Abstract: A magnet structure, comprises: a plurality of permanent magnet members; and an adhesive layer bonding the permanent magnet members to each other, wherein the adhesive layer contains an adhesive, and a plurality of gap members, the gap members have insulation properties, each surface S of the permanent magnet members in contact with the adhesive layer has a plurality of convex parts, a reference plane is a plane including a mean line of a roughness curve of the surface S, Ry is a maximum value of heights of the convex parts from a deepest part of the surface S in a direction perpendicular to the reference plane, Rv is a distance between the reference plane and the deepest part, Rp is Ry?Rv, W1 is a width of the gap member in a direction perpendicular to the reference plane, and W1 is larger than 2Rp.

Abstract: A permanent magnet includes a magnet member, and an adhesive layer covering a surface of the magnet member, wherein the adhesive layer includes a resin and a plurality of foaming agents, and wherein at least part of the foaming agents protrudes from a surface of the resin.

Abstract: A magnet structure, comprises: a plurality of permanent magnet members; and an adhesive layer bonding the permanent magnet members to each other, wherein the adhesive layer contains an adhesive, and a plurality of gap members, the gap members have insulation properties, each surface S of the permanent magnet members in contact with the adhesive layer has a plurality of convex parts, a reference plane is a plane including a mean line of a roughness curve of the surface S, Ry is a maximum value of heights of the convex parts from a deepest part of the surface S in a direction perpendicular to the reference plane, Rv is a distance between the reference plane and the deepest part, Rp is Ry?Rv, W1 is a width of the gap member in a direction perpendicular to the reference plane, and W1 is larger than 2Rp.

Abstract: A permanent magnet includes a magnet member, and an adhesive layer covering a surface of the magnet member, wherein the adhesive layer includes a resin and a plurality of foaming agents, and wherein at least part of the foaming agents protrudes from a surface of the resin.

Abstract: In order to reduce the coefficient of friction of a coated type magnetic recording medium and improve the running stability and electromagnetic conversion characteristics thereof, a carbon black having a mean primary particle diameter of 25 to 65 m.mu.m with the standard deviation .sigma. of the particle size distribution lying at 12 to 24 m.mu.m is incorporated in the magnetic layer.

Abstract: In a magnetic recording medium comprising a substrate and a magnetic layer thereon, the magnetic layer is formed by coating a composition of a binder, preferably radiation-curable binder and a needle magnetic material, passing the coating through a magnetic field to forcedly re-orient the magnetic particles to form pores having an average pore area of 6.times.10.sup.-5 to 7.times.10.sup.-1 .mu.m.sup.2, and curing the coating, thereby minimizing output fluctuation and improving durability. Preferably lubricant is present in the pores.