Browse Prior Art Database

Fast Drying and Permanent Adherence of Magnetic Ink on Paper

IP.com Disclosure Number: IPCOM000081550D
Original Publication Date: 1974-Jun-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 43K

Publishing Venue

IBM

Related People

Mitchell, JW: AUTHOR [+2]

Abstract

A special ink modification is designed to solve the so-called "smear" problem, encountered upon wet rubbing of magnetic ink droplets deposited on paper.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 54% of the total text.

Page 1 of 3

Fast Drying and Permanent Adherence of Magnetic Ink on Paper

A special ink modification is designed to solve the so-called "smear" problem, encountered upon wet rubbing of magnetic ink droplets deposited on paper.

As it is now known, the magnetic ink for magnetic ink jet (MIJ) is a fluid which is formed by a colloidal dispersion of metal-oxide particles. In order to give the system long-time stability (no settling or coagulation), such solid particles are dispersed in the fluid by coating them with a layer of "surfactant" which is usually a relatively large organic molecule. Because of the nature of this system, when droplets of ink are deposited on the paper surface, due to the large surfactant and pigment concentration, the droplets do not penetrate the paper fibers and stay preferably at the surface. This produces an undesirable long drying time and also a smearing of the printed dots upon wet rubbing. It has been found that the mechanism for drying of the ink drops is not by evaporation of the surfactant layer, but rather it depends almost exclusively on adsorption of the surfactant molecules by the paper fibers.

Due to the very slow adsorption of the ink the drying time is exceedingly large. For example, for a droplet of 10 mils diameter the drying time on regular bond paper may exceed several minutes.

Apart from the drying process, as the surfactant is originally water soluble, the dried spots are subject to resolubilizing and smearing upon wet rubbing. It is necessary to produce "fixing" or binding of the surfactant on the paper to avoid this effect.

These problems may be solved by a "modification" of or

"addition" to the ink composition that will achieve the following:.
1) The substance added to the magnetic ink will be

water-soluble

and compatible with the surfactant and the rest of the ink

components so that ink stability is not affected.
2) The substance added to the ink will be nonvolatile (or less

volatile than water) so as not to increase the evaporation rate

of the ink (prevent nozzle clogging).
3) The substance added should increase the rate of adsorption of

the ink on paper, when present in smell concentration (1 to

10%).
4) Finally, such substance will prevent smear by blocking the

resolubilizing of the surfactant after drying, thus creating a

permanent bond or fixing between ink and paper...