Abstract: Acicular hematite particles of the present invention contain zirconium of 0.05 to 30% by weight (calculated as Zr) based on the total weight of the particles, which is present within the particle, which have an average major axis diameter of not more than 0.3 .mu.m and a pH value of not less than 8, and contain not more than 300 ppm of soluble sodium salt, calculated as Na and not more than 150 ppm of soluble sulfate, calculated as SO.sub.4.Such acicular hematite particles are suitable as non-magnetic particles for a non-magnetic undercoat layer of a magnetic recording medium which exhibits a low light transmittance, an excellent smooth surface, a high strength and an excellent durability, and can be prevented from being deteriorated in magnetic properties due to the corrosion of magnetic acicular metal particles containing iron as a main component which are dispersed in a magnetic recording layer thereof.

Abstract: A fine yellow composite iron oxide hydroxide pigment of the present invention has an average major axial diameter of not less than 0.005 .mu.m and less than 0.1 .mu.m, which comprises:fine goethite particles as core particles, containing aluminum inside thereof in an amount of 0.05 to 50% by weight, calculated as Al, based on the weight of said core particles; anda composite oxide hydroxide of Fe and Al, coated on the surface of each core particle. Such fine yellow composite iron oxide hydroxide pigment are excellent in transparency and heat resistance.

Abstract: Black non-magnetic composite particles for black toner according to the present invention, comprise:black hematite particles or black iron oxide hydroxide particles as core particles;fine particles which are adhered or exist on at least a part of the surface of each magnetite particle, and comprise oxides, oxide hydroxides or oxides and oxide hydroxides composed of at least one element selected from the group consisting of Si, Zr, Ti, Al and Ce; anda methyl hydrogen polysiloxane coating layer formed on said fine particles or said fine particles and the exposed surface of the magnetite particle,the average particle size of said black non-magnetic composite particles being 0.08 to 1.0 .mu.m.Such black non-magnetic composite particles are suitable for a black toner which can exhibit not only an excellent flowability but also a high volume resistivity.

Abstract: Acicular hematite particles of the present invention comprise a geometrical standard deviation of major axis diameter of not more than 1.50, a geometrical standard deviation of minor axis diameter of not more than 1.35, a BET specific surface area of 35.9 to 150 m.sup.2 /g and an average major axis diameter of 0.004 to 0.295 .mu.m. Such acicular hematite particles are suitable as non-magnetic particles for a non-magnetic undercoat layer of a magnetic recording medium having a low light transmittance, an excellent smooth surface, a high mechanical strength and an excellent durability.

Abstract: The present invention relates to acicular hematite particles containing aluminum of 0.05 to 50% by weight, calculated as Al, having an average major axial diameter of not more than 0.3 .mu.m and a pH value of the particles of not less than 8, and containing soluble sodium salts of not more than 300 ppm soluble sodium, calculated as Na, and soluble sulfates of not more than 150 ppm soluble sulfate, calculated as SO.sub.4, which have an excellent dispersibility in a binder resin, and a magnetic recording medium which uses the hematite particles as non-magnetic particles for a non-magnetic undercoat layer, which has small light transmittance, smooth surface, high strength and high durability, and which is capable of suppressing the deterioration in the magnetic properties caused by a corrosion of the magnetic particles containing as a main ingredient in the magnetic recording layer.

Abstract: In accordance with the present invention, there are provided non-magnetic black particles composed primarily of Fe and having a hematite structure, which shows an excellent blackness, heat resistance, and dispersibility in a vehicle, and which particles contain manganese in an amount of 5 to 40% by weight based on the weight of the non-magnetic black particles, a soluble sodium salt in an amount of not more than 500 ppm (calculated as Na), and a soluble sulfate in an amount of not more than 200 ppm (calculated as SO.sub.4), and have an average particle size of 0.1 to 10.0 .mu.m and a pH of not less than 5.

Abstract: In accordance with the present invention, there are provided non-magnetic black particles composed primarily of Fe and having a hematite structure, which shows an excellent blackness, heat resistance, and dispersibility in a vehicle, and which particles contain manganese in an amount of 5 to 40% by weight based on the weight of the non-magnetic black particles, a soluble sodium salt in an amount of not more than 500 ppm (calculated as Na), and a soluble sulfate in an amount of not more than 200 ppm (calculated as SO.sub.4), and have an average particle size of 0.1 to 10.0 .mu.m and a pH of not less than 5.5.

