PRODUCTION OF MAGNETIC RECORDING MEDIUM

PURPOSE: To obtain a process for producing a magnetic recording medium having an excellent squareness ratio, surface roughness, output, electromagnetic conversion characteristics, etc. CONSTITUTION: The apparatus for this process has an ultrasonic treating vessel 20 for ultrasonically treating a magnetic coating material 3 which is an object to be treated while passing this material therethrough, an ultrasonic horn 30 which is inserted into this ultrasonic treating vessel and has a working end face to apply ultrasonic vibration on the magnetic coating material and an ultrasonic vibrator transducer 40 which is connected to the base part side of the ultrasonic horn 30. The working depth H regulated by the distance from the working end face 31 of the ultrasonic horn to the wall surface of the ultrasonic treating vessel 20 facing the working end face is set at 2 to 40mm and the time for irradiation with ultrasonic waves is so set that the magnetic coating material subjected to the ultrasonic treatment under conditions of the range of the following equation (1) is applied on a base: H/6.6