Pressurized roller pens and inks for such pens
AssigneePaul C. Fisher
InventorsRaymond S. Williams, Paul C. Fisher
Life of this patent
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Abstract
A pressurized roller pen includes a thixotropic viscoelastic ink that is a gel at rest, but becomes a thin liquid under the shearing action of the pen's revolving ball-point. This ink includes a polyacrylic resin polymer, at least one highly polar solvent, at least one solvent of low or medium polarity, and colloidal silica, together with pigments, dyes, surfactants and/or pH modifiers.
Claims10
A ball-point marking instrument including a sealed marking fluid reservoir having a socket located at one end thereof;
- a ball rotatably mounted within said socket so as to extend into the interior of and to the exterior of said reservoir;
- a marking fluid within said fluid reservoir in contact with said ball;
- a charge of pressurized gas within said reservoir at the extremity remote from the socket, said pressurized gas serving to force said marking fluid against said ball, said marking fluid comprising from about 1% to about 6% by weight of a polyacrylic resin polymer, at least about 5% by weight of at least one solvent of high polarity, at least one solvent of low or medium polarity, about 1% to about 10% colloidal silica, and at least one coloring agent, said marking fluid having a thixotropic ratio in the range of about 25:1 to about 150:1 measured on a Brookfield HBT viscometer at 25.degree. C., using either a No. 6 or No. 7 spindle, and a viscosity less than about 40,000 cps measured with a Brookfield HBT viscometer using a No. 6 spindle at 25.degree. C. at 100 rpm.
An ink composition comprising a polyacrylic resin polymer, glycerol, at least one solvent of low or medium polarity, colloidal silica, a non-ionic or anionic surfactant, and at least one coloring agent, said marking fluid having a thixotropic ratio in the range of about 25:1 to about 150:1 measured on a Brookfield HBT viscometer at 25.degree. C., using either a No. 6 or No. 7 spindle, and a viscosity less than about 40,000 cps measured with a Brookfield HBT viscometer using a No. 6 spindle at 25.degree. C. at 100 rpm.
Dependencies are inferred from the claim text.