Magnetic recording media containing elastomeric polyurethane binders in the magnetic coating

US4058646A · kind A · utility

Assignee

• BASF SE

Inventors

• Guenter Vaeth · Schifferstadt, DE
• Rudolf Bachmann
• Heinrich Hartmann · Schifferstadt, DE
• Hans-Joerg Hartmann
• Herbert Spoor · Schifferstadt, DE
• Karl Uhl
• August Lehner
• Winfried Gutermann
• Herbert Motz · Beindersheim, DE

Key dates

• Filing date: Sep 2, 1975
• Grant date: Nov 15, 1977
• Expiry date: Sep 2, 1995

Classification

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

Abstract

The invention relates to magnetic recording media comprising a non-magnetic base and, applied thereto, a firmly adhering magnetic coating based on a finely divided magnetic pigment dispersed in a binder which contains at least 50 percent by weight of a special polyurethane elastomer. This polyurethane elastomer is a thermoplastic polyurethane which is soluble in tetrahydrofuran and free from isocyanate groups, and which has been manufactured from (A) 1 mole of one or more hydroxyl-containing polyesters and/or hydroxyl-containing polyethers of molecular weight from 600 to 4,000, (B) from 3.5 to 15 moles of a branched-chain aliphatic diol of 4 to 10 carbon atoms or a mixture of aliphatic diols of 2 to 10 carbon atoms, of which at least 50 mole percent is a branched-chain aliphatic diol of 4 to 10 carbon atoms, (C) from 0 to 1 mole, but not more than 15 mole percent of the aliphatic diols according to B, of an aliphatic polyol with from 3 to 6 OH groups and 3 to 18 carbon atoms, and (D) from 4.5 to 18 moles of a diisocyanate of 6 to 30 carbon atoms, the amount of NCO groups being approximately equivalent to the amount of OH groups of the sum of the components A to C. Magnetic recordin…