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Fluid to Redisperse Residues of Magnetic Ink

IP.com Disclosure Number: IPCOM000083310D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Kovac, Z: AUTHOR [+2]

Abstract

In a magnetic ink which is a colloidal dispersion of oleic-coated magnetite in a suitable mixture of non-ionic and cationic surfactants, the ratio of: Fe(3)O(4)/surfactant is critical to maintain a stable colloid and avoid precipitation of Fe(3)0(4) from the system.

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Fluid to Redisperse Residues of Magnetic Ink

In a magnetic ink which is a colloidal dispersion of oleic-coated magnetite in a suitable mixture of non-ionic and cationic surfactants, the ratio of: Fe(3)O(4)/surfactant is critical to maintain a stable colloid and avoid precipitation of Fe(3)0(4) from the system.

There are two problems which result when a magnetic ink jet (MIJ) printer using such an ink is cleaned, namely: 1) Dilution of small amounts of ink with a cleaning fluid. 2) Repeptization of dried ink.

With reference to the first problem, when trying to remove used ink from a MIJ printer, if pure water is used agglomeration takes place and Fe(3)O settles out thereby plugging the filters. Also, it is customary to pinch-off the main stream and remove the ink in the nozzle during overnight shut-off of the printer. In this case, if water is used as a cleaning fluid, plugging of the nozzle by agglomerated Fe(3)O(4) usually occurs.

It has been ascertained that the source of the problem is the fact that pure water decreases the charge density around the Fe(3)O(4) particles, which maintain colloidal stability via electrostatic repulsion. Thus, upon addition of excess water to traces of magnetic ink, the particles of Fe(3)O(4) are deprived of the protective repulsion charges and they tend to agglomerate into large lumps settling out of the fluid.

Relative to the second problem, when the magnetic ink has solidified by drying on a surface, the resultant residue is mai...