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Magnetic Ink of Low Viscosity for Electrostatic Printing

IP.com Disclosure Number: IPCOM000082233D
Original Publication Date: 1974-Oct-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 30K

Publishing Venue

IBM

Related People

Kovac, Z: AUTHOR [+2]

Abstract

For magnetic ink used in magnetic ink jet (MIJ) printing, it is desirable to look for as high a magnetic moment as possible compatible with ink viscosity and good ink stability. Thus, a magnetic moment of 25 emu/gr seems a minimum desirable value in MIJ printing, to achieve excellent drop deflection at relative low current in the deflection devices. This 25 emu/gr of ink corresponds to a Fe(3)O(4) concentration of 35% Fe(3)O(4), for a basic value of 70 emu/gr of the solid Fe(3)O(4) derived from the following relation: (emu/gr of Fe(3)0(4)) (% Fe(3)0(4)) = (emu/g ink) 100 [1] 70 emu/g x Chi = 25 emu/g . 100 Chi = 35.5 gr Fe(3)O(4) % gr ink.

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Magnetic Ink of Low Viscosity for Electrostatic Printing

For magnetic ink used in magnetic ink jet (MIJ) printing, it is desirable to look for as high a magnetic moment as possible compatible with ink viscosity and good ink stability. Thus, a magnetic moment of 25 emu/gr seems a minimum desirable value in MIJ printing, to achieve excellent drop deflection at relative low current in the deflection devices. This 25 emu/gr of ink corresponds to a Fe(3)O(4) concentration of 35% Fe(3)O(4), for a basic value of 70 emu/gr of the solid Fe(3)O(4) derived from the following relation: (emu/gr of Fe(3)0(4)) (% Fe(3)0(4)) = (emu/g ink) 100 [1] 70 emu/g x Chi = 25 emu/g . 100 Chi = 35.5 gr Fe(3)O(4) % gr ink.

Such a high concentration of Fe(3)O(4) in the colloidal system requires also a relatively large concentration of surfactant (TRITON* + ARQUAD**), to maintain good colloidal dispersion and ink stability. Therefore, the viscosity of the ink for a 25 emu/g fluid also becomes relatively high, around 15 centipoises (pure water = 1 centipoise).

For many electrostatic printing applications, specific conditions are required to achieve good printing speed and print quality; for example, 100 kilocycles using 1 mil nozzle diameter. For these parameters, good ink stream stability appears to require a fluid with a viscosity around 2 centipoises or less.

As stated above, the magnetic ink used in MIJ (a suspension of oleic acid coated Fe(3)O(4) dispersed in TRITON + ARQUAD surfactant and added with 8% glycerol + 5% ethylene glycol ether) has typically a magnetic moment of 25 emu/g corresponding to about 35% gr of Fe(3)O(4). This gives the ink extremely high-optical density. It has been demonstrated th...