Abstract: The present invention provides a new fluorine-containing acetophenone derivative useful as a photo initiator, and a surface layer material containing the fluorine-containing acetophenone derivative. The present invention provides inexpensively an article with a hard coat excellent in anti-staining property, lubricity, scratch resistance and abrasion resistance, and provides a method for forming the hard coat.

Abstract: An electron-beam curable polyurethane resin for magnetic recording media is produced by modifying a polyurethane resin having active hydrogen in the molecule thereof with a compound having at least two acrylic double bonds, wherein the modification is performed on the active hydrogen so that the polyurethane resin becomes electron-beam curable. By subjecting a known thermosetting polyurethane resin to electron-beam sensitive modification, the resulting resin is highly crosslinked and is thus capable of being suitably used for magnetic recording media. Also, an electron-beam curable polyurethane resin having excellent crosslinking characteristics can easily be produced from the known thermosetting polyurethane resin. Furthermore, by using the electron-beam curable polyurethane resin, a high-performance magnetic recording medium can be provided.

Abstract: In a magnetic recording medium which comprises a magnetic layer having magnetic metal powder and a binder as major components, the magnetic layer being disposed on one side of a non-magnetic support member, the binder comprises a vinyl chloride copolymer, a polyurethane resin having a group which contains metal sulfamate as a functional group, and a curing agent. The polyurethane resin comprises a group containing metal sulfamate by 0.5 to 3 per molecule, a blending weight ratio of the vinyl chloride copolymer and the polyurethane resin of 30/70 to 70/30, and the curing agent is present in an amount of 10 to 60 weight parts to 100 weight parts of the total of the vinyl chloride copolymer and the polyurethane resin. The invention also provides a magnetic recording medium which further comprises a non-magnetic underlayer and a backcoat layer, wherein a binder comprising polyurethane resin having a group which contains metal sulfamate also is used.

Abstract: A magnetic layer of a magnetic recording medium comprising a magnetic powder dispersed in a binder resin contains a powder of Ti-containing Al.sub.2 O.sub.3. The magnetic recording medium may alterenatively incorporate the Ti-containing Al.sub.2 O.sub.3 powder in the back coating or in both the magnetic layer and the back coating. A superior running stability and a superior durability are attained.

Abstract: A magnetic recording medium comprising a plastic base and a magnetic layer formed thereon by applying a dispersion of a ferromagnetic powder in a resin binder, the magnetic layer containing the ferromagnetic powder which has a BET specific surface area of at least 35 m.sup.2 /g and .alpha.-Al2O3 particles having a particle size not exceeding one half the mean particle diameter of the ferromagnetic powder and less than 0.1 .mu.m in diameter, the .alpha.-Al2O3 particles being added in an amount greater than 5% but less than 15% by weight on the basis of the weight of the ferromagnetic powder. The magnetic powder is a metallic magnetic powder containing iron as the major constituent. The .alpha.-Al2O3 particles are cube-shaped.

Abstract: This invention concerns a radiation-curable, magnetic coating material and a magnetic recording medium made with the coating, which is characterized in that a water-soluble or water-dispersed resin having at least one radiation-curable, unsaturated double is contained as a vehicle. The vehicle may also contain a water-soluble or water-dispersible resin, or mixtures thereof free from such an unsaturated double bond. The invention provides a magnetic recording medium with improved durability, softness, flexibility, and heat resistance.

Abstract: The invention provides a method for manufacturing a magnetic recording tape which is free from the problems of the phenomenon of dropout as well as runout of the tape roll throughout the life of the tape. The inventive method comprises providing a coating layer on a surface of a film base of the tape having been provided with the magnetic coating layer on the other surface with a coating composition comprising a radiation-sensitive curable polymeric material, which is a thermoplastic resin modified to be radiation-sensitive with or without admixture of a thermoplastic elastomer, and a filler dispersed therein and, prior to winding of the tape into a roll, irradiating the coating layer with a high energy radiation of, preferably, electron beams whereby the coating composition is fully radiation-cured to form a backing layer of the tape.

