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US 4,225,352 AGranted
Anti-corrosive pigment and anti-corrosive aqueous paint
AssigneeToda Kogyo Corporation
InventorsHajime Makino, Wataru Shinoda, Kazuhiro Yamamura
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Abstract
An anti-corrosive pigment comprises an ion oxide-calcium oxide sintered composite of an average particle size in a range of 0.7-7 .mu.m, which contains at least 25% by weight of 2CaO.Fe.sub.2 O.sub.3 and has a extremely low water-solubility of calcium content. An anti-corrosive aqueous paints contains the above pigment and has a superior storage stability without causing a gellation.
Claims6
An anti-corrosive pigment having excellent storage characteristics and substantially free from gelation under storage produced by
- (a) mixing 57-70% by weight, calculated as Fe.sub.2 O.sub.3, of an iron compound selected from the group consisting of Fe.sub.2 O.sub.3, Fe.sub.3 O.sub.4 and FeOOH with 30-43% by weight, calculated as CaO, of a calcium compound selected from the group consisting of CaO, CaCO.sub.3 and Ca(OH).sub.2 ;
- (b) calcining the resultant mixture at a temperature in the range of from 1250.degree. to 1400.degree. C. and sufficient to form an iron oxide-calcium oxide sintered composite containing at least 25% by weight of 2CaO-Fe.sub.2 O.sub.3 having a crystal grain size of at least about 0.7 to 20 .mu.m and a calcium oxide solubility of less than 1%;
- and
- (c) pulverizing the resultant sintered composite into powder having an average particle size between 0.7 and 7 .mu.m.
1 more element
Dependencies are inferred from the claim text.