Fuji Electric Co., Ltd.

Fuji Electric Device Technology Co., Ltd.

Yoshihito Osawa

Shinji Shirai

Masayuki Ishikawa

Masayuki Ishkawa

A method of manufacturing a magnetic recording medium that includes a nonmagnetic underlayer, a magnetic layer, a protective layer, and a lubricant layer sequentially laminated on a nonmagnetic substrate. The method includes applying a lubricant onto the protective layer to form the lubricant layer, which includes ejecting shots of a heated lubricant liquid onto the protective layer from a nozzle. The heated lubricant liquid contains a perfluoropolyether lubricant, and each shot is of a quantity in a range of 0.1 to 10 pico liters.

Method of manufacturing a magnetic recording medium

A method refines a lubricant comprising a compound having a perfluoropolyether structure via supercritical extraction. A lubricant is refined using the method and a magnetic recording medium that utilizes the refined lubricant. The refined lubricant exhibits excellent lubrication performance and long term stability in the magnetic recording medium. In one embodiment of the supercritical extraction, the lubricant contacts an extracting medium of supercritical carbon dioxide under a predetermined condition in a pressure vessel to remove ionic impurities and perfluoropolyether compounds having a weak polarity terminal group contained in the lubricant.

Method to refine lubricant for a magnetic recording medium

A method to refine a lubricant on a magnetic recording medium includes a compound A including a perfluoropolyether molecular structure having two hydroxyl groups at each of two ends and a compound B including the perfluoropolyether molecular structure having one hydroxyl group at each of two ends. The method includes putting the lubricant into a pressure vessel set at a pressure and a temperature and removing the compound B dissolved in an extracting medium of a supercritical carbon dioxide fluid that flows at a predetermined rate through the pressure vessel held at a predetermined temperature and at a predetermined pressure. The method performs recovering the compound A dissolved in the extracting medium that flows through the pressure vessel held at the predetermined pressure and at a temperature lower than the predetermined temperature or at the predetermined temperature and at a pressure higher than the predetermined pressure.

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Nagano, Japan

Yoshihito Osawa