Minnesota Mining and Manufacturing Company

Imation Corporation

John S Roden

Ronald S Sapieszko

David M Hopstock

Gunther H Dierssen

Joseph K Bailey

Ranjit Thakur

Surface treatment agents incorporating both acidic functionality and electron withdrawing functionality are extremely effective for promoting compatibility of magnetic pigments with binder systems incorporating quaternary ammonium functionality. Such surface treatment agents are particularly effective in combination with binder systems incorporating quaternary ammonium functional, nonhalogenated vinyl copolymers such as are described in U.S. Pat. No. 5,510,187.

Magnetic recording media incorporating a quaternary ammonium functional

The present invention provides a hexagonal magnetic ferrite pigment suitable for high density magnetic recording applications. The pigment is characterized by small particle size, a modified magnetoplumbite structure, and relatively high magnetic moment. The pigment is capable of being prepared by firing suitable precursor particles in air at temperatures below 850.degree. C.

Hexagonal magnetic ferrite pigment for high density magnetic recording

Process of making hexagonal magnetic ferrite pigment for high density

An aqueous ferrofluid comprises a plurality of colloidally-dispersed magnetite particles and a dispersing aid. The magnetite particles are coated with an anti-agglomeration agent which is a carboxy-functional polymer.

Aqueous ferrofluid

Environmentally stable magnetic recording composition comprising fine metal particles based on iron, cobalt, or nickel, the particles having a chromium-based outer layer formed by exposing the particles to a solution containing dichromate or chromate ions under high-shear mixing conditions.

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White Bear Lake, MN, United States of America

John S Roden