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US 5,851,416 AGranted
Stable polysiloxane ferrofluid compositions and method of making same
AssigneeFerrofluidics Corporation
InventorsKuldip Raj, Ronald E. Rosensweig, Lutful M. Aziz
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Abstract
A ferrofluid composition comprising a colloidal dispersion of finely divided magnetic particles in a silicone oil carrier in which the surfaces of the magnetic particles are modified with (a) a first surfactant comprising a hydrocarbon having at least one polar group and (b) a second surfactant comprising a silicone oil surfactant having at least one polar group and which is soluble in the silicone oil carrier.
Claims7
A method for preparing a ferrofluid composition comprising the steps of:
- (a) mixing magnetic particles with a hydrocarbon carrier containing a first surfactant that includes a hydrocarbon with at least one polar group;
- (b) heating the resulting mixture of step (a) to a temperature that is sufficient to promote sorption of the surfactant on the particles;
- (c) adding a silicone carrier containing a second surfactant to the mixture of step (b), the a second surfactant including a silicone oil surfactant, soluble in the silicone oil carrier that has at least one polar group with an active hydrogen;
- (d) heating the mixture of step (c) to a temperature that is sufficient to allow the silicone surfactant to sorb on the particles;
- (e) evaporating the hydrocarbon carrier.
2 more elements
Dependencies are inferred from the claim text.