Opaque ink composition containing hollow microspheres for use in ink jet printing

Claim 1

A nonpigmented ink suitable for use in ink jet printing comprising: (a) from about 2 to about 20 percent by weight of a resin component; (b) from about 5 to about 25 percent by weight of hollow microspheres; and (c) the remainder being a suitable carrier vehicle comprised of water, ammonium hydroxide, and a volatile solvent; all percentages being based upon the total weight of the ink; the hollow microspheres having permeable walls comprised of a synthetic polymeric material, a central void region filled with water, capable of diffusing through the walls of said microspheres, an inside diameter from about 0.1 to about 0.5 micron and an outside diameter from about 0.4 to about 1 micron; the resin component, the hollow microspheres and the carrier vehicle being chemically nonreactive with each other; and the specific gravity of the ink being about equal to or greater than the specific gravity of the microspheres wherein, the ink has a viscosity at 25 degrees C. from about 3 to about 10 centipoises, an electrical resistivity from about 100 to about 3500 ohm-cm, and a sonic velocity from about 1300 to about 1700 meters/second.