Fuji Electric Co., Ltd.

Fuji Electric Device Technology Co., Ltd.

Shinji Shirai

Youichi Tei

Yoshihito Osawa

Yoshimasa Hattori

Masayuki Ishikawa

Teruhisa Yokosawa

Katsuya Masuda

Masayuki Ishkawa

Mihoyo Iwase

Yoichi Tei

Takahiro Tokumoto

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.

Method of refining a lubricant for use on a magnetic recording medium

A lubricant for a magnetic recording medium that imparts resistance to degradation, improved lubrication quality and better CSS durability to the medium, even when using a low levitating head. The lubricant is a perfluoropolyether compound having a cyclic triphosphazene end group within the molecule. A magnetic recording medium using at least one perfluoropolyether compound having a cyclic triphosphazene end group within the molecule as a lubricant. A method of making a magnetic recording medium which resists degradation when using a low levitation head including the sequential steps of: forming a foundation layer on a non-magnetic base, forming a magnetic layer on the foundation layer, forming a protection layer on the magnetic layer, and forming a lubrication layer on the protection layer. The lubrication layer includes at least one perfluoropolyether lubricant having a cyclic triphosphazene end group within the molecule.

Magnetic recording medium and method for manufacturing the same

To avoid troubles associated with high-density recording and fast transfer rate, such as decomposition of lubricant involved in a low floating height magnetic head and migration of lubricants involved in high speed rotation of a magnetic recording medium, and to provide a magnetic recording medium which achieves stable resistance to environment and stable lubricating characteristics, a magnetic recording medium includes a base body and the layers formed on the base body, including a non-magnetic metal underlayer, a magnetic layer, a protective layer, and a lubricant layer. The lubricant of the lubricant layer includes a perfluoropolyether liquid lubricant having an alcohol end group(s) and a perfluoropolyether liquid lubricant having an amine end group(s) of tertiary amine structure.

Magnetic recording medium and method for manufacturing same

A perfluoropolyether liquid lubricant is provided which has an amine functional group at at least one of ends of a chain molecule. A magnetic recording medium using the lubricant assures increased bonding force between a carbon protective layer and a lubricant layer.

Liquid lubricant, magnetic recording medium using the same, and method

A magnetic recording medium having a carbon protective layer for protecting a magnetic layer formed on a non-magnetic base includes a liquid lubrication layer formed by coating on the carbon protective layer. The liquid lubrication layer includes a hydrocarbon containing lubricant and a perfluoropolyether containing lubricant.

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Nagano, Japan

Shinji Shirai