Abstract: Provided is a polishing tool capable of forming a high-quality surface of a workpiece for a short period of time. A polishing tool includes: a rotation shaft arranged parallel to a sending direction of moving the polishing tool relative to a workpiece; and at least two polishing bodies. The polishing body includes a foamed resin such as a foamed polyurethane resin, and has an outer peripheral surface having a porosity higher than that of the polishing body. The polishing body includes a non-foamed resin such as a non-foamed polyurethane resin being a material more rigid than that for the polishing body. When polishing-processing, the polishing body performs polishing removal on a surface of the workpiece, and the polishing body smoothes a waviness formed on the surface through the polishing removal.

Abstract: (1) A magnetic recording system is disclosed, which comprises a thin-film magnetic head and a magnetic recording medium comprising a nonmagnetic support having thereon a magnetic layer comprising mainly ferromagnetic particles and a binder resin, wherein said binder resin comprising mainly a vinyl chloride resin, and said ferromagnetic particles are surface-treated with at least an organic compound.

Abstract: A magnetic recording medium comprising a nonmagnetic support and a magnetic layer, wherein the magnetic layer is provided on one surface of the nonmagnetic support, comprises a ferromagnetic particle, and has a surface roughness of from 2 to 10 nm; the nonmagnetic support has plural layers; at least one layer of the plural layers comprises an antistatic agent; and the nonmagnetic support has a surface roughness of from 5 to 30 nm on the opposite surface to the surface on which the magnetic layer is provided.

Abstract: A magnetic recording medium having improved electromagnetic characteristics and running properties is disclosed. The magnetic recording medium comprises a non-magnetic support having thereon a plurality of magnetic layers consisting of two or more layers composed of a first lower magnetic layer and a second upper magnetic layer, provided on said support by either co-coating the lower magnetic layer and the upper magnetic layer in the wet state, or coating the lower magnetic layer and then the upper magnetic layer while the lower magnetic layer is still in the wet state; wherein the cobalt-modified iron oxide is employed as the ferromagnetic powder contained in the lower magnetic layer, ferromagnetic metal is employed as the ferromagnetic powder contained in the upper magnetic layer, both the ferromagnetic powder contained in the lower magnetic layer and the ferromagnetic powder contained in the upper magnetic layer having an average major axis length of 0.25 .mu.

Abstract: A magnetic recording medium having two or more magnetic layers is disclosed, comprising a first magnetic layer and a second magnetic layer which-have been provided in this order on a surface of a nonmagnetic support, and which contain ferromagnetic particles and a binder, wherein said second magnetic layer (outermost layer) contains nonmagnetic particles having a pH of less than 7, and a Mohs' hardness of 6 or more, in an amount of from 1 to 20 parts by weight, per 100 parts by weight of the ferromagnetic particles in the second magnetic layer, and said first magnetic layer contains nonmagnetic particles having a pH of 7 or more, and a Mohs' hardness of 6 or more, in an amount of from 5 to 50 parts by weight, per 100 parts by weight of the ferromagnetic particles in the first magnetic layer.

Abstract: A magnetic recording medium is disclosed, comprising a non-magnetic support with an undercoating layer having formed thereon one or more magnetic layers. The undercoating layer contains a polyester resin or polyurethane resin having at least one polar group selected from the group consisting of --SO.sub.3 M, --OSO.sub.3 M, --COOM, and --OPO.sub.3 M.sub.2 (wherein M represents a hydrogen atom, an alkali metal, or an ammonium base, and M in different polar group or plural M's within the same polar group may be the same or different), and a glass transition temperature (Tg) of from 40.degree. C. to 80.degree. C. The magnetic layer contains a binder resin having at least one polar group selected from the same group as defined above. The recording medium has excellent adhesion between the non-magnetic support and the magnetic layer, high running durability and excellent electromagnetic characteristics.

Abstract: A magnetic recording medium comprising a non-magnetic support having thereon an undercoating layer and a magnetic layer, wherein the undercoating layer is provided between the non-magnetic support and magnetic layer, and a binder used for the undercoating layer comprises a resin having an elution amount of 0.05 to 0.4 mg/cm.sup.2 when placed in a mixed solvent of methyl ethyl ketone and cyclohexanone having a weight ratio of 1:1 at 25.degree. C. for 30 seconds.

Abstract: A magnetic recording medium comprising a non-magnetic support having thereon a magnetic layer containing (a) ferromagnetic particles, (b) a binder containing at least one resin substituted with at least one polar group selected from an --SO.sub.3 M group, a --COOM group, an --OSO.sub.3 M group, an ##STR1## group and a ##STR2## group, wherein M represents H, Li, Na or K and M' represents H, Li, Na, K or an alkyl group, and (c) at least one fatty acid lubricating agent comprising at least one fatty acid derivative represented by formula (I): ##STR3## in which R represents a hydrocarbon group having from 11 to 21 carbon atoms, X represents hydrogen or a methyl group, R' represents a hydrocarbon group having from 1 to 8 carbon atoms and n is an integer of from 2 to 20.

Abstract: In a magnetic recording medium comprising a nonmagnetic support, a magnetic recording layer provided on one surface of said support and a back layer containing carbon black provided on another surface of said support, the improvement wherein said back layer has thickness of not larger than 0.6 .mu.m and contains an inorganic filler powder having a Mohs' scale of hardness of not less than 5, a mean particle diameter of smaller than the thickness of the back layer and not smaller than 1/5 of the thickness thereof, and the maximum particle diameter of not larger than 11/10 of the thickness of the back layer.

