Abstract: A magnetic recording medium comprises:

Abstract: A magnetic recording medium using black magnetic acicular composite particles produced by forming a single carbon black coat between the surface of magnetic acicular cobalt-coated iron oxide particle or magnetic acicular metal particle and a coating comprising at least one organosilicon compound, in an amount of from more than 10 to 40 parts by weight based on 100 parts by weight of the magnetic acicular particles, exhibits not only a smooth surface, a smaller light transmittance and a lower surface electrical resistivity value, but also a small friction coefficient and an excellent running durability.

Abstract: A color toner comprises: a binder resin, and a colorant having an average particle diameter of 0.005 to 0.

Abstract: A magnetic recording medium comprises: a non-magnetic base film; a magnetic recording layer formed on one surface of the non-magnetic base film, comprising a binder resin and magnetic particles; and a back coat layer formed on a surface opposite of the non-magnetic base film to the surface on which the magnetic recording layer is formed, comprising a binder resin and plate-shaped non-magnetic composite particles having an average plate surface diameter of 0.1 to 5.0 &mgr;m, an average thickness of 0.001 to 0.

Abstract: Composite magnetic metal particles containing iron as a main component, comprise: magnetic metal particles containing iron as a main component, and a polyether-modified polysiloxane coat formed on surface of the magnetic metal particles in an amount of 0.02 to 10% by weight, calculated as Si, based on the weight of the composite magnetic metal particles containing iron as a main component; and have an average major axis diameter of 0.02 to 0.30 &mgr;m and a soluble sodium salt content of not more than 10 ppm.

Abstract: Black magnetic toner comprising:

Abstract: A black toner comprising:

Abstract: A magnetic recording medium comprises:

Abstract: Magnetic composite particles having an average particle diameter of 0.06 to 1.0 &mgr;m and a coercive force value of less than 39.790 kA/m, comprising: magnetic core particles, a coating formed on surface of said magnetic core particles, comprising at least one organosilicon compound selected from the group consisting of: (1) organosilane compounds obtainable from alkoxysilane compounds, and (2) polysiloxanes or modified polysiloxanes, and an organic blue-based pigment coat formed on said coating layer comprising said organosilicon compound, in an amount of from 1 to 50 parts by weight based on 100 parts by weight of said magnetic core particles. The magnetic composite particles are suitable for black magnetic toner not only exhibiting a deep black color but also having excellent light resistance and fluidity.

Abstract: The present invention relates to titanium oxide particles having an average particle size of not more than 0.3 &mgr;m, and a BET specific surface area of 15 to 200 m2/g, containing a soluble sodium salt of not more than 230 ppm, calculated as Na, and a soluble sulfate of not more than 150 ppm, calculated as SO4, and having a pH value of not less than 8. The titanium oxide particles of the present invention are suitable as non-magnetic particles for a non-magnetic undercoat layer of a magnetic recording medium which uses magnetic particles containing iron as a main ingredient, and even more particularly, are suitable as non-magnetic particles for a non-magnetic undercoat layer of a magnetic recording medium which uses magnetic particles containing iron as a main ingredient, show an excellent dispersibility in a binder resin, contain only a small amount of soluble sodium salt and soluble sulfate, and have a pH value of not less than 8.

Abstract: A magnetic recording medium composed of a non-magnetic base film and a magnetic recording layer containing a binder resin, magnetic particles, and as a filler black composite hematite particles having an average diameter of 0.08 to 1.0 &mgr;m. The composite particles have cores of hematite particles which are surface coated with an organosilicon compound. A carbon black coating is formed on the organosilicon coating layer. In addition, the hematite core particles may have an oxide or hydroxide coating layer formed on the surface of the hematite core particle, between the organosilicon coating layer and the surface of the core particles. The magnetic recording medium has not only an excellent durability and a good electromagnetic performance, but also a low light transmittance, a small surface resistivity and an excellent surface smoothness.

Abstract: Hematite particles aggregates as non-magnetic particles of the present invention are capable of forming a non-magnetic undercoat layer of a magnetic recording medium having a more excellent surface smoothness, which can exhibit not only an excellent dispersibility but also have an improving ability of a surface smoothness of a coating film produced therefrom by calendering treatment, a non-magnetic undercoat layer for magnetic recording medium which contains the hematite particles aggregates is exhibits a more excellent surface smoothness, and a magnetic recording medium having the non-magnetic undercoat layer, is exhibits a more excellent surface smoothness.

