GB886144A - Improvements in and relating to methods of manufacturing magnetic tape - Google Patents

Abstract

886,144. Magnetic structures. INTERNATIONAL BUSINESS MACHINES CORPORATION. Aug. 11, 1960 [Aug. 26, 1959], No. 27812/60. Class 38 (2). A magnetic recording medium has its magnetic constituent held by a rubbery polymeric binder which is cured by sub-atomic radiation providing an absorption of 0.5 to 2.0 megarads in the medium. The medium may be a tape having a polyethylene terephthalate backing bearing fine acicular ferric oxide particles embedded in a binder including a butadiene-acrylonitrile copolymer and a phenolic resin. Tape 12 irradiated on a reel 11 may be held edgewise to the radiation source, the reel 11 being moved during exposure by wobble cam 17 to avoid " shadows." In a continuous process a wide band of base material is coated with a magnetic particle-binder mix by a fountain roller, the coating is smoothed by a blade, and the particles are aligned by a magnet. The band 19 is then dried and split by knife edges at roller 21 into tapes 22a-22e taken up by reels 26a-26e independently driven on spindle 27 and so arranged that the tapes cross under roller 25 where they receive curing radiation in passing source 24. Suitable radiation sources are X-ray generators, electron accelerators or radioactive elements such as radium and <SP>60</SP>Co. Curing is carried to a stage which gives a compromise between wearability, grip of magnetic particles by the binder, flexibility of the tape and " stick " to recording heads.