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US 5,407,600 AGranted
Stable aqueous alumina sol and method for preparing the same
AssigneeNissan Chemical Industries, Ltd.
InventorsMikio Ando, Isao Yogo, Takanobu Kikawa
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AssigneeNissan Chemical Industries, Ltd.
InventorsMikio Ando, Isao Yogo, Takanobu Kikawa
Estimating the term…
A stable aqueous sol of amorphous alumina containing Al.sub.2 O.sub.3 up to 15% by weight and 0.1 to 0.5 gram equivalent of an anion of acid to 1 mol of aluminum in the sol, in which the colloidal particles of amorphous alumina have a controlled thickness in a range of 20 to 100 millimicrons and a uniform length in a range of 200 to 500 millimicrons is produced by a process comprising feeding an aqueous solution of an acid into an aqueous slurry containing 1 to 7% by weight of metallic aluminum, 10 to 200 ppm by weight as Si0.sub.2 of a water-soluble silicate and 0 to 20 ppm by weight of a water-soluble sulfate as S0.sub.4 to the water in the slurry while maintaining the slurry at a temperature of 80.degree. C. to boiling point under normal pressure, said acid being in an amount of 0.1 to 0.5 gram equivalent to 1 mol of the metallic aluminum in said slurry, at a rate of 0.001 to 0.03 gram equivalent of the acid to 1,000 g of the water in the slurry per minute, and continuing heating the slurry after completion of the feeding of the acid at a temperature of 80.degree. C. to boiling point of the slurry until a sol of amorphous alumina having a uniform length of 200 to 500 millimicrons is formed.
A method for preparing a stable aqueous sol of amorphous alumina containing Al.sub.2 O.sub.3 in an amount up to 15% by weight and an anion of acid in an amount of 0.1 to 0.5 gram equivalent to 1 mol of aluminum in the sol, in which the colloidal particles of amorphous alumina have a uniform thickness in a range of 40 to 100 millimicrons and a uniform length in a range of 200 to 500 millimicrons, the length being 5 to 10 times the thickness, comprising feeding an acid into an aqueous slurry of metallic aluminum while maintaining the slurry at a temperature of 80.degree. C. to boiling point under normal pressure, said slurry containing 1 to 7% by weight of the metallic aluminum and said acid being in an amount of 0.1 to 0.5 gram equivalent to 1 mol of the metallic aluminum in said slurry, at a rate of 0.001 to 0.03 gram equivalent of the acid to 1,000 g of the water in the slurry per minute, adding into the slurry a water-soluble silicate or silicic acid in an amount of 10 to 200 ppm by weight as SiO.sub.2 to the water in the slurry before particles of amorphous alumina having a particle size of less than 3 millimicrons formed in the slurry begins to grow in the slurry, and continuing heating the slurry after completion of the feeding of the acid at a temperature of 80.degree. C. to boiling point of the slurry under normal pressure until a sol of amorphous alumina having a uniform length of 200 to 500 millimicrons is formed.
A method for preparing a stable aqueous sol of amorphous alumina containing Al.sub.2 O.sub.3 in an amount up to 15% by weight and an anion of acid in an amount of 0.1 to 0.5 gram equivalent to 1 mol of aluminum in the sol, in which the colloidal particles of amorphous alumina have a uniform thickness in a range of 40 to 100 millimicrons and a uniform length in a range of 200 to 500 millimicrons, the length being 5 to 10 times the thickness, comprising feeding an aqueous solution having a concentration of 10 to 20% by weight of hydrochloride into an aqueous slurry containing 1 to 7% by weight of metallic aluminum having a particle size in weight average of 10 to 100 microns and a water-soluble silicate in an amount of 10 to 200 ppm by weight as SiO.sub.2 to the water in the slurry while maintaining the slurry at a temperature of 80.degree. C. to boiling point under normal pressure, said acid being in an amount of 0.1 to 0.5 gram equivalent to 1 mol of the metallic aluminum in said slurry, at a rate of 0.001 to 0.03 gram equivalent of the acid to 1,000 g of the water in the slurry per minute, and continuing heating the slurry after completion of the feeding of hydrochloride at a temperature of 80.degree. C. to boiling point of the slurry under normal pressure until a sol of amorphous alumina having a uniform length of 200 to 500 millimicrons is formed.
A method for preparing a stable aqueous sol of amorphous alumina containing Al.sub.2 O.sub.3 in an amount up to 15% by weight and an anion of acid in an amount of 0.1 to 0.5 gram equivalent to 1 mol of aluminum in the sol, in which the colloidal particles of amorphous alumina have a thickness distributed in a range of 20 to 100 millimicrons and a uniform length in a range of 200 to 500 millimicrons, comprising feeding an acid into an aqueous slurry of metallic aluminum while maintaining the slurry at a temperature of 80.degree. C. to boiling point under normal pressure, said slurry containing 1 to 7% by weight of a metallic aluminum and said acid being in an amount of 0.1 to 0.5 gram equivalent to 1 mol of the metallic aluminum in said slurry, at a rate of 0.001 to 0.03 gram equivalent of the acid to 1,000 g of the water in the slurry per minute, adding into the slurry a water-soluble silicate or silicic acid in an amount of 10 to 200 ppm by weight as SiO.sub.2 to the water in the slurry and a water-soluble sulfate in an amount of 5 to 20 ppm by weight as SO.sub.4 to the water in the slurry before particles of amorphous alumina having a particle size of less than 3 millimicrons formed in the slurry begins to grow in the slurry, and continuing heating the slurry after completion of the feeding of the acid at a temperature of 80.degree. C. to boiling point of the slurry under normal pressure until a sol of amorphous alumina having a uniform length of 200 to 500 millimicrons are formed.
A method for preparing a stable aqueous sol of amorphous alumina containing Al.sub.2 O.sub.3 in an amount up to 15% by weight and an anion of acid in an amount of 0.1 to 0.5 gram equivalent to 1 mol of aluminum in the sol, in which the colloidal particles of amorphous alumina have a thickness distributed in a range of 20 to 100 millimicrons and a uniform length in a range of 200 to 500 millimicrons, comprising feeding an aqueous solution having a concentration of 10 to 20% by weight of hydrochloride into an aqueous slurry containing 1 to 7% by weight of metallic aluminum having a particle size in weight average of 10 to 100 microns, a water-soluble silicate in an amount of 10 to 200 ppm by weight as SiO.sub.2 to the water in the slurry and a water-soluble sulfate in an amount of 5 to 20 ppm by weight as SO.sub.4 to the water in the slurry while maintaining the slurry at a temperature of 80.degree. C. to boiling point under normal pressure, said acid being in an amount of 0.1 to 0.5 gram equivalent to 1 mol of the metallic aluminum in said slurry, at a rate of 0.001 to 0.03 gram equivalent of the acid to 1,000 g of the water in the slurry per minute, and continuing heating the slurry after completion of the feeding of hydrochloride at a temperature of 80.degree. C. to boiling point of the slurry under normal pressure until a sol of amorphous alumina having a uniform length of 200 to 500 millimicrons is formed.
Dependencies are inferred from the claim text.