Abstract: A magnetic recording medium of the present invention comprises: a base film; a non-magnetic undercoat layer formed on said base film and comprising a binder resin and non-magnetic acicular particles containing iron as a main component, comprising iron and titanium of 0.05 to 50% by weight, calculated as Ti, based on the total weight of the particles, which is present within the particle; and a magnetic recording layer formed on said non-magnetic undercoat layer and comprising magnetic particles and a binder resin. Such a magnetic recording medium has a low light transmittance, an excellent smooth surface, a high mechanical strength and an excellent durability.

Abstract: The present invention relates to a magnetic recording medium comprising: a non-magnetic substrate; a non-magnetic undercoat layer formed on said non-magnetic substrate, said undercoat layer comprising non-magnetic acicular hematite particles containing 0.05 to 50% by weight of aluminum uniformly within the particles, calculated as Al, based on the total weight of the non-magnetic particles and a binder resin,; and a magnetic recording layer formed on said non-magnetic undercoat layer, said magnetic recording layer comprising magnetic particles containing iron as a main ingredient and a binder resin. The magnetic recording medium has small light transmittance, smooth surface, high strength and high durability.

Abstract: The present invention relates to titanium oxide particles having an average particle size of not more than 0.3 .mu.m, and a BET specific surface area of 15 to 200 m.sup.2 /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 SO.sub.4, 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: Rectangular parallelopipedic lepidocrocite particles of the present invention have a minor axial diameter of 0.045 to 0.5 .mu.m, a major axial diameter of 0.05 to 1.0 .mu.m, and a thickness of 0.001 to 0.3 .mu.m, which are individual. Such rectangular parallelopipedic lepidocrocite particles according to the present invention are firstly used as a coloring pigment for paints, resin moldings, printing ink, road asphalt, cosmetics, etc., and secondly used as a non-magnetic material for non-magnetic undercoat layers which are formed on non-magnetic substrates which constitute a substrate for magnetic recording media, and which have an excellent surface smoothness and a high strength.

Abstract: Yellow iron oxide hydroxide particles comprising:iron oxide hydroxide particle as a core, andcomposite oxide hydroxide of Fe and Al deposited on surface of said iron oxide hydroxide particle as a core wherein the amount of Al in said composite oxide hydroxide is 0.1 to 10% by weight, calculated as Al, based on the weight of said iron oxide hydroxide as a core, the amount of Fe in said composite oxide hydroxide is 0.1 to 50% by weight, calculated as Fe, based on the weight of said iron oxide hydroxide particle as a core, and the ratio of Al to Fe in said composite oxide hydroxide is 0.05:1 to 2:1, calculated as Al and Fe atoms,said yellow iron oxide hydroxide particles having an average major axis diameter of 0.1 to 1.0 .mu.m, an average minor axis diameter of 0.02 to 0.10 .mu.m, an aspect ratio (major axis diameter/minor axis diameter) of 2 to 20, a BET specific surface area of 10 to 180 m.sup.2 /g and a heat-resistance temperature of not less than 255.degree. C.

Abstract: A pigment of the present invention comprises:pigment particle as core particle;a lower coat formed on at least a part of surface of the pigment particle, comprising squaric acid, polyol having an anthraquinone skeleton represented by the general formula (I): ##STR1## wherein m is an integer of 0 to 4, n is an integer of 0 to 4 and m+n is an integer of 2 to 4,or a mixture of the squaric acid and the polyol having an anthraquinone skeleton represented by the general formula (I); andan upper coat formed on at least a part of surface of the obtained particle, comprising at least one alkylene glycol represented by the general formula (II):C.sub.q H.sub.2q (OH).sub.2 (II)wherein q is an integer of 2 to 10.Such pigment has excellent dispersion facility, dispersion homogeneity and dispersion stability, and is suitably used for not only organic solvent-type paints but also water-based paints.

Abstract: A rubber or resin composition comprises:0.1 to 10.0 parts by weight of iron oxide particles composed of iron oxide core which contains 0.21 to 2.14 wt % of silicon, calculated as SiO.sub.2, and 0.01 to 10.0 wt %, calculated as SiO.sub.2, of a precipitate composed of silicon, which adheres to the surfaces of said iron oxide core, a sphere ratio, maximum diameter/ minimum diameter, of said iron oxide particles being of 0.7 to 1.0, an average particle diameter of said iron oxide particles being 0.05 to 1.0 .mu.m, a geometric standard deviation .sigma.g of said iron oxide particles which shows the particle size distribution being not more than 1.40, a bulk density of said iron oxide particles being 0.80 to 1.5 g/cm.sup.3, and a surface activity of said iron oxide particles which is indicated by the number of cyclohexanone molecules adsorbed to the surfaces of the iron oxide particles, number of molecules/nm.sup.2, being not more than 1.70; and90 to 99.9 parts by weight of rubber or thermoplastic resin.

