Toda Kogyo Corporation

Dainichiseika Color & Chemicals Mfg. Co., Ltd.

Tsutomu Katamoto

Naoya Kobayashi

Akinori Yamamoto

Torayuki Honmyo

Nanao Horiishi

Masao Kiyama

Ken Okura

Tokihiro Kurata

Satoru Matsuzaki

Norimichi Nagai

Yasutaka Ota

Kousaku Tamari

Hiroshi Yamamoto

Katsunori Fujimoto

Akihiko Hirayama

Nanao Hiriishi

Mamoru Fujimoto

Kouta Sato

Spinel-type ferrimagnetic particles having a composition represented by the formula:(MO)&#xb7;/2(FeO)where M is a divalent metal and n is a molar ratio of Fe to M (n=Fe/M) which is from more than 2.05 to less than 2.5 (2.05&#x3c;n&#x3c;2.5). They contain a superparamagnetic component in an amount of not more than 2% by mass, has an average particle diameter of 5 to 30 nm. The particles are respectively coated on surface with a hydroxide of at least one metal Si, Al, P and Zn in an amount of not more than 10% by mass, calculated as the metal. The spinel-type ferrimagnetic particles can exhibit a high coercive force irrespective of fine particles, and are excellent in dispersibility and chemical stability, as well as the magnetic recording medium for high-density recording can exhibit not only excellent frequency characteristics and high output characteristics, but also an excellent weather resistance and a high reliability.

Spinel-type ferrimagnetic particles, process for producing the same, and magnetic recording medium using the same

A chlorine-containing resin composition for covering an electric wire of the present invention, has a heat stability of not less than 240 minutes and a volume resistivity of 5.0&#xd7;10to 1.0&#xd7;10&#x3a9;&#xb7;cm when measured according to JIS K6723, and comprises:

Mg-Al-based hydrotalcite-type particles, chlorine-containing resin composition and process for producing the particles

The Mg&mdash;Al-based hydrotalcite-type particles according to the present invention have a plate surface diameter as large as from 0.1 to less than 1.0 &mgr;m, an adequate thickness ranging from 0.02 to 0.08 &mgr;m and a heat-resisting time of not less than 160 minutes when measured by a specific method, and are, therefore, suitable as a stabilizer for chlorine-containing resins.

Mg-Al based hydrotalcite-type particles, chlorine-containing resin stabilizer and process for producing the particles

Heat-resistant yellow pigment particles of the present invention comprise a composite metal oxide containing Fe, Ti and Li, and comprising a crystal phase having a pseudobrookite-type structure. Such the heat-resistant yellow pigment particles are free from contamination of harmful metals such as Pb, Cr, Cd, etc., show a clear yellow color, are excellent in heat resistance, chemical resistance and light resistance, and have a low specific gravity.

Heat-resistant yellow pigment

The disclosure describes lamella lepidocrocite particles containing 10 to 30 atm % of titanium calculated as Ti/(Ti+Fe) and having a BET specific surface area of 150 to 350 m.sup.2 /g.

Lamella lepidocrocite particles and process for producing the same

Disclosed herein is an iron oxide coloring agent capable of suppressing aging of resins comprising plate-like hematite particles coated with amorphous silicon dioxide or hydrated alumina containing silicon dioxide fine particles or hydrated alumina fine particles having an average particle diameter of 50 to 1,000 .ANG..

Iron oxide coloring agent for suppressing aging of resins

Disclosed herein are black pigment particles comprising polycrystalline particles having a mixed composition of Fe.sub.2 TiO.sub.5 and Fe.sub.2 O.sub.3 --FeTiO.sub.3 solid solution.

Black pigment particles

Disclosed herein is a coating composition comprising plate-like iron oxide particles having an average particle diameter of 4 to 25 .mu.m, a lamellar thickness of 0.16 to 5 .mu.m and a plate ratio (average particle diameter:lamellar thickness) of 5:1 to 25:1, at least one pigment selected from the group consisting of a coloring pigment,a mica pigment and a metal powder pigment, a film-forming polymer, and an organic solvent.

Coating composition having platelike iron oxide particles

Disclosed herein are plate-like hematite particles having an average particle diameter of 0.5 to 5.0 .mu.m, a lamellar thickness of 50 to 500.ANG. and a plate ratio (the ratio of the average particle diameter to the lamellar thickness) of 50:1 to 500:1, an iron oxide pigment showing a golden color and comprising the plate-like hematite particles, and a process for producing the plate-like hematite particles.

Plate-like hematite particles, a pigment comprising the same and showing

Disclosed herein is a coating composition comprising plate-like iron oxide particles having an average particle diameter of 0.5 to 5.0 .mu.m, a lamellar thickness of 50 to 500.ANG. and a plate ratio (the ratio of the average particle diameter to the lamellar thickness) of 50:1 to 500:1, at least one pigment selected from the group consisting of a coloring pigment, a mica pigment and a metal powder pigment, a film-forming polymer, and an organic solvent.

Coating composition

Disclosed herein is a non-magnetic pigment comprising plate-like potassium ferrite particles having an average diameter of 0.03-30.0 .mu.m and a process for producing the same.

Non-magnetic pigments

Disclosed herein are electroconductive iron oxide particles having a volume resistivity less than 5.times.10.sup.6 .OMEGA.-cm, and comprising iron oxide particles selected from hematite and maghemite, and SnO.sub.2 particles containing Sb as a solid solution deposited on the surfaces of the iron oxide particles, and a process for producing the same.

Growing community of inventors

Hatsukaichi, Japan

Tsutomu Katamoto