Daikin Industries, Ltd.

Daikin Kogyo Co., Ltd.

501 Daiken Industries Ltd.

Shigeo Daimon

Yoshiyuki Shibuya

Takuya Arase

Kazuo Okamura

Ikuo Kitamura

Tadashi Ino

Fumihiro Kamiya

Takashi Shibanuma

Nobuyuki Tomihashi

Masayuki Tsuji

Kohji Tamura

Katsushi Tokunaga

Nobuhiro Shinka

Naoki Miyamoto

Ikuo Kiatamura

The present invention provides acicular fine particles made up of iron and carbon, and these acicular metal iron fine particles can be prepared by contacting acicular iron carbide fine particles with a reducing agent containing no carbon atom. Further, the present invention provides a magnetic coating composition and magnetic recording medium containing the above acicular metal iron fine particles.

Acicular metal iron fine particles, process for preparing same, magnetic

Coated acicular fine particulate materials, processes for preparing same

Acicular fine particles containing metallic iron, iron carbide and

The present invention provides acicular particles (A) containing an iron carbide, which have (a) a free carbon content of at most 20 wt. %, and (b) and Fe.sub.5 C.sub.2 ratio(x) of at least 70% and a coercive force of 3.times.+300 to 7.times.+270 Oe, the ratio(x) being expressed by ##EQU1## where S1 is the X-ray diffraction strength of Fe.sub.5 C.sub.2, and S2 is the X-ray diffraction strength of Fe.sub.3 O.sub.4. The invention further provides particles (B) containing nickel and an iron carbide. The invention further provides acicular particles containing an iron carbide which are obtained by heating an aqueous dispersion of ferric hydroxide in an alkaline system in the presence of a water-soluble compound capable of coordinating to iron to obtain acicular .alpha.-ferric oxide and contacting the product with a carbon-containing reducing-and-carburizing agent or with a mixture of the agent and a carbon-free reducing agent, with or without contacting the product with the carbon-free reducing agent. These particles (A) and (C) are controllable in coercive force and usable for magnetic record media of various standards.

Particles containing iron carbide

A magnetic coating composition comprising acicular particles containing iron carbide and a main magnetic material.

Magnetic coating composition and magnetic recording medium

The present invention provides a process for preparing a magnetic coating composition with use of magnetic particles containing carbon or magnetic particles consisting primarily of an iron carbide, the process being characterized in that the process includes the step of pre-kneading the magnetic particles with an organic solvent.

Process for preparing magnetic coating composition

The present invention provides a process for preparing iron carbide fine particles having an average particle size (long axis) of 0.1 to 2 .mu.m and an average axial ratio of 3 to 20, which comprises,

Process for preparing iron carbide fine particles

Fine iron carbide particles consisting essentially of iron carbide, which are characterized in that, in the step of the variation of the weight under the condition of combustion, the increase of the weight in the equilibrium after arrival at the maximum weight is 22% or less, on the basis of the weight before combustion.

Process for preparing carbide fine particles

Particles containing FeC are prepared by mixing (a) a boron compound or alkaline earth metal compound with (b) iron oxyhydroxide or iron oxide particles, or coating the former compound (a) to the latter particles (b), and then carburizing the mixture or coated particles with a carburizing agent.

Magnetic particles composed mainly of FeC and a process for preparing

The present invention provides acicular particles (A) containing an iron carbide, which have (a) a free carbon content of at most 20 wt. %, and (b) an Fe.sub.5 C.sub.2 ratio(x) of at least 70% and a coercive force of 3x+300 to 7x+270 Oe, the ratio(x) being expressed by ##EQU1## wherein S1 is the X-ray diffraction strength of Fe.sub.5 C.sub.2, and S2 is the X-ray diffraction strength of Fe.sub.3 O.sub.4. The invention further provides particles (B) containing nickel and an iron carbide. The invention further provides acicular particles containing an iron carbide which are obtained by heating an aqueous dispersion of ferric hydroxide in an alkaline system in the presence of a water-soluble compound capable of coordinating to iron to obtain acicular .alpha.-ferric oxide and contacting the product with a carbon-containing reducing-and-carburizing agent or with a mixture of the agent and a carbon-free reducing agent, with or without contacting the product with the carbon-free reducing agent. These particles (A) to (C) are controllable in coercive force and usable for magnetic record media of various standards.

A process for producing cobalt-modified iron oxide particles, which comprises the steps of:

Process for producing magnetizable particles

A process of electrostatic printing which comprises the steps of forming a reverse image of a dielectric toner on an electroconductive support or a photoconductive support, fixing the reverse image to give an electrostatic printing master sheet, and conducting electrostatic printing in which electrification of the dielectric toner image on the master sheet, development with a toner, transfer of the resulting toner image to a material to be printed and fixing are repeatedly carried out to give numerous sheets of duplicates.

Process of electrostatic printing with fluorinated polymer toner additive

A polymer containing perfluoroalkyl group in its side chain which is an addition reaction product of a polymer having the following general formula: ##STR1## wherein R is phenyl group or alkoxyl group having 1 to 12 carbon atoms, R.sup.1 is alkyl group having 1 to 12 carbon atoms, and n is an integer of 10 to 2,000, with an epoxy compound selected from the group consisting of ##STR2## wherein R.sub.f is perfluoroalkyl group having 3 to 20 carbon atoms and R.sup.2 is alkyl group having 1 to 12 carbon atoms, the addition reaction product containing 0.1 to 50% by mole of the group derived from the epoxy compound having the formulae (IIa) to (IIc) per 1 mole of the recurring unit of the polymer having the formula (I). The polymer is good in compatibility with film-forming resins and solvents and improves the leveling property of a coating composition when incorporated thereinto and the surface smoothness of the film obtained from the composition.

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Settsu, Japan

Shigeo Daimon