Abstract: The disclosure describes a non-magnetic undercoating layer for a magnetic recording medium, coated on the surface of a non-magnetic substrate comprising:non-magnetic particles selected from the group consisting of particles (1) and (2):(1) coated acicular or spindle-shaped .alpha.-Fe.sub.2 O.sub.3 particles which are produced by adhering not less than 0.01 to 20 wt % (calculated as Al, SiO.sub.2 or Al and SiO.sub.2, and based on acicular or spindle-shaped .alpha.-Fe.sub.2 O.sub.3 particles as a core material) of an oxide or a hydroxide containing Al, Si or both Al and Si to the surfaces of acicular or spindle-shaped .alpha.-Fe.sub.2 O.sub.3 particles as a core material, and have a molecular weight-dependent parameter .alpha. represented by the following formula of not less than 0.5:As=K.sub.1 .multidot.M.sup..alpha.wherein M represents the number-average molecular weight of a binder resin, As represents the saturation adsorption of said binder resin, and K.sub.

Abstract: The disclosure describes a non-magnetic undercoating layer for a magnetic recording medium, coated on the surface of a non-magnetic substrate comprising:non-magnetic particles selected from the group consisting of particles (1) and (2):(1) coated acicular or spindle-shaped .alpha.-Fe.sub.2 O.sub.3 particles which are produced by adhering not less than 0.01 to 20 wt % (calculated as Al, SiO.sub.2 or Al and SiO.sub.2, and based on acicular or spindle-shaped .alpha.-Fe.sub.2 O.sub.3 particles as a core material) of an oxide or a hydroxide containing Al, Si or both Al and Si to the surfaces of acicular or spindle-shaped .alpha.-Fe.sub.2 O.sub.3 particles as a core material, and have a molecular weight-dependent parameter .alpha. represented by the following formula of not less than 0.5:As=K.sub.1 .multidot.M.sup..alpha.wherein M represents the number-average molecular weight of a binder resin, As represents the saturation adsorption of said binder resin, and K.sub.

Abstract: Hematite particles for a non-magnetic undercoat layer for a magnetic recording medium, comprise: high-density acicular hematite particles having an average major axial diameter of not more than 0.3 .mu.m, a major axial diameter distribution in geometrical standard of not more than 1.50 and a BET specific surface area of not less than 35 m.sup.2 /g, showing a pH of not less than 8, and containing not more than 300 ppm of soluble sodium salt, calculated as Na, and not more than 150 ppm of soluble sulfate, calculated as SO.sub.4.

Abstract: A rubber or resin composition comprises:0.1 to 10.0 parts by weight of iron oxide particles composed of iron oxide core which contains 0.21 to 2.14 wt % of silicon, calculated as SiO.sub.2, and 0.01 to 10.0 wt %, calculated as SiO.sub.2, of a precipitate composed of silicon, which adheres to the surfaces of said iron oxide core,a sphere ratio, maximum diameter/minimum diameter, of said iron oxide particles being of 0.7 to 1.0, an average particle diameter of said iron oxide particles being 0.05 to 1.0 .mu.m, a geometric standard deviation .sigma.g of said iron oxide particles which shows the particle size distribution being not more than 1.40, a bulk density of said iron oxide particles being 0.80 to 1.5 g/cm.sup.3, and a surface activity of said iron oxide particles which is indicated by the number of cyclohexanone molecules adsorbed to the surfaces of the iron oxide particles, number of molecules/nm.sup.2, being not more than 1.70; and90 to 99.9 parts by weight of rubber or thermoplastic resin.

Abstract: The disclosure describes modified particles comprising inorganic particles as core particles, and at least one polysiloxane modified with at least one selected from the group consisting of polyethers, polyesters and aralkyls, which is coated on the surfaces of said core particles.

Abstract: The disclosure describes a non-magnetic undercoating layer for a magnetic recording medium, coated on the surface of a non-magnetic substrate comprising:non-magnetic particles selected from the group consisting of particles (1) and (2):(1) coated acicular or spindle-shaped .alpha.-Fe.sub.2 O.sub.3 particles which are produced by adhering not less than 0.01 to 20 wt % (calculated as Al, SiO.sub.2 or Al and SiO.sub.2, and based on acicular or spindle-shaped .alpha.-Fe.sub.2 O.sub.3 particles as a core material) of an oxide or a hydroxide containing Al, Si or both Al and Si to the surfaces of acicular or spindle-shaped .alpha.-Fe.sub.2 O.sub.3 particles as a core material, and have a molecular weight-dependent parameter .alpha. represented by the following formula of not less than 0.5:As=K.sub.1 .multidot.M.sup..alpha.wherein M represents the number-average molecular weight of a binder resin, As represents the saturation adsorption of said binder resin, and K.sub.