claims 2 or 3.