Abstract: Coated polymeric sheet comprising polymer substrate a cross-linked polymer, wherein the coating is characterized by:A. being smooth, having a surface roughness not greater than 0.05 nanometers R.sub.a, except that;B. in the otherwise smooth surface, a multiplicity of depressions having depth ranging from 1 to 90% of the thickness of the coating.Backside coatings (containing carbon black in the cross-linked polymer) for magnetic recording tapes benefit from this invention by improved winding characteristics. The concept described is a replacement for rough random surface texture, formerly used in backside coatings, with a controlled surface texture. The process disclosed can also be used to make alphanumeric symbols on the pigment binder coating.

Abstract: 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.

Abstract: Coated polymeric sheet comprising polymer substrate a cross-linked polymer, wherein the coating is characterized by:A. As being smooth, having a surface roughness not greater than 0.05 nanometers R.sub.a, except that;B. in the otherwise smooth surface, a multiplicity of depressions having depth ranging from 1 to 90% of the thickness of the coating.Backside coatings (containing carbon black in the cross-linked polymer) for magnetic recording tapes benefit from this invention by improved winding characteristics. The concept described is a replacement for rough random surface texture, formerly used in backside coatings, with a controlled surface texture. The process disclosed can also be used to make alphanumeric symbols on the pigment binder coating.

Abstract: A wet gravure coating of fine magnetizable particles can be smoothed by a rectangular piece of flexible film that is secured at one end in flat jaws of a clamp to leave its opposite end free to drag against the coating, thus causing the flexible film to form an arc between its secured end and the convergence of the flexible film with the wet coating. The jaws also secure a flat plate which has a straight edge that deflects the arcuate portion of the flexible film toward the coating along a line extending transversely across the full width of the flexible film. The plate can be repositioned during the smoothing to adjust the radius of curvature of the arc in order to correct any defects that may appear in the smoothed coating. When the backing web is wide and is advanced at economically high speeds, the free end of the flexible film can be tensioned so that its trailing edge becomes bowed and in contact with the coating over its full width.