Method of selectively producing high pore volume silica gel
Patent 3959174 Issued on May 25, 1976. Estimated Expiration Date: 
May 25, 1993. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
May 25, 1993. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 2477695 2625492 3243262 3301701 InventorsAssigneeApplicationNo. 322570 filed on 01/10/1973US Classes:423/338By gellingExaminersPrimary: Lovering, Richard D.Attorney, Agent or FirmAbstractHigh pore volume silica materials are useful as thickening, reinforcing and flatting agents. This invention comprises selectively forming silica gels having pore volumes in the range of 1.2 to 3.0 cc/g. These high pore volume silica gels can be produced by the alkaline gelation of a mixture of silicate and ammonium hydroxide at a pH of from 10.6 to 11.2, using a water soluble silica desolubilizing agent selected from the group consisting of ammonia, monohydric alcohols, glycols, ketones and salts. The silica is then aged, neutralized, optionally aged a second time, filtered and washed. This silica may then be dried and directly used, or it may be milled to a smaller size. For use as a thickening agent, the silica is milled in a fluid energy mill to an average particle size of less than about 1 micron, and preferably to less than 0.5 micron. |
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