Abstract: A magnetic recording element having a carrier and a magnetic coating provided thereon containing a magnetic pigment, a binder and a dispersing agent which is an amine or amide compound containing a sulfuric or sulfonic acid group.

Abstract: A composition for making magnetic recording elements comprising finely divided particles of magnetic pigment dispersed in an organic medium comprising polymeric binder, lubricant, dispersing agent and porosity control agent dispersed in volatile organic solvent.

Abstract: A magnetic recording and playback device includes a magnetic head of a metallic soft magnetic material which, during operation, is in mechanical contact with a magnetic tape moved passed the head. In order to prevent corrosive detrition of the contact face of the magnetic head under the influence of moisture from the tape, the magnetic head has a negative voltage with respect to ground.

Abstract: A method of manufacturing a magnetic pigment of .gamma.-Fe.sub.2 O.sub.3 particles in which the process starts with an alkaline or acid reacting aqueous dispersion of .gamma.-Fe.sub.2 O.sub.3. According to the invention, a water-soluble ammonium salt, which is derived from a low molecular weight, weakly acidic organic acid, is added to the aqueous dispersion, the .gamma.-Fe.sub.2 O.sub.3 particles flocculating. The flocculated .gamma.-Fe.sub.2 O.sub.3 is separated, washed with water which preferably also comprises such a water-soluable ammonium salt, and is then dried. The ammonium salt volatilizes in the drying process used either as such or after decomposition. A suitable ammonium salt is ammonium acetate. The pigment obtained according to the invention has a low content of salt absorbed at the surfaces of the pigment particles, for example, a content lower than 0.1 and, for example 0.03% by weight.

Abstract: A magnetic recording element with a carrier and a magnetic coating which comprises a magnetic pigment dispersed in a binder in which the sulphate ions present on the surface of the pigment particles are bound in the form of a water-insoluble salt, as well as methods of manufacturing the magnetic recording element in which the magnetic pigment or a non-magnetic FeOOH pigment from which the magnetic pigment can be manufactured is treated with an aqueous solution of a water-soluble salt the cations of which form water-insoluble salts with the sulphate ions present on the surface of the pigment particles and the treated pigment is then processed according to known methods to a magnetic recording element or in which the above-mentioned salt is mixed with the ingredients of the magnetic coating and the resulting magnetic coating lacquer is provided on a carrier and dried.

Abstract: The invention relates to a method of manufacturing an improved pigment of FeOOH particles. The starting material is an acidic or alkaline aqueous dispersion of FeOOH particles which has been manufactured according to known methods. According to the invention, a water-soluble ammonium salt, which is derived from a low-molecular weight, weakly acidic organic acid and which volatilizes either as such or after decomposition not greater than 450.degree. C., is added to the aqueous dispersion. As a result of the addition of the ammonium salt, the FeOOH pigment flocculates. It is then separated and washed with water which preferably is also provided with the ammonium salt. According to a further embodiment of the invention the resulting pigment which, after drying, has a very low salt content, is converted into an Fe pigment or a .gamma. Fe.sub.2 O.sub.3 pigment which also has a very low salt content. A magnetic recording element which is based on the Fe or .gamma. -Fe.sub.2 O.sub.

Abstract: An improved magnetic recording composition employing as a novel dispersion agent a salt of an amine and a mono- or diester of phosphoric acid with a higher olefinic alcohol or alkoxylated derivatives of the same.

Abstract: The invention relates to a magnetic recording medium, in particular a magnetic tape. It has been found that the addition of a silane compound containing a chlorinated hydrocarbon group, to the coating of a magnetic recording medium considerably improves the mechanical and electromagnetic properties thereof. A particularly suitable silane compound is .alpha.-chloropropyltrimethoxy silane.