Maxell Holdings, Ltd.

Maxell, Ltd.

Toshio Hiroi

Masao Fujita

Shinji Kawakami

Kenji Tanaka

To provide a transmission-type electromagnetic-wave absorber that can satisfactorily absorb electromagnetic waves of high frequencies in or above the millimeter wave band while reducing the reflection of electromagnetic waves on the surface of the absorber. The transmission-type electromagnetic-wave absorber includes an electromagnetic-wave absorbing layercontaining a magnetic iron oxidea that magnetically resonates at a frequency in or above the millimeter-wave band and a binderb containing an organic material. The real part of the complex relative permittivity of the electromagnetic-wave absorber is 5.5 or less at 1 GHz.

Electromagnetic wave absorber

Provided are an electromagnetic-wave absorbing composition that can favorably absorb electromagnetic waves of high frequencies in or above a millimeter-wave band and that can be applied to a desired portion in the form of a paste, and an easily deformable electromagnetic-wave absorber having flexibility. The electromagnetic-wave absorbing composition includes a rubber binder, a filler made of a particulate carbon material, and a magnetic iron oxide that magnetically resonates in a frequency band in or above a millimeter-wave band as an electromagnetic-wave absorbing material. The electromagnetic-wave absorber includes a rubber binder, a fillermade of a particulate carbon material, and a magnetic iron oxide that magnetically resonates in a frequency band in or above a millimeter-wave band as an electromagnetic-wave absorbing material, and is a nonresonant-type electromagnetic-wave absorber that is not provided with a reflective layer for reflecting incident electromagnetic waves.

Electromagnetic wave absorbing composition, and electromagnetic wave absorption body

Provided is an electromagnetic-wave absorber composition and an electromagnetic-wave absorber that can favorably absorb a plurality of electromagnetic waves of different frequencies in a high frequency band in or above the millimeter-wave band. The electromagnetic-wave absorber composition includes a magnetic iron oxide that magnetically resonates at a high frequency in or above the millimeter-wave band and a resin binder. The electromagnetic-wave absorber composition has two or more extrema separated from each other on a differential curve obtained by differentiating a magnetic property hysteresis loop at an applied magnetic field intensity of from 16 kOe to &#x2212;16 kOe. The electromagnetic-wave absorber includes an electromagnetic-wave absorbing layer formed of the above-described electromagnetic-wave absorber composition.

Electromagnetic wave absorbing composition and electromagnetic wave absorbing body

An electromagnetic wave absorbing sheet is provided that can adequately absorb electromagnetic waves at high frequencies in and above the millimeter wave band, can have excellent flexibility, and can easily be placed in any desired portion. The electromagnetic wave absorbing sheet includes an electromagnetic wave absorbing layercontaining a magnetic iron oxidethat magnetically resonates at frequencies in and above the millimeter wave band and a resin binder. The electromagnetic wave absorbing sheet absorbs radiated electromagnetic waves by magnetic resonance of the magnetic iron oxide. The electromagnetic wave absorbing sheet has a flexibility evaluation value F (g/mm) of more than 0 and 6 or less, which is determined by measuring an applied weight (g) that is required to bend a ribbon-like electromagnetic wave absorbing sheet in the elastic deformation region so that a distance d between the inner surfaces of the ribbon-like sheet at a position L spaced 10 mm from the bent portion of the ribbon-like sheet is 10 mm, and dividing the applied weight (g) by a cross-sectional area D (mm) of the ribbon-like sheet.

Electromagnetic-wave-absorbing sheet

The magnetic recording medium disclosed in the present application includes a non-magnetic support, an undercoat layer, a magnetic layer containing magnetic particles, and a back coat layer. The coercive force Hc of the magnetic layer in the thickness direction at 25&#xb0; C. is not 4100 oersteds (Oe) or more, and the coercive force Hc of the magnetic layer in the thickness direction at a temperature between 55&#xb0; C. and 80&#xb0; C. inclusive is not less than 1200 oersteds (Oe) and not more than 3700 oersteds (Oe).

Coating-type magnetic recording medium for heat-assisted recording, and heat-assisted magnetic recording apparatus and heat-assisted magnetic recording method using the same

Provided is an electromagnetic-wave absorber that can favorably absorb electromagnetic waves of a plurality of different frequencies in a high frequency band equal to or higher than the millimeter-wave band. The electromagnetic-wave absorber includes an electromagnetic-wave absorbing layerin which a plurality of magnetic layers-are stacked, each magnetic layer containing magnetic iron oxide that magnetically resonates at a high frequency in a band equal to or higher than the millimeter-wave band. A value of an anisotropic magnetic field (H) of the magnetic iron oxide contained in at least one of the magnetic layers is different from that of the magnetic iron oxide contained in another of the magnetic layers.

Electromagnetic absorber

In a magnetic recording medium according to the present invention, if a straight line W having a length of 500 nm and a width of 15 nm is displayed parallel to a width direction of the magnetic layer and a straight line L having a length of 500 nm and a width of 15 nm is displayed parallel to a longitudinal direction of the magnetic layer, the number of magnetic particles that intersect the straight line W is N1, and the number of magnetic particles that intersect the straight line L is N2, then, a relationship of N1/0.5&#x3e;60 and N2/0.5&#x3e;60 is established where N1/0.5 is the number of magnetic particles per micrometer obtained by dividing N1 by 0.5 &#x3bc;m and N2/0.5 is the number of magnetic particles per micrometer obtained by dividing N2 by 0.5 &#x3bc;m.

Magnetic recording medium

A magnetic recording medium of the present invention includes a non-magnetic substrate, and a magnetic layer containing a magnetic powder. The magnetic powder is constituted by an &#x3b5;-iron oxide powder. The magnetic layer has a squareness in a thickness direction of 0.65 or more. In a differential curve obtained by differentiating a hysteresis curve in the thickness direction of the magnetic layer, two or more peaks are present. In a case where, out of peaks in the same direction among the above-described peaks, a local maximum of a largest peak in a magnetic field range of +500 oersted [Oe] or more is taken as Pand a local maximum of a largest peak in a magnetic field range of &#x2212;500 oersted [Oe] or more and less than +500 oersted [Oe] is taken as P, a relationship below is satisfied:0.25&#x2264;2/1&#x2264;0.60.

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Kyoto, Japan

Toshio Hiroi