Abstract: Described is a magnetic recording medium comprising a non-magnetic substrate and a magnetic layer formed thereon composed mainly of magnetic powder and a binder, said binder containing a compound represented by a following formula: ##STR1## wherein X represents tertiary amine sulfonate or tertiary amine sulfuric ester, Y represents a monomer having vinyl group which is copolymerizable with vinyl chloride and i, j, k represent polymerization degrees.

Abstract: A radiation curable resin which is a polyurethane acrylate having (meth)acryloyloxy groups at the terminal end of the molecule and in the molecular chain thereof, and containing metal sulfonate groups in the molecule in a ratio of 3.0 to 1,500 equivalent/10.sup.6 g of the resin, said polyurethane acrylate being obtained by reaction of(1) a copolyester having hydroxyl groups at both terminal ends of the molecule and containing metal sulfonate groups therein,(2) a diisocyanate,(3) a compound (A) having at least one (meth)acryloyloxy group and two hydroxyl groups,(4) a compound (B) having at least one (meth)acryloyloxy group and one hydroxyl group, and optionally(5) a polyol other than the above (1) or (3). the radiation curable resin containing a compound (C) having at least one carboxylic acid group and two hydroxyl groups in addition to the above components (1) to (5) is also disclosed.

Abstract: A magnetic recording medium comprising a non-magnetic base and a magnetic layer attached thereto consisting essentially of magnetic powders and a binder. Included within the binder are spherical small sized particles of a benzoguanamine-formaldehyde resin or a benzoguanamine-melamine-formaldehyde resin which serve to improve the running characteristics, reduce the friction coefficient, and improve the strength of the layer.

Abstract: A magnetic recording medium comprised of a non-magnetic substrate and a magnetic layer formed on one surface of the substrate and consisting essentially of a binder and magnetic powders. As the binder, a thermoplastic polyurethane-urea resin is employed, in which hydrophilic polar groups are introduced. The thermoplastic polyurethane-urea resin contains urethane and urea bonds in the molecule thereof and may be synthesized from a long-chain diol with a molecular weight of about 500 to 5000, a short-chain diol with a molecular weight of about 50 to 500, an organic diisocyanate and an organic diamine.

Abstract: A magnetic recording medium has a magnetic layer consisting essentially of a binder and magnetic particles on one surface of a non-magnetic substrate. The thermoplastic polyurethane-urea resin in which unsaturated bonds sensitive to radiation are introduced is used as the binder.The thermoplastic polyurethane-urea resin in which the radiation-sensitive unsaturated bonds are introduced has both urethane and urea bonds in the molecular structure thereof. It is synthesized from long chain diol with a molecular weight of approximately 500 to 5000, a short chain diol with a molecular weight of approximately 50 to 500, an organic diisocyanate, an organic diamine, and a compound containing radiation-sensitive unsaturated double bonds, and cured by radiation.The thermoplastic polyurethane-urea resin in which not only the radiation-sensitive double bonds but also hydrophilic polar groups are introduced may also be used as the binder. These hydrophilic polar groups may for example include --SO.sub.3 M, --OSO.sub.

Abstract: A magnetic recording medium has, on a nonmagnetic support, a magnetic layer consisting mainly of an acicular iron oxide magnetic powder and a binder. In order to improve the S/N ratio, a fine magnetic powder having a specific surface area as determined by the BET method, of not less than 35 m.sup.2 /g is used. In order to improve the dispersibility of the magnetic powder and to improve the squareness ratio and durability thereof, the binder contains a resin which has a molecular weight of not more than 50,000 and has at least one polar group selected from the group consisting of polar groups having the general formulas: ##STR1## (wherein M is hydrogen, lithium, sodium or potassium; and M.sub.1 and M.sub.2 are hydrogen, lithium, sodium, potassium or alkyl groups.

Abstract: The magnetic recording medium comprises a non-magnetic substrate and a magnetic layer formed thereon composed mainly of magnetic powder and a binder. The binder contains a binder component having an absorbed amount of the binder component to a surface of the magnetic powder more than 1.5 mg per square meter of a surface area of the powder measured in 3 weight % solution in methyl ethyl ketone solvent, and the magnetic layer has a pigment volume concentration of the magnetic powder between 60 and 75%.The binder provides an improved strength and high pigment volume concentration of magnetic coating layer, and improved durability of the magnetic recording medium.

Abstract: A magnetic recording medium having a magnetic layer which is cured by irradiating radiation onto the magnetic layer in which magnetic or magnetizable powder material surface-treated with a silicon compound having a silanol group and/or a silanol-forming group upon hydrolysis and a double-bond sensitive to radiation irradiated is present with a binder. The magnetic recording medium having the aforesaid structure has a sufficient durability.

Abstract: The thermoplastic polyurethane resin having a molecular weight larger than about 5,000 is obtainable by the polyaddition of a long chain diol (A) having a molecular weight ranging from about 500 to 3,000, an organic diisocyanate (C) and a short chain triol (D) having a molecular weight lower than about 500 and specified structures and, as desired, a short chain diol (B) having a molecular weight ranging from about 50 to 500, in specified ratios.The thermoplastic polyurethane resin provides particularly enhanced heat resistance and solvent resistance with improved dispersibility of a pigment or the like and other resins and favorable compatibility with a solvent or the like.

Abstract: The magnetic recording medium contains as a binder a thermoplastic polyurethane resin having a molecular weight larger than about 5,000 and produced by the polyaddition of a long chain diol (A) having a molecular weight ranging from about 500 to 3,000, an organic diisocyanate (C) and a short chain triol (D) having a molecular weight lower than about 500 and specified structures and, as desired, a short chain diol (B) having a molecular weight ranging from about 50 to 500, in specified ratios. The binder may contain a nitrocellulose, a vinyl chloride resin, a polyvinyl butyral, a bisphenol A type polyether or a vinyl chloride-hydroxy carboxylate copolymer as a binder component.The binder provides particularly enhanced heat resistance and solvent resistance with improved dispersibility of a pigment or the like and other resins and favorable compatibility with a solvent or the like.