Abstract: A process for the preparation of a magnetic paint comprising a ferromagnetic powder, an abrasive and a binder, which comprises the steps of preparing the abrasive dispersion comprising the abrasive and the binder, and then mixing said abrasive dispersion and the ferromagnetic powder.

Abstract: A magnetic recording medium which comprises a non-magnetic support having on the surface side thereof a magnetic recording layer and on the opposite side thereof a backing layer is disclosed. The backing layer contains carbon black and a binder and has a thickness of 2 .mu.m or less. The carbon black is composed of fine-grained carbon black having a mean grain size of 10 to 30 m.mu. and coarse-grained carbon black having a mean grain size of 100 to 150 m.mu.. In the backing layer the ratio of the content of carbon black to the binder ranges from 1:0.5 to 1:3.5 by weight.

Abstract: A magnetic recording medium is described, comprising a non-magnetic support having coated thereon on opposite surfaces a magnetic layer containing a magnetic substance and a binder-containing backing layer, wherein the magnetic layer has a light transmittance of 2% or more for light having a wavelength of 900 nm, the backing layer has a transmittance of from 1 to 10% for light having a wavelength of 900 nm, the magnetic recording medium as a whole has a transmittance of 1% or less for light having a wavelength of 900 nm, and the backing layer has a center line average roughness (Ra) of 0.05 .mu.m or less at a cut-off value of 0.08 mm.

Abstract: A magnetic recording material, which comprises a non-magnetic support having provided on one side thereof a magnetic layer and on the other side thereof a backing layer is disclosed. The binder of the backing layer is comprised of a combination of a cellulose resin, a vinylidene chloride resin, a polyurethane resin and a polyisocyanate. Use of the backing layer increases the durability of the tape and aids in preventing drop out.

Abstract: A magnetic recording material, which comprises a magnetic layer coated on a non-magnetic support is disclosed. The magnetic layer contains both carbon black fine powder having a mean primary grain size of less than 10 m.mu. and carbon black coarse powder having a mean primary grain size in the range of 50 to 120 m.mu. in a mixing ratio ranging from 95/5 to 5/95. The material is improved in both RF output and audio output.

Abstract: A magnetic recording medium comprised of a non-magnetic support base having a magnetic layer provided thereon is disclosed. The magnetic layer is comprised of carbon black having an average particle size of 30 to 50 m.mu. and an iron oxide which contains Co. The iron oxide containing the Co has a specific surface area of 25 m.sup.2 /g or more. The carbon black and the iron oxide containing the Co are dispersed in a binder. By utilizing the particular type of carbon black in combination with the particular iron oxide containing Co in the magnetic layer it is possible to greatly improve the running characteristics of the magnetic recording medium as well as obtain an improved RF output.

Abstract: A magnetic recording medium is disclosed. The medium comprises a non-magnetic support having provided on opposite surfaces a magnetic recording layer and a backing layer containing two types of carbon black and a binder and having a thickness of 2 .mu.m or less, one of said carbon black being fine carbon black having an average particle size of 30 to 100 m.mu. and the other of said carbon black being coarse carbon black having an average particle size of 150 to 500 m.mu., and the mixing weight ratio of said carbon black and the binder being 1:1.5 to 1:3.5.

Abstract: A magnetic recording medium which comprises a non-magnetic support having on the surface side thereof a magnetic recording layer and on the opposite side thereof a backing layer having a thickness of 2 .mu.m or less, which contains carbon black and a binder and optionally, an inorganic powder, in which the backing layer contains at least two kinds of carbon black, one being fine-grained carbon black having a mean grain size of 10 to 30 m.mu. and the other being coarse-grained carbon black having a mean grain size of 150 to 500 m.mu. such that the weight ratio (P/B) of the total amount of carbon black and inorganic powder (P) to binder (B) is from about 1/0.5 to 1/3.5. The recording medium described provided smooth and stable tape-running for an extended period and a high S/N ratio.

Abstract: A method for preparing a magnetic recording medium is described, comprising (1) pre-dispersing ferromagnetic particles having an S.sub.BET specific surface area of 35 m.sup.2 /g or more and having an adjusted water content of 0.8 wt % or more with a binder, (2) adding an additional binder and a lubricating agent thereinto, mixing and dispersing them to prepare a diserpsion of a magnetic coating composition, and (3) coating the resulting dispersion of a magnetic coating composition on a non-magnetic support.

Abstract: A magnetic coating composition comprising a binder dissolved in a solvent and magnetic grains dispersed therein is applied onto a surface of a non-magnetic substrate continuously moved. The coating film thus overlaid on the non-magnetic substrate is subjected to a preliminary orientation step for orientating the magnetic grains in the coating film, and then to a preliminary drying step. A final orientation step is then conducted while intermediate drying is carried out. Thereafter, final drying is effected.

Abstract: A magnetic recording material comprised of a non-magnetic support base having provided thereon a magnetic recording layer on one side and the back layer on the other side is disclosed. The magnetic recording layer is comprised of ferromagnetic particles dispersed in a binder in combination with carbon black particles having an average primary particle size of 30 .mu.m or less. The back layer is comprised of a binder having dispersed therein carbon black having an average primary particle size in the range of 50 to 150 m.mu.. The magnetic recording material has improved electromagnetic properties and improved durability, particularly with respect to video S/N and dropout.