Minnesota Mining and Manufacturing Company

Kevin K Kuck

James G Carlson

Robert P McCollam

John D Munter

Donald M Lewis

Joseph H Lam

Alvin M Berg

Daniel Y Chang

Norman E Gehrke

Michael J Brost

Thomas M Bohlsen

Benedict L Bezenek

Stephen A Johnson

John C Harvey

Disclosed is a video tape suitable for use in high speed contact duplication. The magnetic layer comprises a magnetic pigment dispersed in a polymeric binder at amounts of magnetic pigment between 75 and 88 percent by weight of the magnetic layer with a total pigment loading (magnetic+nonmagnetic pigments) of at least 80 percent by weight. The tape is provided with a backside coating comprising at least two nonmagnetic pigments dispersed in a polymeric binder, the first nonmagnetic pigment, being a conductive material and having a relatively small particle size of between about 0.015 and 0.15 .mu.m, and the second nonmagnetic pigment having a relatively large particle size of between about 0.15 and 1.5 .mu.m. The magnetic layer has a lubricant absorption value of at least 4 and a surface roughness of between 5 and 15 nm. The backside coating has a surface roughness of between 10 and 150 nm. The polymeric binder of either or both of the magnetic layer and the backside coating may preferably comprise a hard component resin and a soft component resin, wherein the soft component resin is a polyurethane having a plurality of pendant carboxy groups.

Video recording tapes suitable for high speed contact duplication

A magnetizable layer can be applied to a flexible backing web by gravure coating at high speeds by independently driving the backing web at a speed that is substantially different from the surface speed of the gravure roll. Especially high coating speeds have been achieved when the gravure roll rotates oppositely to the direction in which the backing web is advancing. In one embodiment, a nip roll presses the backing web against the backup roll, there is a gap between the gravure roll and a backup roll, and an idler roll is positioned downstream of the gap to force the backing web into contact with the gravure roll over a short arc. When that backup roll has a hard surface such as metal, its surface can be machined with precision, and that precision can be maintained in spite of exposure to solvent vapors.

Differential-speed gravure coating of magnetizable layers in the

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Lino Lakes, MN, United States of America

Kevin K Kuck