Browse Prior Art Database

Modification of Magnetic Ink Process

IP.com Disclosure Number: IPCOM000084147D
Original Publication Date: 1975-Sep-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Kovac, Z: AUTHOR

Abstract

Dialkyl dimethyl ammonium chloride (ARQUAD* 2HT-75) produces bilayer micelles which can grow to large size. Presence of these micelles is assumed to affect ink filterability and stream stability.

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Modification of Magnetic Ink Process

Dialkyl dimethyl ammonium chloride (ARQUAD* 2HT-75) produces bilayer micelles which can grow to large size. Presence of these micelles is assumed to affect ink filterability and stream stability.

Magnetite for one magnetic ink, as precipitated, has a range of particle size between 50-300 Angstroms in diameter and there are variations in distribution of sizes. Due to this variation, the final surface area of Fe(3)O(4) available for adsorption varies. In making magnetic inks the same amount of surfactants is used for a given weight of Fe(3)O(4), independent of actual surface area formed in each batch. These variations are reflected in batch-to-batch variation in viscosity of ink and formation of micelles in ink.

Micelles are formed when nonadsorbed surfactants are free in ink. Nonionic surfactant (TRITON** N101) used in ink, forms spherical micelles which are smaller than Fe 0 particles. However, ARQUAD 2HT-75 forms large bilayer micelles which are not restricted in size.

For this reason it is important to eliminate free ARQUAD in the ink.

A process to eliminate or at least reduce the number of micelles is as follows:

After Fe(3)O(4) has been formed, coated with oleate, heated, and rinsed from NH(4)Cl, ARQUAD 2HT-75 is added to the slurry. The slurry is then heated to boiling. After cooling, this slurry is centrifuged to separate Fe(3)O(4) from excess water and ARQUAD 2HT-75. In this way unadsorbed ARQUAD remains in the rinse wa...