Active anti-corrosion pigments based on calcium oxide, aluminium oxide and iron oxide

Claim 2

An anti-corrosion pigment consisting essentially of about 25.0 to 2.5 mole % of CaO and about 75.0 to 97.5 mole % of Me 2 O 3 , wherein Me 2 O 3 is (1-x) Al 2 O 3 and x Fe 2 O 3 , x is from 0 to 1 and up to about 25 mole % of the Fe 2 O 3 may be replaced by the corresponding quantity of Mn 2 O 3 , and having a specific surface area according to BET of about 0.1 to 200 m 2 /g and a percentage weight loss per gram of pigment, as determined by the Thompson corrosion test, of less than about 0.05% per gram of pigment.

Claim 3

A pigment according to claim 1, having a specific surface area of about 1 to 150 m 2 /g.

Claim 4

A process for the production of an anti-corrosion pigment according to claim 1, comprising calcining the corresponding metal oxides, or materials which form the metal oxides on calcination, at about 200° to 900° C.

Claim 5

A process according to claim 3, wherein calcining is effected at about 300° to 900° C.

Claim 6

A process according to claim 3, wherein calcining is effected at about 400° to 600° C.

Claim 7

A process according to claim 3, wherein a hydroxide, hydroxy salt, carbonate, basic carbonate, nitrate, sulphate, chloride, formate, acetate or oxalate is used as the CaO-component.

Claim 8

A process according to claim 3, wherein the starting material for the Al 2 O 3 is a natural or synthetic oxide, oxide hydroxide, hydroxide, amorphous hydroxide of aluminum, solid solution of aluminum with iron or silicate-containing compounds of aluminum, or the "red sludge" obtained in the digestion of iron-containing aluminum ores for the production of aluminum metal.

Claim 9

A process according to claim 3, wherein the starting material for the Fe 2 O 3 is an oxide, hydroxide, hydroxy salt, carbonate, basic carbonate, nitrate, chloride, sulphate, formate, acetate or oxalate of Fe(II), or a Fe(II)-Fe(III)-oxide, calcination being carried out in the presence of an oxygen-containing gas.

Claim 10

A process according to claim 3, wherein the starting material for the Fe 2 O 3 is an α-, β- or γ-iron(III)-oxide, α-, β-, γ- or δ-iron(III)-oxide hydroxide, amorphous iron(III)-hydroxide, iron(III)-sulphate, nitrate, chloride, formate, acetate or other iron(III)-salt of an organic compound or an iron(II)-iron(III)-oxide.

Claim 11

A process according to claim 3, wherein the pigment contains Mn 2 O 3 and the starting material therefor is a naturally occurring manganese mineral, synthetically produced manganese dioxide, or manganese dioxide obtained as a waste product in organic synthesis.

Claim 12

A process according to claim 3, wherein the starting materials used for Al 2 O 3 , Fe 2 O 3 and Mn 2 O 3 when present are mixed hydroxides or oxide hydroxides of Al(III), Fe(III) and Mn(II) or Mn(III).

Claim 13

A process according to claim 5, wherein a hydroxide, hydroxy salt, carbonate, basic carbonate, nitrate, sulphate, chloride, formate, acetate or oxalate is used as the CaO-component, the starting material for the Al 2 O 3 is a natural or synthetic oxide, oxide hydroxide, hydroxide, amorphous hydroxide of aluminum, solid solution of aluminum with iron or silicate-containing compounds, the starting material for the Fe 2 O 3 is an oxide, hydroxide, hydroxy salt, carbonate, basic carbonate, nitrate, chloride, sulphate, formate, acetate or oxalate of Fe(II), or a Fe(II)-Fe(III)-oxide in which event calcination is carried out in the presence of an oxygen-containing gas, or is an α-, β- or γ-iron(III)-oxide, α-, β-, γ- or δ-iron(III)oxide hydroxide, amorphous iron(III)-hydroxide, iron(III)-sulphate, nitrate, chloride, formate, acetate or other iron (III)-salt of an organic compound or an iron(II)-iron(III)-oxide, and the starting material for the Mn 2 O 3 if present is a naturally occurring manganese mineral, synthetically produced manganese dioxide, or manganese dioxide obtained as a waste product in organic synthesis.

Claim 14

A process according to claim 5, wherein a hydroxide, hydroxy salt, carbonate, basic carbonate, nitrate, sulphate, chloride, formate, acetate or oxalate is used as the CaO-component, and the starting materials used for Al 2 O 3 , Fe 2 O 3 and Mn 2 O 3 when present are mixed hydroxides or oxide hydroxides of Al(III), Fe(III) and Mn(II) or Mn(III).

Claim 15

An anti-corrosion paint or anti-corrosion lacquer pigmented with an anti-corrosion pigment according to claim 1.