Corrosion resistant ferromagnetic metal powders and method of preparing the same
AssigneeFuji Photo Film Co., Ltd.
InventorsMasashi Aonuma, Yasuo Tamai
Life of this patent
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Abstract
Corrosion resistant ferromagnetic metal powders in which a volatile corrosion inhibitor is adsorbed on at least a part of the surface of ferromagnetic metal powders having an average particle size of 1000 A or less are disclosed. A method of preparing the corrosion resistant ferromagnetic metal powders is also disclosed.
Claims76
A method of preparing a corrosion-resistant ferromagnetic metal powder after forming said ferromagnetic metal powder comprising washing the formed ferromagnetic metal powder with a solution containing
- (a) at least one volatile corrosion inhibitor, said volatile corrosion inhibitor being an organic amine, amide or imide, or an organic or inorganic salt thereof, containing 1 to 4 nitrogen atoms and 1 to 12 carbon atoms and having a molecular weight of 50 to 200 and a vapor pressure of about 0.1.times.10.sup.-5 to 1.times.10.sup.2 mmHg at a temperature of 15.degree. to 25.degree. C.;
- (b) (1) water, (2) an organic solvent miscible with water, or (3) a mixture of water and at least one organic solvent miscible with water;
- and
- (c) an anionic surface active agent selected from the group consisting of a carboxylic acid or salt thereof, a salt of a sulfuric acid ester, a salt of a phosphoric acid ester, a salt of a dithiophosphoric acid ester and a salt of a sulfonic acid.
A method of preparing a corrosion resistant ferromagnetic metal powder after forming said ferromagnetic metal powder comprising washing the formed ferromagnetic metal powder with a solution containing
- (a) at least one volatile corrosion inhibitor, said volatile corrosion inhibitor being an organic amine, amide or imide, or an organic or inorganic salt thereof, containing 1 to 4 nitrogen atoms and 1 to 12 carbon atoms and having a molecular weight of 50 to 200 and a vapor pressure of about 0.1.times.10.sup.-5 to 1.times.10.sup.2 mmHg at a temperature of 15.degree. to 25.degree. C.;
- and
- (b) (1) water, (2) an organic solvent miscible with water, or (3) a mixture of water and at least one organic solvent miscible with water;
- and additionally contacting said ferromagnetic metal powder thereafter with an aqueous solution containing an anionic surface active agent selected from the group consisting of a carboxylic acid or salt thereof, a salt of a sulfuric acid ester, a salt of a phosphoric acid ester, a salt of a dithiophosphoric acid ester and a salt of a sulfonic acid.
A method of preparing a corrosion resistant ferromagnetic metal powder after forming said ferromagnetic metal powder comprising drying the formed ferromagnetic metal powder in an atmosphere containing at least one volatile corrosion inhibitor, said volatile corrosion inhibitor being an organic amine, amide or imide, or an organic or inorganic salt thereof, containing 1 to 4 nitrogen atoms and 1 to 12 carbon atoms and having a molecular weight of 50 to 200 and a vapor pressure of about 0.1.times.10.sup.-5 to 1.times.10.sup.2 mmHg at a temperature of 15.degree. to 25.degree. C.;
- and additionally contacting said ferromagnetic metal powder with an aqueous solution containing an anionic surface active agent selected from the group consisting of a carboxylic acid or salt thereof, a salt of a sulfuric acid ester, a salt of a phosphoric acid ester, a salt of a dithiophosphoric acid ester and a salt of a sulfonic acid.
Dependencies are inferred from the claim text.