Toda Kogyo Corporation

Masaru Isoai

Tosiharu Harada

Kazuhiro Fujita

Yasuhiko Fujii

Tomoyuki Imai

Toshiki Matsui

Kazushi Takama

Atsushi Takedoi

Tomoko Okita

Satoshi Hatakeyama

Mamoru Tanihara

Tokihiro Kurata

Shigekazu Jikuhara

Kazuyuki Hayashi

Keisuke Iwasaki

Yasuyuki Tanaka

Minoru Ohsugi

Kohji Mori

Hiroshi Sumita

Hirofumi Kawasaki

Yosiro Okuda

Toshiharu Harada

Hiroyuki Kondo

Yoshitaka Yoshinaga

Calcium-iron oxide composite particles

Calcium-iron oxide composite particles and resin molded product containing the same

A method of decoloring a colored concrete, comprises adding to the colored concrete, a decoloring pigment comprising a titanium oxide pigment, or a titanium oxide pigment and a pigment having a complementary color relative to color of the colored concrete. Such method can decolore the color of the colored concrete residue which attaches to or remains in production facilities in order to return a color thereof to that of an ordinary plain concrete, without works or treatments for washing-out or removing the colored concrete residue which attaches to or remains in the production facilities, in which the works or treatments are required in the case where the production facilities are used for the production of an ordinary plain concrete after the colored concrete has been produced therein, and without works or treatments for purifying a waste water generated upon washing-out or removing the residue and for making the waste water harmless; and a pigment used therefor.

Method of decoloring colored concrete

Disclosed herein are non-magnetic particles for a non-magnetic undercoat layer of a magnetic recording medium, comprising acicular or spindle-shaped .alpha.-Fe.sub.2 O.sub.3 particles coated with at least one selected from the group consisting of an A1 compound, a silane coupling agent, a titanate coupling agent, an aluminate coupling agent and a zirconate coupling agent; a non-magnetic undercoating layer containing such non-magnetic particles; and magnetic recording medium having such an undercoating layer.

Non-magnetic particles for non-magnetic undercoating layer of magnetic

Disclosed herein are magnetic iron oxide particles which have a spindle shape and a substantially uniform particle size and shape, and are substantially free of dendrites and have a large axial ratio (major axial diameter/minor axial diameter) and an excellent print-through characteristic, and a method of producing the same.

Magnetic iron oxide particles and method of producing the same

Disclosed herein are a process for producing acicular goethite particles comprising the step off: blowing an oxygen-containing gas into a ferrous salt reaction solution containing colloidal ferrous hydroxide or iron-containing colloidal precipitates which is obtained by reacting an aqueous ferrous salt solution with less than one equivalent of an aqueous alkali hydroxide solution, an aqueous alkali carbonate solution, or an aqueous alkali hydroxide and alkali carbonate solution based on Fe.sup.2+ in said aqueous ferrous salt solution, in the presence of ascorbic acid or a salt thereof so as to oxidize said colloidal ferrous hydroxide or iron-containing colloidal precipitates and to produce acicular goethite particles throught green rust; and a process for producing acicular magnetic iron oxide particles by reducing the acicular goethite particles obtained in the above process to produce acicular magnetite particles, and if necessary, oxidizing the acicular magnetite particles to obtain acicular maghemite particles, and if necessary, modifying the acicular magnetite or maghemite particles with Co or Co and Fe.sup.2+.

Process for producing acicular goethite particles and acicular magnetic

Disclosed herein are a process for producing acicular goethite particles comprising the step of: blowing an oxygen-containing gas into a ferrous salt reaction solution containing colloidal ferrous hydroxide or iron-containing colloidal precipitates which is obtained by reacting an aqueous ferrous salt solution with less than one equivalent of an aqueous alkali hydroxide solution, an aqueous alkali carbonate solution, or an aqueous alkali hydroxide and alkali carbonate solution based on Fe.sup.2+ in said aqueous ferrous salt solution, in the presence of ascorbic acid or a salt thereof so as to oxidize said colloidal ferrous hydroxide or iron-containing colloidal precipitates and to produce acicular goethite particles throught green rust; and a process for producing acicular magnetic iron oxide particles by reducing the acicular goethite particles obtained in the above process to produce acicular magnetite particles, and if necessary, oxidizing the acicular magnetite particles to obtain acicular maghemite particles, and if necessary, modifying the acicular magnetite or maghemite particles with Co or Co and Fe.sup.2+.

Process for producing acicular geothite particles and acicular magnetic

Magnetic iron oxide particles and method of producing same

Disclosed herein are magnetic iron oxide particles comprising spindle-like magnetite or maghemite particles having an aspect ratio(major:minor) of less than 4:1 and containing 0.1 to 20 atomic % of Si to Fe, and a process for producing the same.

Spindle-like magnetic iron oxide particles and process for producing the

Growing community of inventors

Hiroshima, Japan

Masaru Isoai