Magnetic storage medium

US4677030A · kind A · utility

Assignee

• Agfa-Gevaert NV · BE

Inventors

• Johannes Gerum · Germering, DE
• Burkhard Nippe · Munich, DE
• Walter Meckel · Neuss, DE

Key dates

• Filing date: Jan 9, 1985
• Grant date: Jun 30, 1987
• Expiry date: Jan 9, 2005

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/31609
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

What is claimed is a magnetic storage medium in which the polyurethane binder system forms a three-dimensional network independently of reactive low molecular weight substances present on the magnetic pigment or in the dispersion and the production of such a storage medium. The binder in the colored magnetic layer consists of a reaction product of polyisocyanates having an average functionality of from 2.1 to 4 (A) with predominantly difunctional aromatic amino-terminated polyurethanes having an average molecular weight of at least 10,000 (B) and optionally one or more hydroxyl group-containing polyesters having an OH number of from 100 to 450 (C), and/or predominantly difunctional aromatic polyamines having a molecular weight of from 100 to 400 (D) the ratio of isocyanate groups present in (A) to the isocyanate reactive groups present in (B), (C) and (D) being from 0.3:1 to 20:1, preferably from 0.8:1 to 20:1. With this binder system, it has been possible to achieve direct linkage of the polymeric binder chains and to suppress side reactions. This has enabled a soft polyurethane agent to be used, with the result of smooth dispersion of the magnetic lacquer and hence increase in th…