Magnetic recording medium with dual layer front coating and method of manufacture
AssigneesImation Corp., Quantegy, Inc.
InventorsDavid C. Lowery, Ryosuke Isobe
Life of this patent
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Abstract
A magnetic recording medium including a non-magnetic substrate, a back coat, a lower layer, and a magnetic upper layer. The substrate defines a front side and back side, with the back coat being formed on the back side. The lower layer is disposed over the front side of the substrate and includes a primary powder material and conductive carbon black material dispersed in a binder. The primary lower layer powder material comprises particles having a coercivity of less than 300 Oe coated with an electroconductive material. The magnetic upper layer is disposed over the lower layer and includes a magnetic powder dispersed in a binder.
Claims22
A magnetic recording medium comprising:
- a non-magnetic substrate defining a front side and a back side;
- a back coat formed on the back side;
- a lower layer disposed over the front side, the lower layer including a primary powder material and a conductive carbon black material dispersed in a binder system, wherein the primary powder material includes particles having a coercivity in the range of 0-300 Oe coated with an electroconductive material, and further wherein a relationship of an amount of the electroconductive coating material and an amount of conductive carbon black material is:
- 14−2x≦y≦30−x, and 8≦y, and 0.5≦x≦13, where
- x is a percent weight of the conductive carbon black and y is a percent weight of the electroconductive coating material;
- and
- a magnetic upper layer disposed over the lower layer, the upper layer including a magnetic metal particle powder dispersed in a binder.
A magnetic recording medium comprising:
- a non-magnetic substrate defining a front side and a back side;
- a back coat formed on the back side;
- a lower layer disposed over the front side, the lower layer including a primary powder material and a conductive carbon black material dispersed in a binder system, the conductive carbon black comprising 1 to 5 parts by weight based upon 100 parts by weight of the primary powder material, wherein the primary powder material includes particles having a coercivity of less than 300 Oe coated with an electroconductive material;
- and
- a magnetic upper layer disposed over the lower layer, the upper layer including a magnetic metal particle powder dispersed in a binder.
A process for producing a magnetic recording medium, the process comprising:
- applying a lower layer coating material onto a front face of an elongated non-magnetic substrate strip;
- applying a magnetic upper layer coating material onto the coated lower layer coating material;
- drying the lower layer and upper layer coating materials to form the medium that includes a lower support layer and an upper magnetic layer;
- winding the medium;
- storing the wound medium in an environment below ambient temperature;
- and
- calendering the wound medium.
Dependencies are inferred from the claim text.