Abstract: A black composite iron oxide pigment of the present invention comprises composite iron oxide particles having an average particle size of 0.08 to 1.

Abstract: Iron oxide hydroxide composite particles having an average particle diameter of 0.005 to 1.0 &mgr;m, comprises: iron oxide hydroxide particles as core particles, a coating formed on surface of said iron oxide hydroxide particles, comprising at least one organosilicon compound selected from the group consisting of: (1) organosilane compounds obtainable from alkoxysilane compounds, and (2) polysiloxanes or modified polysiloxanes, and an organic pigment coat formed on said coating layer comprising said organosilicon compound, in an amount of from 1 to 30 parts by weight based on 100 parts by weight of said iron oxide hydroxide particles. The iron oxide hydroxide composite particles of the present invention contain no harmful elements and exhibit not only excellent chemical resistances such as acid resistance and alkali resistance, but also excellent heat resistance.

Abstract: A magnetic recording medium of the present invention comprises:

Abstract: The present invention provides particles for a non-magnetic undercoat layer of a magnetic recording medium, which comprises acicular hematite particles having an average major axial diameter of not more than 0.3 &mgr;m, a geometrical standard deviation in the major axial diameter of not more than 1.50 and a BET specific surface area of not less than 40 m2/g, and containing a total amount of sodium of not more than 50 ppm calculated as Na. The acicular hematite particles have an excellent dispersibility in a vehicle so that a non-magnetic undercoat layer containing the particles is excellent in surface smoothness and strength. A magnetic recording medium using the non-magnetic undercoat layer is excellent not only in electromagnetic performance, but in storage stability.

Abstract: High-density acicular hematite particles comprise acicular hematite particles and a coat comprising an oxide of tin or oxides of tin and antimony, formed on at least a part of surfaces of said acicular hematite particles; and have an average major axial diameter of not more than 0.3 &mgr;m, a pH value of not less than 8, a soluble sodium salt content of not more than 300 ppm, calculated as Na, and a soluble sulfate content of not more than 150 ppm, calculated as SO4. Such high-density acicular hematite particles is suitable as non-magnetic particles for a non-magnetic undercoat layer of a magnetic recording medium using magnetic particles containing iron as a main ingredient, have an excellent dispersibility in vehicle and a low volume resistivity.

Abstract: Black iron-based composite particles of the present invention comprise: as a core particle black iron oxide particle or black iron oxide hydroxide particle having an average particle size of 0.08 to 1.0 &mgr;m; a coating layer formed on the surface of the black iron oxide particle or black iron oxide hydroxide particle, comprising at least one organosilicon compound selected from the group consisting of: (1) organosilane compounds obtained from alkoxysilane compounds, (2) polysiloxanes, or modified polysiloxanes and (3) fluoroalkyl organosilane compounds obtained from fluoroalkylsilane compounds; and carbon black coat formed on said coating comprising said organosilicon compound, in an amount of 1 to 30 parts by weight based on 100 parts by weight of said black iron oxide particles or black iron oxide hydroxide particles.

Abstract: Black magnetic toner comprising: a binder resin, and black magnetic composite particles comprising: magnetic iron oxide particles having an average particle diameter of 0.055 to 0.95 &mgr;m; a coating layer formed on the surface of said magnetic iron oxide particles, comprising at least one organosilicon compound selected from the group consisting of: (1) organosilane compounds obtainable from alkoxysilane compounds, (2) polysiloxanes or modified polysiloxanes, and (3) fluoroalkyl organosilane compounds obtainable from fluoroalkylsilane compounds; and a carbon black coat formed on said coating layer comprising said organosilicon compound, in an amount of 1 to 25 parts by weight based on 100 parts by weight of said magnetic iron oxide particles. Such a black magnetic toner can be free from being deteriorated in electric resistance due to the existence of the carbon black coat, and as a result, is suitable as a high-resistance or insulated magnetic toner.

Abstract: Composite particles having an average particle diameter of 0.001 to 10.