Magnetic recording media

• US 3,995,089 A
• Filed: 04/02/1975
• Issued: 11/30/1976
• Est. Priority Date: 06/13/1972
• Status: Expired due to Term

• Current Assignee: Badische Anilin- & Soda-Fabrik AG
• Original Assignee: Badische Anilin- & Soda-Fabrik AG
• Inventors: Mayer, Dieter, Motz, Herbert, Hartmann, Hans-Joerg, Hartmann, Job Werner, Klein, Ursula, Felleisen, Peter
• Primary Examiner(s): Lesmes, George F.
• Assistant Examiner(s): Roche, R. J.
• Application Number:
  US05/564,473
• Time in Patent Office: 608 Days
• Field of Search: 360/131, 360/134, 428/900, 428/402, 428/143, 428/147, 252/62.54, 427/127, 427/128
• US Class Current: 428/336
• CPC Class Codes: G11B 5/62 Record carriers characterised by the selection of the material
• CPC Class Codes: G11B 5/708 characterised by addition of non-magnetic particles to the layer
• CPC Class Codes: Y10S 428/90 Magnetic feature
• CPC Class Codes: Y10T 428/24413 Metal or metal compound
• CPC Class Codes: Y10T 428/265 1 mil or less
• CPC Class Codes: Y10T 428/31609 Particulate metal or metal compound-containing

Abstract

A magnetic recording medium in the form of a card having a non-magnetic support with a magnetic coating on one side of the support and a backcoating on the opposite side of the support, which backcoating exhibits improved scratch resistance and adherence to the support and improved frictional characteristics and consists essentially of 20 to 50% by weight of a binder mixture containing 10 to 60% by weight of an elastomeric polyurethane and, incorporated in the binder mixture, a non-magnetic pulverulent mixture of 10 to 40% by weight of conductive carbon powder and 60 to 90% by weight of platelet-shaped and spherical particles.

Claims

1. A magnetic recording medium in card form comprising a flat non-magnetic support, a magnetic coating on one side of the support and a backcoating comprising polymeric binder, conductive particles and non-magnetic pigments on the opposite side of the support, wherein the said backcoating consists essentially of

i. 20 to 50% by weight of a binder containing 10 to 60% by weight of an elastomeric flexible polyurethane substantially free of isocyanate groups, and ii. a non-magnetic pulverulent mixture of 10 to 40 parts by weight of conductive carbon powder (a), 40 to 90 parts by weight of an intimate mixture (b) of 20 to 45% by weight of kaolinite powder having platelet-shaped particles and 55 to 80% by weight of quartz powder having spherical particles, and optionally 5 to 40 parts by weight of corundum powder (c) having spherical particles the coefficient of friction (C_m) between the back surface of a card and the magnetized surface of an adjacent card being less than 0.50.

2. A magnetic recording medium as set forth in claim 1 wherein the non-magnetic pulverulent mixture consists of 10 to 25 parts by weight of carbon black powder (a) and 75 to 90 parts by weight of mixture (b).

3. A magnetic recording medium as set forth in claim 1 wherein the non-magnetic pulverulent mixture consists of 10 to 40 parts by weight of conductive carbon powder (a), 40 to 85 parts by weight of mixture (b) and 5 to 40 parts by weight of corundum powder (c) .

4. A magnetic recording media as set forth in claim 1 in which said backcoating has a thickness of from 7 to 13 μ

.

5. A magnetic recording media as set forth in claim 1 in which said backcoating has a thickness of from 9 to 11 μ

.