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Method of Solvent Exchange for Dispersed Particles

IP.com Disclosure Number: IPCOM000050893D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Pickart, DE: AUTHOR

Abstract

Magnetic particles can be dispersed in water by known techniques. However, the binders used in disk and tape coatings are not normally water-soluble, so the water must be removed and replaced with an organic solvent without degrading the dispersion. Removal of the water by drying causes the particles to adhere together and makes them difficult to redisperse. Filtration or decantation is difficult due to the small particle size. This problem can be overcome by adding a higher boiling solvent followed by removal of the water using a distillation process. Reduced pressure can be used if the organic solvent is quite high boiling. If azeotropic mixtures are formed and the organic solvent is not soluble in water, the water layer can be decanted from the distillate and the organic layer returned to the distilling column.

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Method of Solvent Exchange for Dispersed Particles

Magnetic particles can be dispersed in water by known techniques. However, the binders used in disk and tape coatings are not normally water- soluble, so the water must be removed and replaced with an organic solvent without degrading the dispersion. Removal of the water by drying causes the particles to adhere together and makes them difficult to redisperse. Filtration or decantation is difficult due to the small particle size. This problem can be overcome by adding a higher boiling solvent followed by removal of the water using a distillation process. Reduced pressure can be used if the organic solvent is quite high boiling. If azeotropic mixtures are formed and the organic solvent is not soluble in water, the water layer can be decanted from the distillate and the organic layer returned to the distilling column.

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