Abstract: This invention provides a magnetic recording medium with excellent electromagnetic characteristics and running durability. According to the invention, a magnetic powder is kneaded with a cross-linkable or polymerizable resin binder, together with a phosphoric ester having a polymerizable, unsaturated double bond or bonds, the resulting coating material is applied to a substrate, and then the coating is cross-linked or polymerized. The addition of the phosphoric ester in place of an ordinary dispersing agent improves the mechanical properties of the magnetic coating and the durability and running quality of the magnetic recording medium.

Abstract: In a magnetic recording medium made by applying a non-magnetic undercoat and a magnetic top coat on a base, the undercoat comprises a radiation-curable coating material which contains a compound with a molecular weight of not less than 400, having one type of double bond selected from among acrylic, allylic, and maleic double bonds, the undercoat being formed by exposure to radiation. Specifically, the undercoating material contains at least two types of compounds selected from (A) those having a molecular weight of over 5000, preferably over 8000 and having two or more double bonds selected as above, (B) those having a molecular weight of 400 or more but less than 500, preferably in the range of 600 to 3000, and two or more double bonds selected as above, and (C) those having a molecular weight of less than 400 and one or more double bonds selected from among acrylic, allylic, maleic, and styrenic double bonds.

Abstract: The invention provides a novel magnetic recording tape comprising a film base, a magnetic coating layer on one surface and a backing layer on the other surface, the backing layer containing an abrasive powder having a hardness of at least 4 in the Mohs scale, such as silicon carbide and the like, dispersed in a binder matrix formed by curing a radiation-sensitive polymer by irradiating with a high energy radiation, such as electron beams accelerated at a voltage of 100 to 750 kilovolts.

Abstract: A magnetic recording medium having a magnetic layer on one surface of a substrate and a back layer on the other surface, which is characterized by that the back layer is that formed by dispering a filler such as carbon black, graphite, SiO.sub.2, TiO.sub.2, Al.sub.2 O.sub.3,Cr.sub.2 O.sub.3, SiC, CeO.sub.2, CaCO.sub.3, zinc oxide, geothite, .alpha.Fe.sub.2 O.sub.3, talc, kaolin, CaSO.sub.4, boron nitride, Teflon powder, graphite fluoride, molybdenum disulfide, zirconia etc. In a binder containing a radiation sensitive curable resin such as acryl-modified vinyl chloride - vinyl acetate - vinyl alcohol copolymer, acryl-modified polyurethane elastomer, acryl-modified polyester resin, etc. and curing it prior to rolling. The obtained back layer is very tough and can reduce the number of dropouts.

Abstract: A magnetic recording medium comprises a substrate and a magnetic recording layer formed thereon and which is made of a magnetic coating material consisting essentially of a magnetic powder dispersed in a binder, the coating material containing a titanium coupling agent. The magnetic powder is coated with the coupling agent or is mixed with the agent and then dispersed in the binder. The binder is prepared by mixing and plasticizing a radiation-sensitive modified resin with a radiation-sensitive soft resin and subjecting the mixture to radiation cross-linking and polymerization. Process for producing the medium comprises coating the magnetic particles with the titanium coupling agent, blending the coated particles with the binder to form a magnetic coating material, and then applying the material to the substrate.

Abstract: A magnetic recording medium consisting of a base coated with a magnetic coating material, characterized in that the binder composition in said magnetic coating material is ternary, consisting of from 30 to 70% of a polyurethane resin having an --OH group in the terminal position, from 10 to 50% of an epoxy resin, and from 10 to 50% of a vinyl chloride-vinylidene chloride copolymer, all by weight on the basis of the total weight of the binder together with a curing agent. The magnetic recording medium exhibits superior electromagnetic properties and physical properties such as stability on repeated runs and bonding strength of the coating.

Abstract: A magnetic recording medium having improved electromagnetic conversion characteristics and physical properties prepared by using a three-component binder consisting of a polyurethane resin, a phenoxy resin and a vinyl chloride-vinylidene chloride resin.