Abstract: Toner and developer compositions incorporating nonpolymeric, homogeneous, amorphous mixtures of compounds as the binder are described. The mixtures comprise at least two nonpolymeric, thermoplastic organic compounds each having at least two linking components joining one multivalent organic nucleus with at least two organic appended groups wherein either the multivalent organic nucleus or at least one of the appended groups in an aromatic group. The mixtures have glass transition temperatures of 50.degree. to 120.degree. C. Methods for developing electrostatic images with the developer compositions are also described.

Abstract: This disclosure relates to a process for preparing acicular magnetic iron oxide particles by (a) adding an aqueous solution of a ferrous salt to an aqueous solution of a stoichiometric excess of alkaline hydroxide while substantially avoiding local excesses of the ferrous salt, to form an aqueous dispersion of ferrous hydroxide particles, (b) oxidizing these particles to form non-magnetic alpha ferric oxide hydrate particles, and (c) converting the non-magnetic particles to magnetic iron oxide particles by dehydration and reduction or dehydration, reduction and oxidation. The ferrous salt solution is subjected to reducing conditions prior to and/or during the addition to the alkaline hydroxide solution to reduce contaminating ferric ions that are normally present to ferrous ions.

Abstract: Magnetic recording elements containing substantially transparent magnetic recording layers which exhibit excellent magnetic recording and reproducing characteristics. Such elements contain a support and a transparent magnetic recording layer. The recording layer has a thickness up to about 5 microns and contains acicular, magnetizable particles having an average width of less than about 0.06 micron and an average length up to about 1 micron. These particles are substantially homogeneously dispersed in a medium that comprises a binder and has a refractive index which is substantially the same throughout the thickness of the magnetic recording layer. The concentration of the binder is at least about 10 parts per 100 parts, by weight, of the particles and is up to about 30 parts, by weight, for particles having an average length of at least about 0.06 micron and up to about 40 parts, per 100 parts, by weight, for particles having an average length of less than about 0.06 micron.

Abstract: A process of preparing magnetic recording elements containing substantially transparent magnetic recording layer which exhibit excellent magnetic and reproducing characteristics is as follows:(a.) forming a substantially homogeneous dispersion of acicular magnetizable particles in a medium comprising a solution of substantially transparent binder in solvent using particles having an average width of less than about 0.06 micron and an average length up to about 1 micron; the concentration of the binder being at least about 10 parts per 100 parts, by weight, of the particles; up to about 30 parts, by weight, for particles having an average length of at least about 0.06 micron and up to about 40 parts, by weight, for particles having an average length of less than about 0.06 micron,(b.) coating a support with the dispersion in an amount sufficient to provide a final dry layer thickness up to about 5 microns,(c.) removing substantially all solvent from the layer and(d.

Abstract: A process for preparing acicular gamma ferric oxide (maghemite) crystals exhibiting excellent magnetic recording properties is disclosed. These acicular gamma ferric oxide crystals are new materials and can be used in magnetic media such as magnetic tapes to obtain a low level of white noise without sacrificing other electroacoustic properties. The crystals are basic in character, contain alkali metal ions and have an acicularity ratio of at least 15, often 15 to 40. These crystals are prepared under very carefully controlled reaction conditions, as more fully described in the following specification. In general, however, the process involves (1) reacting ferrous salt with a stoichiometric excess of an alkali hydroxide under non-oxidizing conditions and at a temperature below about 60.degree. C.

Abstract: A process is disclosed for inhibiting in a polymerization reaction crosslinking of photocrosslinkable condensation homopolymers and copolymers by use of a synergistic inhibitor composition comprising specified amounts of a hindered phenolic compound and a phosphoric acid ester in the presence of monomers from which said homopolymers and copolymers are formed. Residue from the inhibitor composition remains in the polymeric product and serves as a stabilizer against heat deterioration and premature crosslinking of the product during recovery and storage. The stabilized homopolymers and copolymers are useful for manufacture of radiation sensitive elements. Photographic elements formed from the stabilized condensation polymers are particularly useful as lithographic plates.

Abstract: Aluminum-silicon-iron alloys exhibiting an excellent combination of properties are disclosed. The process for preparing these alloys is also disclosed. In this process an aluminum-silicon-iron alloy powder is formed, sintered and hot-pressed simultaneously with or after sintering. The alloy powder can contain 4-9%, by weight, aluminum, 8-11%, by weight, silicon and the remainder iron. Pressures for hot-pressing of at least 1000 psi. and sintering temperatures of at least 1205.degree. C are disclosed. The process can also include the additional step of nitriding the alloy powder prior to sintering. Such nitriding prevents or retards grain growth during sintering and provides increased electrical resistivity and hardness in the end product.

Abstract: Magnetic recording elements comprising a magnetic layer containing dispersed particles which improve the wear resistance of the layer are disclosed. Such elements comprise a non-magnetic support and a magnetic recording layer that contains dispersed in a binder, ferromagnetic particles for recording and non-ferromagnetic particles of different average particle size. These non-ferromagnetic particles of different particle size have a Mohs Hardness above that of the ferromagnetic particles. These non-ferromagnetic particles consist essentially of (a) particles having an average particle size similar to or larger than that of the ferromagnetic particles, of about 0.3 to about 2 microns, present at a concentration of about 0.005 to about 0.025 parts, by weight, based on the weight of the ferromagnetic particles, and (b) smaller particles having an average particle size up to about 0.1 micron, present at a concentration of about 0.02 to about 0.

Abstract: A magnetic head assembly wherein the material of the pole tips or of the pole pieces comprises a hot-pressed sintered iron-silicon-aluminum alloy, the particles of such alloy preferably being provided with a nitride layer or coating prior to sintering for preventing or retarding grain growth during sintering and to provide increased electrical resistivity and hardness in the end product. The preferred hot-pressed sintered material is characterized by a substantially uniform grain size most preferably of between about 40 microns and 60 microns, a porosity of substantially less than one percent, a Vickers hardness greater than 600, and a resistivity of at least about 100 micro-Ohm-cm.

Abstract: A magnetic recording element having greatly improved resistance to wear and tear is disclosed. This element includes in a magnetizable layer a carbonic acid ester lubricant such as ethyl cetyl carbonate, ethyl lauryl carbonate, didodecyl carbonate or phenyl cetyl carbonate. The lubricant can be present in an amount between 1 and 40% by weight of the binder, and advantageously about 20%. A typical binder is a copolymer of vinyl chloride with vinyl acetate, with or without polyurethane.