Patents by Inventor George N. Robertson

George N. Robertson has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Process for preparing nanoscale quinacridone
    Patent number: 7211139
    Abstract: This invention relates to a method for production of nanoscale size quinacridones through a wet-salt attrition process by combining a crude quinacridone pigment in the presence of (i) an inorganic salt, (ii) an organic liquid in which the quinacridone pigment and salt are substantially insoluble, and (iii) a quinacridone derivative in an amount less than 10 wt. % relative to the quinacridone pigment; discharging the ground quinacridone pigment into water; adding an acid to produce a solution pH of 1.5 or lower; and isolating the quinacridone pigment.
    Type: Grant
    Filed: May 3, 2005
    Date of Patent: May 1, 2007
    Assignee: Sun Chemical Corporation
    Inventors: George N. Robertson, Edward H. Sung